Native Vegetation Management in Queensland

7/23/2019 Native Vegetation Management in Queensland

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Native Vegetation Management in Queensland

Background, Science and Values

Edited by: S. L. Boulter, B. A. Wilson, J. Westrup,

E. R. Anderson, E. J. Turner and J. C. Scanlan



Photographs courtesy of Jenny Milson, DPI

Front cover (left to right):

Acacia aneura (Mulga)

Ipomoea pes-caprae (Beach morning glory)

Back cover (top to bottom):

Brachychiton collinus (Hill kurrajong)

Clerodendrum floribundum (Lolly bush)

Acacia cambagei (Gidgee)

Nymphaea violacea (Water lily)

Astrebla squarrosa (Bull mitchell)

DNRQ00116

ISBN 0 7345 1701 7

© The State of Queensland, Department of Natural Resources, 2000Department of Natural Resources

Locked Bag 40

Coorparoo DC, Qld 4151

Copies of this publication are available from:

Marketing Officer

Scientific Publishing

Department of Natural Resources

A Block, 80 Meiers Road

Indooroopilly Qld 4068, Australia

Phone: +61 7 3896 9515

Fax: +61 7 3896 9672

Email: <[email protected]>

Website: <www.dnr.qld.gov.au>

sp#14272



iii

Queensland’s diverse array of landscapes and

vegetation is second to none. These unique assetscontribute to ecological processes critical for

sustaining life and the long-term productivity of our

primary industries. They provide space for

recreation, habitat for native animals, and the

natural beauty that helps define our State.Demands on our State’s natural resources by both

our urban and rural communities are unlikely to

diminish as we move into the 21st century. We

have a collective responsibility to ensure that theeconomic and social benefits we accrue from

development are not at the expense of the long-

term quality of the environment.

Planning for the sustainable management of ournative vegetation requires a scientific understanding

of complex ecological processes. It also requires an

understanding of economic and social pressures of

an increasing population on our limited resources.

Our understanding of ecological processes is

evolving and Queensland already has a great wealthof expertise, not the least of which comes from the

thousands of landholders who manage the land and

produce the food and fibre products that we depend

on. There is also a growing body of scientific

research into ecological processes. The role of thisliterature review is to make the findings of this

research accessible to the many people who are

actively involved in vegetation management acrossthe State.

In the long term, our future will depend on how

we use and manage our natural resources. This

literature review highlights the importance of

scientific understanding in balancing ecologicallysustainable development with the protection of

biodiversity and other environmental and social

values to the future of Queensland’s environment.

Rod Welford

Minister for Environment and Heritage and Minister

for Natural Resources

Foreword



iv

Table of contents Foreword. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Executive summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

1. Queensland’s resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 Queensland’s land and vegetation resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.2 Landscape health. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.2.1 Rate of clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.2.2 Current extent of regional ecosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2. Land tenure and legislation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.1 Leasehold and freehold tenures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.2 European settlement and development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.3 Managing vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.4 Other legislation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3. National and international issues and their local impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.1 Ecologically sustainable development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

3.2 Conservation of biological diversity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

3.3 Greenhouse effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

4. Regional and local processes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.1 Impacts of habitat loss on biodiversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

4.1.1 How much habitat is required for conservation of biodiversity at a regional level? . . . . . . . . . . . . . . . 42

4.1.2 Fragmentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

4.1.3 Condition of vegetation remnants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.1.4 Impacts of domestic grazing within remnant vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

4.1.5 Ecosystem repair and management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

4.1.6 Vegetation with particular ecological and catchment values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.1.6.1 Riparian zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

4.1.6.2 Wetlands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 584.1.6.3 Marine and adjacent coastal vegetation communities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

4.2 Land degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

4.2.1 Tree decline and dieback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

4.2.2 Pest invasions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

4.2.3 Tree removal: implications for soil processes and accelerated soil loss . . . . . . . . . . . . . . . . . . . . . . . 64

4.2.4 Soil structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

4.2.5 Nutrient cycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

4.2.6 Soil acidification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

4.2.7 Hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

4.2.8 Salinity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

4.3 Management and production aspects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 804.3.1 Crop production. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

4.3.2 Animal production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

4.3.3 Pasture production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

4.3.4 Improved pastures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

4.3.5 Regrowth management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

4.3.6 Fire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

4.3.7 Timber production and farm forestry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.3.8 Alternative products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

4.4 Other values of native vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

4.4.1 Non-value benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

4.4.2 Urban and peri-urban . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

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5. Social and economic issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

5.1 Rural social issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

5.1.1 Socioeconomic issues related to native vegetation management . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

5.1.2 Social issues and sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

5.1.3 Community involvement issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

5.1.4 Partnerships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

5.2 An economic analysis of broadscale tree clearing in Queensland. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

5.2.1 Introduction.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

5.2.2 Marginal costs and benefits of clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1055.2.3 Assessing the costs and benefits of clearing options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

5.2.4 Net on-farm benefits from tree clearing in Queensland. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

5.2.5 Indirect external impacts from tree clearing.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

5.2.6 The non-use values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

5.2.7 Measures to reduce tree-clearing activities.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

6. Planning and monitoring native vegetation management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

6.1 Vegetation management planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

6.1.1 Planning defined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

6.1.2 Regional approaches to planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

6.1.3 Planning for vegetation management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

6.1.4 Property planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

6.1.5 Configuration of remnant vegetation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

6.1.6 How do the different layers of planning relate? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

6.2 Monitoring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Endnotes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122

Appendix 1 Overview of the bioregions of Queensland . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

Appendix 2 Description of land types (native pasture communities). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

Appendix 3 Queensland Herbarium vegetation and regional ecosystem survey and mapping program. . . . . . . 132

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

























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Preface

This review is an update of a report to the Working

Group of the Ministerial Consultative Committee on

Tree Clearing: The Production, Economic and Environmental Impacts of Tree Clearing in Queensland:a Report to the Working Group of the Ministerial Consultative Committee on Tree Clearing , J. C. Scanlan

and E. J. Turner (eds), 1995.The original report represented the findings of a

Scientific Forum that examined the impact treeclearing on leasehold land had, or is likely to have

had, on production, economics and the

environment. This was conducted having due

regard to the Government’s stated objectives ontree clearing and the Draft State Guidelines on

Broadscale Tree Clearing.

In describing the purpose of the original report, the

editors noted the following limitations:

While an attempt has been made to provide acomprehensive review, not all issues have beencovered in equal depth. A majority of the researchreported here has an agricultural production focus.This is a reflection of the amount of researchconducted and available, rather than any bias in thecompilation of this report. Some of the issues notcovered in detail include induced salinisation,eucalypt dieback, soil acidification, weed introductionand spread, soil biology, and general consideration oflocal and regional ecosystem processes.

In August 1999, the State Liaison and Coordination

Group on Native Vegetation Management,

representatives from Department of PrimaryIndustries, the Environmental Protection Agency

and Department of Natural Resources agreed on

the need to update this review. This update is a

collation of review material submitted by staff fromthese three departments plus others from Central

Queensland University, Griffith University, CSIRO

and Brisbane City Council.

The purpose of this revised publication was to

update and collate current scientific informationrelevant to all aspects of tree clearing and

sustainable native vegetation management. It is

primarily intended to provide professional technical

support material for staff dealing with tree-clearingissues and a comprehensive assessment of the

environmental, economic and production

information relating to the impacts of tree clearing.

This version aims to broadly cover the relevant

research and diverse debate to provide informationthat can be used to assess how vegetation should be

managed. The majority of the recent research

focuses strongly on issues of sustainable production,

biodiversity conservation and environmental health,

and this is reflected in the overall content of thisreview. In this update, we have included information

on issues identified in the original report as having

been considered in less detail. These include salinity,dieback, weeds and accelerated greenhouse effect.

Acknowledgments

Principal editor

Sarah Boulter Department of Natural Resources

Editorial

Bruce Wilson Environmental Protection Agency

Jude Westrup Department of Natural Resources

Eric Anderson Department of Primary Industries

Ed Turner Department of Primary IndustriesJoe Scanlan Department of Natural Resources

Contributors

Numerous experts from various fields contributedto preparing the main text of the sections. Their

names are listed at the beginning of each section.

The original report, The Production, Economic and Environmental Impacts of Tree Clearing in Queensland:a Report to the Working Group of the Ministerial

Consultative Committee on Tree Clearing , J. C. Scanlanand E. J. Turner (eds), 1995, was prepared by a

scientific forum with the following membership:

Department of LandsJoe Scanlan Ed TurnerPat Lyons Elton Miller

Jim Walls Geoff Edwards

Department of Environment and HeritageDes Boyland Bruce Wilson

Peter Stanton Gethin MorganStephen Barry Keith Claymore

Department of Primary IndustriesBill Burrows Eric Anderson

Bob Miles Bob Shepherd

George Bourne Blair BartholomewTony Constantini

A large number of people provided comment and

review of earlier drafts of this review. Special

thanks must go to Joe Scanlan and Kay Dorricott

for coordinating contributions for two sections. Inparticular, comprehensive comments were provided

on the entire document by Ed Turner, Bill Burrows,

Eric Anderson, Joe Scanlan, Jude Westrup, Melva

Hobson, Andrea Leverington, and Paul Hauenschild.Others provided significant comment on areas of

interest: Bruce Wilson, Adrian Jeffreys, Blair

Bartholomew, Brian Vandersee, Chris Hill, Don

Begbie, Grant Wardell-Johnson, John Ludwig, RossWilson, Mick Capelin, Nev Hunt, Paul Lawrence,

Rachel McFadyen, Rod Hewitt, Ross Berndt, Mardi

Schmidt, Wojciech Poplawski, Ian Gordon, Bruce

Cook, Geoffrey Lawrence, Adam Geitzelt, CliveMcAlpin, Alan Dale, Tara Martin, and Jennifer

Finlay. Bronwen Fletcher and Kirsten Kenyon

assisted with the final editing and compilation.Bronwen Fletcher assisted with preparation of thesection summaries.



vii

Thirteen bioregions have been described for

Queensland. There is evidence of declininglandscape health in all areas of the State. Land

degradation includes soil fertility and structure

decline, salinity, erosion and loss of habitat.

A number of pressures on the condition of landsinclude climatic conditions, population growth,

economic pressures, urbanisation, vegetation

clearance, agriculture, forestry operations and

mining.

Tree clearing can have direct and indirect impactson landscape and ecosystem health. Impacts or

changes may be desirable or undesirable, and this

can depend on the value placed on vegetation.

Managing native vegetation requires considerationof many interrelated and complex factors.

Some impacts on landscape and ecosystem health

attributable to tree clearing:

• Vegetation clearing causes habitat fragmentation

and loss. Loss of habitat leads to decreases in

abundance of individual species, changes tocommunity dynamics and a decline in ecosystem

functioning. A loss of essential ‘ecosystem

services’ can include disruption of nutrient

cycling, atmospheric cycling, water quality,genetic diversity, production inputs, soil

formation and fertility, pollination, natural pest

control and bioremediation. This can affect both

production and environmental values.Information on the predicted and actual

relationship between species loss and habitat

retention is presented. This indicates that there

are habitat retention thresholds below which therate of species loss may dramatically increase.

• Clearing of vegetation also results in the loss of

other values such as scenic and intrinsic values.

Quantifying and assessing these values,

especially in economic terms, is just beginningfor Queensland.

• Tree clearing has a direct impact on the

hydrological regime. Generally the removal of

deep-rooted trees increases deep drainage and

this may result in the expression of salinity at or

near the soil surface. Areas likely to be impactedare largely restricted to areas with between

600 and 1500 mm annual rainfall. Assessment of

salinity hazard risk can ensure clearing will notresult in salinity.

• There is considerable evidence from much of

Queensland that removal of large woody

vegetation can increase pasture growth ascompetition for water and nutrients is removed.

This response has been the main incentive for

the development of Queensland’s rural

industries. There are some studies that havedemonstrated the improvement of pasture

growth with retained trees.

Executive summary

This review looks at a wide range of physical,

ecological, social and economic issues that relate to

native vegetation and, in particular, tree clearing, in

Queensland. While the review necessarily has ascientific focus, the intent is to provide a greater

understanding of the need for sound policies and

administrative procedures involving the production–biodiversity nexus in attaining sustainable naturalresource use and management. The review has

tried to look at vegetation management as one part

of sustaining the landscape.

The responsibility for managing freehold and

leasehold lands rests largely with individuals, butwith government setting the policy and regulatory

framework that will stimulate change towards the

sustainable use of natural resources. Part of the

sustainability question is ensuring economicviability for both individuals and the State in the

long term. The continuing challenge is to achievelasting changes in attitudes to the sustainable use

and management of natural resources, particularlyin regard to native vegetation management.

Sustainability is the primary goal of land managers,

government agencies and the global community.

The precise meaning of sustainability is debatable,

and generally reflects the values of the user.Sustainability may be economic, social and

ecological, and consideration of vegetation

management will require finding a balance between

these considerations.Decision making about management options needsto be put into both the social and economic

context. This review, while focusing primarily on

the physical context, also considers these issues.

To meet the requirements of sustainability, and the

consideration of economic and social issues inmanaging native vegetation, planning and

monitoring are essential tools. Queensland has

substantial bioregion mapping and information that

can serve as a basis to regional vegetationmanagement planning. The regional planning

process could become an integral and connecting

component of a whole planning system, and offer a

participative, adaptive and equitable planningprocess.

Approximately 68% of Queensland is under

leasehold tenure, and regulated by the Land Act 1994(Qld). Of the remaining land, 24% is freehold tenure.The historical development of agricultural and

pastoral lands, and the accompanying development

of statutory controls of land clearing are discussed.

At the national, State and local level, there are a

number of legislative and policy documents that dealwith native vegetation management.



viii

• Clearing of trees releases carbon stored as

biomass in standing vegetation and thiscontributes to greenhouse gas emissions.

Australia has international obligations to ensure

growth in emissions remains below 108% of

1990-95 levels.

There are other impacts for which the evidence ofthe direct effects of tree clearing is conflicting:

• Well-pastured blocks have been demonstrated tobe efficient in minimising run-off, although there

are other studies that demonstrate an increase in

run-off following the clearing of trees—making itdifficult to generalise about the impacts of tree

cover on soil surface erosion. In riparian areas,

trees have been shown to protect streambanks

from mass failure and erosion by adding to bedand bank stability.

There are other changes in ecosystem health that

result from post-clearing management, rather than

clearing per se:

• Erosion of soil is controlled by a number of

factors, including slope, ground cover andinfiltration rate. These factors are affected by

management practices such as grazing pressures

and the use of fire. Fire has historically played

a role in vegetation dynamics. There is someevidence that Indigenous fire management

affected plant demographics and structure,

although the extent of this is still debated in

the literature. Fire is still used as a managementtool today.

• Soil compaction is more likely to occur underheavy grazing, particularly where the soil is wet

or poorly structured naturally.

• Some land uses are particularly acidifying to soil.They include those cropping activities that

include the removal of large quantities of

harvested material, application of ammonia-

based fertilisers and introduction of legumes.Particular soil types are more vulnerable to

acidification than others.

• Changes in vegetation structure and composition

can be attributed to management practices suchas grazing pressures and fire. Poor managementof grazing in remnants can result in declining

condition of remnants through browsing, soil

compaction, reduced ground cover, changes in

structure and species composition, and weedinvasion.

• Where vegetation is retained, it is important to

assess and manage the condition of the

vegetation and associated ecosystems to ensure

sustainability.

• The functioning of remnants can be impacted by

the size and shape of remaining vegetation, aswell as connectivity. Small remnants can be

impacted by large proportions of their area being

affected by changed physical conditions and

increased vulnerability to pest invasions. Theimportant role of remnants in the landscape

is discussed.



165

Index

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brigalow ( Acacia harpophylla) . . . . . 57, 65, 67, 72, 75, 80,82–3, 86–7

brigalow development scheme . . . . . . . . . . . . . . . 16, 89

Broadscale Tree Clearing Policy (BTCP). . 14, 18–9, 32, 120

buffel grass (Cenchrus ciliaris) 48, 50–1, 54, 63, 72, 75, 86

buffer zones . . . . . . . . . . . . . . . . . . . . . . . . . . 54, 72, 81

bush foods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Cadellia pentastylis. . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Callitris columellaris . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Callitris glaucophylla . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Callitris spp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Calyptorhynchus lathami . . . . . . . . . . . . . . . . . . . . . . . . 42

Calyptorhynchus magnificus . . . . . . . . . . . . . . . . . . . . . 42

camphor laurel (Cinnamomum camphora) . . . . . . . . . . . 64

carrying capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Cassia nemophila . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Casuarina spp. . . . . . . . . . . . . . . . . . . . . . . . . . . . 61, 72cat’s claw creeper (Macfadyena unguis-cati) . . . . . . . . . 64

Celtis sinensis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Cenchrus ciliaris. . . . . . . . . . . 48, 50–1, 54, 63, 72, 75, 86

Chinchilla white gum (Eucalyptus argophloia) . . . . . . . . 42

Chinese celtis (Celtis sinensis) . . . . . . . . . . . . . . . . . . . 64

Cinnamomum camphora . . . . . . . . . . . . . . . . . . . . . . . . 64

climate change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

community participation . . . . . . . . . . . . . . 98, 101–3, 111

community values . . . . . . . . . . . . . . . . . . . . . . . . . . 107

compaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

competition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

corridors . . . . . . . . . . . . . . . . . . 40, 46–8, 54, 56–7, 120

dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47–8

Corymbia citriodora . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

crop production . . . . . . . . . . . . . . . . . . . . . . . . 69, 80–1

Cryptostegia grandiflora. . . . . . . . . . . . . . . . . . . 58, 64, 88

cultural heritage values . . . . . . . . . . . . . . . . . . . . . . . 20

Dawson gum (Eucalyptus cambageana) . . . . . . . . . . . . . 72

development

history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16, 106

Dichanthium spp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

dieback . . . . . . . . . . . . . . 5, 36, 40, 48, 51–2, 60–2, 120

arboreal wildlife . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

drought. . . . . . . . . . . . . . . . . . . . . . . . . . 5, 36, 60, 62

insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

mistletoe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

nutrient enrichment. . . . . . . . . . . . . . . . . . . . . . . . . 61

pathogens. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

salinity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

senescence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

symptoms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

waterlogging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

discharge areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Dodonaea viscosa . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83166

Aboriginal people

fire management . . . . . . . . . . . . . . . . . . . . . . 3, 54, 88

Acacia aneura . . . . . . . . . . . . 49, 54, 57, 66, 75, 82–3, 87

Acacia argyrodendron . . . . . . . . . . . . . . . . . . . . . . 63, 85

Acacia cambagei. . . . . . . . . . . . . . . . . . . . . . . . 63, 72, 86

Acacia harpophylla . . . . 57, 65, 67, 72, 75, 80, 82–3, 86–7

Acacia nilotica . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Acacia shirleyi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Acacia spp. . . . . . . . . . . . . . . . . . . . . . . . . 2, 63, 72, 85

Acacia stenophylla . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

acidification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Aepyprymnus rufescens . . . . . . . . . . . . . . . . . . . . . . . . . 42

Albizia lebbeck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Alstonia constricta . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

alternative products . . . . . . . . . . . . . . . . . . . . 89–90, 93

animal production . . . . . . . . . . . . . . . . . . . . . . . . . 81–3

heat stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

liveweight gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Anredera cordifolia . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Aristida spp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51, 88

armillaria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Atalaya hemiglauca . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Baccharis halimifolia . . . . . . . . . . . . . . . . . . . . . . . . . . 63

belalie ( Acacia stenophylla). . . . . . . . . . . . . . . . . . . . . . 82

biodiversity . . . . . . . . . . . . . 22, 26–31, 40, 104, 107, 119

conservation . . . . . . . . . . . . . . . . . . . . . . . . 22, 29, 42

decline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42–4

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

ecosystem

diversity. . . . . . . . . . . . . . . . . . . . . . . . . . 22, 27, 30

function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

genetic diversity . . . . . . . . . . . . . . . . . . . . . 22, 27, 30

habitat loss . . . . . . . . . . . . . . . . . . . . . . . . . 40, 42–60

landscape health ( see also ecosystem services) . . 22, 27

loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5, 40, 106

national policies . . . . . . . . . . . . . . . . . . . . . . . . 29–30

origin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–3

productivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110–1

riparian zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

society benefits . . . . . . . . . . . . . . . . . . . . . . . . 98, 110

species

diversity. . . . . . . . . . . . . . . . . . . . . . . . . . 22, 27, 30

loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43–5, 50

bioregional planning . . . . . . . . . . . . . . . . . . . . . 114, 117

bioregions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2, 7

black speargrass (Heteropogon contortus) . . . . . 51, 75, 88

blackberry (Rubus fruticosus) . . . . . . . . . . . . . . . . . . . . 64

blackwood ( Acacia argyrodendron) . . . . . . . . . . . . . 63, 85bluegrasses (Bothriochloa spp. and Dichanthium spp.) . . 51

Bothriochloa spp.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Index



167

ecologically sustainable development (ESD). . . . . . . 22–6

Brundtland Report. . . . . . . . . . . . . . . . . . . . . . . . 22–3

core objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

government adoption . . . . . . . . . . . . . . . . . . . . . . . 26

economic analysis . . . . . . . . . . . . . . . . . . . . . . . 103–111

choice modelling. . . . . . . . . . . . . . . . . . . . . . . 108, 110

contingent valuation method . . . . . . . . . . . . . . . 107–8

cost benefit . . . . . . . . . . . . . . . . . . . . . . . 98–9, 105–9marginal analysis. . . . . . . . . . . . . . . . . . . . . . . . 105–6

off-site costs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

productivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

economic issues . . . . . . . . . . . . . . . . . . . . . . . . . 98–111

ecosystem function

repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40, 53–5

resilience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

threats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

ecosystem services. . . . . . . . . . . . . . . . . . . . . . . . 44, 93

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

ecotones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

ecotourism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

edge effects . . . . . . . . . . . . . . . . . . . . . . . . 40, 47–9, 64

microclimate. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

El Niño Southern Oscillation (ENSO) . . . . . . . . . . 2–4, 31

Environmental Protection and Biodiversity Conservation Act 1999 (Cwlth) . . . . . . . . . . . . . . . . 14, 17

Eremocitrus glauca . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Eremophila gilesii . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

Eremophila mitchellii . . . . . . . . . . . . . . . . . . . . . . . . . . 83

erosion . . . . . . . . . . . . . . . . 41, 53, 56, 64–7, 87, 109–11

ground cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

management practices . . . . . . . . . . . . . . . . . . . . . . 67

modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

pasture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65–6

tree clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . 64–55

vegetation cover . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Eucalyptus argophloia. . . . . . . . . . . . . . . . . . . . . . . . . . 42

Eucalyptus cambageana . . . . . . . . . . . . . . . . . . . . . . . . 72

Eucalyptus coolabah. . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Eucalyptus crebra . . . . . . . . . . . . . . . . . . . . . . . . . 67, 83Eucalyptus erythrophloia . . . . . . . . . . . . . . . . . . . . . . . . 67

Eucalyptus grandis . . . . . . . . . . . . . . . . . . . . . . . . . 75, 84

Eucalyptus intertexta. . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Eucalyptus laeviopinea . . . . . . . . . . . . . . . . . . . . . . 73, 75

Eucalyptus melanophloia . . . . . . . . . . . . . . . . . . . . . . . 51

Eucalyptus melliodora . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Eucalyptus ochrophloia . . . . . . . . . . . . . . . . . . . . . . . . . 82

Eucalyptus populnea. . . . . . . . . . . . . . 50, 54, 67, 71, 83–4

Eucalyptus spp.. . . . . . . . . . . . . . 2, 63, 66, 71, 75, 83, 87

farm forestry . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89–93definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

national policy . . . . . . . . . . . . . . . . . . . . . . . . . . 90–1

fire management. . . . . . . . . 36, 41, 49, 54, 63, 65, 88–90

Fisheries Act 1994 (Qld). . . . . . . . . . . . . . . . . . . . . . . . 19

Flooded gum (Eucalyptus grandis) . . . . . . . . . . . . . . 75, 84

flower and foliage markets . . . . . . . . . . . . . . . . . . . . . 89

fodder . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80–2, 86, 89

fragmentation . . . . . . . . . . . . . . . . . . . . . . . . . . . 40, 64

species loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

dispersal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46–7

ecosystem function . . . . . . . . . . . . . . . . . . . . . . . . . 49

isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45–7

remnant size . . . . . . . . . . . . . . . . . . . . . . . . . 40, 45–7freehold tenure. . . . . . . . . . . . . . . . . . . . . . . . . . . . 14–5

freeholding leases . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

gidgee ( Acacia cambagei) . . . . . . . . . . . . . . . . . 63, 72, 85

grazing . . . . . . . . . . . . . . . . . . . . . . . . . 50–3, 63, 67, 81

artificial watering points . . . . . . . . . . . . . . . . . . . . . 53

erosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

fire management. . . . . . . . . . . . . . . . . . . . . . . . . . . 88

flora . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

livestock handling . . . . . . . . . . . . . . . . . . . . . . . 81, 86

productivity . . . . . . . . . . . . . . . . . . . . . . . . . . 108, 121

remnants. . . . . . . . . . . . . . . . . . . . . . . . . . . . 40, 50–4

riparian zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

soil

acidification. . . . . . . . . . . . . . . . . . . . . . . . . . . 73–4

erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

fertility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

species change . . . . . . . . . . . . . . . . . . . . . . . . . . 50–1

sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

thickening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

wetlands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

green panic (Panicum maximum) . . . . . . . . . . 73, 83, 85–7

greenhouse

biomass estimates . . . . . . . . . . . . . . . . . . . . . . . . . 35

carbon

accounting. . . . . . . . . . . . . . . . . . . . . . . . . . . . 35–6

credits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

emissions . . . . . . . . . . . . . . . . . . . 33, 35–6, 109–10

trading . . . . . . . . . . . . . . . . . . . . . . . . . . 37, 90, 110

climate change . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22, 31–7emission reduction . . . . . . . . . . . . . . . . . . . . . . . . . 36

forests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

gas emissions . . . . . . . . . . . . . 31–3, 104, 108–9, 110–1

international policies. . . . . . . . . . . . . . . . . . . . . . . . 32

inventory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

land use change and forestry . . . . . . . . . . . . . 22, 32–3

sinks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22, 32, 37

soil carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35–6

thickening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

tree clearing . . . . . . . . . . . . . . . . . . . . . . . . . 33, 35–6

Heteropogon contortus . . . . . . . . . . . . . . . . . . . 51, 75, 88

honey production . . . . . . . . . . . . . . . . . . . . . . . . . 89, 93

hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74–5

evaporation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74



168

hydrology (continued)

rainfall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

watertable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Integrated Planning Act 1997 (Qld) . . . . . . . . . 14–5, 118–9

introduced legumes . . . . . . . . . . . . . . . . 75, 78, 81, 86–7

kangaroo grass (Themeda triandra) . . . . . . . . . . . . . . . . 51

Kyoto Protocol . . . . . . . . . . . . . . . . . . . . . . . . 22, 32, 37

lancewood ( Acacia shirleyi) . . . . . . . . . . . . . . . . . . . . . 82

Land Act 1962 (Qld) . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Land Act 1994 (Qld) . . 2–3, 14–5, 18, 20, 32, 89, 115, 119

cultural and heritage values. . . . . . . . . . . . . . . . . . . 20

native title . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

land degradation . . . . . . . . . . . . . . . . . . . . . 60–80, 104

cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

ecosystem function . . . . . . . . . . . . . . . . . . . . . . . 28–9

land tenure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14–9

Land Use Change and Forestry (LUCF). . . . . . . . 22, 32–7landscape

ecology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114, 116

health. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–7

planning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Lantana camara . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

leaf litter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67, 71

leasehold tenure. . . . . . . . . . . . . . . . . . . . . . . . . . . 14–8

conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16–7

tree-clearing controls . . . . . . . . . . . . . . . . . . . . . 18–9

Leucaena leucocephala subsp. globate . . . . . . . . . . . . . . 86Leucaena spp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86–7

liveweight gains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Local Agenda 21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Local Government Act 1993 (Qld) . . . . . . . . . . . . . . . . . 15

LUCF see Land Use Change and Forestry

Macfadyena unguis-cati . . . . . . . . . . . . . . . . . . . . . . . . 64

Macroptilium atropurpureum . . . . . . . . . . . . . . . . . . . . . 86

Madeira vine ( Anredera cordifolia) . . . . . . . . . . . . . . . . 64

mangroves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59–60

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Medicago spp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Melaleuca spp.. . . . . . . . . . . . . . . . . . . . . . 58, 60, 72, 75

microclimate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81, 85

Montreal Process . . . . . . . . . . . . . . . . . . . . . . . . . 41, 91

mulga (Acacia aneura) . . . . . . 49, 54, 57, 66, 75, 82–3, 87

mycorrhizal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72–3

National Framework for Management andMonitoring of Australia’s Native Vegetation . . . . . . 17, 54

National Greenhouse Gas Inventory (NGGI). . . . 22, 33–7

National Greenhouse Strategy (NGS). . . . . . . . . . . 22, 32National Strategy for Australia’s Biodiversity . . . . . 22, 29

National Strategy on Ecologically SustainableDevelopment (NSESD) . . . . . . . . . . . . . . . . . . . . . . 22–3

native pasture

communities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Native Title Act 1993 (Cwlth) . . . . . . . . . . . . . . . . . 14, 20

native title . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

native vegetation

aesthetic values . . . . . . . . . . . . . . . . . 81, 93–5, 100–1

amenity values. . . . . . . . . . . . . . . . . . . . . 93–5, 100–1

coastal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48commercial values. . . . . . . . . . . . . . . . . . . . . . . . . . 41

Commonwealth legislation. . . . . . . . . . . . . . . . . . . . 17

community benefit . . . . . . . . . . . . . . . . . . . . . . . 98–9

condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48–9

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

ecological benefits. . . . . . . . . . . . . . . . . . . . . . . . . . 41

economic benefits . . . . . . . . . . . . . . . . . . . . . . . . . . 41

erosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

landholder attitudes . . . . . . . . . . . . . . . . . . . . . . . . 111

landholder perception . . . . . . . . . . . . . . . . . 98, 102–3

local government controls . . . . . . . . . . . . . . . . . 19–20

management. . . . . . . . . . . . . . . . . . . . . . . . . . . . 53–5

monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . 114–22

planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114–22

national policies . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

non-remnant ‘woody’ . . . . . . . . . . . . . . . . . . . . . . . 31

non-use values . . . . . . . . . . . . . . . . . . . 98, 107, 110–1

nutrient cycling . . . . . . . . . . . . . . . . . . . . . . . . . . 71–3

pre-European . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2–3

productivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Queensland legislation . . . . . . . . . . . . . . . . . . . . 18–9

remnant size. . . . . . . . . . . . . . . . . . . . . . . . . . . . 45–7

remnants. . . . . . . . . . . . . . . . . . . . . . . . . . . 40, 48–53

resilience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27–9

retention . . . . . . . . . . . . . . . . . . . . . . . . 26, 43–4, 120

salt-tolerant . . . . . . . . . . . . . . . . . . . . . . . . . . . 79–80

social issues. . . . . . . . . . . . . . . . . . . . . . . . . . . 98–111

society benefits . . . . . . . . . . . . . . . . . . . . . . . . . 107–8

structural changes . . . . . . . . . . . . . . . 36, 51–2, 84, 87

thickening . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

urban and peri-urban . . . . . . . . . . . . . . . . . . . . . . . 95

water uptake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74Nature Conservation Act 1992 (Qld) . . . . . . . . 14, 18–9, 30

NGGI see National Greenhouse Gas Inventory

NGS see National Greenhouse Strategy

nitrogen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

cycling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29, 72, 86

fixing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72, 86

nutrient cycling. . . . . . . . . . . . . . . . . . . . . . . . . 71–3, 93

ooline (Cadellia pentastylis) . . . . . . . . . . . . . . . . . . . . . 42

oversown legumes . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Panicum maximum . . . . . . . . . . . . . . . . . . . . 73, 83, 85–7

Parkinsonia aculeata. . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Parthenium hysterophorus . . . . . . . . . . . . . . . . . . . . . . . 63

parthenium weed (Parthenium hysterophorus) . . . . . . . . 63



169

participatory approaches . . . . . . . . . . . . . . . . . . 98, 103

Paspalum dilatatum . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

pasture. . . . . . . . . . . . . . . . . . . . . . . . . . . . 61, 80, 83–7

exotic . . . . . . . . . . . . . . . . . . . . . . . . . . 51, 81, 83, 86

native . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51, 86

nutrient cycling. . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

oversown legumes. . . . . . . . . . . . . . . . . . . . . . . 73, 83

productivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

tree clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83yield. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83–4

pest animals. . . . . . . . . . . . . . . . . . . . . . . . . . . 62–4, 82

diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

pest plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62–4, 88

diversity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Phytophora cinnamomi . . . . . . . . . . . . . . . . . . . . . . . . . 61

Pinus spp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

planning

definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114–5

poplar box (Eucalyptus populnea) . . . . 50, 54, 67, 71, 83–4

woodlands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

precautionary principle . . . . . . . . . . . . . . . . . . . . . . . 24

property management planning . . . . . . . . 103, 114–5, 119

Prosopis velutina . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Queensland Implementation Plan (QIP) . . . . . . . . . 22, 32

Quilpie mesquite (Prosopis velutina) . . . . . . . . . . . . . . . 63

rare species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

recharge

areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75, 79

rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

regeneration. . . . . . . . . . . . . . . . . . . . . . . . . . . 54–5, 79

regional ecosystems (REs) . . . . . . . 3, 7, 40, 114, 117, 119

biodiversity surrogates . . . . . . . . . . . . . . . 30, 114, 117

conservation status. . . . . . . . . . . . . . . . . . . . . . . . . . 7

mapping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Regional Forest Agreement (RFA) . . . . . . . . . . . . . . 41, 91

regional planning . . . . . . . . . . . . . . . . . . . 111, 114, 116–8

regional strategies . . . . . . . . . . . . . . . . . . . . . . . 114, 117

regional vegetation management plans (RVMPs) . 114, 119

regrowth . . . . . . . . . . . . . . . . 5, 7, 31, 41, 75, 80, 86, 87

rehabilitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

remnant vegetation . . . . . . . . . . . . . . . . . 7, 108, 119–20

clumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

strips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

REs see regional ecosystems

reserve system . . . . . . . . . . . . . . . . . . . . . . . . . . 30, 101

reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43, 105

restoration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

revegetation . . . . . . . . . . . . . . . . . . . . . . . 40, 54, 79, 91

RFA see Regional Forest AgreementRhodes grass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

riparian zones. . . . . . . . . . . . . . . . . . . . 40, 53, 54, 56–8

buffers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

riparian zones (continued)

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56, 58–9

habitat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

instream fauna . . . . . . . . . . . . . . . . . . . . . . . . . . 57–8

large woody debris . . . . . . . . . . . . . . . . . . . . . . . . . 58

rubber vine (Cryptostegia grandiflora) . . . . . . . . 58, 64, 88

Rubus fruticosus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

run-off . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53, 66–7, 74Rural Lands Protection Act 1985 (Qld). . . . . . . 14, 18–9, 63

RVMPs see regional vegetation management plans

saline soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

salinity . . . . . . 41, 74–80, 95, 98, 104–5, 107–10, 119–20

climate and rainfall . . . . . . . . . . . . . . . . . . . . . . . . . 77

cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75–6

hazard modelling . . . . . . . . . . . . . . . . . . . . . . . . 78–9

impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75–6

landform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

mapping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

soil properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

tree clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

vegetation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

salt-tolerant vegetation . . . . . . . . . . . . . . . . . . . . . 79–80

shade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72, 82, 85

shelter . . . . . . . . . . . . . . . . . . . . . . . . . . . 81–2, 85, 120

silver-leaved ironbark (Eucalyptus melanophloia) . . . . . . 51

siratro (Macroptilium atropurpureum) . . . . . . . . . . . . . . . 86

SLATS see Statewide Landcover and Trees Study

social issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98–111

partnerships . . . . . . . . . . . . . . . . . . . . . . . . . . 98, 103

sodic soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72, 76

soil

acidification. . . . . . . . . . . . . . . . . . . . . . . 29, 73–4, 87

grazing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

land use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

remediation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

tree clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

biota . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35–6, 110

fauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

fertility . . . . . . . . . . . . . . . . . . . . 41, 65, 72, 80, 84, 93

infiltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

minerals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

nitrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72–3, 86

nutrients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71, 73

organic carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

organic matter . . . . . . . . . . . . . . . . . . . . . . . . . 72, 80

structure. . . . . . . . . . . . . . . . . . . . . . 41, 50, 52, 67–71

compaction. . . . . . . . . . . . . . . . . . . . . 41, 50, 53, 68definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

degradation

impacts. . . . . . . . . . . . . . . . . . . . . . . . . . . . 69–70

prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70



170

soil (continued)

repair. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

management . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

soil water content . . . . . . . . . . . . . . . . . . . . . . . . 69

tree clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

temperature . . . . . . . . . . . . . . . . . . . . . . . . . 71, 81, 85

spotted gum (Corymbia citriodora) . . . . . . . . . . . . . . . . 90

Statewide Landcover and Trees Study (SLATS) . 5, 35, 122

stock-carrying capacity . . . . . . . . . . . . . . . . . . . . . . . 83stocking rate . . . . . . . . . . . . . . . . . . . . . . . . . 66, 82, 87

Stylosanthes spp.. . . . . . . . . . . . . . . . . . . . . . . . . . 74, 87

sustainability . . . . . . . . . . . . . . . . . . . . 22–6, 101–2, 121

biodiversity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

indicators . . . . . . . . . . . . . . . . . . . . . . . . . . 24–5, 121

landholder adoption . . . . . . . . . . . . . . . . . . . . . . 25–6

markets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

modelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

sustainable production. . . . . . . . . . . . . . . . . . . . . . . . 54

Themeda triandra . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

thickening . . . . . . . . . . . . . . . . . . . . . . 36, 51–2, 84, 109

threatened species . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

threshold parameters . . . . . . . . . . . . . . . . . . . . . . . . 120

thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43–8

Thunbergia grandiflora . . . . . . . . . . . . . . . . . . . . . . . . . 64

timber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

production . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89–93

tree clearing

animal production. . . . . . . . . . . . . . . . . . . . . . . . . . 81

controls . . . . . . . . . . . . . . . . . . . . . . . . . . . 17–20, 111

crop production . . . . . . . . . . . . . . . . . . . . . . . . . 80–1

cultural and heritage values. . . . . . . . . . . . . . . . . . . 20

economic analysis . . . . . . . . . . . . . . . . . . . . . . 103–111

economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98–111

erosion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

greenhouse gas emissions . . . . . . . . . . . . . . . . . . . . 32

habitat loss . . . . . . . . . . . . . . . . . . . . . . . . . 40, 42–60

history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16–7

hydrology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74–6indirect off-site impacts . . . . . . . . . . . . . . . . . . 109–10

introduced legumes. . . . . . . . . . . . . . . . . . . . . . . . . 86

land degradation. . . . . . . . . . . . . . . . . . . . . . . . . . 4–5

methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

native title . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

nitrogen cycling . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

off-site effects . . . . . . . . . . . . . . . . . . . . . . . . . 98, 100

on-farm benefits . . . . . . . . . . . . . . . . . . . . . . . . 108–9

organic carbon . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

pasture production . . . . . . . . . . . . . . . . . . . . . . . 83–5

pest management . . . . . . . . . . . . . . . . . . . . . . . . . . 64production benefits . . . . . . . . . . . . . . . . . . . . . . . . 105

rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5, 7

species decline . . . . . . . . . . . . . . . . . . . . . . . . . . 42–4

species loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42–8

tree hollows. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

tree management plans . . . . . . . . . . . . . . . . . 115, 118–9

tree–crop competition. . . . . . . . . . . . . . . . . . . . . . . 80–1

tree–grass interactions. . . . . . . . . . . . . . . . . . 71–2, 83–5

animal production . . . . . . . . . . . . . . . . . . . . . . . . 81–2

moisture competition . . . . . . . . . . . . . . . . . . . . . . . 84

nutrient competition . . . . . . . . . . . . . . . . . . . . . . . . 84

Trifolium spp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Vegetation Management Act 1999 (Qld) . . . . . . 2, 7, 14, 18–9, 32, 44, 58, 76, 119

Water Resources Act 1989 (Qld). . . . . . . . . . . . . . 14, 18–9

weeds see pest plants

wetlands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40, 58–9

definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

habitat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

wildlife

dispersal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

habitat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120refuges. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

riparian zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

wind erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

windbreaks. . . . . . . . . . . . . . . . . . . . . . . . . . . . 41, 81–2

wiregrasses ( Aristida spp.) . . . . . . . . . . . . . . . . . . 51, 88

yapunyah (Eucalyptus ochrophloia) . . . . . . . . . . . . . . . . 82

yellow box (Eucalyptus melliodora) . . . . . . . . . . . . . . . . 82

yellow jacket (Eucalyptus intertexta) . . . . . . . . . . . . . . . 54

zero till . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 Ziziphus mauritiana . . . . . . . . . . . . . . . . . . . . . . . . . . . 84



171



172



1

1 Queensland’s resources

Contributors

Queensland’s land and vegetation resources

Bruce Wilson, Environmental Protection Agency

Sarah Boulter, Department of Natural ResourcesMirranie Barker, Department of Natural Resources

Jude Westrup, Department of Natural ResourcesLandscape health

Sarah Boulter, Department of Natural Resources


Tim Danaher, Department of Natural Resources

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2

1.1 Queensland’s land and vegetation resources

Queensland is a large and diverse State that lies

between latitudes 10°S-29°S and longitudes 138°E-

153°E. Climate ranges from subtropical in the southeast to wet and wet–dry tropics in the north and to

semiarid and arid in the south–west. Queenslandsupports about 65% of Australia’s known frog,

reptile, bird and mammal species, and 47% of itsvascular plant species (EPA 1999c). Landscapes

vary from tall open forest, woodlands, and tropical

rainforests and vine forests to semi-arid woodlands

grasslands and deserts in the interior.

Assessment of the extent, condition andmanagement of natural resources of such a diverse

State, both historically and in the future, requires

some classification based on the natural resource

factors that affect land use. Sattler and Williams

(1999) have described 13 bioregions of Queenslandand the major geology, landforms, soils, native

vegetation and ecosystem types that occur there.

These regions are used to provide a context for

biodiversity assessments and have been used to

develop tree-clearing guidelines under the Land Act

1994 (Qld) and Vegetation Management Act 1999

(Qld). A summary of each bioregion is given in

appendix 1.

Weston et al. (1981) have produced a map (see

figure 1.1, p.9) and description of 14 native pasture

communities of Queensland. These are widely usedto make general assessments about the capability,

degradation and other land-resource related issues

and are summarised in appendix 2.

Pre-European settlement vegetation

Australia supports a rich diversity of vegetation,

both in structure and composition. This diversity isparticularly demonstrated by the presence of a high

proportion of species endemic to the Australian

continent. Also unique to the Australian flora are

the presence of unusual structural attributes, in

particular scleromorphy, and the dominance of twotree and shrub groups, Eucalyptus spp. and Acacia spp. (Barlow 1994; Fox 1999). The origin,

adaptation and differentiation of the regional

Summary This section provides a brief introduction to

Queensland’s land and vegetation resources, their

past and present state, and methods being used tofurther refine knowledge of the current status of all

vegetation types.

Queensland is a large and diverse State. Climate

ranges from subtropical in the south-east to wet

and wet–dry tropics in the north, and to semiaridand arid in the south-west. Landscapes vary from

tall open forest, woodlands and tropical rain/vine

forests to semiarid woodlands grasslands anddeserts in the interior.

The unique mosaic of native flora in Queensland,

and all of Australia, is the result of global patterns

and processes of geomorphology, climate, evolution

and recruitment over geological time. Atmosphericand oceanic perturbations in the form of the

El Niño Southern Oscillation (ENSO) have

contributed to climatic variability, particularly in theeastern two thirds of Australia.

While the extent of the impact of Aboriginal landuse on vegetation dynamics prior to European

settlement is widely debated in the scientific

literature, there is some anecdotal and scientific

evidence that Aboriginal fire management may haveresulted in changes to the geographic and

demographic structure of many vegetation types.

While new technologies and agricultural techniques

have increased yields and outputs per unit area, the

overall condition and productivity of Queensland’slandscape have declined considerably over time.

This overall decline is a reflection of current and

historic land uses. Agricultural practices are

partially responsible for soil erosion and structuraldecline, salinity, soil acidification, and native

pasture decline. Land degradation factors include

vegetation clearance as well as urbanisation,

agricultural practices, forestry and mining.

The rate of clearing in Queensland has increasedfrom 289 000 ha/year in 1991–95 to

340 000 ha/year in 1995–97. During this period,clearing on leasehold land decreased by 12%,

while it increased on freehold land. The majorityof clearing was carried out to convert woody

vegetation to pasture.

Vegetation maps are being produced over substantial

parts of Queensland. These are particularly

important in determining the previous and currentextent of native vegetation, and therefore

conservation status, of regional ecosystems. It is

estimated that in 1995 approximately 81% of the

State was covered by remnant vegetation. Statistics

are given on the amount of remnant vegetation bybioregion and subregion and by the status of

ecosystems under the Vegetation Management Act

1999 (Qld).

The bioregions of Queensland group the State intoareas with broadly similar landscape patterns.

These areas provide a useful context for assessing

the natural resources of the State. A summary of

these regions is provided in appendix 1. Appendix 2details 14 native pasture communities of

Queensland used to make general assessments

about land capability, degradation and other land-

resource related issues.



3

Prior to European settlement, Aboriginal land use,

migration and fire patterns also influencedvegetation composition and distribution (AUSLIG

1990; Barlow 1994; Bowman 1998; Groves 1999;

Orchard and Wilson 1999). Although a highly

contentious issue, there is evidence that Aboriginalburning, in particular, may have played a role in

the modification and maintenance of the Australian

flora (Bowman 1998). Some authors have used

explorer and early settler quotes to suggest thatAboriginal burning created a structurally more

open grasslands and grassy woodland landscape

(Ryan et al. 1995). However, Benson and Redpath

(1997), in a review of scientific evidence andhistorical sources, refute this conclusion,

suggesting that this analysis over emphasises the

influence of Aboriginal fire management and

ignores the evidence that climate was the majordeterminant of vegetation change and distribution.

There is, however, considerable evidence that

Aboriginal people used fire to achieve short-term

ecological outcomes, creating habitat mosaics thatfavoured some species or increased local

abundances of food plants. Bowman (1998) cites a

large body of ecological evidence that suggests

Aboriginal burning may have resulted in changes tothe geographic range and demographic structure of

many vegetation types. Anderson (1999) notes,

however, that Indigenous fire management arises

from ‘diffuse social, cultural, spiritual andecological practices’ rather than a desire to meet

certain management or biodiversity goals.

The importance of these evolutionary factors increating Australia’s rich and unique flora is in

trying to understand the landscape for managementand conservation of the extant biodiversity.

structure, composition and diversity of Australia’s

vegetation have been attributed to global patternsand processes of geomorphology, climate, evolution

and recruitment over geological time. Rainfall,

associated temperature patterns and climatic

variability in particular has been significant indetermining vegetation distribution and change.

Atmospheric and oceanic perturbation in the form

of El Niño Southern Oscillation (ENSO) have

contributed to historic climatic variability,particularly in the eastern two-thirds of Australia.

Nicholls (1991) suggests that this variability can be

viewed as causing an adaptation ‘to climate in such

a way that demographic composition (ofvegetation) is in a state of unstable equilibrium’.

These factors, in association with changes and

effects over geological time (see table1.1), have

created the unique mosaic of Australian flora.

Table 1.1 Factors influencing pre-1770 diversity, distributionand structure of Australian flora. Adapted from Barlow1994; Fox 1999; Specht 1994; Groves 1999; Frakes 1999.

Major factor Associated factors

location southern and oceanic hemispherelocation, meridional, latitude andIndo-Australian position, insularity,age, size, shape and physiognomy

climate circulation patterns, rainfall patternsand seasonality, insolation,temperature, albedo, variability, ENSO

landforms and soils soil type, drainage, nutrient levels

fire lightning strikes, anthropogenic

Queensland’s terrestrial vegetation communities

can be broadly grouped into forests (including

woodlands), arid shrublands, grasslands,

heathlands and wetlands (EPA 1999c). For thepurposes of conservation, Queensland’s

Environmental Protection Agency (EPA) has recently

published a hierarchical framework classifying

Queensland’s vegetation into Regional Ecosystems(REs) (Sattler and Williams 1999). The recording of

some 1084 REs based on dominant vegetation,

geomorphic land zone and bioregion, demonstrates

the wide range and diversity of habitats existingacross the State (Williams 1979; EPA 1999c) (see

section 1.2.1).

Table 1.2 Post-1990 estimates of land degradation by State and land use. Adapted from RIRDC 2000; † Cregan and Scott 1998;*Hayes 1997.

Soil health issues by State NSW QLD VIC TAS SA WA`000 ha `000 ha `000 ha `000 ha `000 ha `000 ha

Soil structure decline/compaction 14 695 2 645 10 530 317 1 300

Sheet and rill 2 288 1 343 3 180 226

Gully and tunnel 9 460 4 220 340

Wind erosion 20 045 74 000 1 630 321 8 300 50

Wind/water in rangeland 7 300Salinity *120 *10 *120 *20 * 402 *1 804

Acid soils (pH Ca<4.8) †13 500 †8 400 †3 000 †1 000 †2 800 †4 700

Area of State 801 690 172 720 22 760 6 780 98 400 252 550

Note: Blank cells indicate no data yet found. Cells are not exclusive and area may be affected by several types of land degradation.



4

19 communities in Queensland (see table 1.5). This

assessment has not been repeated, and someauthors suggest that the results may, in part, reflect

the pasture condition during an El Niño event, and

therefore underrate pasture condition (B. Burrows

2000, pers. comm., 24 April). Changes in pasturecomposition and other aspects of land degradation

are due to various combinations of factors. The

following identifies some of the more important

factors in grazing lands:• increased grazing pressures from domestic, feral

and native animals

• reduced burning or controlled burning regimes

• provision of stock watering facilities• use of bore drains

• use of feed supplements

• climatic extremes

• declining soil fertility status• development of salinisation

• changes in animal types and breeds

• indirect factors such as the need to service

property debt and maintain cash flows.

Table 1.4 Overview of relationships between pressures on,and condition of land resources. Source: EPA 1999c.

Pressure Resulting condition ifpressures are poorly managed

Underlying pressures Underlie and/or exacerbate manyof the following pressures

- weather and climate- population growth- economic pressures

Vegetation clearance Degraded soils, particularly:- erosion

- dryland salinitySpread of noxious species(can lead to degraded soils)Increased grass cover

Agriculture Vegetation clearance- bare surface production Erosion (can lead to loss of

systems soil fertility and structure)- intensive cultivation Soil fertility decline- grazing and associated Soil structure decline

fire regimes- application of fertilisers Irrigation salinity

and agricultural chemicals- irrigation Acidification- introduction of exotic Land contamination

species Noxious plants and animals

(can lead to native pasturedecline and erosion)Native pasture decline

Urbanisation Vegetation clearanceLoss of productive landLand contamination from wastes

Pest plants and animals Pest plants and animals(can lead to native pasture declineand erosion)

Forestry operations Depletion of forest resourcesErosion and chemicalcontamination of soils

Mining Depletion of mineral resourcesDisturbed land

Land contamination from wastes

1.2 Landscape health There is considerable evidence that the condition

and productivity of Queensland’s lands have

declined over time (e.g. Mills et al. 1989; Tothill &Gillies 1992). The health of the landscape in

Queensland reflects current and historic land-use

practices (see section 2.2 for history of

development and section 4.2 for some current

effects of land-use practices). In reporting on thestate of the environment in Queensland, the

Environmental Protection Agency (EPA 1999c)

recorded the contribution of some agriculturalpractices to soil erosion and structure decline,

salinity, soil acidification (table 1.2), and native

pasture decline. In a collaborative report, the

Australian Conservation Foundation and NationalFarmers Federation (Virtual Consulting Group &

Griffin nrm 2000), identified the degradation of

Australia’s resource base and environment as a

national issue and not just a farming issue, with

profound economic, social and ecological impacts.They estimated the annual cost of degradation as

at least $2 billion, with potential to increase to

$6 billion annually by 2020 (see table 1.3). In theiranalysis, they identify production benefits and

other benefits that reside mostly in the domain of

the public, and recommend strategic investment by

both government and the private sector.

Table 1.3 Cost estimates of land and water degradation.Source: Virtual Consulting Group and Griffin nrm (2000).

Form of degradation Estimate($ million per year)

Salinity 270

Acid soils 300

Sodic soils or structural decline 200

Erosion 80

Irrigation salinity 65

Water quality 450

Total 1 365

The EPA (1999c) identified a number of landdegradation factors, including pest invasions,

vegetation clearance, urbanisation, land

contamination, forestry and mining and their

relationship to the condition of land resources (seetable 1.4). A number of these ecosystem health

issues are explored in greater detail in section 3.2.

While tree clearing is a factor in land degradation

issues, particularly in regard to loss of biodiversity,deterioration and degradation of pastoral lands is

primarily attributed to inappropriate land

management practices. For example, de Corte et al.

(1991), reported extensive soil erosion andincreases in woody weeds in a survey area where

tree clearing was very limited.In an assessment of the condition of northern

Australian pasture communities in 1991, Tothill

and Gillies (1992) recorded the condition of



5

Table 1.5 Assessment of condition of rangelands in northernQueensland in 1991. Adapted from Tothill & Gillies, 1992.

Condition assessment1991 (%)

Pasture Sustainablecommunity condition Deteriorating Degraded

Plume sorghum 90 5 5

Schirizachyrium 22 66 12

Rainforest 40 50 10

Heathland pastures not assessed

Bladygrass 17 62 21

Black speargrass 32 52 16

Ribbongrass 95 5 nil

Aristida–Bothriochloa 50 33 17

Seasonal riverine plains 40 40 20

Brigalow pastures 40 37 23

Gidgee pastures 35 32 33

Queensland bluegrass 26 36 38

Bluegrass–browntop 20 75 5

Mitchell grass 58 33 9

Spinifex 52 34 14

Mulga—perennial shortgrass 19 52 29

Georgina gidgee 70 20 10

Saltwater couch 90 5 5

Mulga—annual shortgrass 20 40 40

Many ecological processes are poorly understood

for most of Queensland’s native vegetation

communities (Australian Science and TechnologyCouncil 1993), particularly the relationship

between tree clearing and hydrology, nutrient

cycling (Harrington 1990) and native fauna (Recher& Lim 1990). Tree clearing has been identified as asignificant factor in the loss of biodiversity, salinity

risk, changes in nutrient cycling, missed production

opportunities (as well as gains), and reduced water

quality (e.g. EPA 1999c; RIRDC 2000).

1.2.1 Rate of clearing

An essential part of determining the impact of

vegetation clearing is having accurate data aboutthe extent of land clearing and overall vegetation

cover. In 1995 the Queensland Department of

Natural Resources (DNR) initiated the StatewideLandcover and Trees Study (SLATS) to monitor thechange in woody vegetation cover over Queensland

(DNR 1999b). Landsat Thematic Mapper (TM)

imagery (30 m resolution) is used to compare the

vegetation cover between 1988, 1991, 1995, 1997and 1999 over the entire State. Images are analysed

using a combination of automated and manual

interpretation techniques on computer workstations.

This is followed by a period of field checking foreach satellite scene. To date, the 1991–95 and

1995–97 change detection has been completed for

the entire State (DNR 1999a, DNR 1999b).

Describing the period between 1995–97, the DNR

(1999b) reported an average annual State-wideclearing rate of 340 000 ha/year (see figure 1.2,

p.10), which is an increase on the 1991–95 average

of 289 000 ha/year. The current preliminary

estimate of 1988–91 clearing is 475 000 ha/year(25%) (DNR 1999b). The greatest proportion of

clearing occurred in the brigalow belt bioregion with

this accounting for 57% of total clearing. By

combining clearing data with Digital Cadastral DataBase and Tenures Administration System data, DNR

(1999b) reported that during the 1995–97 period

approximately 40% of clearing occurred on

leasehold land, 57% on freehold land and theremaining 3% on Crown land and other tenures.

The 1995–97 rate of clearing on leasehold tenure

was 12% less than the 1991–95 rate, while on

freehold tenure it increased by 54% (DNR 1999b).

In their analysis of vegetation change data, DNR(1999b) reported that approximately 86% of woody

vegetation change was clearing of woodyvegetation to pasture. However, there was a

significant increase in the proportion of landcleared for cropping between 1991–95 and

1995–97 from 4 to 9% respectively.

An important consideration in assessing clearing is

determining the proportion that was regrowth

treatment of areas previously cleared. In the SLATSreport, the proportion of 1995–97 clearing for

regrowth control could not be accurately

calculated, requiring the analysis of earlier

sequences of imagery. However, using 1988 and

1991 imagery, DNR (1999b) did identify that aminimum of 18% of the 1995–97 clearing was

regrowth control. This proportion may increase as

earlier imagery is analysed and older regrowthidentified. A partial analysis based on EPA’s

remnant vegetation mapping (see section 1.2.2)

indicates that regrowth control may account for

30–40% of clearing.

The report was also able to detect a significantamount of natural tree death in the area covered by

Dalrymple Shire (west of Townsville) due to a

prolonged drought. In total, an area of 69 000 hawas affected over the period 1991–97, with mostdeath believed to have occurred in the 1994–97

period (DNR 1999b).



7

1.2.2 Current extent of regionalecosystems

The Queensland Herbarium has been producing

vegetation maps and survey reports since the early

1970s. This program has been accelerated during

the 1990s as the lack of vegetation mapping oversubstantial parts of Queensland has limited the

scope and quality of land use decision making

and sustainable land management. The informationderived from this survey and mapping has a widerange of uses, but is particularly important in

determining the previous and current extent,

and therefore conservation status, of regional

ecosystems.

This section gives a summary of statistics derivedfrom this survey and mapping completed to April 5

2000, on the remnant area and clearing rates by

the Vegetation Management Act 1999 (Qld) status

across the bioregions of Queensland (see table 1.6and figure 1.3, p.11). Details about the surveying

mapping methodology are outlined in appendix 3.

It is estimated that in 1995 approximately 81% of

the State was covered by remnant vegetation (see

table 1.6).

The amount of remnant vegetation acrossindividual bioregions ranged from 30–40% in the

New England Tableland, Brigalow Belt and

Southeast Queensland regions to 98–100% in the

Channel Country, Northwest Highlands and CapeYork Peninsula regions (see figure 1.3, p.11).

The amount of remnant vegetation varied acrossprovinces within bioregions (figure 1.3). The

Brigalow Belt in particular showed the highest

variability with the amount of provinces clearedranging from less than 15% to over 90%.

The amount of remnant vegetation varies across

different ecosystems within bioregions (see table

1.6). Under the Vegetation Management Act 1999

(Qld) status classification, as at January 2000 it isestimated that:

• approximately 1 000 000 ha (approximately

0.5% of the State) are classified as endangered

regional ecosystems (<10% of preclearing extent

remains or, 10–30% if total remnant area is<10 000 ha). Of this, about 500 000 ha occur on

freehold land, 370 000 ha on leasehold land, and

114 000 ha on protected areas, reserves, State

forest etc.

• over 4 000 000 ha (2.5%) are classified as ‘of

concern’ regional ecosystems (10-30% of

preclearing extent remains or >30% if total

remnant area is <10 000 ha). Of this, about1 700 000 ha occur on freehold land,

1 800 000 ha occur on leasehold land and500 000 ha occur on reserves/State forests etc.

• over 650 000 ha of the ‘of concern’ regional

ecosystems have greater than 80% of theirpreclearing distribution remaining. These

ecosystems are listed because of their limited

extent, but are often not suited to, or are

currently threatened by, land clearance (e.g. thiscategory includes many naturally restricted

heathlands and shrublands that occur on skeletal

soils).

In the 1995–97 period about 7% (17 000 ha) of the

total amount of remnant clearing occurred in‘endangered’ ecosystems, while 33% (77 000 ha)

occurred in ‘of concern’ ecosystems, and the

remaining 60% (142 000 ha) occurred in ‘no

concern at present’ ecosystems.

These clearing figures differ from those on totalwoody vegetation reported previously (see section

1.2.1). They do not include the clearing of non-

remnant (e.g. ‘regrowth’) woody vegetation and

some areas of remnant clearing that are beyond the

scale of mapping (<5 ha), but do include theclearing of non-woody vegetation. In the 1995–97

period, about 60–65% of the total 340 000 ha of

woody vegetation that was cleared occurred in areasmapped as remnant vegetation by the herbarium.



8



9Figure 1.1 Native pasture communities. Source: DNR.

Pasture sparse or absent

Bladygrass

Black speargrass

Queensland bluegrass

Brigalow pasture

Aristida–Bothric

Gidgee pasture

Mulga pasture

Mitchell grass

Spinifex

Channel pasture

Bluegrass–browntop

Schizachyrium pasture

Native sorghum

Native pasture communities



10 Figure 1.2 Average annual clearing rate (1995–97). Source DNR 1999b.



11Figure 1.3 Map of Queensland showing the percentage of each province covered by remnant vegetation. Data used is remnantvegetation mapping by the Queensland Herbarium completed April 2000. Source: EPA.



12 Figure 2.1 Land Tenures in Queensland (1997). Source DNR 1999b.



13

2 Land tenure and legislation

Contributors

Land tenure and legislation


Mirranie Barker, Department of Natural Resources

Native title issues

Cyril Cordery, Department of Natural Resources

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14

Summary This section discusses the differences between

freehold and leasehold tenures, the history of land

management in Australia with particular reference toQueensland, opportunities for managing vegetation

under different tenures and legislation that effects

native vegetation management in Queensland.

• Property rights at law are the relationship that

an individual has with an object.

• Under freehold tenure, the landholder, in effect,

‘owns’ the land, although ownership is not

absolute as the State retains certain rights to the

land e.g. mineral rights which may be exercisedat any time. The State may also control land use

with legislation.

• Under leasehold tenure, land is leased from the

freehold owner (often the State), under strict

conditions, for a defined period, and rent isusually payable. Leasehold tenure, and the

conditions under which these leases are held,are administered under the Land Act 1994 (Qld).

• Approximately 68% of Queensland is held under

some form of leasehold tenure.

• Early European settlement saw the developmentand clearing of considerable areas. Early clearing

of properties involved the cutting and ringbarking

of trees to improve pasture growth, but little

emphasis was placed on utilising the clearedtimber. Early legislation sought to realise the

commercial value of timber cut on properties. In

the mid 1900s, various schemes such as theBrigalow Land Development Scheme, were run toencourage development of the land. This

included encouraging the clearing of large areas

of land to secure ownership. Subsequent

legislation has been developed to protect andsustain native vegetation values.

• Currently in Queensland, the Broadscale Tree

Clearing Policy governs the clearing of trees on

leasehold land. A lessee must obtain approval to

clear under the Land Act 1994 (Qld). Anapplication for clearing must be accompanied by

a tree management plan detailing the type, area

and location of vegetation proposed to be cleared.

• On the proclamation of the VegetationManagement Act 1999 (Qld), amendments to theIntegrated Planning Act 1997 (Qld) (IPA) will

require that owners of freehold land submit an

application before clearing vegetation, although

there are several important exemptions.

• At the Commonwealth level, there are a number

of policy and legislative documents that relate tovegetation management. These include a

national framework for Management and

Monitoring of Australia’s Native Vegetation and

the Environment Protection and Biodiversity Conservation Act 1999 (Cwlth) (EPBC), which has

implications for management of native vegetation

in Queensland. The EPBC provides that actions

deemed likely to have a significant impact on theenvironment are subject to a rigorous

assessment and approval process. This has the

potential to protect threatened species and

ecological communities.

• Other State legislation important to nativevegetation management includes:

- Nature Conservation Act 1992 (Qld)

- Water Resources Act 1989 (Qld)

- Integrated Planning Act 1997 (Qld)

- Rural Lands Protection Act 1985 (Qld)

• There are several native title considerations to be

made with respect to vegetation management.

After the ‘Mabo’ decision in the High Court in

1992, it was recognised that the Crown does nothold absolute title over all land, and that the

rights of the Aboriginal and Torres Strait Islander

people, according to their laws and customs,

should be recognised. The Native Title Act 1993(Cwlth) (amended in 1998) recognises native title

rights, provides validation for past acts that may

be invalid under native title, and provides a

process by which claims for native title andcompensation can be determined.

• Cultural heritage values, which are independent

of tenure, may require conservation and

management to protect their cultural heritage

significance. Legislation providing for this iscurrently being drafted.

• The Land Act 1994 (Qld) also makes provisions

for the consideration of both native title and

cultural heritage values in assessing tree-clearing

permits.



The Act makes certain provisions relating to

leasehold interests. They include:• the duration of a term lease shall be no greater

than 50 years, or 100 years in some

circumstances (Land Act 1994 (Qld) s. 155)

• an obligation to pay rent to the State (Land Act 1994 (Qld) Chapter 5, Part 1)

• obligations to fulfil lease conditions that may

cover a variety of matters from residency to

development and improvements (Land Act 1994(Qld) Chapter 5, Part 2). These conditions are

usually negotiated with the lessee

• lease conditions can be reviewed every 10–15

years for new leases under the Land Act 1994(Qld) (s. 211)

• restrictions on land use in accordance with lease

conditions and the purpose of the lease (Land Act 1994 (Qld) s. 153 and Chapter 5, Part 2,Division 1)

• restrictions on who may hold certain lease types

(e.g. corporations cannot hold grazing

homestead perpetual leases) (Land Act 1994(Qld) Chapter 4, Part 2, Division 2)

• restrictions on subdivision of leases (Land Act 1994 (Qld) Chapter 6, Part 4, Division 5), which

relates to maintaining viable property sizes• aggregation controls also apply to certain lease

types, for example, no more than two living

areas of grazing homestead perpetual leases can

be held by an individual (Land Act 1994 (Qld)s. 146)3

• a liability to forfeiture of the lease for non-

compliance with lease conditions of the Act,

non-payment of rent, or if the lessee acquiredthe lease by fraud (Land Act 1994 (Qld) s. 234).

Approximately 68% of Queensland is held under

leasehold tenure. The balance of land is made up of

freehold estates and a small proportion under other

tenures (table 2.1 and figure 2.1, p.12). The Actallows for the conversion of leasehold land to

freehold tenure by application, unless the lease is

over a reserve or is a term lease granted for

pastoral purposes (Land Act 1994 (Qld) Chapter 4,Part 3, Division 3—Conversion of tenure). A lessee

may be entitled to pay the purchase price off over aterm of years, with the maximum term to repay

being 30 years (DNR 1998a).

Table 2.1 The area of land covered by different tenures in1997. Adapted from DNR (1999b).

Tenure Area (km2) %Queensland

Leasehold 1 184 435 67.9

Freehold 424 641 24.3

Other tenures (Commonwealthlands, mining tenures, main

roads, water, railways, ports,action pending, etc) 23 292 1.3

Other reserves (State forest,timber reserves, national parks) 114 017 6.5

Totals 1 746 385 100.0

2.1 Leasehold and freehold tenures

The common understanding of property in western

societies is that a property owner has a right to

exclusive ownership and control. At law, however,

‘property’ is defined not as the object or land itself,but the relationship that an individual has with that

object (Hepburn 1998). In essence, a landholder

does not own the land, but a bundle of rights to

that property. These principles operate inQueensland historically at common law (‘unwritten

law’ based on custom or court decisions) and are

incorporated in statute law. At common law there

are two doctrines that govern these legallyenforceable property rights:

• The doctrine of tenure provides that radical or

ultimate tenure (cf. beneficial ownership) to all

land is vested in the Crown2, and the landholdermerely holds land ‘of the Crown’.

• The doctrine of estates provides that alandholder does not own land, but an estate in

it. In essence, an estate is a right to possessionor enjoyment for a defined duration (Tooher &

Dwyer 1997).

Freehold land is the most complete alienation of

land from the State, although ownership is not

absolute, as the State is empowered to withholdcertain rights e.g. mineral rights. In addition, use of

the land may be controlled by legislation, for

example, the Integrated Planning Act 1997 (Qld), and

Local Government Act 1993 (Qld). (DNR 1998a).

Leasehold tenure is the right to use land for theduration of the lease, after which time the land

reverts to the freehold owner (which may be the

State). Under leasehold ownership, rent is generally

payable and conditions of use may be imposed bythe lease agreement.

The distinction between freehold and leasehold

tenure is significant for the management of native

vegetation in Queensland, as each tenure type

offers different avenues for State legislative controls.

In Queensland, the Land Act 1994 (Qld) (the Act)

regulates the administration and management ofnon-freehold land (in particular, leasehold land), as

well as the creation of freehold land. There are

three main types of leases under the Act:• term leases (for a term anywhere between 1 and

100 years)

• perpetual leases (held by the lessee in perpetuity)

• freeholding leases (these are leases where theissue of freehold title has been approved, but

freehold title is issued only after the lessee

finalises the payment of the purchase price).

15



16

Leases from the State are granted for a purpose,

e.g. business, grazing, pastoral and residentialdevelopment. In the case of leases granted for

pastoral purposes, the land may be used only for

grazing or agriculture. Although a lease is issued

for a particular purpose, the Minister may approvethe conduct of additional or fewer uses on the

subject land for the term of the lease. The Act also

provides a statutory obligation of a duty of care for

the land (DNR 1998a).

2.2 European settlement anddevelopment

We had at length discovered a country ready for theimmediate reception of civilised man, and fit tobecome eventually one of the great nations of theearth...Of this Eden it seemed I was the only Adam;and it was indeed a sort of paradise to me.Explorer Thomas Mitchell

The arrival of European settlers saw the succession

of a new culture to Australia. With it came aninherent tradition of land management and usesbased on European experience, and concepts of

sustainability that were not appropriate to the

Australian environment. The resulting impact of

development and management practices on theAustralian biota is widely acknowledged and

described (see section 1.2 Landscape health).

The economic development of the early colony, and

later the State of Queensland, was closely linked to

the pastoral industry. While the British ColonialOffice maintained a policy of government-

controlled settlement, squatters saw the

opportunity of millions of hectares of unoccupied

land and took what they could defend (Roberts1968). The new Queensland parliament faced early

conflicts, with pastoralists seeking large areas of

land and town interests seeking smaller holdings.

In 1860, a series of four land Acts were introducedto cover various aspects of land-use policy and

tenure. The primary aim of the initial legislation

was to ‘secure rapid, efficient and real

settlement...in pastoral land’ (Kingston 1965). The

Unoccupied Crown Lands Occupation Act 1860allowed for the creation of agricultural reserves

under the condition that basic improvements,

including housing, fencing and clearing beundertaken (Powell 1998). The Act provided that

the land should be stocked within twelve months or

be subject to forfeiture (Kingston 1965). This

emphasis on stocking and developing the countrycarried on into later legislation. Early pastoralists

used ring barking as a quick and cheap method of

improving pastures without the cost of cutting and

clearing timber. Much of the timber cleared from

pastoral lands was wasted. Sheep provided greaterreturns for significantly less effort than timber,

transportation of which was difficult. Trees were

believed to be an inexhaustible resource, so

wastage of timber on pastoral properties did not

initially concern the government (Bolton 1992;Powell 1998).

The early history of Queensland saw a government

preference for granting leasehold tenure for pastoral

land, while encouraging closer settlement for

agriculture with freehold tenure. This is stillreflected in the distribution of these tenures today

(see figure 2.1, p.12). Further, to encourage landdevelopment, a number of major government

settlement schemes and incentives, whichincorporated land clearing, were established for

land development. This continued until recently

with the Brigalow Land Development Scheme

running from 1960 to 1985. Under this scheme,allocated blocks of land were drawn in a ballot,

with winners having to demonstrate their ability to

develop the land. Clearing of large blocks of

vegetation was encouraged in property developmentplans, although there was some provision for

retaining areas for conservation purposes(Breckwoldt 2000).

Over time, improvements in the efficiency of

clearing methods, and agricultural research, enabledcost-effective development of a wider range of land

types. Early development was associated with

clearing for cropping and involved felling trees with

axes and the digging out or burning of tree stumps.The subsequent adoption of ring barking trees to

increase growth of pastures affected greater areas.

This phase of clearing lasted until the 1950s. After

World War II, the availability of heavy machinery

(surplus war equipment), and the development ofchemicals for stem injection, gave further impetus

to larger areas of land development. The

development and introduction of ‘improved’ pasturegrasses and legumes accompanied this, again

increasing the development of properties. Larger

tractors became available in the early 1960s and

were extensively used in the Brigalow LandDevelopment Scheme. Continued increases in the

power of machines enabled their use for clearing

eucalypt communities. Most clearing is currently

undertaken using a large chain pulled by two

bulldozers. Blade ploughs are particularly effectivefor regrowth control of root-suckering species, and

have become popular in Queensland since 1980,

despite their high cost. Increased stocking rates andcrop yields were achieved by the introduction of

new practices and technologies such as the

introduction of heat-tolerant and tick resistant

Brahman cattle breeds, new pasture species andnew crop varieties (Turner 1975; Breckwoldt 2000).

Few foresaw the possible environmental

implications of uncontrolled tree clearing during the

early history of Queensland. In 1803, the effects ofearly land clearing prompted Governor King toissue a proclamation forbidding the felling of trees

along rivers and watercourses in order to prevent



process. The EPBC Act contains an extensive

regime for the conservation of biodiversityincluding:

• identification and monitoring of biodiversity, and

the preparation of bioregional plans

• listing of nationally threatened species andecological communities

• the identification of key threatening processes.

The matters of environmental significance that areidentified as triggers for the Commonwealth

assessment and approval process includenationally threatened species and ecological

communities (Commonwealth of Australia 1999). It

is conceivable that individual plant species and

regional ecosystems could be included under this.An issue such as tree clearing could also be

included as a key threatening process. The

Commonwealth has also flagged its intention to

include greenhouse issues as triggers under theEPBC Act.

Other Commonwealth legislation that potentiallyaffects native vegetation includes:

• Australian Heritage Commission Act 1975 (Cwlth)

• Australian Quarantine Act 1908 (Cwlth)• Natural Heritage Trust of Australia Act 1997 (Cwlth)

• Natural Resources Management (Financial Assistance) Act 1992 (Cwlth)

• Primary Industries and Energy Research and Development Act 1989 (Cwlth).

Further, there is a considerable body of national

policies, strategies and plans also directly relating

to native vegetation management, most of which

have been negotiated between the Commonwealthand the States (table 2.2). Recently, the

Commonwealth has drafted the National

Framework for Management and Monitoring of

Australia’s Native Vegetation (Commonwealth ofAustralia 2000). An initiative of the Australian and

New Zealand Environment and Conservation

Council (ANZECC), the framework describes three

key elements to implement a unified goal inmanaging Australia’s native vegetation:

• desired native vegetation outcomes

• best practice management and monitoringmechanisms• work plans (actions and timelines for each

jurisdiction).

further erosion and flooding (Bolton 1992). Despite

large fines, the directive was clearly disregarded(Powell 1998). Other minority groups also voiced

concern that continued extensive tree clearing

would have a detrimental impact on climate and

rainfall (Powell 1998). Apart from a concern withthe impact of deforestation on climate, an influential

lobbyist group, the Acclimatisation Society of

Queensland, promoted the importation of exotic

species of plants and animals to ‘improve’ theAustralian environment.

The value of timber was later recognised, and by

1839 licenses were required to cut red cedar from

Crown lands. The Crown Lands Alienation Act 1876introduced prohibition on cutting a number oftimber species on vacant Crown land or pastoral

leases (Powell 1998). As timber became more

valuable, speculators would obtain cheap land,

remove all the timber and forfeit the selection(Frawley 1983). In 1884, new legislation sought to

claim a royalty on certain timbers cut fromleasehold interests. Though this was overturned in

1888, attempts in 1886 under the Crown Lands Act Amendment Act 1886, to reduce timber speculation

on selections, resulted in the limiting of timber

cutting without the Land Commission’s permission,

by payment of a royalty if the landholder sold thetimber within the first five years of the lease

(Department of Public Lands 1926; Powell 1998). It

became practice for genuine selectors to simply

destroy the timber, while speculators waited for thefirst five years before extracting the valuable timber

(Frawley 1983). This early control was aimed atCrown realisation of the commercial value of

timber.

2.3 Managing vegetationCommonwealth legislation and nationalpolicies

While States retain primary legislative power to

regulate management of natural resources, the

Commonwealth government has progressively

increased the extent to which it endeavours to

influence or support the policies of State andTerritory jurisdictions (Griffin nrm 1999). The scale

of some land and water degradation issues, as well

as obligations associated with international treatieson environmental issues (e.g. greenhouse and

biodiversity), are frequently the drivers in this

increased Commonwealth role. Of particular

significance to native vegetation, the CommonwealthEnvironment Protection and Biodiversity Conservation Act 1999 (EPBC), which comes into force in July

2000, has significant potential to impact on native

vegetation. The EPBC Act provides that certain

actions (i.e. a project development, undertaking oractivities) which are likely to have a major impact

on a matter of national environmental significance,

are subject to a rigorous assessment and approval17



18

Table 2.2 Key national policies, strategies and plans relevantto native vegetation. Source: Griffin nrm 1999.

1989 • Murray–Darling basin: NRM Strategy

1992 • Decade of Landcare Plan• Convention on Biological Diversity• Inter-governmental Agreement on the Environment• National Forest Policy Statement• National Strategy for Ecologically

Sustainable Development• United Nations Framework Convention on

Climate Change

1993 • National Landcare Program FrameworkPartnership Agreements

1994 • COAG Water Reform Framework

1995 • Wood and Paper Industries Strategy (includingcommencement of the Regional ForestAgreements processes)

1996 • Murray–Darling Basin Sustainability Plan• National Strategy for the Conservation of

Australia’s Biodiversity

1997 • COAG Heads of Agreement on Roles andResponsibilities for Environment

• Decade of Landcare Plan: National Overview• Kyoto Protocol to the United Nations Framework

Convention on Climate Change• National Weeds Strategy• Nationally Agreed Criteria for the Establishment of a

Comprehensive Adequate and Representative ReserveSystem for Forests in Australia

• Natural Heritage Trust Partnership Agreements• Plantations 2020 Vision• Wetlands Policy of the Commonwealth Government

of Australia

1998 • National Greenhouse Strategy

1999 • Great Artesian Basin Sustainability Initiative• National Principles and Guidelines for

Rangeland Management• Conservation of Australian Species and Ecological

Communities Threatened with Extinction: A National

Strategy (ANZECC Working Document)Feb 2000 • National Framework for the Management and

Monitoring of Australia’s Native Vegetation

May 2000 • UNCCD UN Convention to Combat Desertification

Queensland

Over the history of Queensland, the legislative and

policy emphasis, as it relates to natural resource

management, has shifted to a more formalrecognition of the need for sustainable land

management. While the early introduction of

conditions under which lands could be held was

aimed at the development and expansion of ruralindustries, the continuation of leasehold tenure in

Queensland has allowed continued legislative

control of the conditions of occupation. Broadscale

tree clearing was first regulated for most leaseholdtenures through the Land Act 1962 (Qld), which

required permits for tree clearing. Although there

was increasing emphasis on conservation values, it

was not until several major amendments in theearly 1990s that real emphasis was placed on

sustainability within Queensland legislation (Fisher

& Walton 1996). Sustainability concepts are now

embodied in the Land Act 1994 (Qld), and in otherState legislation.

In a review of native vegetation management and

monitoring practices undertaken in August 1999,five major pieces of Queensland legislation were

identified as important to native vegetation

management (Griffin nrm 1999):

• Land Act 1994 (Qld)• Nature Conservation Act 1992 (Qld)

• Water Resources Act 1989 (Qld)

• Integrated Planning Act 1997 (Qld)

• Rural Lands Protection Act 1985 (Qld).

Since the publication of that review, the VegetationManagement Act 1999 (Qld), which has significant

implications for managing native vegetation on

freehold properties in Queensland, has been passed.

Under the Land Act 1994 (Qld), a lessee is required

to obtain a permit to clear trees on leaseholdproperties (Land Act 1994 (Qld) Chapter 5, Part 6),

with specific exceptions (see s. 257). The Act

(s. 262) sets out matters that must be considered

when assessing an application for tree clearing.

These include local guidelines for broadscale treeclearing approved by the Minister or, in the

absence of local guidelines, the contents of a

Broadscale Tree Clearing Policy (BTCP) approved bythe Governor in Council. Thirty-four local

guidelines for broadscale tree clearing were

approved in 1997. These were repealed in

December 1999 at the same time that a new BTCPwas approved. The new policy increased the level

of protection for regional ecosystems with an ‘of

concern’ conservation status.

Legislative controls of clearing native vegetation

were recently extended to freehold land through theVegetation Management Act 1999 (Qld) which was

passed in December 1999, but at the time of

writing, had not yet been proclaimed. This Act

amends the Integrated Planning Act 1997 (Qld) tomake clearing on freehold land a form of

assessable development for which approval is

required. Exemptions from requiring approval apply

to clearing in certain circumstances (VegetationManagement Act 1999 (Qld) s. 84). These

exemptions include clearing of regrowth and

clearing or harvesting as part of a sustainableforest management operation. Applications areassessed for compliance with the requirements of

the Integrated Planning Act 1997 (Qld) using an

assessment code that forms part of a regional

vegetation management plan approved by theMinister (Vegetation Management Act 1999 (Qld)

Part 2 Division 3). If a relevant regional

management plan is not approved, an assessment

code that forms part of a State policy for vegetationmanagement is used. Note that under the Act

vegetation is defined as ‘a native tree’ or ‘a native

plant, other than a grass or mangrove’ (VegetationManagement Act 1999 (Qld) s. 8 ).



19

Table 2.3 Summary of legislation affecting rural land use, development and management. Adapted from Hyam 1995;Fisher and Walton 1996.

Act Area of control affectingland use/activity

Queensland

Aboriginal Land Act 1991 and Regulation Provide for the grant, and the claim and grant, of land asAboriginal land and for other purposes

Aborigines and Torres Strait Islanders (Land Holding) Act 1985 Titling and administration of traditional landsand Regulations

Beach Protection Act 1968 Regulates land use and land management of Queensland beaches

Coastal Protection and Management Act 1995 Adds a planning dimension to the measures contained in theBeach Protection Act 1968

Environment Protection Act 1994 Provides for the protection of the environment from a comprehensiverange of sources of environmental degradation in accordance withthe principles of ESD

Forestry Act 1959 Provides for the effective establishment and management offorest lands in Queensland

Integrated Planning Act 1997 Provides a system whereby any development may be approvedanywhere in the State through a uniform process based on asingle application

Land Act 1994 Consolidates the law relating to the administration andmanagement of non-freehold land and the creation of freehold land

Mineral Resources Act 1989 and Regulations An Act to encourage and regulate mining in QueenslandNative Title (Queensland) Act 1993 Mirrors Commonwealth legislation

Nature Conservation Act 1992 Provides for the management of protected areas and the conservationof endangered species

Property Law Act 1974 An Act relating to the law of conveyancing of property

Queensland Heritage Act 1992 Provides for the conservation of the cultural heritage and environment ofQueensland

Rural Lands Protection Act 1985 Provides for the management and control of plants and animals affectingrural land

Soil Conservation Act 1986 An Act that provides for the requirements for conservation of soil

Water Resources Act 1989 Provides for the construction and control of irrigation waters in Queensland

Commonwealth

Native Title Act 1993 Provides for circumstances in which native title has not been extinguished

at law

Under both the Broadscale Tree Clearing Policy forLeasehold land and the Vegetation Management Act 1999 (Qld), a clearing application must be

accompanied by a tree management plan (for

leasehold land) or a property vegetationmanagement plan (PVMP) (for freehold land) which

details the type, area and location of vegetation

proposed to be cleared.

Other State legislation that controls the

management and monitoring of native vegetation

includes:

• The Nature Conservation Act 1992 (Qld) which

provides for the issue of conservation orders on

any tenure in order to protect environmental and

conservation values, and provides for thedesignation of an area as being of major interest

or critical value.

• The Water Resources Act 1989 (Qld) imposes

controls over the clearing of beds and banks of

watercourses.

• The Rural Lands Protection Act 1985 (Qld)

identifies exotic woody weed species that are tobe controlled and allows landholders to control

these species without first seeking tree clearingpermits, provided the overstorey trees are not

removed.

• The Fisheries Act 1994 (Qld) provides that a

person must not remove, destroy or damage a

marine plant without a permit (s. 123). Burning

salt couch and pruning mangroves are used asexamples of unlawful damage. Grazing salt

couch could be construed as ‘damage’ under this

definition. ‘Marine plant’ is defined broadly, to

include ‘a plant (a tidal plant) that usually growson, or adjacent to tidal land; whether it is living,

dead, standing or fallen; material of a tidal plant,

or other plant material on tidal land; a plant, ormaterial of a plant, prescribed under a regulationor management plan to be a marine plant,

(s. 8(1)). This definition allows for plants

adjacent to tidal land, such as melaleuca forests

in freshwater wetlands contiguous with tidalland, to come under the provisions of the

Fisheries Act 1994 (Qld), with respect to

vegetation disturbance.

Local government

Local governments may also regulate native

vegetation management through ordinances andpolicy instruments that affect all tenures in urban

and peri-urban areas. For example, the Brisbane City

Council is progressively introducing a number of

planning and policy instruments to protect



20

vegetation: Vegetation Protection Ordinances (VPOs),

zoning controls and requirements, strengthening ofVPOs under the IPA, the Brisbane City Bushland

Acquisition Program and Community Partnerships.

2.4 Other legislation There is a considerable body of legislation,

including planning law, which impacts upon, or

controls activities on rural land holdings (see table2.3). A considerable proportion of this

contemporary legislation reflects developments in

environmental law, and embraces many of theconcepts of sustainability (see section 3.1

Ecologically sustainable development).

Native title issues

As discussed in section 2.1, on European

settlement in Australia, the Crown was deemed to

acquire radical title to all lands in the colony, andabsolute title to all uninhabited lands. However, the

High Court, in Mabo and Others v. Queensland (No. 2) (1992) 175 CLR 1, held that not all land

rights derive from a Crown grant. A majority of theCourt held that the common law of Australia

recognises a form of native title to the land. Native

title is the recognition of rights, which are held by

Aboriginal and Torres Strait Islander peopleaccording to their laws and customs. The common

law provides that the Crown could extinguish

native title by valid exercise of their sovereign

power by one of the following:• legislation

• granting a tenure (such as private freehold)which is inconsistent with the continued

existence of native title• using the land in a manner inconsistent with the

continued existence of native title.

In practice, native title is not an issue in respect of

valid private freehold grants, but is an issue that

must be assessed in respect of dealings involvingall other lands. Whether native title does, or does

not, survive on a given parcel is therefore a

question of fact, not of policy or discretion by

governments, and depends upon two mainconsiderations:

• whether there has been a lawful extinguishment

of that title

• whether the relevant Aboriginal or Torres StraitIslander people have maintained a continuous

connection with the land.

The Australian Government gave a legislative

response to the Mabo decision by passing theNative Title Act 1993 (Cwlth). The objects of the

legislation were to:

• validate past acts which may otherwise be

invalid due to the existence of native title• set the standards for future dealings with land

where native title exists

• recognise and protect native title and provide for

its coexistence with land management systems• establish a mechanism for determining claims to

native title and for compensation where native

title has been extinguished or impaired by past

acts.

Following the commencement of theCommonwealth Native Title Act, the High Court, in

Wik Peoples v. State of Queensland (1996) 141 ALR129, held that the grant of a pastoral lease does not

necessarily extinguish native title and that pastoralleases may coexist with native title. This decision

meant that native title might potentially coexist

over a large number of leasehold properties. The

Commonwealth responded with the passing of theNative Title Amendment Act 1998.

Native title implications in respect of all dealings,

authorised or implemented by the Department of

Natural Resources, including tree clearing permits,

vegetation permits, sale of forest products and the

like, must be assessed with regard to the provisionsof the Native Title Act 1993 (Cwlth). The Land Act 1994 (Qld) also makes provision for both native

title and cultural heritage values (see Part 3 fornative title and s. 262(2)(k) for cultural heritage

values) to be considered in assessing a tree-

clearing permit.

Cultural heritage values

Native title and cultural heritage are different, and

are protected by various pieces of legislation.Cultural heritage values are independent of tenure

and may require conservation and management toprotect their cultural heritage significance. A draft

model for new legislation outlines possible ways toprotect cultural heritage as it relates to land and

water. The implications of the proposed legislation

with respect to native vegetation management are

potentially significant, but cannot be detailed untilthe proposed legislation is forthcoming.



3 National and international issues and their local impacts

Contributors

Ecologically sustainable development


Conservation of biological diversity

Rod Fensham, Environmental Protection Agency

Geoffrey T. Smith, Department of Natural ResourcesBruce Wilson, Environmental Protection Agency

Greenhouse effect

Beverley Henry, Department of Natural Resources

Lyn Allen, Department of Natural Resources

21

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• Biodiversity is crucial to maintaining a healthy

landscape, providing useful products andmaintaining critical ecosystem services such as

pollution breakdown and absorption, water

quality, pollination, natural pest control and

nutrient cycling. Natural biodiversity providesecosystems and landscape with resilience

against extreme (local) events.

• A National Strategy for Conservation ofAustralia’s Biodiversity has been developed. In

Queensland, biodiversity conservation isincorporated in planning and management

strategies at all government levels. Conservation

of regional ecosystems and their role as

surrogates for species is an importantcomponent in biodiversity management and

protection strategies in Queensland. However,

comprehensive strategies plan and manage

biodiversity at a range of levels and scales.

Greenhouse effect

• The warming of the earth’s atmosphere as a

result of the release of greenhouse gases such as

methane and carbon dioxide has increased overthe past 200 years, resulting in changing

temperature and rainfall patterns, and rising sea

levels.

• The global response has been the signing of the

Kyoto Protocol, where countries madecommitments to reducing emissions to a certain

percentage below 1990 levels by 2008–12, with

Australia’s target being 108% growth on the

1990 emission level.

• Australia is undertaking action through the

National Greenhouse Strategy (NGS), including

measures in relation to sinks, directed at

reducing land-based emissions and enhancingsequestration in vegetation and agricultural soils.

In response to NGS, the Queensland Government

has also developed the Queensland

Implementation Plan (QIP).

• The Australian Greenhouse Office has initiatedcalculations of land-based source and sinks in

the form of a National Greenhouse Gas Inventory(NGGI). A significant component of this is the

Land Use Change and Forestry sector (LUCF),which was responsible for approximately 20% of

Australia’s emissions in 1990.

• The Kyoto Protocol has provided for the concept

of carbon credits and carbon trading. Examples

of sinks that could generate carbon credits forQueensland include conservation of forests from

clearing or logging, and agroforestry. However,

eligibility for carbon credits from restrictions in

land clearing is yet to be determined.

Summary This section examines the national and

international issues of ecologically sustainable

development, biological diversity and thegreenhouse effect, as they relate to the management

of native vegetation. The issues are outlined in

general, together with local implications for native

vegetation management.

Ecologically sustainable development (ESD)

• The concept of ESD is defined in the Bruntland

Report, as ‘development that meets the needs ofthe present without compromising the ability of

future generations to meet their own needs’. The

Commonwealth Government and the State

Governments have accepted ESD, leading to theformulation of a National Strategy on ESD,

providing core objectives and guiding principles

across a broad range of issues.

• There has been discussion as to whether thestrategy provides the necessary framework formajor institutional changes and changes in

current production–consumption patterns.

Associated with this debate is the definition of

ESD itself, which has been criticised as beinglimited in terms of its operational component, so

not providing for the aforementioned necessary

changes. Emphasis remains on the need for

meeting material wants and sustaining economicgrowth, with biotic communities and ecosystems

being valued only incidentally.

• Despite these problems of definition, ESD is thestated primary objective of most land-use

management.

• A review by the Productivity Commission in 1999found that there is a lack of clarity in

Commonwealth departments and agencies as to

what constitutes ESD-related policy, a lack of

long-term focus, and failure to follow ‘goodpractice’ policy-making principles.

• The agricultural industry has developed a

number of sustainability indicators both at the

regional, national and on-farm levels. Theindicators are related to the profitability,managerial skills and off-site impact of

agricultural land use, and the land and water

quality required to sustain production.

Conservation of biological diversity

• Biodiversity has been defined as the variety of

life in all its forms—the different plants, animals

and micro-organisms, the genes they contain

and the ecosystems or assemblages they form.Traditionally, biodiversity has been considered on

the genetic, species and ecosystem level, but isnow also considered on the landscape level, in

recognition of the complex interactions thatoccur across a landscape.

22



3.1 Ecologically sustainabledevelopment

What is ‘ecologically sustainabledevelopment’?

In reporting on the state of the environment inAustralia, sustainable development was identified

as the ‘central issue of our time’ (DEST 1996). With

both the environment and agriculture showingsigns of stress (Tothill & Gillies 1992; IndustryCommission 1998) the need for systems of

sustainable land use is generally agreed to be

paramount (eg: McIvor 1990b; Williams 1990;

Pickup & Stafford Smith 1993; Dovers & Norton,1994a,b; Bishop et al. 1999). Concern for the

environmental impact of development globally has

led to international adoption of the notion of

ecologically sustainable development (ESD), whichseeks to integrate a range of environmental and

development issues. Determining the application of

this principle in practice is not straightforward, andhas implications for the retention and managementof native vegetation.

The notion of ESD has historical links to classical

economic theory, energy analysis and sustained

yield management modelling of indefinitely

renewable resources (eg: fisheries and forestry)(Dovers & Norton 1994a,b; Callicott & Mumford

1997). The concept gained international acceptance

with the United Nations World Commission on

Environment and Development (the Bruntland

Commission) in 1987. The commission’s reportoutlined how governments might achieve the

objectives of economic development and

environmental protection, and interpreted ESD as‘development that meets the needs of the present

without compromising the ability of future

generations to meet their own needs’ (World

Commission on Environment and Development1990). Following on from this initial report, a

number of international and national policy

documents have sought to further refine and

implement a global plan for sustainable

development. In 1992, the Australian Governmentfinalised its own National Strategy on Ecologically

Sustainable Development (NSESD) that was

subsequently endorsed by the QueenslandGovernment.

The NSESD defines ESD as:

Using, conserving and enhancing the community’sresources so that ecological processes, on which lifedepends, are maintained and the total quality of life,now and in the future, can be increased.(Commonwealth of Australia 1992b)

23

The core objectives of ecologically sustainable

development are:

• to enhance individual and community well-

being and welfare by following a path ofeconomic development that safeguards the

welfare of future generations

• to provide for equity within and between

generations

• to protect biological diversity and maintain

essential ecological processes and life-supportsystems.

The guiding principles are:

• Decision-making processes should effectively

integrate both long- and short-term economic,

environmental, social and equity

considerations.

• Where there are threats of serious orirreversible environmental damage, lack of full

scientific certainty should not be used as areason for postponing measures to prevent

environmental degradation.

• The global dimension of environmental impactsof actions and policies should be recognised

and considered.

• The need to develop a strong, growing and

diversified economy which can enhance the

capacity for environmental protection shouldbe recognised.

• The need to maintain and enhance

international competitiveness in anenvironmentally sound manner should berecognised.

• Cost effectiveness and flexible policy

instruments such as improved valuation,

pricing and incentive mechanisms should be

adopted.

• Decisions and actions should provide for broadcommunity involvement on issues which affect

them.

These guiding principles and core objectives need

to be considered as a package. No objective orprinciple should predominate over the others. Abalanced approach that takes into account all

these objectives and principles is required to

pursue the goal of ESD.

Box 3.1 The core objectives and guiding principles from theNational Strategy for Ecologically Sustainable Development(Commonwealth of Australia 1992b).



• consideration of the whole property as an

integral part of the geomorphic (hydrological andecological) processes (landscape) of which it is

part (eg: McIvor 1990b; Williams 1990; Pickup &

Stafford Smith 1993; Dovers & Norton 1994a,b;

Lefroy & Hobbs 1998; McIvor & MacLeod 1999;McIntyre et al. 2000; Simpson & Whalley 1999)

• promotion of better environmental outcomes,

(e.g. improved soil fertility, health and structure,

protection of biodiversity and ecosystemamenities, reduction of erosion, salinity).

It is generally acknowledged that in order to put

sustainability into practice, land managers and

developers need to acknowledge that the current

environment is the result of three factors:• evolutionary history (millions of years) including

that of historic and prehistoric humans

• biophysical parameters and processes (soil,

climate, nutrient cycling)• management parameters (percentage developed,

grazing type and pressure).It is important to distinguish between these

evolutionary and biophysical factors as they must

be planned for in management strategies, so thatmanagement factors can then be adjusted in order

to meet sustainability goals.

In the context of the grazing ecosystem,

sustainability would require land use to take place

in an ecologically conservative fashion, withinapparently safe limits that have been determined by

an integrated assessment of current and potential

threats (Dovers & Norton 1994a). In the absence of

sufficient ecological information, sustainabilityincludes the adoption of the precautionary

approach to environmental issues. The

precautionary principle requires that if the full

impact of a decision is unknown and theconsequences of that decision are irreversible, then

that decision should not be made.

A recent Australian workshop explored the

modelling of sustainable agriculture on natural

ecosystems. In addition to production, theconservation of land and water and to a certain

degree, biodiversity, is an outcome of theagricultural system, rather than an ameliorating

afterthought (Lefroy & Hobbs 1998). Production isdesigned using ecological assemblages based on

proportional representation of functional groups

(cf. taxonomic, biogeographic or aesthetic groups)

found in nature. As this does not necessarily meanlocal, indigenous species, care must be taken to

avoid using scenarios where weeds may become a

problem. In determining the level of biodiversity to

be imitated, the existing biota must be looked at inevolutionary terms. The difficulty in this approach

is the ability to retain mutualistic or cooperativefunctions that are generally lost in intensively

managed systems, and social and economicconstraints such as the slow rate of adoption by

The strategy provides core objectives, guiding

principles (see box 3.1) and a broad strategicframework for key industry sectors across a broad

range of issues. It seeks to integrate economic,

social and environmental concerns and provide

protection to the community based on the notion ofintergenerational equity. At a State level, various

Queensland Acts include sustainable development

in their purpose (see section 2).

Economists Constanza and Daly (1992) present an

alternative perspective, distinguishing growth as‘pushing more matter–energy through the

economy’ and development as ‘squeezing more

human want satisfaction out of each unit of matter

energy that passes through’. Economic growthequates to increased throughput, and sustainable

economic development to increased efficiency.

However, Callicott and Mumford (1997) note that a

‘no-growth concept’ of ESD could also be achievedby changing human wants to fewer material goods,

more amenities (clean air and water) and services(education), which would improve profits and

create jobs. This shift would facilitate ESD lessthrough production efficiency, but more from a

demand-driven shift in the economy. In a

Commonwealth inquiry into ecologically

sustainable land management, the IndustryCommission (1998) similarly identified the absence

or poor functioning of markets for key natural

resources (i.e. water, farm forestry, native flora and

fauna) and recommended improvement of thesemarkets (e.g. tradeable rights to water, separate

tenure for land and trees). CSIRO research in northAustralia, is identifying improved markets for

‘clean, green’ agriculture, to demonstrate theeconomic benefits of creating a niche market for

sustainable agriculture.

Sustainability can be simply defined as the ability

to maintain something undiminished over some

time (Callicott & Mumford 1997). Based on thisdefinition, Callicott and Mumford (1997) argue that

definitions need to be reconstructed bearing in

mind the inapplicability of the sustained yield

notion to most natural resources, which are

vulnerable to risks other than over-harvesting(e.g. land degradation).

Principles, assessment and indicators

While a useful definition of ESD can be debated ad

infinitum, other authors have circumvented these

difficulties by focusing on determining principles,assessment procedures (Bosshard 2000) and

indicators of sustainability (Dove 1997). There are

a number of guiding principles that are generally

accepted within the literature. Common elements ofapproaches to sustainable land-use planning

include:• identifying the best combination of sustainable

land uses for an area

24



landholders (Lefroy & Hobbs 1998). Dawson and

Fry (1998) assert that to be successful, such amodel needs to be based on scientific

understanding, to mimic the natural variability

found at farm and landscape scale and to be

designed within an adoption framework.

McIntyre et al. (2000) have formulated a set of

principles for sustainable management for grazing

in subtropical woodlands. The principles

incorporate ecological indicators for grazingproperties relating to soils, pastures, trees and

wildlife. For some of these principles, thresholds

were determined. Pickup and Stafford Smith (1993)

suggest an assessment process that is a stepwise,iterative application of procedure to determine

economic viability, ecological adequacy and social

feasibility. While they acknowledge that the

application is somewhat daunting, they suggest theprocess is valuable in providing a basis for

application based on current local knowledge, and

identifies many critical research issues. Dovers and

Norton (1994a,b) have also suggested criteria forassessing sustainability based on an ecological

framework.

Some authors have attempted to describe regionaland on-farm indicators of sustainability. For

example, table 3.1 details a set of indicators

developed under the following broad categories

developed by SCARM:• profitability (reflected by long-term, real, net

farm income)• land and water quality to sustain production

• managerial skills

• off-site environmental impacts (Dove 1997).

King et al. (in prep) described the work in Australia

on sustainability indicators as ‘an industry of itsown’. They identify a number of reasons why use

by farmers is limited, such as measurements being

meaningless to landholders, production agriculture

being viewed as separate to conservation

agriculture, the theoretical nature of indicators, lackof enthusiasm by farmers in measuring degradation

of their own farms, the threatening nature of the

subject of land conservation, monitoring beingperceived as negative by farmers, and the

perception by farmers that they are being assessed.

Key findings of this study were:

• that the knowledge of farmers in developingindicators has been largely ignored

• there are links between indicators used by farmers

and those developed through traditional science

• off-farm indicators used by farmers may beuseful in policy development.

25

Table 3.1 Sustainability indicators for agriculture (Dove 1997).

Regional/national indicators On-farm indicators

Profitability • Net farm income • Disposable income per household• Equity • Non-farm income• Productivity • Farm operating surplus as % land value• Term of trade • Farm income per hectare per 100 mm growing season rainfall

• Operating costs as % land value• Land value per household• Machinery value as % of farm income• Farm income per farm labour unit• Financing costs as % total income• Return on capital

Land and water quality • Water use efficiency • Water use efficiencyto sustain production • Nutrient balance • Acidification

• Enterprise diversity • Organic matter (Organic C%)• Native vegetation • Exchangeable sodium (Exch. Na %)• Rangeland condition • Soil erosion• Change in area of productive

agricultural land

Managerial skills • Farmer education level • Financial• Participation rate • Administration• Implementation of sustainable • Risk management

management practices • Land• Machinery• Staff management

• People skills• Crop and pasture production• Livestock production• Succession plan• Marketing• Farm safety

Off-site environmental impacts • Chemical residues in • Salinity of water leaving farm/districtagricultural produce • Nutrient in water leaving farm/district

• Salinity in streams • Health of livestock leaving farm/district• Dust storm frequency • Health of plants leaving farm/district

• Length of contact zonewith conservation areas



1983; McIvor 1990b; Dovers & Norton 1994;

ANZECC and ARMCANZ 1999). For manyresearchers and managers, the primary objective is

still the need to optimise production, although

there is some acknowledgment that management

trade-offs are paramount in preventing irreversibleland degradation (McIvor 1990b; Pickup & Stafford

Smith 1993; McIntyre et al. 2000). Other authors

consider that sustaining biodiversity should be the

primary concern of sustainability (Noss 1983;Dovers & Norton 1994a; Dovers & Norton 1994b;

Callicott & Mumford 1997; Callicott et al. 1999).

Their broad interpretation of ecological

sustainability for biological conservation involvesconverting natural resources (efficiently) into a

commercial commodity without running down the

natural capital (i.e. biodiversity, and

consequentially ecological services and function)beyond the degradation threshold (Tilman 1999b).

James et al. (1999) offer an economic costs

scenario likely to ensure the persistence of

biodiversity. Their analysis explores the costs insetting aside areas for restricted use, and in fencing

other areas for exclusion. They assert that this is a

‘modest investment in sustaining biodiversity’. Their

purpose was to explore ways in which productioncould (more or less) continue while biodiversity

protection was implemented.

Decisions about what proportion of a property to

develop in the rural context make up part of the

management parameters of sustainability. A greatdeal of debate about the appropriate amount of

vegetation to retain on properties gives rise toguidelines of between 20%4and 34% (Burrows et

al. 1988b; Walpole 1999; McIntyre et al. 2000) forvarious vegetation types and for various purposes

(wildlife habitat, shade and shelter, nutrient

recycling and erosion control) as part of

sustainable property management. The treeclearing guidelines determined by the VegetationManagement Act 1999 (Qld) and the Land Act 1994

(Qld) provide for a vegetation management

framework, while the stated purpose includesallowing for ecologically sustainable land use

(Vegetation Management Act 1999 (Qld) S 3.1 (e)).Based on the above analysis, conservation of

regional vegetation diversity alone cannot addressall facets of sustainable property management, and

must be included with a wider interpretation of

sustainable management. Statewide reductions in

clearing to achieve biodiversity outcomes will haveshort-term and long-term economic consequences,

and part of the challenge of sustainability is

ensuring the economic viability of landholders. The

challenge in implementing this legislation ismarrying the short-term profitability of the

property with the long-term goal of sustainability,and in this way incorporating sustainability of

biodiversity with sustainable property management.

Pickup and Stafford Smith (1993) have identified

the following difficulties in prescribing guidelinesfor sustainable land use:

• the scale at which properties are managed

• the variability of influencing factors

• lack of research information to provideconceptual models

• lack of effective techniques for measuring and

combatting land degradation

• a failure by bureaucracies to transmit aconsistent message to landholders

• land managers lacking the tools to help with

making decisions at the property scale.

Where principles are recommended, adoption of

these practices by landholders may be limited bythe following:

• character of the land

• economic constraints

• available technology• legal aspects of land use

• land tenure and management• production-focused government policies as

opposed to those that focus on the sustainabilityor fate of individuals (Hollick 1995)

• historical or cultural aspects.

In 1999, an inquiry was conducted to examine the

progress of Commonwealth departments and

agencies in incorporating ESD into their policy,decision-making processes, and day-to-day

operations (Productivity Commission 2000). The

overall progress of ESD implementation has been

variable, with the best examples in natural resource

management. The major impediments forimplementation were identified as being the lack of

clarity regarding what constitutes ESD-related

policies, failure to follow ‘good practice’ policy-making principles, lack of long-term focus and

often lack of tools to assist in policy making. Many

organizations regarded ESD as relating solely to

environmental issues, when in fact it has a broaderscope, including factors such as externalities and

open access resources with undefined property

rights (Productivity Commission 2000). The inquiry

recommended that improvement of ESD

implementation could be achieved by focusing onimproving the practices of policy making within

departments and agencies, improving coordination

between agencies and other stakeholders,undertaking regular monitoring and review of policy

initiatives, encouraging longer term strategic

thinking and developing a longer-term commitment

to monitoring environmental indicators(Productivity Commission 2000).

The current Queensland framework and theimplications for land managers

Despite the difficulties in defining sustainability as

outlined above, the notion has become a common

objective of natural resource management (Noss

26



3.2 Conservation of biologicaldiversity

Biological diversity: definition and values

Biological diversity, or biodiversity, refers to thevariety of life in all its forms—the different plants,

animals and micro-organisms, the genes they

contain and the ecosystems or assemblages they

form. Traditionally, biological diversity is consideredat three different levels: genetic, species and

ecosystem (Commonwealth of Australia 1993).

However, biodiversity is also defined in relation to

environmental and ecological distinctiveness andthe complex interactions that occur across a

landscape. The regional landscape level of

biological diversity is now well accepted (Noss

1990; Sattler 1993a) and is recognised in the Nature

Conservation Act 1992 (Qld).

Humans are dependent on biological systems and

processes, and derive their food, many medicines

and industrial products from both wild and

domesticated components of biological diversity.This diversity also underpins and sustains

functions important to maintaining a ‘healthy’

landscape. This functional role of biological

diversity, and the suite of processes that make upthe complex interacting system of the earth

according to how it supports humans, have been

collectively referred to as ‘ecosystem services’ (e.g.

Daily 1997). These services are such pervasivefeatures of the environment that they are often

assumed to be constant until they break down orbecome depleted (Mooney & Ehrlich 1997). Indeed,

it is the global extent of emerging land degradation,poor quality surface water and declining wild

stocks that have focused international attention on

the functional roles of biodiversity (Baskin 1994,

Baskin 1997, Daily 1997).

What ecosystem services might include

Ecosystem services operate at a variety of scales,from global to local. Delineating the boundaries of

connected processes is difficult, if not impossible.

Examples at a local level include the role of birdfauna in maintaining insect populations at levelslow enough to prevent defoliation and associated

dieback of eucalypts in northern New South Wales

and Victoria (Ford 1990; Loyn 1987), and native

ants improving recruitment of grass species in theMitchell Grass Downs region (Phelps & Phelps

1999). Other examples of global ‘services’ provided

by biodiversity include pollution breakdown and

absorption, soil formation, nutrient cycling,recovery from unpredictable events, contribution to

climate stability and protection of water resources

(table 3.2).

Does biodiversity matter to ecosystemservices?

The importance of biodiversity to the functioning of

ecosystems has been identified by a number of

authors (e.g. Daily 1997; Naeem 1998). Biologicaldiversity can be measured by assigning organisms

to functional groups by trophic level, guild and

other ecosystem roles or outputs (Naeem 1998).

These groups are arguably of greater importance indetermining the role of biodiversity in providing

ecosystem services than in the identity of their

component species (Ewel et al. 1991; Ewel 1986).

Four conclusions emerge from theoretical modellingand field research on the role of biodiversity in

ecosystem function. They are:

1. Species richness adds to the net ecosystem

productivity up to a (small) number of species,

beyond which the level of productivity remainsfairly constant (Tilman et al. 1996; Tilman 1997).

Productivity increases more with diversity offunctional groups than with increases in

randomly selected species because of theimportance of complimentary niche roles and the

interactions among selected species (Loreau

1998; Hector et al. 1999).

2. Resilience to the impact of extreme (local) events

is enhanced by greater regional biodiversity, asthe functional ‘short-fall’ on the loss of

individual species can be filled by other species,

and so biodiversity has an element of

redundancy (Naeem 1998). Greater (regional)

species richness is an insurance against theimpact of extreme (local) events (Yachi & Loreau

1999; Petchey et al. 1999; Hector et al. 1999;

Tilman 1999a).

3. Local extinctions or reduction in biomass (withinfunctional groups) can trigger loss of ecosystem

functions, degradation or collapse and the

transition and ‘run-down’ to a new equilibrium

with a lower level of productivity (Westoby 1989,Ash et al. 1997; Tothill & Gillies 1992).

4. Simplified human-managed ecosystems are

efficient producers of target products, but tend tobe inefficient with regard to such services as

maintenance of soil fertility (i.e. losing soil,nutrients and water) (Baskin 1997; Paoletti et al.

1992).

Diversity can be increased by the introduction of

exotics, although it may increase only temporarily

beyond that of the natural ecosystem after which itcan decline, depending on the competitive

advantage of the exotic species. Australia’s species

richness has increased by >2700 alien plants (Low

1999), including many useful to agricultural

production (Bridgewater 1990; Tothill & Hacker1996), yet few would argue that this has been

entirely beneficial (EPA 1999c).

27



technology. The challenge is to improve economic

production and halt or reverse degradation.

Identifying threats to ecosystem functioning,

predicting outcomes and assessing risk is difficult.When does a phenomenon constitute a degrading

process or a temporary disturbance? How should

biodiversity be managed in order to maintain the

resilience that permits an ecosystem oragroecosystem to recover from a disturbance?

(Sousa 1984). Cause and effect can be separated by

kilometres (e.g. down a river) or generations into

the future, complicated by lag effects and feedbackmechanisms (see for example section 4.2.8

Salinity). However, environmental modelling,

together with appropriate survey capability can

Threats to ecosystem functioning

The complete replacement of the life support

functions of the biosphere with a synthetic

analogue is a technical impossibility. Even thesmall-scale experiment ‘Biosphere 2’ (Marino &

Odum 1999; Alling et al. 2000) demonstrated the

difficulty, or futility, of building a self-perpetuating

functioning ecology on a planetary scale. But no-one is proposing to eliminate the entire biosphere.

Rather, rising human population, falling terms of

trade and concern for the future drive attempts to

increase the efficiency of resource use whilelimiting further degradation. Agricultural

efficiencies can be raised in terms of yield/ha (if

not yield/input) with the application of modern

28

Table 3.2 Categories of ecosystem services derived from biodiversity.

Ecosystem service Details

Global

Atmospheric composition and climate • Plants play an integral role in atmospheric cycling through photosynthesis, respiration andtranspiration (See section 3.3 Greenhouse effect).

• Local patterns of precipitation and temperature effects may include proximity to the ocean,topography and vegetation cover (Meyer-Homji 1992; Smith 1994; Smith et al. 1992;Williams 1991).

• Sustained reduction of rainfall following clearing, based on loss of function of vegetation cover

to water balance regulation through increasing the height of the planetary boundary layer,heat fluxes, evapotranspiration (Lyons et al. 1993) and release of aerosols demonstrated in theWestern Australian wheatbelt (Chambers 1998).

Cycling of water, nutrients and • Cycled essential elements include carbon, nitrogen, phosphorus, potassium, magnesium,atmospheric chemical elements manganese, calcium, sulphur and sodium.

• Living organisms make a major contribution to rendering these and other nutrients available asorganic compounds or soluble ions.

• The same processes and the chemical attributes of the biosphere are essential to water andair purification (Daily et al. 1997).

Genetic library • Provision of a gene pool contributes both directly (medicine, food, resilience to disease andpests) and indirectly (continuation of evolutionary processes).

Regional and local processes

Natural resources/production inputs • Plants concentrate nutrients and other complex molecules required from inorganic sources,which consumer organisms generally are not capable of synthesising (Dorit et al. 1991).

• Non-food resources supplied by ecosystems include fossil fuel, timber, paper, fibre for textiles,

chemicals for industry and pharmaceuticals.

Soil formation, fertility and retention • Living decomposers turn dead organic matter, including potentially toxic plant products, toinorganic ions and humus, aiding soil structure, pore size, ped formation, nutrient store andbuffering the soil against pH changes (White 1997b).

• Some bacteria fix nitrogen from the atmosphere, while symbiotic mycorrhizal fungi improvethe ability of plants to utilise soil nutrients.

• Larger organisms bury and process organic wastes, improving the structure of the soil.(Baskin 1997; Daily et al. 1997).

Pollination and dispersal of plants • Worldwide, 91% of flowering plants are pollinated by animals, 8.3% are pollinated by wind orare self fertile and 0.06% are dispersed by water (Nabhan & Buchmann 1997)

• Pollination and seed dispersal are frequently mediated by animals (e.g. bats, insects and birds)in Australia. (Specht & Specht 1999)

Natural pest control • Herbivorous and wood-boring insects are preyed upon by predatory insects, spiders (Reichert& Bishop 1990; Reichert & Lockley 1984; De Barro 1992), insectivorous birds, micro batsand reptiles (Davidson and Davidson 1992).

• Intensive agriculture that has displaced natural systems entirely or that introduces massivedisturbance through the use of pesticides that attack non target (beneficial) species are veryvulnerable to pest damage (Carson, 1962; Pimental & Greiner 1997).

Hydrology and flood control • Vegetation can determine whether rainfall contributes to evapotranspiration and interception,soil surface evaporation, root zone storage, run-off and deep drainage (to groundwater)(White 1997b; Meyers 1996; DNR 1997).

• The control exerted over hydrology by percent cover and deep rooted perennial vegetation has

been evidenced in Australia in shorter and higher flood hydrographs and rising groundwatertables (Hobbs & Hopkins 1990).

Bioremediation • Wetlands vegetation (from unicellular algae to macrophytes that float or are anchored) inparticular have been demonstrated to purify water (Sainty et al. 1994)

• Efficient and/or hardy species from natural functional groups can be recruited (and bred) foruse in particular tasks such as treatment of urban run-off and natural processing of wasteproducts such as leachate and mining tailings (Sainty, et al. 1994).



contribute to regional and catchment-level risk

assessments. For example, a limited riskassessment for survival of selected (rare) species in

the aquatic ecosystems of the Fitzroy basin has

been made as part of the Water Allocation

Management Planning (WAMP) process (DNR1998b). However, extinctions of individual species

are only the final outcome of prolonged or

profound degradation (Recher 1999). Function loss

may arise once a species or functional groupdeclines or becomes an extinct keystone species

(Krebs 1994; Mooney & Ehrlich 1997). Ecosystems

don’t need to collapse entirely to impact on the

quality of ecosystem services or productivity(Hobbs & Hopkins 1990).

More intense agroecosystems tend to be less

complex than the natural ecosystems they replace.

These simplified systems are efficient in terms of a

target product but may lack the resilience orbuffering effect of native ecosystems. Monocultures

can be efficient and yet vulnerable to extremeweather events and disease. Extensive land use, or

utilisation of native vegetation for grazing orforestry varies in impact, depending on stocking

rates and grazing management or harvesting

regime (Wilson 1990). Further, it is possible to use

non-indigenous plants and animals to satisfyproduction as well as performing certain ecological

services, although this is often imperfect (see also

section 3.1). Adaptations to highly local conditions

are often seen to be optimal, however, the functionsand efficiencies of local species and communities

are also limited to natural variety and evolution. Indeciding ideal levels of management in terms of

replacing or adding species, continued delivery ofecosystem services should be an integral aim at

paddock, landscape and catchment scales. The

recognition that ecosystems respond to sustained

disturbance in a non-linear fashion has focusedattention on thresholds (McIntyre et al. 2000).

Cumulative incremental losses can degrade

ecosystem function (Saunders et al. 1991). If

threatening processes persist and/or interact,‘steady states’ can be pushed or suddenly degraded

to a point where productivity is permanentlyreduced to a new ‘equilibrium’. By identifying

thresholds, management can seek to stay withinsafe limits to avoid collapses or losses of function.

The species of naturally occurring communities are

a moveable feast, changing over time with

invasions and other disturbances and shifts such as

climate change. Others have argued that speciesare positioned along environmental gradients,

fulfilling particular or general ecological functions

regardless of their taxonomy or that of their

neighbours. Some geographic areas will perform atless than maximum ecological efficiency, defined as

biomass production, if a functional group is poorly

or not represented. For example, pasture

production can be increased in north Queensland

by the addition of vigorous exotic legumes.

However, such successful introductions can initiatea one-way directional shift. Legumes can change

environmental parameters such as pH

(acidification) and increase soil nitrogen (Cregan &

Scott 1998; Noble et al. 1997).

Agroecosystem design, development andmanagement will benefit from the strategic

retention of trees or regional ecosystems and theuse of ecological analogues in pastoral and

cropping systems. Future shocks and directionalshifts can be expected from sources such as global

climate change and outbreaks of weeds and

diseases. Intact native biota can be seen as a buffer

against rapid (detrimental) change and as a sourceof genetic resources.

Strategies for conservation of biodiversity

At an international level, the Convention on

Biological Diversity sets out the broad guidelines

and outcomes necessary for the conservation of

biodiversity. This convention was ratified byAustralia in 1996. Within Australia, biodiversity

conservation principles were incorporated into the

development of ecologically sustainable

development strategies (e.g. Commonwealth ofAustralia 1992b). Subsequently, a National Strategy

for the Conservation of Australia’s Biological

Diversity has been developed and has been

accepted by the Commonwealth, State and Territorygovernments (ANZECC 1993). This strategy sets

out broad directions covering a range of

substrategies and programs such as the National

Forest Policy, the National Reserve System, NationalHeritage Trust Programs and treaties such as the

Japan Australia Migratory Bird Agreement (JAMBA)

and others listed in table 2.2.

In Queensland, there is no overarching State-wide

strategy for the protection of biodiversity. However,biodiversity conservation is a component of a range

of planning and management strategies covering a

range of regions and levels of detail and

government. Examples include catchment, localgovernment, landcare, bushcare and property

plans, and regional planning initiatives such as theSouth West Strategy (Williams 1995), Water

Allocation Management Plans (WAMPS), thedeveloping Nature Conservation Strategy for South-

East Queensland 2001-06 and the SEQ Regional

Coastal Management Plan process.

Most strategies and plans emphasise the need totake a regional approach to maximise the

effectiveness of actions required to manage

biodiversity. Sattler and Williams (1999) set out a

framework for bioregional planning in Queenslandthat describes landscapes across the State, based

on climate, geology, landform, soils and vegetation,

providing a relevant context for assessing and

prioritising biodiversity. The development ofGeographic Information Systems (GIS) allows this

29



Examples of ecosystem-level planning and

management are the definition and prioritisation ofregional ecosystems based on conservation status,

which has been incorporated into State-wide tree

clearing guidelines and the Regional Forest

Agreement process in south-east Queensland (andelsewhere in Australia).

Landscape level

This level attempts to bring together the otherlevels and emphasises the complex ecological

structure, functioning and processes of the differentcomponents of biodiversity. Scale is also an

important aspect of landscape considerations. For

example, a wheat paddock that displaces most of

the native species from an area cannot beconsidered sustainable with respect to biodiversity

conservation at a paddock scale, but could readily

be a part of a landscape where biodiversity is

sustainably protected at a regional scale. Anotherexample is that a species or ecosystem that is

abundant across the Brigalow Belt bioregion as awhole, may be considered threatened at a

subregional province level.

Examples of landscape-level planning andmanagement are the development of regional

vegetation management strategies and property

plans that incorporate concepts such as the size

and relative placement of remnant ecosystems,provision of wildlife corridors and special

management of areas that act as wildlife refuges.

An adequate reserve system where management is

specifically directed to conservation is also an

essential part of a landscape-scale strategy for theprotection of biodiversity. Conservation reserves in

Queensland total about 6 800 000 ha or 4% of the

State and provide the foundation for the protection

of biodiversity. Unfortunately, a reserve-basedstrategy will not be sufficient to conserve

biodiversity (Recher & Lim 1990; Nix 1993; Kitching

1994). Many plants and animals will be dependent,

not only upon the habitat contained within theboundaries of a protected area, but also upon its

landscape setting. Most birds, for example, need to

be able to exploit resources as they becomeavailable over a large area. Furthermore, theimpending likelihood of accelerated climate change

accentuates the necessity for a well-connected

natural landscape. The range of many eucalypts is

determined by climate and yet they are extremelypoorly dispersed. If the habitat for immobile species

were restricted to isolated reserves, many species

would become extinct as they became trapped in

unfavourable habitat as the climate changed. Clearlythe reserve system needs to be complemented by

facilitating pro-active management of other lands to

protect biodiversity. This may be partially achievedthrough voluntary conservation agreements, but islikely also to require a legislative framework and

importantly, financial incentives (in a variety of

forms) to protect threatened ecosystems

bioregional framework to be applied to those

regional planning processes using boundariesbased on varying criteria (e.g. local government

or catchment).

In practice, all the strategies mentioned previously

address biodiversity at one or all of the levels at

which it is recognised—the genetic, species,ecosystem and landscape levels. The different levels

of biodiversity and examples of their managementstrategies in Queensland are:

Genetic levelProtecting species and communities across theirgeographical range maximises the protection of

their gene pool and takes into account both the

extent of genetic variation, and its geographical

distribution. During the last decade, much attentionhas been paid to the importance of population

genetics (Ellstrand 1992; Storfer 1996), because

fragmentation of the landscape has caused a

decrease in population size and density, which can

then result in the erosion of a species’ geneticdiversity. For many species there is a lack of the

critical data on the spatial organisation of genetic

variability and on critical population genetic factorssuch as gene flow, inbreeding levels and effective

population size, which is necessary to manage the

landscape at this level.

Species levelAt the species level, the emphasis is on savingelements of biodiversity that can then be managed

in conjunction with higher levels. Rare and

threatened species projects (bridled nailtail wallaby,

hairy-nosed wombat, golden shouldered parrot andbilby) are examples of species-level planning and

management where individual species are

prioritised and managed, sometimes through

species recovery plans (Reville 1992). Themanagement of these and other species with

particular management requirements or commercial

uses (e.g. macropods, crocodiles, and waterfowl),

can also be addressed by the preparation andimplementation of Conservation Plans under theNature Conservation Act 1992 (Qld).

Ecosystem levelThis level emphasises protecting ecosystems as

important in their own right (e.g. wetlands andrainforest) and recognises their associated

functions, such as the role wetlands play in

nutrient cycling and absorption and in the

hydrological cycle. It also recognises that specieswill not be adequately protected without

conserving their habitat (e.g. Nature Conservation Act

1992 (Qld); ANZECC 1993; ANZECC-MCFFA 1995).

Ecosystems are also often assumed to act as

surrogates for other levels of biodiversity. In otherwords, protecting and managing regional

ecosystems will protect and manage their

associated species and genetic components.

30



(Young et al. 1996). Careful integration of

conservation and primary production land uses canbenefit landholders, the wider community and

wildlife (Harrington 1990, Nix 1993).

Biodiversity values of non-remnant‘woody’ vegetation

There are numerous examples of areas of non-

remnant vegetation (which include ‘thinned’,

‘regrowth’ or ‘highly disturbed’ areas) that have afloristic and faunal diversity value higher than thatin adjacent cleared areas, although not generally as

high as in remnant areas. Dorricott et al. (1997)

found that thinned or regrowth brigalow woodland

areas were associated with relatively high faunalspecies richness and, in one case, a higher number

of fauna species than in nearby unmodified,

ungrazed areas of similar vegetation. Thinned

brigalow woodlands in New South Wales have alsobeen shown to be associated with almost as many

native fauna species as adjacent uncleared brigalow

woodland (Ellis & Wilson 1992). In the Mulga Lands

bioregion, thinning mulga trees, combined withappropriate follow-up management (Pressland

1976b) has the potential to restore micro-

heterogeneity, re-establish critical functioning and

create a diverse system (Tongway & Ludwig 1995)and therefore to be compatible with conservation

objectives (Cameron & Blick 1991).

There is little data available on the development of

the structure and floristic composition of regrowth

vegetation over time. Johnson (1997) has shown

that cleared brigalow communities near Theodoremay be able to return to communities similar in

structure and floristics to ‘untouched’ stands,

although the transition may take more than50 years. Thus, while regrowth areas are not an

immediate substitute for remnant habitat, they

could provide an effective source for long-term

habitat restoration.

It is important to distinguish between the impact ofclearing and the conservation value of regrowth

vegetation, given the above and the associated

impact of introducing exotic pasture species that

often accompanies clearing. In a study comparingfloristic diversity of remnant, cleared/no exotic

pasture introduction, and cleared/exotic pasture

vegetation, Fairfax and Fensham (2000) found that

floristic diversity was highest in the remnants evenwhen exotic species were present. The floristic

diversity in cleared/no exotic pasture was slightly

lower, but was significantly lower in adjacent areas

where clearing was accompanied by theintroduction of improved pastures. McIvor (1998)

has also shown that the introduction of exotic

species and cultivation is associated with a

significant reduction in the density and total numberof native plant species in northern Queensland.

3.3 Greenhouse effect Background

Over the last 200 years, the heavy burning of fossil

fuels in conjunction with the clearing of forests and

other native vegetation for agriculture, and therelease of soil carbon to the atmosphere as carbon

dioxide from intensive use of the soil, has created a

heavy imbalance in the global carbon cycle. Eachyear, as much as 6000 Mt/year of carbon dioxide isbeing released into the atmosphere. Oceans,

terrestrial vegetation and soils absorb about half of

this, leaving the rest to build up in the atmosphere.

The global warming caused by increasedgreenhouse gases results in changes in temperature

and rainfall patterns, as well as rising sea levels

(Rawson & Murphy 1999).

Australia’s vegetation is already fairly well adapted

to significant climatic variability, primarily as aresult of the El Niño Southern Oscillation (ENSO).

While impacts on vegetation resulting fromgreenhouse changes may be very difficult to

differentiate from those due to ENSO variability,modelling suggests increased carbon dioxide loads

may result in an increased frequency of ENSO

events, with the average cycle falling from

5 to 3 years (Wollast & McKenzie 1989).

Rawson and Murphy (1999) have identified anumber of potential distinctions for Australian

ecosystems:

• an increased occurrence of droughts/floods, or

greater climatic variability that may lead tofurther stresses in small populations and

possible extinctions

• climatic change resulting in alterations to the

competitive interactions of species. For example,increased rainfall could lead to species better

adapted to wetter areas invading or gaining

advantage over species adapted to drier

environments• increased carbon dioxide concentrations in the

atmosphere will favour some species over others

depending on which photosynthetic pathway

they utilise• the available water for plant growth, which will

influence species distribution, will be dependent

on the ‘new’ climate and the water-holding

capacity of the soil in new locations• changes in plant productivity and interaction

with grazing may threaten some species

• fragmentation will make migration of species

more difficult.

Higher levels of carbon dioxide in the atmospherewill tend to enhance the growth of vegetation,

however, some plants do not respond to this excess

as much as others. It is likely that those speciesthat respond well to higher concentrations ofcarbon dioxide will increase their ranges by

migration. Little is known about the specific

responses of most native plants in Australia 31



that may be included are conservation of native

vegetation, revegetation activities not meeting thedefinitional requirements for afforestation or

reforestation under Article 3.3, management to

increase carbon storage in forests, enhanced

carbon storage in agricultural soils throughmanagement practices such as reduced tillage,

increased residue inputs and management of

stocking intensity.

• Article 3.7 provides for countries for which net

emissions from Land Use Change and Forestry(LUCF) was a net source in 1990, to include the

net emissions from land use change in the

baseline. This is the so-called ‘Australia clause’.

Australia is undertaking action to address

greenhouse issues through the NationalGreenhouse Strategy (NGS) including measures in

relation to sinks directed at reducing land-based

emissions, enhancing sequestration in vegetation

and agricultural soils and improving understanding

of carbon fluxes and measurement capacity in theterrestrial biosphere. The Queensland

Implementation Plan (QIP), developed by the

Queensland Government in response to the NGS,includes land management and carbon sink

initiatives. The following are some of the strategic

recommendations:

• implement tree clearing controls on State landsthrough provisions of the Land Act 1994 (Qld)

• develop a comprehensive vegetation

management framework to address native

vegetation management issues consistently

across all tenures• deliver planning certainty to landholders,

industry and the community

• promote ecologically sustainable development ofthe land and protect biodiversity values

• develop legislation to support tree crop

ownership and rights to harvest

• remove legal impediments to plantation andnative farm forestry for crediting carbon

(Queensland Government 1999).

The passage of the Vegetation Management Act 1999

(Qld) and changes to the Broadscale Tree ClearingPolicy on Leasehold Land, which restrict areas inwhich clearing of remnant vegetation can occur in

Queensland, are likely to lead to reductions in

greenhouse gas emissions in the land use change

sector.

(AGO 1998a). In a review of the ability of models to

calculate the impact of climate change onQueensland grazing lands, Hall et al. (1998)

demonstrated considerable variation in impacts

between regions. Models developed in the study

showed that more complex variation was to beexpected when regional climate change scenarios

were evaluated in combination with varying soil

and pasture parameters.

Global response

Increasing international concern about the

implications of climatic change and recognition thata global response was required to solve a global

environmental problem resulted in the drafting of

the United Nations Framework Convention on

Climate Change (UNFCCC). Under the KyotoProtocol to the UNFCCC, negotiated in 1997,

developed countries have agreed to potentially

legally binding targets of reduced greenhouse gas

emissions as a whole, to 5% below 1990 levels by

2008-12. Developing countries have been assigneddifferentiated emissions reduction or limitation

targets that reflect differing economies and

capacities for reduction. As a signatory to theUNFCCC, Australia has an obligation to produce a

national inventory of greenhouse gas emissions and

removals and to implement appropriate greenhouse

response measures to limit emissions. Should theprotocol be enforced, Australia will be required to

limit growth in greenhouse gas emissions to 8%

above 1990 levels by the first commitment period—

2008–12.

Articles 3.3, 3.4 and 3.7 provide a framework fordealing with greenhouse gas sinks.

• Article 3.3 provides that sink activities counted

towards the first commitment period are confined

to afforestation, reforestation and deforestation

since 1990. Forests established since 1990 arerecognised as sinks, while deforestation since

1990 must be recognised as an emission. Growth

between 1990 and 2008 in eligible forests cannot

be counted, although afforestation anddeforestation will need to be implemented prior

to 2008 to allow for lag effects, since it takestime to establish a new forest and growth rates

often peak many years after planting.

• Article 3.4 establishes a process for negotiatingadditional sink activities that may apply in the

first commitment period and must be applied in

subsequent periods. While an agreement on

allowable additional activities is subject tofurther considerable domestic and international

policy debate, there may yet be incentives for

other vegetation retention or enhancement. Some

additional human-induced activities in the land-use change and forestry and agricultural soils

categories, may be negotiated for inclusion for

the first commitment period, provided they have

taken place since 1990. Examples of activities32



33

measures such as reduction in tree clearing or

management practices for agriculture and forestrylands, are essential. Consideration of equity in the

costs of greenhouse gas abatement will become a

significant issue in the period leading up to the first

Kyoto commitment period.

Emissions and removals of greenhouse gases,primarily carbon dioxide, from the LUCF sector are

complex and difficult to estimate. Naturalexchanges due to the uptake of carbon dioxide in

photosynthesis, and its loss through respiration andthe decay of organic matter, which occurs between

the terrestrial biosphere and the atmosphere are

large, and anthropogenic effects are small relative

to this background. The Australian GreenhouseOffice has undertaken the National Greenhouse

Gas Inventory (NGGI) of land-based sources and

sinks using established international guidelines

(Rawson & Murphy 1999). The inventorymethodology is based on the assumption that

anthropogenic fluxes of greenhouse gases to orfrom the atmosphere are equivalent to the change

in stocks of carbon in biomass and soils andfurther, that the changes in stocks can be estimated

from the human activity (such as land-use change)

and the practices (e.g. burning) used to effect the

change. Emissions in any year are, in part, a resultof activities in previous years through the slow,

non-uniform decay of woody debris and change in

soil carbon. Knowledge of both the time taken and

the magnitude of these processes is required.

All activity data and emission factors that go into

compilation of the inventory have an associateduncertainty which is often high due to lack of

relevant well-documented data and limited

understanding of processes contributing to theoverall uncertainty of emissions estimates.

Insufficient measurements and natural variability

mean that it is difficult to assign a probability

distribution to many of the parameters and thus toquantify uncertainty in the estimate of emissions.

The Revised 1996 Intergovernmental Panel on

Climate Change (IPCC) Guidelines provide a basic

methodology and default data that may be used for

national greenhouse gas inventories, but countriesare encouraged to incorporate national data, or

more sophisticated methodology, where possible.

This has been done for some categories in theAustralian and Queensland inventories but most

rely on incomplete or default data. The estimate of

emissions from LUCF is the sum for different

categories as outlined in table 3.3.

Selected parameters are discussed below forillustration but this list is not exhaustive.

Uncertainty in the LUCF and Agriculture inventories

in Queensland is being addressed through work bythe Department of Natural Resources and theDepartment of Primary Industries.

Estimates of greenhouse gas emissions andremovals for Land Use Change and Forestry(LUCF)—National Greenhouse GasInventory (NGGI)

The net emission from, or absorption of, carbon in

the terrestrial biosphere is associated with changes

in land use and other human activities that result

in changes in carbon stocks in vegetation and soil.

A natural undisturbed forest is considered to beneither a net emission source nor a net absorption

sink of carbon. Net change in carbon stock may

occur when there is a change in land use ormanagement and may involve the management of

native vegetation. The Land Use Change and

Forestry sector has been identified as producing

about 20% of total Australian emissions in 1990.Land clearing of native vegetation in Australia is

estimated to have resulted in the emission of

103 Mt CO2-e (carbon dioxide equivalents) to the

atmosphere in 1990, and 65 Mt CO2-e in 1997.

This compares with total net greenhouse gasemissions from sectors other than land clearing of

389 Mt CO2-e in 1990 and 431 Mt CO

2-e in 1997

(NGGIC 1999b).

Continued growth in emissions from the energy and

transport sectors has meant increasing economic

and political pressure to decrease land clearing.

The transfer of carbon from the atmosphere and itsstorage as biomass in vegetation and soils is

potentially one mechanism of reabsorbing carbon

released by the burning of fossil fuels. In the short

term, this appears to be an effective mechanism incombination with others. Vegetation can absorb

significant amounts of carbon in a period of about

50 to 100 years, and so can be used as a buffer

while the changes that will be required to bringabout a reduction in the rate of burning of fossil

fuels are introduced to activities and attitudes. In

the long term, the only solution is to reduce the

amount of fossil fuels burnt. Forestry and managedplantations have provided a net sink of 26 Mt CO

2

1997 for Australia (NGGIC 1999b). Regrowth

following clearing is also a significant sink,

absorbing 16 to 17 Mt of carbon dioxide in 1990and 1996 nationally.

When vegetation is disturbed or cleared, the

biomass can break down to release large volumes of

carbon as carbon dioxide. In 1997, about 13% of

Australian carbon dioxide emissions were associatedwith land clearing. As the State with the highest rate

of tree clearing for agriculture and with large areas

of land managed for agriculture (see section 1.2),

reduction in net emissions associated with land-usechange in Queensland has been identified as having

the potential to contribute significantly to limiting

growth in total emissions of greenhouse gases inAustralia. Improved quantification of emissions andremovals of greenhouse gases for LUCF, and of

estimates of the impact on net emissions of



34

Table 3.3 Summary of the major parameters required in calculation of emissions and removals associated with the Land UseChange and Forestry sector of the National Greenhouse Gas Inventory.

Source or sink category Parameters required for calculations of emissions and removals in theLUCF sector of the NGGI

Changes in forest and other woody biomass stocks

1. Managed native forests Area of forests by type and age class; annual growth rate of above-ground biomass (frequentlyby conversion of commercial volume using expansion factor and wood density); carbon fractionof biomass.

2. Plantations Area of hardwood and softwood plantations; annual growth rate of above-ground biomass

(conversion of commercial volume requires expansion factor and wood density); carbon fractionof biomass.

3. Commercial harvest Volume of harvested timber by product converted to total biomass harvested using expansionfactors and density; carbon fraction of biomass.

4. Fuelwood consumed Total fuelwood consumed less that removed from forests during clearing.

Forest and grassland conversion

a. Above ground

(i) Clearing (burning) (CO2)

1. Closed tropical and temperate forest Annual rate of clearing by forest class; proportion of clearing that is regrowth; biomass ofvegetation cleared; carbon fraction of biomass; clearing practice (i.e. proportion of biomass burntin the year cleared); proportion of biomass burnt that is taken off-site as fuelwood; efficiency ofburning (i.e. proportion remaining unoxidised as charcoal.

2. Open forest

3. Woodland and scrub(i)* Non CO

2gases (CO

2-e) Biomass burned on-site; carbon fraction of biomass; elemental C:N ratio; emission factors for

each gas from fires.

(ii) Clearing (decay)

1. Closed tropical and temperate forest Rate of clearing by forest class for the inventory year and for the previous y years, where y is thetime taken for decay of slash (10 years assumed in the NGGI); proportion of clearing that isregrowth; biomass of vegetation cleared; carbon fraction of biomass; clearing practice(i.e. proportion of biomass left to decay as slash); time for decay.

2. Open forest

3. Woodland and scrub

(iii) Regrowth

1. Closed tropical and temperate forest Rate of clearing by forest class for the inventory year and for the previous z years, where z is theaverage time for cyclic reclearing (10 years assumed in the NGGI); proportion of clearing that isregrowth; biomass of vegetation cleared; proportion of cleared land maintained for crops orpasture; carbon fraction of biomass

(crops/pasture and woody vegetation); carbon increment per year in regrowth (currentassumption for linear growth over a nominal 25 years to reach the original biomass); biomass ofcrops or pasture.

2. Open forest


b. Below ground (soil and roots)

1. Closed tropical and temperate forest Below-ground biomass: Root biomass of vegetation cleared (based on root to shoot ratio of 0.25in the NGGI); carbon fraction of root biomass; rate of clearing by forest type in the inventoryyear and the previous y years, where y is the time of decay of roots (10 years assumed in theNGGI); proportion of the clearing that regrows to woody vegetation and to crops/pasture; root toshoot ratio of woody regrowth and crops/pasture; carbon fraction of regrowth by type.Soil Carbon: rate of clearing in the inventory year and in the previous x years, where x dependson the time course of change in soil carbon towards equilibrium; agriculture use and

management of cleared land; native soil carbon (preferably corrected for bulk density, and to adepth of 1 m—current default is 30 cm); base factor (fraction of soil carbon lost due toconversion from forest to agriculture); factors to allow for management (tillage, input); pattern ofchange of soil carbon after conversion (exponential change assumed in the Australian NGGI);time factor for change towards new equilibrium.

2. Open forest


Other

1. Prescribed burning of forests Area of forest burned in prescribed burns and wildfires; fuel load per ha; burning efficiency;and wildfire (CO

2-e) carbon fraction of biomass; elemental C:N ratio; emission factors for each gas from fires.

2. Pasture improvement, minimum tillage Annual rate of conversion of unimproved pasture or minimum tillage (in Western Australia) overthe 25 years up to the inventory year; soil carbon increase due to conversion; fraction ofimproved pasture not used in cropping rotation.



Area of clearing: The Statewide Landcover and

Trees Study (SLATS) mapping of vegetation coverand land use provides rates of woody vegetation

clearing that are the basis for calculation of

emissions from LUC (table 3.4, see also section 1.2).

For the national inventory (NGGI) prepared for the

UNFCCC, Australia has defined ‘forest’ according tothe National Forestry Industry (NFI) definition—

woody vegetation with a mature, or potentiallymature, stand height exceeding 2 m and with a

canopy cover equal to, or greater than, 20%. Thedefinition, for the purposes of the Kyoto Protocol, is

the subject of ongoing negotiations. The SLATS

study is able to detect change in woody vegetation

cover down to about 10%. Resolution of definitionalissues will have an impact on the monitoring of

rates of deforestation and also of reforestation and

afforestation.

Table 3.4 The rates of clearing for 1981 to 1997 inQueensland, used in the NGGI.

Years Clearing (ha/y) Source

1981–87 297 559 Graetz (1999)

1988–90 475 000 ( 25%) SLATS (preliminary)

1991–95 289 000 ( 10%) SLATS

1995–97 340 000 ( 10%) SLATS

Biomass: In the NGGI, forests are allocated to three

categories based on Carnahan classes (AUSLIG,1990). A biomass (tonnes dry matter/ha) is

assigned to each forest category for the purpose of

estimating the initial carbon stocks before clearing

(table 3.5). The carbon fraction in dry matter ofwoody biomass is assumed to be 0.5 (NGGIC

1999b). Biomass harvesting by the Department of

Primary Industries in the TRAPS permanent

monitoring transects is giving improved estimatesof biomass and understanding of the dynamics of

woodlands in Queensland (Back et al. 1997).

Table 3.5 Biomass estimates for forest classes used toestimate carbon stocks.

Forest class Biomass (t dm/ha)

Tropical and temperate closed forest 233

Open forest 90

Woodland and scrub 51

Growth rates in managed forests: The QueenslandForest Service maintains databases of plantation

and native forest growth measured in permanent

and temporary plots. These data will provide

improved inputs for the forest inventory, and inparticular, to estimates of changes in stocks in

managed native forests.

35

Soil carbon: One of the greatest areas of

uncertainty in inventory calculations for the LUCFsector is the change in soil carbon following

clearing of native forests for agriculture. The carbon

content of soils before clearing of native vegetation

is variable, but the NGGI assigns an average valuefor each of the three broad forest classes listed

above. In the 1997 NGGI, estimates of loss of soil

carbon are based on international default values

from the Revised 1996 IPCC Guidelines. Thegreatest proportion of clearing in Queensland is for

pasture. The default assumption is that 30% of the

carbon present in the top 30 cm of soil before

clearing is lost over 20 years, following conversionof forest to unimproved pasture (NGGIC 1999b).

Recent research indicates use of the default value

may significantly overestimate the loss in some

soils (Christopher et al. 1997). If soil carbon losswere negligible following conversion, the estimated

emissions for LUC in Queensland would be about

40% lower than current estimates.

A program of paired site measurements (DNR) and

modelling (CSIRO) is being undertaken by theNational Carbon Accounting System to provide

improved data and understanding of soil carbon

levels and dynamics. These measurements will aim

to address some difficulties in previousmeasurements including bulk density correction

and, where possible, carbon density to at least 1 m.

Improved understanding of the degree to which

clearing and post-clearing land managementpractices (such as reduced tillage or grazing

intensity) and climatic factors (particularlytemperature and rainfall) influence the magnitude

and dynamics of soil carbon change will helpreduce uncertainty.

Carbon pools: Data relating to the stocks and

changes in stocks in other carbon pools are

required to improve estimates of fluxes associated

with LUCF. These pools include:- coarse woody debris

- fine litter

- charcoal.

For example, practices regarding management ofcoarse woody debris, may become a considerationin carbon accounting for Kyoto compliance, since

the current alternatives of immediate release of

stored carbon through burning or slow decay over

many years impact on the committed emissions inyears following deforestation.

+–+–+–



36

Proliferation of woody vegetation: A number of

authors have drawn upon historical sources tosuggest that there was more open grassland in pre-

European Australia than is present today (Pyne,

1991; Flannery, 1994). This assessment is, however,

challenged by other interpretations of the historicalevidence (Benson & Redpath 1997) including semi-

quantitative (Croft et al. 1997) and quantitative

assessment (Fensham & Holman, 1998). The area

of woody vegetation in Queensland was assessed tobe 76 000 000 ha using NOAA AVHRR imagery

(Danaher et al. 1992), with 60 000 000 ha of

grazed woodland (Burrows 1995). Because of the

large area involved, even a small increase in thecarbon density in the grazed woodlands represents

a potentially large impact on terrestrial carbon

stocks. There is ongoing debate concerning

whether the sink due to proliferation of woodyvegetation (also known as vegetation thickening

and/or woody weed invasion) should be included in

Australia’s national greenhouse gas inventory of

anthropogenic emissions.

Vegetation thickening has been defined as involvingan increase in the biomass of woody plants

(measured as an increase in basal area and height)

typically resulting from an increase in grazing

intensity and constancy and other managementactions that suppress fire frequency and intensity

(Noble, 1997a). Increase in aboveground woody

biomass and associated increase in soil carbon

stocks can be attributed to both human-induced(direct and/or indirect) and natural factors.

A component of thickening has been ascribed toaltered fire management and the introduction of

grazing by ruminants in arid and semiaridsavannas in Africa (Scholes & van der Merwe,

1996), America (Archer et al. 1995) and Australia

(Burrows et al. 1998). Burrows et al. (1998) base

their arguments that thickening in Queensland’sgrazed woodlands is occurring and is human-

induced, on several anecdotal sources of evidence,

carbon isotope ratios in soil organic matter

showing a shift from C4

grasses to woody C3

species over time, and on detailed measurements of

basal area increment in over 30 TRAPS sites(standard layout of 5 x 100 m permanent

transects). There are also cases where the primarycause of change in vegetation structure is not

anthropogenic but is climate driven. For example,

Fensham and Holman (1999) have presented

evidence that extensive dieback in savannas canresult from extreme drought events. With current

knowledge and measurement capacity it is not

possible to resolve the separate impacts of natural

and anthropogenic factors on growth and structuralchange in vegetation, but ongoing research and

measurements will help to quantify the magnitudeof the fluxes due to all causes. In fact, it is not clear

in greenhouse gas accounting how attribution can

be made for processes when both natural factors

and anthropogenic intervention are required forchange in carbon stocks.

Burrows et al. (1998) estimate the magnitude of the

vegetation-thickening sink (due to all factors) in the

approximately 60 000 000 ha of Queensland’s

grazed woodlands, to be in excess of 100 Mt CO2

per year. Inclusion of a proportion of this sink in

Australia’s national inventory would most likelymean that in 1990, the LUCF sector in Australia

was a net sink rather than a net source ofgreenhouse gases. The IPCC Revised 1996

Guidelines for National Greenhouse Gas Inventories

allow for the inclusion of ‘any forest which

experiences periodic or ongoing humaninterventions that affect carbon stocks’ and for

which ‘the necessary data are available’. Thus,

inclusion of change in carbon stocks due to

proliferation of woody vegetation in the grazedsavannas depends on resolving the change

resulting from human activity and documenting thesupporting data for the magnitude of the change.

Emissions estimates: Table 3.6 gives the estimated

rates of emissions or removals associated withLUCF for Australia for 1990 and 1997 (NGGIC

1999b). Estimates for Queensland are also given,

based on the same methodology. It is important to

note that ongoing research is providing new dataand understanding of processes that will

significantly affect the estimated emissions from

LUCF. Table 3.6 presents a possible range in

estimates with inclusion of changes to data inputs

or definitions. Full carbon accounting over timewould assist accurate estimates of the magnitude

and uncertainty in stocks and fluxes of all pools in

the terrestrial biosphere, but sufficient data are notyet available.

Measures to reduce emissions: Restricting clearing

of native vegetation has the potential to decrease

net emissions in Queensland. Based on the current

data and methodology, restricting clearing of100 000 ha of undisturbed woodland in Queensland

will result in emissions savings in the order of 5 to

12 Mt CO2-e.Other measures that may result in reduction in thenet emissions from the LUCF and Agriculture

sectors include:

• reduced harvest of forests

• increased planting of woody vegetation• fire regime management

• sustainable management of cropping and grazing

lands to conserve soil carbon levels

• management of rangelands for optimal stockinglevels.

The magnitude and, in some cases, even the

direction of the impact of these and other measures

over time is unknown.



Carbon credits and carbon trading

The Kyoto Protocol provides for mechanisms to

facilitate the achievement of greenhouse gas

commitments by parties in a more cost effectivemanner than if they acted alone.

• Joint Implementation (JI) (Article 6) allowsexchanges between Annex 1 countries of

Emission Reduction Units (ERUs).

• Clean Development Mechanism (CDM) (Article

12) involves arrangements between an Annex 1country and a non-Annex 1 country to generate

Certified Emissions Reduction (CERs).

• Emissions Trading (Article 17) allows Annex 1

countries to use international emissions trading

to assist in meeting their emission commitments.

The principles, modalities, rules and guidelines for

these mechanisms will be negotiated at the 6thConference of Parties (COP 6), in The Hague, in

November 2000. The role of sinks in the

mechanisms, particularly in CDM, has yet to bedetermined. Incorporating land-based sinks and

emissions reductions into a national emissions

trading system would provide additional stimulus to

the creation of forest and agricultural soil sinks andthis would likely result in associated environmental

(e.g. sustainability, biodiversity) and socioeconomic

benefits.

Emissions trading is likely to be market-driven with

carbon credits generated or purchased bycompanies to offset other greenhouse emissions.

One suggested structure would be for emissions

trading to be based on emission permits (probably

in units of tonnes CO2-e) that would be

interchangeable with carbon credits issued for each

tonne CO2-e sequestered on Kyoto land. There are

many issues yet to be negotiated concerning

measuring, monitoring and verifying carbon creditsthat relate to baseline, permanence of the sink,

leakage (unmonitored impacts of a project outside

the monitored boundary) and how to treat impactsof natural events such as pests and fire. In addition,administrative issues such as a system for issuing,

trading and tracking carbon credits, a system for

establishing ownership of carbon rights and for

measuring and verifying carbon credits, and a

legislative framework for codifying these systemshave to be established. Queensland legislation

dealing with carbon rights is currently under

discussion.

Examples of sinks projects that could generate

carbon credits for Queensland include conservationof forests from clearing or logging, agroforestry,

and enhancement of carbon sequestration in

rangeland soils through improved management of

stocking rates. It is difficult to estimate withconfidence the sink potential of these activities with

the current level of understanding and data and

measurement capacity for the terrestrial biosphere.

There are natural limits on the availability of largeareas of land suitable for forest, and costs of

establishment and maintenance are considerable.

This, coupled with the fact that the absolute rate ofsequestration will be low for the first years afterplanting of trees will mean that the sink due to

revegetation activities is likely to be relatively small

in the first commitment period. Plantings under

programs such as bushcare and landcare are likelyto deliver limited greenhouse benefits for the first

commitment period, but the longer-term

sequestration potential and associated

environmental benefits must also be consideredand valued. Build-up of soil carbon in grazing lands

is likely to be slow and inherent variability may

make measurement and verification difficult overshort periods, although potential sequestration islarge because of the areas involved. Non-

greenhouse benefits of sustainable management of

grazing lands are important.

The greatest potential for net greenhouse gas

emissions reduction from the land-based sector inthe first commitment period is likely to be from

restrictions in land clearing. However, eligibility for

carbon credits under the Kyoto Protocol has yet to

be determined.

37

Table 3.6 Estimated emissions from the LUCF sector as published in the NGGI for Australia. Values for Queensland for LUCestimated using the 1997 NGGI methodology are given, but the uncertainty is seen in the possible range. Vegetation thickening iscurrently not included in the NGGI.

Category Australia Queensland

Emissions (Mt CO2-e) Emissions (Mt CO

2-e)

1990 1997 1990 1997

Total (all sectors) 492 496

LUCF

NGGI methodology 76 (15% total) 38 (8% total) (30–70) (15–50)Including thickening (-40–70) (-50–50)

LUC

NGGI methodology 103 (21% ) 65 (13%) 63 47

Possible range (35–70) (20–55)



38



4 Regional and local processes

Contributors

Impacts of habitat loss on biodiversity


Rod Fensham, Environmental Protection AgencyKay Dorricott, Environmental Protection Agency

David Hannah, Environmental Protection AgencyImpacts of domestic grazing withinremnant vegetation

Geoff Smith, Department of Natural Resources

Andrew Franks, Department of Natural ResourcesAnnie Kelly, Department of Natural Resources

Riparian zones

Jo Voller, Department of Natural Resources

Sally Boon, Department of Natural Resources

Ecosystem repair and management

Andrew Grodecki, Department of Natural ResourcesBruce Wilson, Environmental Protection Agency

Wetlands, mangroves, and other coastal vegetation

Estelle Ross, Environmental Protection Agency

Tree decline and dieback, nutrient cycling

Peter Voller, Department of Natural ResourcesChris Chilcott, Department of Natural Resources

Pest invasions

Joe Scanlan, Department of Natural Resources

Dane Panetta, Department of Natural Resources

39

Tree removal: implications for soil processes andsoil loss

Bruce Carey, Department of Natural ResourcesMark Silburn, Department of Natural Resources

Craig Strong, Griffith UniversitySoil structure

Des McGarry, Department of Natural Resources

Soil acidification

Phil Moody, Department of Natural Resources

Andrew Noble, CSIRO

Hydrology

Mark Freebairn, Department of Natural Resources

Salinity

Sarah Boulter, Department of Natural ResourcesManagement and production aspects

Joe Scanlan, Department of Natural ResourcesChris Chilcott, Department of Natural Resources

Improved pastures

Ian Partridge, Department of Natural Resources

Timber production and farm forestry

Mark Cant, Department of Natural Resources

Andrew Grodecki, Department of Natural Resources

Alternative products

Jude Westrup, Department of Natural Resources

Urban and peri-urban

Alan Barton, Brisbane City Council

return to contents

http://start.pdf/



40

• Providing linkages between remnant patches of

vegetation can increase the viability ofpopulations and species, aid dispersal and allow

for movement of wildlife between patches. The

effectiveness of corridors varies with a range of

factors: habitat structure and quality, dimensionsof the corridor (particularly length to width

ratio), surrounding land use, use of corridor and

biology of species expected to use the corridor.

Generally, wider, larger corridors or patches arebetter for biodiversity conservation.

• Grazing can impact on remnant condition.

Impacts may include browsing or rubbing of

vegetation, changes in species composition, soil

compaction and erosion, eutrophication of watersources, spread of weeds, and altered fire regime.

Changes in species structure can alter ecosystem

functioning and cause a loss in critical ecosystem

services. Overgrazing and poor land managementpractices for grazing appear to have the greatest

impact, and the seriousness of impacts variesacross the landscape and through time.

• Understanding of size and connectivity limits to

viability of remnants can be applied to ecosystemrepair. Revegetation has the potential to repair

lost ecosystem function as well as protection of

species and amenity. Ongoing research is needed

to provide adequate and efficient managementinformation across the diverse Queensland

landscape to deliver significant levels of

ecosystem repair.

• Riparian vegetation and wetlands provide

vegetation with particular ecological andcatchment values. Riparian vegetation can buffer

streams from nutrient and sediment flows, and

trees can maintain stream bank stability,

enhance stream water quality and are animportant source of biodiversity. Guidelines for

retention of riparian zones require consideration

of combined functions of riparian vegetation.

Wetlands act as buffers for streams, storage andfiltration of sediment, nurseries for commercial

fish and crustaceans.

Maintenance of the productive potential and use ofland and associated ecological processes, requires

a more comprehensive approach to landmanagement than retention of native vegetation at

certain levels. Consideration of land degradation

and production relationships must be part of a

sustainable approach to native vegetationmanagement:

• General tree death or dieback incidents have

been associated with a range of land degradation

and other possible causes. A number of causal

factors are discussed: insects, salinity, nutrientenrichment, pathogens, senescence, drought and

waterlogging.

Summary This section examines the impacts of habitat loss

on biodiversity and subsequent management and

land uses on conservation of biodiversity andecological processes. The evidence permits

preliminary recommendations for retention,

replanting and active management of native

vegetation, and associated land management

practices, but concludes that imperfectunderstanding requires ongoing research and

adaptive management. This section looks at four

major themes—the ecological impacts of habitatloss on biodiversity, associated land degradation

issues, evidence of production and management

effects of managing vegetation, and other values of

native vegetation. The following lists the mainpoints discussed under these themes.

• Land clearing has been identified as one of the

major threats to biodiversity in Australia.

Processes such as land clearing lead tofragmentation of habitat, resulting in loss of

habitat, reduction in size of each habitat and

increased isolation of remnant patches. Habitat

is critical to species survival. Other processesthat can threaten biodiversity, and to which

remnant areas are more vulnerable, include

grazing, predation, changes in fire regime and

competition from feral plants and animals.

• The amount of habitat required to preservebiodiversity at a regional level is not known,

although the amount is likely to be dependent on

each region, and be species specific. Researchindicates that local and regional losses ofbiodiversity (species richness) commence with

habitat loss, but once remnant vegetation

declines to around 30% of preclearing extent,

rates of species loss accelerate dramatically.Regional ecosystems are the best available

surrogate for biodiversity at the species level. On

available evidence, 30% is the minimum

benchmark for the rate of retention of RegionalEcosystems to ensure against substantial

extinction in the longer term, although there are

many factors influencing this figure.

• The total area and pattern of native vegetation

across the landscape are important to habitatvalue for plants and animals. Size, shape,

connectedness, condition and land use of remnant

vegetation become important to the viability of

remnants once clearing or other disturbance hascommenced. It is important to recognise the role

of corridors of vegetation in mitigating the effects

of habitat fragmentation. The size of remnants

required to conserve biodiversity varies withspecies and habitat type. Larger fragments are

likely to support greater diversity, and reduce the

area affected by ‘edge effects’.



41

• Condition of remnant vegetation can be affected

by the occurrence of undesirable plant and animalspecies. Disturbance (e.g. grazing, changes in fire

regime) can allow the opportunity for the

establishment of undesirable species. Native

vegetation can host predator species that controlproduction pests in surrounding land uses.

• The role of vegetation in prevention of soil loss

and maintenance of soil condition iscomplicated. Erosion of soil is controlled by a

number of factors, including slope, ground coverand infiltration rate. These factors are affected by

management practices such as grazing, fire and

vegetation clearing. There are some studies that

demonstrate an increase in run-off following theclearing of trees, although pastured blocks have

been demonstrated to be efficient in minimising

run-off. In riparian areas trees have been shown

to protect stream banks from mass failure anderosion by adding to bed and bank stability.

• The physical condition of soil structure can bestrongly impacted by post-clearing activities. Soil

compaction can occur with use of heavy

machinery during tree clearing if the soil is wetor particularly vulnerable to structure decline.

Compaction is more likely to occur under heavy

grazing, particularly again where the soil is wet

or fragile.

• Vegetation exerts a considerable influence on soilfertility. Trees have been described as nutrient

pumps, transporting nutrients from deep within

the soil, and redepositing them in leaf litter.

Removal of trees will have impacts on theavailability of nutrients and organic matter.

• Some land uses are particularly acidifying, and

include cropping, which involves the removal of

large quantities of harvested material;

application of ammonium-based fertilisers; andintroduction of legumes. Particular soil types are

more vulnerable to acidification than others, and

careful management and consideration of land

use are recommended.

• Tree clearing has a direct impact on the

hydrological regime. Generally the removal ofdeep-rooted trees increases deep drainage. This

may result in the expression of salinity at or near

the soil surface. While Queensland currently haslimited salinity problems compared to other

States, there is potential for significant increases

in saline-affected lands in the next 10–30 years.

Areas likely to be impacted are largely restrictedto areas with between 600 and 1500 mm rainfall

per annum. Assessment of salinity hazard risk

can ensure clearing will not result in salinity.

Revegetation plays a significant role inmanagement of saline-affected land.

• Cropping is generally conducted on cleared land.

There is often a long-term decline in productivity

as the time since initial clearing and

development increases. Windbreaks can be

useful in protecting high-value crops from winddamage, although there may be some sacrifice in

productivity close to treed windbreaks where

trees compete with the crops.

• Tree clearing is primarily conducted in

Queensland to promote increased pastureproductivity. Vegetation can also provide fodder

for grazing livestock, as well as shade andshelter from harsh climatic conditions. These

benefits can have significant production benefits.

• There is substantial Queensland evidence thatnon-leguminous trees and shrubs can decrease

pasture production within their projected

canopies and beyond. Individual trees can have a

variety of impacts varying from net increase tono net effect to a net decrease. There are several

important situations that report improved

pasture growth with trees.

• Clearing of vegetation is often followed by

regrowth or regeneration of the original plant.Ongoing regrowth management will be necessary

if the consequential pasture production increases

are required.

• Fire has an effect on plant ecology, the extent of

which depends on fire intensity, frequency andseason of burning. The interaction between an

adaptive trait and fire regime may facilitate

survival or reproduction. Fire may be used as a

management tool for productivity as well asconservation. Changes in the use of fire have

happened over time.• The benefit of retaining and managing native

vegetation for its timber and other commercial

values is only now beginning to be realised. Thepotential of farm forestry enterprises is being

explored at various levels. A number of national

and international policy initiatives and factors,

such as global markets, carbon trading, theMontreal Process, certification and labelling of

forest products, and the Regional Forest

Agreement process, are likely to affect the future

direction of these enterprises. There is potential

to manage private native forest areas tomaximise conservation outcomes for these areas.

• Retaining native vegetation may offer ecological

and economic benefits through new crops,

diversified agriculture or alternative products.Alternative products may include bush foods,

ecotourism, pharmaceutical products, honey, and

landscaping materials.

• Benefits from retaining native vegetation may be

measurable short-term economic benefits andlong term benefits to the landholder and general

community that are not easily measured.Benefits to the whole of society include aesthetic

and amenity benefits.



42

4.1 Impacts of habitat loss on biodiversity

Land clearing has been identified as the major

threat to biodiversity in Australia (Ecological

Sustainable Development Working Party on

Biological Diversity 1991; Glaznig 1995). Systematicassessment of fauna from various parts of Australia

attributes declines in species directly or indirectly

to habitat loss (Saunders et al. 1985; Loyn 1987;

Dickman et al. 1993; Barrett et al. 1994; Smith &Smith 1994). For example, Garnett (1992), in a

review of bird populations, cited clearance of

habitat as the most frequently inferred means of

decline for 150 birds classified as threatened orextinct. Many species of fauna are dependent on

trees and the habitat they provide, and therefore

undergo decreases in abundance and extent

following tree clearing. For example, the glossyblack cockatoo (Calyptorhynchus lathami, classified

as Vulnerable) is dependent on brigalow–belahcommunities for habitat, the red-tailed black

cockatoo (Calyptorhynchus magnificus) depends onsupply of eucalypt seeds as its major food source,

the rufous bettong (Aepyprymnus rufescens) relies on

eucalypt woodland for habitat, and various reptiles

live almost solely on trees and under logs (e.g. treedtella and tree skink both of which occur on gidgee

and brigalow). Australia has a large number of

obligate tree-hollow nesting birds. Hollows are

characteristic of mature tree communities, and takecenturies to form (Abensperg-Traun & Smith 1993).

Studies carried out in Queensland’s brigalow region(Russell et al. 1992), and in similar areas in

northern New South Wales (Barrett et al. 1994;Ellis & Wilson 1992), have shown that there are

substantially more fauna species in treed areas

compared to adjacent cleared areas.

There are many plant species threatened by land

clearance in Queensland, including ooline (Cadellia pentastylis) and other softwood species, Chinchilla

white gum (Eucalyptus argophloia), and several grass

and herb species from the Darling Downs region

(Fensham 1998b). However, overall there appear to

be fewer obvious examples of plant species directlyimpacted by clearing compared to fauna species.

This could be at least partly because plants can

survive for extended periods in small remnants(<5 ha) which are too small to support fauna

species. However, the long-term viability of such

remnants is questionable (Hobbs & Saunders 1994)

and the decline in flora populations may be moreinsidious (McIntyre 1992), but in the long term just

as severe as declines in fauna.

Other agents also contribute to the decline of

biodiversity, and their impact is oftenindistinguishable from those of land clearing. Theseother agents include grazing (Foran et al. 1990;

Morton and Price 1994; see section 4.1.4),

predation, changed fire regime (e.g. Morton 1990)

and competition from feral plants and animals

(Humphries et al. 1991; Low 1999). Recher (1999)predicts that, with current patterns and trends of

land use, up to 50% of Australia’s bird species may

be lost in the next century. However, not all native

species are disadvantaged by land clearance. Treeclearing, and the associated creation of more open

landscapes with increased grass cover and artificial

water points, is associated with increased

abundance of species such as plains turkeys,galahs, cockatiels, woodswallows, budgerigars,

zebra finches, diamond doves, pipits, songlarks and

some macropods (e.g. Saunders & Curry 1990).

However, it is not the species that prosper underEuropean management, but rather those that suffer,

that should form the main focus of biodiversity

conservation.

This section will look first at the question of how

much habitat is required to ensure biodiversity atthe landscape level. The physical effects of habitat

loss on biodiversity, including fragmentation andlandscape connectivity, and the implications of

disturbance (particularly grazing) and remnantcondition for biodiversity will be discussed.

Ecosystems with particular roles in landscape

functioning (e.g. riparian zones, wetlands) are

examined in more detail. There is also a briefdiscussion on ecosystem repair to reinstate

biodiversity.

4.1.1 How much habitat is requiredfor conservation of biodiversity

at a regional level?Despite the widespread view amongst scientists that

habitat loss is the major threat to biodiversity in

Australia, the relationship between species survival

and habitat loss is not well understood. Thefollowing is a review of the existing literature on

species and habitat loss at a landscape scale, with

Australian, and particularly Queensland, examples.

Habitat-versus-species relationships are likely to be

region and species specific. Most Australianmammal extinctions have occurred in arid areas

where habitat loss has been minimal. However, theprocess that led to these extinctions actually

highlights the importance of habitat (Morton 1990).It is thought that the key desert resources that

allowed species to survive the severe droughts of

the interior became contracted with the advent of

pastoralism. The concentration of fauna in thesehabitat enclaves made them easy prey for feral

foxes and cats, resulting in the significant decline in

medium-sized mammals. The extinction of fauna in

relation to tree clearing follows some of these sameprocesses. Clearing of habitat forces animals into

remnant vegetation, where they face a range ofproblems associated with the reduction of habitat,

including increased predation, inbreeding, lack ofdispersal opportunities, and a suite of influences

known as ‘edge effects’ (see Andren 1994).



43

Extinction due to habitat loss may be particularly

acute in Australia because of the extraenvironmental strains of drought and flood.

Ecosystems, and their component functions

subjected to stresses, display a degree of elasticity

in condition from which recovery is possible

(although the return state may not be the same asthe original). Thresholds represent those levels of

environmental change or damage, beyond whichrecovery is not possible. It is generally thought that

the relationship between habitat loss and speciesloss is non-linear. Initial losses in habitat are

accompanied by relatively small reductions in

species numbers, but as habitat loss increases,

large losses in species are associated with smallreductions in habitat (Connor & McCoy 1979;

Shafer 1990; Koopowitz et al. 1994). These simple

models suggest that with 30% habitat loss, 10% of

species will be lost; while at 50% habitat loss,15% of species will be lost. The models can also

offer information on threshold levels for ecosystemsand species. This basic information has been used

to limit clearing of every land type in south-westernNew South Wales to 30% of its original extent

(Southern Mallee Regional Planning Committee

1999).

Bennett and Ford (1997) carried out a study on

the woodland avifauna of northern Victoria anddocumented a dramatic decline in species numbers

once habitat fell below 10% tree cover. They

highlighted the lag phase between habitat loss and

species decline and indicated that many of the

species persisting in regions with more than 10%habitat retention are imperilled because of small

population sizes. There is ample evidence of a ‘lag

time’ between habitat and subsequent species loss.The status of birds continued to decline in the

Adelaide region between the 1970s and 1980s,

despite relatively little loss of habitat in the region

during this time (Paton et al. 1994). Other exampleswhere bird species have become locally extinct long

after fragmentation has ceased come from Western

Australia (Saunders 1989) and Victoria (Traill et al.

1996).

The scientific advisory group to the Commonwealthof Australia (Pitman et al. 1995) concluded that

biodiversity could be adequately protected if 15%

of each forest type was contained in a conservation

reserve and if the non-reserved part of that foresttype was managed in a sustainable way. The non-

reserved forest estate is, in general, not analogous

to clearing pastoral lands because the expressed

aim of forestry management is to recover foreststructure through the regeneration of native tree

species, where as pastoralism often involves the

reduction in woody species and establishment ofnative or exotic ‘grassland’ or pasture. It wouldappear that retention rates in the pastoral

landscape must greatly exceed those for Australian

forests if the conservation viability of the two

regions is to be matched.

In Queensland, the Eastern Darling Downs is one of

the most heavily fragmented regions and naturalhabitat is currently about 23% of the original area

(Fensham 1998b). Two field zoologists have

assessed the mammal fauna of the Eastern Darling

Downs based on historical records and their currentknowledge of distributions (Craig Eddie & Pat

McConnell 2000, pers. comm., 14 June). They

suggest that the original fauna was likely to have

comprised 32 native species. Of this, four species(13%) were assumed to be locally extinct in the

region. A further eight species were regarded as rare

which, together with the presumed extinct species,

represent 39% of the mammals in the region.

An extensive bird inventory was conducted at‘Coomooboolaroo’ in Duaringa Shire over the period

from 1873 to 1924 (Woinarski & Catterall 1999).

The owner during this time recorded around 225

bird species from the property, with about 30 ofthese being irregular visitors. In a recent census of

the property (over a shorter time frame), it wasrevealed that 150 bird species still live on or visit

‘Coomooboolaroo’, and the number may wellincrease with further surveys. If the irregular visitors

are excluded from the original list, the currently

known fauna represents 77% of the original fauna.

The property has not been exceptionally cleared;indeed, the landholders here have been clearly

sympathetic to wildlife and their environment. The

loss of birds is apparently not restricted to the

softwood and brigalow scrubs that have sufferedthe most clearance regionally, as there have also

been declines in many bird species associated withthe eucalypt forests and woodlands that make up

the bulk of the property. The loss of birds at‘Coomooboolaroo’ is almost certainly symptomatic

of the broader region. Data from 1995 for Duaringa

Shire indicated that habitat retention is currently

about 42% of the original area, which is the samerate as that for the entire Brigalow Belt bioregion at

that time. At even larger scales, there is good

evidence for the loss of birds across the tropical

savannas of northern Australia (Franklin 1999).

In a worldwide review of fauna studies, Andren

(1994) found that 30% habitat retention was acritical threshold. He verified that species loss

occurs above 30% habitat retention, but that below

this level the retention of species is more reliant onlandscape configuration than habitat loss per se.

When habitat is examined as individual remnants,

there is considerable literature to demonstrate that

large remnants provide more viable habitat andcontain more species than small remnants (section

4.1.2). Various bird studies have suggested that

10–20 ha provide a minimum viable habitat size for

many birds (Catterall et al. 1998). Ecosystemfunction is greatly impaired as remnants reduce in

size and particularly as their edge to area ratio

increases. This is clearly visible in relation to exotic

invasion. Buffel grass, while clearly of great valueto the cattle industry, is particularly invasive and



44

between production and conservation, the

productive potential of individual RegionalEcosystems (REs) may be accounted for. Regional

Ecosystems represent the best available surrogate

for biodiversity at the species level. Hence they may

provide an appropriate base unit for a system ofthresholds. On available evidence, 30% is the

minimum benchmark for the rate of retention of

REs to ensure against substantial extinction in the

longer term.

While this benchmark is in keeping withapproaches to managing ecosystems for

biodiversity elsewhere in Australia (e.g. Pitman et

al. 1995), there are many factors that can

determine an appropriate level to retain. Forexample, ecosystems that have a restricted

preclearing extent may be cleared down to unviable

areas if the benchmark is strictly adhered to.

Therefore, in the case of the Regional Ecosystemsdefined in Queensland and used in the Vegetation

Management Act 1999 (Qld), in addition to theproportion of preclearing extent, a 10 000 ha

minimum area has been incorporated into thecriteria for assessing status. This helps to ensure

adequate protection of habitats with a restricted

distribution.

The requirements of individual species,

populations, individual ecosystems and themanagement and condition of the surrounding

landscape, would also be expected to impact on the

benchmark. Ecosystems that are left highly

fragmented and surrounded by more intense land

use (such as exotic pasture development; seeMacIntyre et al. 2000 for an example of

recommendations) are likely to require greater

retention than ecosystems that are retained withina native species matrix (e.g. mulga woodlands, see

has been shown to replace native plant species

(Fairfax & Fensham 2000). Many remnants in thepastoral district are heavily invaded by buffel grass,

while other exotics lower the conservation value of

remnants elsewhere. In some vegetation types, such

as rainforest and acacia forest, weed invasionbrings a shift from fire resistance to flammability.

The native species in small and linear remnants are

the most vulnerable to fire, exotic invasion, grazing

and predation.

Clearly we can expect further extinctions if habitatloss continues in Queensland. This is likely to be

most acute in the regions or provinces (see figure

4.1) that have already been extensively cleared,

namely the Central Queensland Coast, the BrigalowBelt and the Southeast Queensland bioregions.

These bioregions have already lost sufficient

habitat that, using derived models (see figure 1.1),

would suggest 20% species loss. This predictedrate of extinction is in keeping with the anecdotal

evidence from Queensland and elsewhere, allowingfor further extinction of rare species as small

remnant populations lose viability and ecosystemfunction is altered. (Ecosystem function or

‘services’ is discussed further in section 3.2.)

Summary

In deciding where habitat should be retained for

conservation purposes, it is generally recognised

that a greater sacrifice should be made in the mostproductive regions and for the most productive land

types—those areas that have been

disproportionately cleared. Patterns of clearing inQueensland reflect both topography and soilfertility and hence lowland areas have been

extensively cleared and fragmented (Martin et al.

2000). In order to provide a balanced trade-off

80

S p e c i e s l o s s

( % )

60

40

20

0

60 20 40 60 80 100

z=0.2

z=0.25

z=0.3

Central westNew South Wales

Coomooboolaroo X

?

?

DarlingDowns

?Northern plains

Victoria

Wheat beltNew South Wales

Area cleared (%)

Figure 4.1 Theoretical species loss from international models. Data from the studies mentioned in the text. Mammals in the

central west New South Wales, wheat belt New South Wales, Darling Downs Queensland, and birds at ‘Coomooboolaroo’central Queensland and northern plains Victoria. The position of the tail of the arrow is the species that are known to beextinct. The position of the arrowhead is the species that are extremely rare. The lines in the graph are taken from a report tothe Southern Mallee Regional Planning Committee (1999), which adapted empirical equations derived by Connor and McCoy(1979) and Simberloff (1992).



45

of biodiversity value as size and arrangement of

fragments (e.g. MacIntyre & Hobbs 1999).

Fragmentation (of remnant or semi-modified

vegetation) leads to several problems for the

protection of biodiversity. Firstly, the viability ofisolated small blocks of vegetation is generally poor

(Hobbs 1991). This may be exacerbated if remnant

vegetation is not protected from domestic livestock

and inappropriate fire regimes. These isolatedblocks are not efficient in supporting a wide variety

of native fauna, and risk further degradation from

salinity, grazing, weed invasion and rising

watertables (Hobbs 1987). Another aspect of theproblem is lack of habitat diversity. In well-

developed agricultural areas, remaining vegetation

tends to be a non-random sample of former

habitats: swamps that could not be drained, steephillsides, and small patches of rainforest

maintained for ‘conservation’. These remnant

patches support a narrower spectrum of flora and

fauna than if all habitats were represented.In practice, problems associated with fragmentationmay be mitigated by interconnecting remnant areas

and/or specifying a minimum size of retention

areas for the protection of biodiversity and/or

managing the condition of patches.

Habitat reduction—what is a viablefragment size required for conservation of biodiversity?

An important element in the physical effect of

fragmentation is the reduction in the size of

individual habitat patches. There is considerableevidence indicating that larger remnants provide

more viable habitat and contain more species than

smaller remnants (e.g. Barrett et al. 1994; Catterallet al. 1998). However, the size of remnants required

to conserve biodiversity varies with species and

habitat types. For example, bird studies in southern

Queensland have concluded that 10 ha provides aminimum viable habitat size (Catterall et al. 1998).

Similarly, studies of birds in woodlands and open

forest in northern New South Wales (Barrett et al.

1994) have shown that remnant patches of 10–20ha are required to provide suitable habitat for the

majority (80%) of bird species. Studies from

Western Australia (Abensperg-Traun et al. 1996b;

Smith et al. 1996) suggest that small remnants(<5 ha) can provide suitable habitat for reptiles

and invertebrates. McIntyre et al. (2000)

recommend woodland patches of 5–10 ha are

required to support the majority of native plant andanimal species in grassy woodlands in south-east

Queensland.

Some unpublished studies from Queensland are

beginning to establish data for some ecosystems.Staff from the Queensland Parks and WildlifeService (Emerald), Griffith University, Queensland

Museum and Northern Territory Parks and Wildlife

Commission, have been investigating the effects of

Cameron & Blick 1982). While the benchmark

works at a bioregional scale, habitat loss at a morelocal scale (e.g. province sensu Sattler & Williams

1999; see figure 1.1) may impact on the

benchmark, for example 1998 local leasehold tree-

clearing guidelines for the Darling Downs increasedState-wide retention thresholds due to a high

amount of habitat loss in the local district. For

many habitats that are agriculturally productive,

such as temperate grassland or brigalow woodland,it is too late to achieve this benchmark. Many other

ecosystems are likely to retain higher levels of

vegetation based on guidelines for vegetation

retention in areas vulnerable to otherenvironmental risks such as salinity or erosion.

4.1.2 Fragmentation

A consequence of agricultural development has

been the vast reduction in intact native vegetation,and subsequently the high degree of fragmentation

of remaining vegetation (Wallace & Moore 1987).

Bennett (1999) identifies three components of the

fragmentation process:• the overall loss of habitats in the landscape

(see section 4.1.1)

• reduction in the size of blocks of habitat

(habitat reduction)• increased isolation of habitats (habitat isolation).

This section examines the latter two in more detail.

The study of landscape ecology recognises the

structure and spatial relationships, and interactions

over space and time between the ecosystems

and/or patches that make up a landscape (Forman& Godron 1986). There are sophisticated software

packages available to quantify landscape structure

(e.g. McGarigal et al. 1998) and theoreticalframeworks available to optimise or reintegrate

fragmented landscapes (Hobbs & Norton 1996;

Hobbs & Saunders 1991; McIntyre & Hobbs 1999).

These procedures work on the assumption thatplanning and managing over an entire landscape

will optimise protection of values compared to

planning and managing at individual patch or

subregional scales. In Queensland, vegetation

mapping could be used as a basis to reintegratehabitats across the landscape, although further

work is required to assess on which options best

meet the requirements of species and ecosystemsover space and time.

In many areas, landscapes cannot be classified into

remnant versus non-remnant areas, and it may be

more appropriate to treat them as ‘variegated’

(McIntyre & Barret 1992; McIntyre 1994; McIntyre &Hobbs 1999). That is, in between remnant

vegetation and vegetation which has been cleared

and planted with crops, there is a continuum of‘semi-modified’ vegetation that will possessbiodiversity and other values. In this case, a

consideration of the matrix that fragments are

embedded in can be just as important a determinant



tree clearing and fragmentation on the fauna of

eucalypt woodlands in central Queensland.Preliminary results indicate a trend in declining

species richness with declining remnant size (David

Hannah pers. comm.; summarised in table 4.1).

Large woodland areas (over 2000 ha) consistentlyhave more species present than medium-sized

remnants (50–300 ha) that, in turn, have more

species than do small remnants (5–20 ha). For

birds, small remnants and linear strips oftencontain widespread generalist bird species that can

utilise the changed conditions of these sites. As

remnant size increases, however, forest-dependent

species become more common. Initial observationssuggest that where herbaceous, log and litter cover

are intact, small mammals and reptiles will persist

within remnants, regardless of size classes and

connectivity. In general, as clearing reduced thesize and cover of tree groves and other vegetation

patches, counts for the grey butcherbird, yellow-

throated miner, striated pardalote, pale-headed

rosella and Carnaby’s skink declined, whereascounts for the red-backed fairy wren and house

mouse increased (Ludwig et al. forthcoming).

Counts for the weebill, Bynoe’s gecko and the

delicate mouse did not significantly change withclearing. Of these ten common fauna species, the

pale-headed rosella was the only species to

significantly change its abundance (higher counts)

with increased levels of livestock grazing,suggesting that clearing more strongly affects

abundances of common fauna than does grazing.

In another fauna survey of a property inWaggamba Shire with 10% total tree cover,

shadelines ranging from 20–200 m in width andsmall patches up to 5 ha, a total of 7 native

mammal, 81 bird, 17 reptile and 7 frog species

were found (Richard Johnson, EPA Roma unpub.).

This represents more than a third of the totalspecies predicted to occur in the surrounding shire

(including about half the total bird species). Thus,

while these shadelines’ sizes and total tree covers

are too small to protect all species, particularlythose that require larger areas (e.g. eastern yellow

robin Eopsaltria australis, imperial hairstreakbutterfly Jalmenus evagoras evagoras), they may have

considerable conservation value.

Habitat isolation—the role of wildlifecorridors

Habitat fragments are often isolated from one

another by a hostile environment (Andrén 1994),

although habitat patches do not exist in an non-interactive matrix, and the surrounding agriculture

or secondary forest (Power 1996; Whitmore 1997)

may offer a habitat or means of dispersal to some

terrestrial species. Ecosystem processes such asseed dispersal, pollination of plants, predator–prey

relationships, gene flow and dispersal of disease

and parasites, can be sensitive to isolation effects

(Bennett 1999). The ideas of dispersal have bornefurther theoretical investigations into the viability of

subpopulations and the concepts of natural

extinctions, recolonisations and the persistence of

the metapopulation as a whole (Hanski et al. 1995;Collinge 1996).

Wildlife corridors are areas of retained native

vegetation that link other remnant vegetation within

an otherwise non-remnant landscape. They areoften seen as an essential element of nature

conservation planning (e.g. Noss 1987; Chenoweth

& Associates 1994), mitigating the impact of habitat

loss and fragmentation. Linked large remnants arelikely to provide more viable habitat at the regional

scale than many small fragments with a high edge

to area ratio (Cale & Hobbs 1994).

Definitions of corridors abound (e.g. Saunders &

Hobbs 1991; Harris & Scheck 1991) but all includethe following:

• a continuous strip of vegetation• usually link larger tracts of vegetation

• used or capable of being used by wildlife formovement

• capable of being a habitat in their own right.

Corridors may be classified according to their

continuity and connectivity as well as by their

origins (Loney & Hobbs 1991). Natural corridors,remnant corridors, restored corridors and riparian

corridors are such examples, with classification not

necessarily mutually exclusive. Riparian corridors

have been referred to as Australia’s ‘ecological

arteries’ (Recher 1993; Sattler 1993b). Thesecorridors usually contain the most fertile and well-

46

Table 4.1 Fauna species richness (mean and standard deviation) in eucalypt woodland remnants of different area and isolationclasses, and eucalypt regrowth and pasture sites in central Queensland.

Site type Description Birds Mammals Reptiles

Large >2000 ha (8 treatments) 55.6 (10.0) 7.5 (3.1) 15.9 (5.8)

Medium patch (connected) 50–300 ha (8 treatments) 47.8 (11.1) 7.1 (2.8) 14.9 (4.2)

Medium patch (unconnected) 50–300 ha (8 treatments) 44.3 (13.5) 7.0 (3.0) 12.8 (3.1)

Linear strip (connected) 50–150 m wide (5 treatments) 42.0 (6.6) 5.5 (1.7) 11.8 (3.6)Linear strip (unconnected) 50–150 m wide (8 treatments) 32.8 (11.3) 5.2 (2.8) 8.8 (6.1)

Small patch (unconnected) 5–20 ha (8 treatments) 26.5 (9.3) 5.4 (1.8) 10.1 (4.6)

Eucalypt regrowth 5 m +/- 3 m high (8 treatments) 29.6 (10.5) 6.9 (3.1) 8.9 (6.3)

Pasture Improved and exotic (8 treatments) 20.8 (4.6) 6.4 (2.5) 7.0 (4.5)



47

Bennett (1999) considers wildlife corridors as one

option of a number that contribute to managing theentire landscape for connectivity. While corridors

can and are applied as a habitat conservation

measure in fragmented landscapes (Noss 1987),

they should not be used as an all-encompassingpanacea for fragmentation. In the absence of

detailed, species- and site-specific research, the

use of corridors should be mixed with other

measures and there is always likely to be a need toretain larger areas of non-fragmented habitat.

Downes et al. (1997) found that wet sclerophyll

corridors in north-eastern Victoria provided useful

habitat for several mammal species, but that there

were intraspecific differences in habitat use bybrown antechinus (Antechinus stuartii). Specifically,

there was a higher proportion of males, and

individuals had lower body weight in corridors than

in forests. Thus fragmentation may lead toreduction in fitness of isolated populations of some

species. This study demonstrated that, whilecorridors can provide useful habitat for mammalian

assemblages, they might not provide a completesolution to the problem of landscape fragmentation.

There has been some published and unpublished

data from Queensland suggesting wildlife corridors

do provide useful habitat in some situations. Work

in northern Queensland in Donaghy’s Corridor(Atherton Tablelands), which is a revegetated strip

of rainforest linking Lake Eacham National Park and

Gadgarra State Forest, provides evidence that

corridors do provide for the movement of species

(Tucker 2000). Preliminary unpublished evidencefrom genetic studies on Rattus fuscipes, Rattusleucopus and Melomys cervinipes indicate that the

previously isolated populations of these species,which occurred at each end of the corridor, are

distinctly different genetically. However, the F1

generation of each species has recently been

identified as being genetically related, indicatingthat the corridor seems to be functioning as a

conduit for these species.

In a north Queensland survey of four species of

rainforest interior insects, Hill (1995) found that adung beetle species and butterfly species occurredin linear corridors, but not in the surrounding

arable land. The remaining two species were

confined to the rainforest habitat. Hill (1997)

argues that emphasis should be placed upon theseinterior (or edge aversive) species, because the

process of habitat fragmentation is likely to have

the greatest impact on such species. Use of

corridors by these species supports the need forthem for conservation purposes. Hill (1997) noted

that corridors were functioning as habitat for the

beetles rather than simply encouraging dispersal,and that with corridors 200 m wide you get about80% of the fauna present in a large habitat patch.

watered part of the landscape, and are highly

significant from both a productive and conservationperspective.

There are three main reasons why corridors may be

used to protect biodiversity in a fragmented

landscape (Simberloff & Cox 1987):

1) They allow increased migration or movement ofwildlife. It is predicted (from ‘equilibrium theory)

that they allow more species to survive than ifvegetation is present as smaller fragments with

no migration.2) They provide habitat for wildlife in their own

right, particularly for fauna that may require

larger diversity and amount of habitat to meet

their food requirements than may be present insmaller isolated fragments.

3) They prevent inbreeding of isolated populations.

The effectiveness of corridors

Simberloff and Cox (1987) and Lindenmayer (1994),

point out there has been a paucity of evidenceavailable to support or refute the values ofcorridors as conduits for the movement of species.

Furthermore, information that is available has often

not been collected from properly designed

experiments, making it difficult to disentangle causeand effect. For example, comparing two remnants

that are not connected by a corridor with two

remnants that are may be confounded by the

additional habitat provided by the corridor in thesecond case and not just the fact that they are

linked.

The effectiveness of corridors is likely to vary witha range of factors including habitat structure and

quality within the corridor, dimensions(length:width ratio) of the corridor, the nature of

the surrounding habitat, human-use patterns and,

most importantly, the biology of the particular

species that are expected to use the corridor and itssurrounding habitat (Simberloff & Cox 1987;

Lindenmayer 1994). For example, highly mobile

species may be able to travel through or inhabit

modified land between remnant fragments, makingcorridors non-essential to their survival.

The degree of isolation is species-specific and is

relative, not only to the biology of each individual

species, but also to environmental conditions

(Harris 1984). Dispersal abilities of individualspecies play a key role in assessment of fragment

suitability, as well as identifying barriers to

dispersal (Goosem & Marsh 1997). Many studies

focus on single species, and largely on mammalsand birds (e.g. Andrén 1994, Laurance 1994, and

Goosem & Marsh 1997), and it is difficult to make

generalisations for a range of species based on

these. Landscape connectivity (e.g. wildlifecorridors) may be a useful management tool in

overcoming the impacts of isolation.



From the above discussion, it is possible to say that

generally, wider and larger corridors or patches areconsidered better for biodiversity conservation than

smaller and narrower corridors or patches (Hussey

et al. 1989), although the optimum width and size

will vary with the nature of habitats that form andsurround the corridor and the ecology of species

using the corridor (Noss 1987). For example, in

Western Australia, bird species’ richness in

woodland corridors on road reserves wassignificantly influenced by the density of the

ground cover below 1 m and the density of

vegetation above 8 m. A study of birds in south-

east Queensland open forest found that corridorshad to be at least 500 m for small forest birds

(Catterall et al. 1991). Hussey et al. (1991) suggest

rainforest corridors may need to be 100 m wide,

while in heath vegetation the minimum requiredwidth might be only 30 m.

4.1.3 Condition of vegetation

remnantsThe effect of patch size is often confounded by the

relationship between patch size and condition. To

ensure both sustainable use and the long-term

viability of the landscape, knowledge of thecondition of remnants is essential. It is traditionally

accepted that remnant size, shape and proximity to

other areas of native vegetation are critical

variables affecting the persistence of native speciesand the invasion by exotic species (Saunders &

Hobbs 1991). Other factors affecting the condition

and functioning of remnants include the type andintensity of disturbances that the remnant has beensubject to and the vegetation type, which vary in

their levels of natural resilience and resistance to

change. Despite these influences, degraded

remnants still provide value in the landscape interms of property productivity and regional

conservation, although it is assumed that remnants

with limited modication are better able to provide

these values across the landscape.

Habitat value of small remnants is usuallycompromised by changes in understorey structure

and composition caused by disturbances such as:• grazing, from domestic livestock and native

fauna• herbicide or pesticide spray drift

• weed invasion, particularly from exotic pasture

species

• native fauna population pressures from reducedhabitat

• edge effects

• alteration of fire regime (Saunders et al. 1991;Barret et al. 1994; Abensperg-Traun et al. 1996b;

Smith et al. 1996).

Apart from biological consequences of

fragmentation, there are physical consequences to

fragmentation. Alterations in radiation, wind and

48

The study from central Queensland, summarised in

table 4.1, also investigated the effects ofconnectivity of remnants on associated fauna

richness. Where a remnant patch or strip of

vegetation is linked to other patches of vegetation,

species numbers increased. This was especiallyevident for bird species’ richness that increased

greatly when linear strips of vegetation connected

up with more extensive woodland areas. Regrowth

vegetation supported greater numbers of faunaspecies than pasture sites. Pasture sites which have

been sown with the introduced pasture grass

Cenchrus ciliaris (buffel grass) generally had fewer

remaining ground-dwelling species (e.g. quails,fossorial skinks and native small mammals) than

pastures which contained a mix of native grass

species (see further discussion on the effect of

reduced grass diversity and loss of biodiversity insection 3.2).

Corridors and patches, as remnants of once

widespread and complex vegetation associations,are subject to species losses and changes in

ecosystem processes (Hobbs 1993b). Being linear,corridors in particular suffer a relatively larger edge

effect (see section 4.1.3), so that damage by fire,

fertiliser drift, weed invasion, wind damage, insect

defoliation, nutrient enrichment from run-on,microclimatic changes, hydrological changes, and

many other impacts, greatly affect their

sustainability (Hussey et al. 1989). Fauna using

corridors as habitat may be more susceptible topredation by increased feral cat and fox

populations that are often associated with afragmented landscape.

In coastal areas, vegetation is generally denser, and

edge effects are likely to result from intensive landuses such as sugarcane cultivation, sown pastures

and urban and peri-urban subdivisions. Given the

extent of the development and the low rate of

retention of native vegetation, coastal corridors willalso have a major function as habitat and should

be made as wide as possible.

In inland areas, harsher and more frequent climatic

extremes and extended seasonal food deficienciesmean that corridors need to be wider than coastalareas. This is also true because the generally

sparser vegetation provides less protection for

animal species from predators. Population densities

may already be relatively low and the chances ofcorridors becoming ‘sinks’ for some species

relatively high. The loss of smaller insect-feeding

birds facilitates insect outbreaks that may lead to

repeated tree defoliation and eventual ruraleucalypt dieback (Ford 1986). In these areas, 200 m

may be a sustainable width, but variables such as

corridor length and grazing pressures also need tobe considered.



49

water fluxes can all affect populations within

fragments. Changes in microclimate are especiallynoted at the edge where original habitat meets

cleared matrix (Saunders et al. 1991; Laurance &

Yensen 1991) and, whilst the effect of this is

unknown, it may result in invasion by shade-intolerant or secondary species (Lovejoy et al. 1986).

Ecosystem function is greatly impaired as remnants

reduce in size and particularly as their edge-to-area ratio increases. Deterioration due to ‘edge

effects’ is the greatest threat to stability of smallremnants or wildlife corridors. This impact of

habitat edges on the viability of biodiversity in

remnants has become an enormously complex

aspect of fragmentation research and has sparked aplethora of investigations into edge effects (e.g.

Laurance & Yensen 1991; Turton & Freiberger 1997;

Didham 1997). In its earliest conception, edge

effects were quantified in a ratio of perimeter lengthto area (see figure 4.2), in an attempt to quantify

size and shape variation (Laurance & Yensen 1991;Didham 1997). Assessment of the ecological

impacts of edge effects by the core-area model(Laurance & Yensen 1991) uses edge penetration

distance to calculate the unaffected area of a

fragment of any shape or size for focal taxa.

Linked large remnants are likely to provide more

viable habitat at the regional scale than many smallfragments with a high edge-to-area ratio (Cale &

Hobbs 1994). The nature and impact of the edge

effects will be greatly influenced by the nature of

the adjacent land use and the corresponding

strength of the edge effect (Soule & Gilpin 1991).Dorricott et al. (1998) have demonstrated edge

effects in the southern brigalow belt (see figure 4.3).

A sustainable remnant will have two zones: theoutside areas that are affected by ‘edge’ processes,

and an inner or core area. Fragments must be wide

enough to ensure that an ecologically viable core

area is sufficiently distant from the edges to reducethe impact of edge effects (Start 1991).

The utility of corridors as habitat is often reduced

because their linear nature makes them prone to

degradation by disturbance. Corridors also must bewide enough to ensure there is a large area in themiddle that is not impacted by edge effects (Start

1991). Corridors must be managed with specific

objectives in mind. Weeds have the potential to be

the most serious threat to corridor integrity andmust be addressed. Similarly, pests, vermin and

feral animals may also live in corridors, and it is

important to control problem species. Fire

management must be considered, especially whenthe dominant tree species is fire sensitive (e.g.

mulga Acacia aneura). Similarly, management

practices and operations, especially stock handlingand mustering, have to be taken into considerationin developing appropriate strategies for overall

management of corridors.

E f f e c t i v e n a t u r a l h a b i t a t ( h a )

100

50

00 50 100 150

Area of remnant vegetation block (ha)

150

circle

no edgeeffect

1:5 strip

1:10 strip

Figure 4.2 The effect of shape of retained vegetation on thearea of natural habitat within that vegetation. Naturalhabitat is defined as that part of the block greater than 75 mfrom the nearest boundary. The difference between the1:1 line and the particular configuration line is an indicatorof the area of ‘edge’ habitat. Source: Scanlan et al. 1992.

Figure 4.3 Showing how size and shape impact on edgeeffects. Source: Dorricott et al. 1998.

Indicates edge effectsfor a difference of 25 m

Size, shape and edge effects10 ha remnants

Indicates effectiveundisturbed habitat

Undisturbedarea 7.5 ha

Undisturbedarea 7 ha

Circular remnanttotal edge=1121 m

Square remnanttotal edge=1265 m

Undisturbed area 4.5 ha

Long narrow remnant total edge=2200 m



50

4.1.4 Impacts of domestic grazingwithin remnant vegetation

As highlighted in section 4.1.1, the greatest threat

to biodiversity in Queensland is loss and

degradation of habitat associated with continued

broadscale vegetation clearing (Scanlan & Turner1995; EPA 1999c).

Broadscale vegetation clearing, however, is not the

only contributor to loss of biological diversity, with

overgrazing by domestic stock commonly accepted

as a significant factor contributing to thedegradation of remnant and riparian vegetation

(Foran et al. 1990; Morton & Price 1994).

According to the State of the Environment Queensland 1999 report (EPA 1999c), grazed woodlands have

undergone considerable structural changes sincethe arrival of domestic stock, with evidence that

many areas support increased unpalatable woody

plant density and biomass. Elsewhere in Australia,

there is a growing amount of evidence to indicatethat domestic grazing has impacted greatly on the

natural environment and its associated biota (e.g.

Hobbs & Hopkins 1990; Morton 1990; Christie

1993; Kirkpatrick 1994; Wilson & Clark 1995;Landsberg et al. 1997a, 1997b and 1997c).

A review of the impacts of grazing in wooded

ecosystems in south-eastern Queensland, recently

undertaken by an Ecologically Sustainable Forest

Management (ESFM) review panel (McDonald et al.1999), suggested that the cumulative impacts of

grazing were poorly studied and understood. It is

likely that this has broader applicability across theState of Queensland. Notwithstanding, stakeholdersin the south-east were of the opinion that if

properly managed, grazing may be compatible with

flora and fauna conservation, particularly in

grasslands (McDonald et al. 1999). Furthermore,the results of long-term grazing experiments in the

northern spear grass region by CSIRO support the

contention that moderate levels of grazing pressure

by domestic livestock and conservation of nativeplant diversity can be largely compatible (EPA

1999c). It is prolonged and continual overgrazing,

however, that is considered to be the primary

source of degradation and loss of biodiversity ofremnant vegetation.

Impacts on flora

Domestic stock are suspected, directly or indirectly,

of impacting on the flora of remnant vegetation

through grazing, browsing or rubbing of vegetation,

soil compaction and erosion, eutrophication ofwater sources, altered nutrient status of soils,

spread of weeds, and altered fire regimes (FERA

1998). The effect of grazing in remnants depends on

the type and intensity of grazing (Fensham 1998b),the predominant season grazed (Pettit et al. 1995),

and management activities associated with grazing,

such as fire regimes and tree treatment. Also of

importance is the location of watering points, and

the establishment of tracks, fence lines and otherinfrastructure, such as yards and buildings.

Braunack and Walker (1985) found that grazing

altered the structure of both gradational texture

profile and duplex profile soils within remnants of a

semiarid poplar box (Eucalyptus populnea) woodlandat Wycanna, southern Queensland. This may be

attributed to the loss of ground cover, resulting insoil erosion and subsequent nutrient loss (Braunack

& Walker 1985). However, an increase in the inputof faecal matter from domestic stock may

compensate for this by supplementing nutrients and

increasing soil pH as was demonstrated in a study

of sheep in Western Australia (Scougall & Majer1991).

Other changes resulting from altered soil structure

include soil compaction and/or surface seal

formation, and the inability of plants to germinate,

grow or survive (Braunack & Walker 1985). In a

study in Western Australia, Scougall and Majer(1991) found that soil moisture was increased by

grazing, largely because of a decrease in the

abundance of plant cover. As a result, less wateruse and increased compaction occurred in the

upper surface layers, leading to greater soil water

retention. (See section 4.2.4 Soil Structure.)

Changes in species composition

The most direct effect of grazing within remnant

vegetation is changes in the species composition ofthe plant community (Friedel & James 1995;

Scanlan & Burrows 1990). Continual, heavydomestic grazing within remnants can rapidly

reduce the abundance of palatable ground-layerplant species, including regenerating seedlings of

canopy species. Preferential grazing of these

palatable species leads to a general increase in the

abundance of unpalatable (grazing-tolerant)species (Yates & Hobbs 1997; Prober & Thiele

1995; Cheal 1993). Palatable shrub foliage within

reach is also browsed. Palatability of species may

vary according to season, age of plant, location, orthe type of grazing (e.g. cattle and sheep). As such,

the response of the plant community to domesticgrazing is very complex.

The introduction of exotic pasture plant species

into Australia with agricultural expansion hasadded a further layer of complexity to the effect of

grazing on remnant vegetation. Clearing

applications indicate that the vast majority of land

clearance in Queensland is directed at theestablishment of buffel grass pasture. Franks et al.

(2000) express their concern over the expansion

and incursion of exotic pasture species into the

remnant vegetation of Queensland, particularly thenorth African perennial, buffel grass (Cenchrusciliaris). They suggest that the life-history traits

sought in successful screening of pasture species

are also the traits that make these species potential



weeds of remnants. Once established within

remnants, these exotic pasture species alter thecharacter and functioning of the plant community

in several key ways. The most readily observed

result is a reduction of diversity and abundance of

native plant species, particularly grasses and herbs(Fairfax & Fensham 2000). Buffel grass poses great

problems to the managers of national parks

because of its capacity to change fire regimes

(R. Fensham 2000, pers. comm. 29 March). Thelocal loss of native species, coupled with the

invasion of exotic pasture species, has been

observed as a response to grazing in a number of

studies (Pettit et al. 1995; Abensperg-Traun et al.1996a, 1996b and 1998; Prober & Thiele 1995;

Cheal 1993).

Fensham’s (1998b) study on the Darling Downs

demonstrated that species richness was generally

greater in moderately or heavily grazed sites thanin sites lightly grazed, although responses varied

with vegetation type. McIntyre and Lavorel (1994)found no significant difference in exotic species

richness at different grazing intensities. McIvor(1998) demonstrated that whilst changes in

diversity of both exotic and native pastures changes

with site and year, his results clearly show that the

introduction of sown species, particularly withcultivation, significantly reduces the density of

native species. McIvor expresses some concern at

the implications of these changes for the

productivity and stability of these pasture systems.The importance of investigating this impact in

different environmental contexts is emphasised byProber and Thiele (1995), who noted that livestock

grazing appeared to have played a more significantrole in degrading remnant quality in white box

woodland species, than fragmentation effects per

se. It must be remembered that all the direct effects

of grazing pressure occur under light grazing aswell as under heavy grazing. The time for the

effects to manifest under a light grazing regime is

greater than under moderate to heavy stocking

rates (Hussey & Wallace 1993).

In a study on the ecological condition and

functioning of remnant poplar box (Eucalyptus populnea) woodlands, it was found that any effects

associated with fragmentation were overridden by

prevailing domestic stock grazing regimes and otherland management practices. Those remnants that

received periodic or light grazing had higher native

species diversity and increased structural complexity

than those subjected to year-round, moderate toheavy grazing. Again, the number of exotic species

did not vary greatly among stocking rates.

A number of significant changes were recorded,

with different grazing intensities for plant andvegetation patch attributes in poplar box andsilver-leaved ironbark (E. melanophloia) woodlands

in central Queensland (Ludwig et al. forthcoming).

51

For example, the authors found that the cover of

clumps of native perennial grasses such askangaroo grass (Themeda triandra), black speargrass

(Heteropogon contortus), wiregrasses ( Aristida spp.)

and bluegrasses (Bothriochloa spp. and Dichanthiumspp.), declined significantly with increased grazingpressure, where as the cover of buffel grass

(Cenchrus ciliaris) clumps increased. Grazing had no

significant impact on tree grove, shrub thicket, log

hummock, and termite mound patch coverattributes. However, in heavily grazed sites, tree

dieback was evident, and unpalatable shrubs (i.e.

Carissa ovata, currant bush) and bare ground

patches were more common.

Changes in habitat structure

York’s (1998) studies on the impacts of grazing andfire on forest biodiversity in New South Wales have

demonstrated that the structure of understorey

vegetation differs substantially between grazed and

non-grazed sites. Grazed sites had significantly less

ground herb cover and small shrubs, but the degreeof impact appeared to vary with geology and soils.

York (1999) further suggests that the effects of

grazing on forest structure may be patchy due tocattle grazing occurring preferentially in more open

areas. Accordingly, York (1998) also reported that, as

sites become more open, grazing intensity increases,

resulting in a reduction in the amount of vegetationin the ground herb and small shrub layers.

In a study of the impacts of cattle and macropods

on grazed woodlands in north Queensland,

Fensham and Skull (1999) found no significantdifference in basal area of eucalypts between nativeand domestic stock grazing. However, the basal

area of non-eucalypt species was significantly less

in those sites grazed by cattle. The physical

location of the sites grazed by macropods naturallyexcluded grazing by cattle and were presumed to

be burnt considerably less than those sites grazed

by livestock. Fire regime must therefore be

considered as a confounding variable, even thoughfires can be considered part of domestic grazing

management and thus constitute part of the overall

effect. Nevertheless, it is generally believed thatgrazing reduces the ability to burn because ofreduced fuel loads.

There is both anecdotal (Royal Commission 1901;

Inter-Departmental Committee 1969; Rolls 1981;

Allingham 1989; Joyce 1990; Simpson 1992; Tothill

& Gillies 1992; Harland 1993; Reynolds & Carter1993) and empirical evidence (Burrows et al. 1985;

Burrows 1995) that woody plants have increased in

both density and biomass under grazing in

northern Australia since European settlement(Tothill et al. 1982). Similar increases in woody

plant cover in grazed vegetation have been reportedin Africa, South America, India and North America

(see S. Archer’s web site bibliography for referencesfrom several countries: <http://cnrit.tamu.edu/

rlem/faculty/archer/bibliography.html>).



52

Using historical data as well as δ13C analyses,Burrows et al. (1998) have shown that woody plant

thickening has occurred in the grazed woodlands of

north-eastern Queensland. It is suggested that

these woodlands were maintained as a firemediated subclimax prior to the introduction of

domestic livestock. Altered fire frequency and direct

effects of reduced cover on increasing soil water at

depth have contributed to the increase in woody

cover. They reported tree basal area growthincrements of 21 ± 0.03 m2/ha/yr (mean of 47

established diverse sites) for eucalypt species in

Queensland’s grazed woodlands over a mean nine-year period with some plots from the early 1980s

(with a focus on central Queensland). Broadly

similar rates of increase in grazed woodlands have

been reported in North America and southernAfrica (S. R. Archer 1999, pers. comm.,

16 November; R. J. Scholes 1999, pers. comm.,

16 November).

The vegetation structure of rangelands in Australiahas great relevance to the pastoral industrybecause of the inverse relationship between the

abundance of trees and grass (Burrows et al. 1990).

The real possibility that the density of the woody

component of woodlands is increasing is thus ofgrave concern for that industry and has been a

prime motivation for the mechanical clearance of

vegetation. There is little doubt that stocks of

woody vegetation can undergo considerable flux.The open question is whether these fluxes are the

result of normal climatic cycles, the result of cattle

grazing through the inverse relationship betweenwood and grass, changes in fire regime, orfeedback resulting from the primary cause of the

greenhouse effect, namely CO2

fertilisation.

Fensham and Holman (1999) have recently

demonstrated that dieback collapses canundoubtedly result from extreme drought events.

Finally, it is important to note that remnant

degradation may occur through removal of grazing

as well as prolonged overgrazing, by forcing

changes to vegetation structures (House 1997).Periodic grazing within remnant vegetation allows

some control of exotic pasture species that, withoutgrazing, would come to dominate the herbaceous

layer and displace native species. This leads to aloss of species diversity and changes in habitat

structure, and can alter the ecological dynamics

within remnant vegetation.

Impacts on fauna

Literature on the effects of grazing on native

vertebrate and invertebrate populations in Australiais limited. Abensperg et al. (1996a, 1996b), in the

wheat belt of Western Australia, used sheep faecal-

pellet density (as a proxy of grazing intensity) and

percentage cover of weeds to allocate disturbancecategories on arthropod abundance. This study

found sheep faecal-pellet density and lichen cover

to be the most important habitat indicators for the

abundance or richness of scorpions, termites andbeetles, but not for spiders, isopods, cockroaches

or earwigs.

Scougall and Majer (1991), in the Western

Australian wheat belt, compared 23 biological

variables between grazed and non-grazedremnants, including a survey of the ant fauna. They

found that the species of ants changed significantlybetween the grazed and non-grazed remnants, as

an indirect result of grazing exclusion. Theyconcluded that domestic stock activity within

remnants compacted the soil to such a degree that

this selected for those species of ants that were able

to cope with the altered soil structure. The changesin species and numbers of ants also affected the

dispersal patterns of many native plant species.

Bromham et al. (1999) found that invertebrate

species composition between grazed and non-grazed remnants also varied. The less abundant

orders, such as cockroaches, millipedes, centipedes,springtails, beetle larvae and scorpions, showed

highest representation in non-grazed remnants.

Arnold and Weeldenburg (1998) studied the effectsof remnant size and grazing on recorded bird

species. Although the mean number of bird species

present in grazed patches was less than in non-

grazed patches, the difference was attributed toremnant size. Stock have also been suspected of

destroying sheltered sites important to feeding and

roosting by the black-breasted button-quail Turnix melanogaster , although it is likely that this effect is

exacerbated during times of drought (Flower et al.1995). Preliminary investigations into the impacts

of broadscale tree clearing and grazing on

vertebrate fauna in central Queensland found thatalthough tree clearing and grazing interacted, the

removal of trees had the greater impact on fauna

(Ludwig et al. forthcoming).

Rare and threatened species

Endangered, Vulnerable or Rare (EVR) species are

generally very susceptible to disturbance, due tolow population numbers, restricted ranges or a

declining population. It is for these reasons thatEVR species should be considered separately when

attempting to manage the effects of grazing onnative flora and fauna.

Little is known of the impacts of grazing on EVR

species. For example, of the 205 EVR species (plant

and animal) in Queensland considered in the Fauna

and Flora Information System (DNR 2000),13 species are considered to be ‘threatened’ and

84 species are ‘possibly threatened’ by grazing.

Management recommendations for these species

tend to be precautionary, based on best availableknowledge.



Effects associated with watering points

Grazing impacts are greatest close to artificial

watering points, and decrease with distance fromthese points (Foran 1980; Andrew & Lange 1986a

and 1986b; Landsberg et al. 1997a and 1997c;

James et al. 1999). Changes cited by James et al.

(1999) across the arid zone include:• the development of a zone of extreme

degradation around the water (up to 0.5 km)where soil crust is broken, erosion is high, and

unpalatable plants dominate• an increase in the number of unpalatable

perennial shrubs beyond the extreme

degradation zone, particularly in semiarid

woodland and arid shrubland habitats• a decrease in abundance of palatable native

perennial grasses, due to selective grazing. These

changes near water can cause a decline in

perennial plant diversity and in fauna dependenton such vegetation such as grasshoppers

(Ludwig et al. 1999).The positioning of point water sources on the edge

of remnants creates further problems in the

effective management of these areas. Theconcentration of stock to a point water source

rapidly degrades the remnant condition

immediately adjacent to these areas, with the

effects decreasing as the optimal foraging rangeincreases (James et al. 1999). With many properties

currently with (uncontrolled) artesian water,

converting from linear (bore drains) to point water

sources as a means of water management, there

appears to be some merit in maintaining existingbore drains. Primary among these is the

distribution of domestic stock impacts across the

broader landscape rather than a concentration onthe edge of remnants.

The removal of established artificial watering points

may have effects on species composition and

abundance and may threaten vulnerable species. In

areas where water supplies are limited theimplementation of artificial watering points may

increase the range of grazing animals other than

domestic stock, exacerbating impacts caused by thelatter (James et al. 1999). This form of alteredcomposition and possible changes in abundance of

fauna in areas containing artificial watering points

may have profound effects on flora at the

ecosystem level, as well as immediately adjacentthe watering point.

Grazing in riparian areas

The effects of stock grazing on remnant riparian

vegetation in Queensland are of particular concern,

as vegetated buffers are required by legislation to

be left around watercourses after clearing. Hancocket al. (1996) nominated grazing as one of the

foremost environmental problems threatening

riparian plant species diversity in Western

Australia, but did not provide data to support this.53

Bennett (1994) suggests that remnant riparian

vegetation in the northern plains of Victoriasupports the greatest diversity of bird species when

compared with other remnant vegetation types. He

indicates that riparian vegetation supports a greater

density of birds and arboreal marsupials than allother remnant types. Bennett expresses concern

with current grazing management on privately

managed riparian sites, implicating grazing as a

cause of remnant degradation.

Effects of continual grazing of riparian zonesinclude the elimination of, or reduction in, canopy

species due to the prevention of regeneration

(Fleischner 1994; Smith 1988). Fleishner (1994)

indicated that grazing may alter riparian vegetationin four main ways:

1) by compaction of soil (increasing run-off and

decreasing the water available to plants)

2) by removal of herbaceous species3) by physical damage to vegetation by rubbing,

trampling and browsing4) by altering the growth form of plants, through

removal of terminal buds and stimulation oflateral branching.

Eutrophication of water and trampling of important

breeding sites for amphibians are of particular

concern.

Conclusion

Studies suggest that the effect of grazing on the

condition of remnant vegetation is not alwaysbenign. Overgrazing and poor land management

practices for grazing appear to have the greatestimpacts, especially on floral composition, the

extent of weed invasion, habitat structure and thediversity of wildlife communities. Significant

impacts appear to occur within the vicinity of

watering points, due to the prolonged use of

remnant vegetation by stock. Furthermore, theseriousness of impacts is variable across the

landscape and through time.

Land managers possess some of the tools and

knowledge necessary to carry out responsibilities

toward the ecologically sustainable management ofQueensland’s natural resources. For example,

together with this review, current research, the

availability of models to predict safe carrying

capacities (e.g. Johnston et al. 1996), and effectivemonitoring (see section 6.2), the efficacy of grazing

management regimes and their impacts on the

condition of forests can be assessed.

4.1.5 Ecosystem repair andmanagement

The decision to retain areas of native vegetation for

biodiversity values may not automatically guaranteethe continuation of biodiversity. Reduction of

vegetation clearing to ensure no net loss of native

vegetation within Australia by July 2001 (CIE 1999)is one aspect of the national goal of native



54

vegetation management, others may also include

assessing and monitoring the condition of theremnant, and managing the remnant to achieve the

goals sought for the area (this may include

production, wildlife and biodiversity

considerations). As the National Framework for theManagement and Monitoring of Australia’s Native

Vegetation (Commonwealth of Australia 2000)

becomes firmly established, the focus across the

State will be upon how remnant vegetation and theecosystems of which they are part is managed. We

will want to know how we can best improve the

condition of what is left and strategically increase

native vegetation cover in Queensland. Managingfor biodiversity may include active measures to

manage and repair ecosystem function. Areas, such

as riparian zones, play an important role in the

function and structure of streams, and influencewater quality and stream bank stability (Campbell

1993). Due to their poor condition, the management

of riparian zones in Queensland has now become a

major conservation issue (Sattler 1993b).

The best management of these areas also requiresdetailed consideration for the protection of

biodiversity. The management of retained

vegetation on lands used primarily for production

will obviously not usually be identical to themanagement of areas set aside primarily for nature

conservation (e.g. national parks). Grazing (e.g.

grasslands on the Darling Downs (Fensham

1998b)) and thinning (e.g. mulga woodlands(Cameron & Blick 1982)) can be compatible with

maintaining the majority of biodiversity values ofvegetation in some cases.

Pre-European condition may represent a good

indicator of management requirements forbiodiversity in some cases, particularly with respect

to fire management. However, management is best

determined by an assessment of the impacts of

management against the requirements ofbiodiversity. For example, poplar box (E. populnea)and yellow jacket (E. intertexta) woodlands in the

Dirranbandi area are considered by many

landholders to be in an ‘unnatural state’ because

their dense shrubby understorey is believed to havereplaced a naturally grassy ground layer. The

absence of this understorey may be associated with

an increase in native herbaceous species richnessbut it can also be associated with an increase in

the abundance of the exotic buffel grass, Cenchrusciliaris. Central to considering management of

remnant areas is understanding the relationshipbetween surrounding and concurrent activities, and

functioning of the remnant. Of particular

importance in Queensland is the impact of

domestic grazing on remnants.

Any strategic approach to ecosystem repair mustconsider the appropriate vegetation management

techniques, the conservation priorities for a

particular regional ecosystem, and the cost of

implementation of any repair programs. There are a

number of national and State policies and programsthat support vegetation management (e.g. The

National Framework for the Management and

Monitoring of Australia’s Native Vegetation

(Commonwealth of Australia 2000) and the bushcareprogram). In addition to this there is also a national

‘Rehabilitation, Management and Conservation of

Remnant Vegetation Research and Development’

program which has been funding research projectsaimed at improving the management of remnant

bushland. Only a small proportion of the established

research projects occur in Queensland (Price & Tracy

1996). The Department of Primary Industries is theprincipal State agency responsible for woodland

research in Queensland and has developed

sustainable production systems for various native

vegetation communities.

The Department of Natural Resources providesfunding principally to the Queensland Forestry

Research Institute for a range of ongoing vegetationmanagement research projects. A number of

universities and State departments around Australiaare engaged in vegetation management research

projects. There is a strong case for the need to

establish a Cooperative Research Centre for

Vegetation Management which has, as part of itsfocus, the task of determining the most effective

techniques for broadscale vegetation management

and ecosystem repair. Landcare is a high-profile,

national program of ecosystem repair andrestoration.

Some local governments have intensive ecosystemrepair programs (e.g. Brisbane City Council and

Gold Coast City Council). The success of these

programs largely depends on a large pool of willingvolunteers, strong financial position, and small

public areas in need of attention. In rural areas of

Queensland, such efforts must overcome small

population densities, vast areas of private land withpotential for repair, and a low economic and

technical capacity by both the local government

and landholders to engage in such work.

There are a number of land management techniquesthat may be used to promote ecosystem health andrepair. A strategic approach to the repair of regional

ecosystems may involve the reclamation,

rehabilitation and restoration of the landscape using

regeneration, revegetation and other vegetationmanagement techniques (for clarification of the

meaning of these terms, see box 4.1).

Revegetation is commonly identified with ecosystem

repair strategies. The expense and relatively limited

and sometimes questionable impact of revegetationmeans that strategic approaches are required.

Hobbs (1993a) has presented an initial frameworkfor developing revegetation strategies that include

the use of buffer zone, corridors and additionalhabitat areas. The Bushcare program, for example,

is the largest component of Natural Heritage Trust



55

Box 4.1 Definitions and descriptions of ecosystem repair terminology.

and nationally will have allocated $346.5 millionover five years, ‘to protect and restore native

vegetation to conserve biodiversity and restoredegraded land and water’ (CIE 1999). While the

bushcare program will achieve a number of other

outcomes and revegetation is only one approach, it

is projected that this expenditure will revegetateonly 150 500 ha (CIE 1999). The most effective

techniques for broadscale vegetation management

will need to be identified to achieve significant

levels of ecosystem repair in Queensland.

Just as the combination of geology, geomorphology

and climate have resulted in a large number ofdistinct regional ecosystems across Queensland,

there are likely to be specific differences in the

condition, conservation imperatives andmanagement options which apply to a given

regional ecosystem or group of regionalecosystems. Tongway and Ludwig (in Jenkins

1996), for example, suggest that rehabilitation ofdegraded rangelands for both restoring production

and overcoming land degradation may be achieved

by thinning mulga and leaving patches of branches

to create a mosaic of retained vegetation and fertileareas of pasture. While some resources have been

developed to provide management advice for

specific types of ecosystems such as rainforest

(Kooyman 1996; Goosem & Tucker 1995), thedifferences between various ecosystems necessitate

research into new resources to support ecosystemrepair efforts. Significant work still needs to be

done to provide adequate and efficient managementinformation across the diverse Queensland

landscape that delivers significant levels of

ecosystem repair.

McLoughlin (1997) has identified and distinguished between 19 terms related to working in natural areas

ranging from nine variations of the term ‘regeneration’ through restoration, reinstatement, reconstruction,

reclamation, rehabilitation and fabrication. Often used as if they are synonymous, these various ecosystemrepair terms may be more basically differentiated as:

• Reclamation—revegetation using a range of species without attempting to reinstate the original

vegetation (Lamb 1994). (This commonly used meaning differs markedly from McLouglin 1997).

Reclamation normally involves claiming or reclaiming land for human use, and in Queensland this term

often applies to activities such as the reclamation of severely disturbed landscapes (e.g. mines), but can

also refer to the drainage of natural coastal mangroves for urban development.• Rehabilitation—revegetation with species that are economically and ecologically suited to a site,

possibly including locally native species (Lamb 1994). Rehabilitation is commonly practiced as a

requirement for mining leases where the principal aim may be to return the area to grazing.

• Restoration—revegetation using only the original locally native species (Lamb 1994). Restoration is an

attempt to restore an original ecosystem and must honestly be acknowledged as an attempt only(McQuillan 1998). As ecosystems are impossible to define precisely, restoration is an indefinite goal that

aims to achieve a fully functioning ecosystem without reaching that final point. Restoration projects

attempt to re-establish all identified ecosystem elements such as the known fauna and flora species and

abiotic factors. Only locally indigenous plant species are allowed to regenerate or to be reintroduced,with a preference for locally collected seed.

• Regeneration is a technique that draws upon the extant soil seed banks and various seed dispersal andgermination mechanisms to increase the amount, and sometimes the diversity, of vegetative cover.

Regeneration activities may use a number of means of achieving this, including intentional variation of

fire, grazing and weed management strategies and silvicultural treatments. For example, fire can be apowerful and yet subtle tool for ecosystem manipulation. The absence of fire, reduction in fire

frequency, heat of the fire and season of occurrence of a fire event have resulted in dramatic changes in

the structure and composition of vegetation communities in many parts of Queensland. Considered

alteration of these fire regimes can also be expected to have positive results. The active management ofareas of depauperate remnant vegetation using the appropriate application of this suite of land

management activities is likely to be a priority across many regional ecosystems.

• Revegetation is the intentional re-establishment of native or exotic vegetation in an area using

regeneration, planting or some other technique. When planting is required, there are at least five key

decisions that can influence the resultant vegetation community. These are: selection of plant species,matching species to each environmental location within a site, deciding upon planting density, selecting

combinations of species and structural mix, and mulching decisions (McLouglin 1997). Direct seeding

has been identified as a very cost-effective technique for revegetation (Boyle 1998; Vanderwoude 1993)

and has been increasingly adopted and adapted for broadscale revegetation projects. The outcomes ofdirect-seeding activities can be affected by species selection, seed germination characteristics, soil

condition, site preparation, and post germination site management (Sun & Dickenson 1995).



56

4.1.6 Vegetation with particularecological and catchmentvalues

4.1.6.1 Riparian zones

Riparian lands are that part of the landscape

adjacent to streams that exert a direct influence on

stream or lake margins, and on the water and

aquatic ecosystems contained within them.Riparian land includes both the stream banks and a

variable sized belt of land alongside the banks

(Karssies & Prosser 1999).

Riparian vegetation performs a range of functions:

• stabilising stream banks against erosion

• reducing delivery of sediment, nutrients and

other pollutants to streams• controlling plant growth in streams

• providing terrestrial habitat and wildlife corridors

• providing aquatic food and habitat through

provision of leaf litter, logs, shade etc

• dissipating flow energy and in the process re-aerates the water reducing the erosional capacity

of the water.

The importance of this zone for the protection of

biodiversity and other natural resource values isbeing increasingly recognised (Bunn et al. 1993).

Recent establishment of a national research

program by the Land and Water Resource Research

Development Corporation (LWRRDC) and Statepartnership agreements with the Cooperative

Research Centre for Catchment Hydrology and the

Cooperative Research Centre for FreshwaterEcology, focusing on the ecology and managementof riparian zones in Australia, give testament to

this interest.

It is clear that riparian zone vegetation contributes

significantly to long-term channel stability and

integrity. For example, research on the NambuccaCatchment in northern New South Wales (Doyle et

al. 1999), indicates that the disastrous state of the

river system is due to a combination of factors,

including the removal of riparian vegetation,artificial channel straightening, and removal of

large woody debris. Elsewhere in Australia,significant funding is now being provided to re-

establish cleared and degraded riparian zones (e.g.Murray River of Green project). In Queensland, a

number of specific riparian vegetation projects

occur as well (e.g. Wet Tropics Tree Planting and

the Mary River Incentive Scheme). The roles ofriparian vegetation highlighted are significant and

must be incorporated into riparian vegetation

management considerations. In many areas, the

remnant riparian zones are presently not wideenough to provide adequate fauna corridors, so to

encourage retention of the remaining vegetation,the benefits may be confined to those listed above.

Riparian zones—maintaining stream bankstability

Riparian and in-stream vegetation strengthens and

protects stream banks against mass-failure and

erosion, adding to bed and bank stability throughboth live vegetation and the dropping of large

woody debris into the channel. The roots of woody

vegetation increase the shear resistance of soils by

providing additional apparent soil cohesion(Abernethy & Rutherfurd 1999a). Even low root

densities provide substantial increases in shear

strength compared to non-root-permeated soils

(Abernethy & Rutherfurd 1999a). By helping todrain water, riparian trees can more than double the

resistance of degraded bank sections to slumping.

Vegetation also reduces direct rainsplash impact

and bend over during floods to dissipate energy anddirectly protect soil. The presence of large woody

debris within the channel increases bed and bank

resistance, dissipates energy and physically protects

the material in the bed and banks.Work by Abernethy and Rutherfurd (1999b)

suggests that the effects of tree roots may be up to

a tenfold increase in cohesion close to the trunks of

riparian trees, falling to about a twofold increaseunder the drip line. Mature trees, with longer and

more firmly anchored roots, provide more

reinforcement than younger trees.

The width of vegetation required for stability

depends on the channel dimensions and theerosional forces in play. Intact vegetation with all

structural layers is required to offer the fullestprotection. The overstorey has the greatest influence

over the processes of mass-failure, with shrubs andgrasses on the bank face and aquatic plants at the

bank toe influential in controlling scour.

Riparian vegetation interacts with a range of

geomorphological, geotechnical, hydrological and

hydraulic factors to affect the type and extent ofriverbank erosion. Abernethy & Rutherfurd (1999b)

calculated that for stability purposes only, the

following minimum riparian zones are

recommended: basic allowance (5 m measured onto

the floodplain from the bank crest) + heightallowance (≥ height of the bank measured vertically

from the toe to the bank crest). It is important to

note that these recommendations consider only thephysical requirement for bank stability, and do not

include consideration of the width required for

long-term viability and sustainability of the

vegetated zone or the contribution such areas maketo wildlife habitat.

Bank erosion is a natural process. Given enough

time, even fully vegetated natural streams erode

back and forth over their floodplain (Abernethy &Rutherfurd 1999b). The recommendation abovedoes not include an allowance for this.



Riparian zones—widths for bufferingsediments and nutrients

Riparian lands have the potential to buffer streams

from hill-slope sediment and nutrient transport.

Experiments in northern Queensland have shownthat grass riparian buffer strips can trap more than

80% of incoming bed load on planar slopes, even

under heavy tropical rainfall (McKergrow et al.

1999). Recommendations resulting from theseinvestigations include that grass filter strips be

provided for about 5 m on the landward side of any

riparian zone and adjacent to agricultural activity,

as the grass is effective in capturing sediment.

The contamination of waterways from fertilisers

and pesticides as a result of excessive or

inappropriate usage is a major concern in some

areas, particularly within the Murray–DarlingBasin. Well-vegetated riparian zones can trap

sediment and associated nutrients and pollutants

by spreading and slowing water flowing through

them towards the watercourse (Barling & Moore1993). Factors such as vegetation type and density,

soil type and moisture content, the intensity of

rainfall, and the slope and the width of the riparian

zone, affect its ability to do this. With respect tovegetation type, density at the ground surface is the

most important characteristic. Forested filter strips

will be more effective where trees do not prohibit

an understorey of dense grass through shading orcompetition. This is only likely in semiarid and

subhumid environments where there is incomplete

canopy cover (Karssies & Prosser 1999).

It is important to note that nutrients and pollutants

in solution will only be reduced through infiltrationinto the soil profile. Soil properties, antecedent

moisture conditions and the amount of run-off

affect infiltration. Riparian lands are the wettest

part of the landscape and, when fed by soilmoisture generated from upslope, may stay close to

saturation for long periods. It is only in the semi-

arid areas of Queensland, where soil moisture is

low, that infiltration is likely to be significant inabsorbing nutrients. Filters of the order of 10 to

30 m width are required to absorb run-off underdry antecedent conditions and greater widths are

required where converging flow drains through anarrow zone (Herron & Hairsine 1998, as quoted in

Karssies & Prosser 1999).

Riparian zones—habitat, maintenance of biodiversity and wildlife corridors

Riparian zones along rivers, creeks and gullies are

an essential component of the landscape for the

maintenance of wildlife distribution, abundance

and diversity, and for the maintenance of in-stream

fauna (Sattler 1993b). Riparian zones act asrefuges, providing resource rich habitats necessary

for survival of (fauna) species during the course of

their normal lifecycles (Gregory et al. 1991; Bunn1993), or in times of drought (Morton 1990). They 57

provide a rich and diverse habitat in their own right

(e.g. Catterall 1993). Therefore, riparian areas oftenprovide habitat for a disproportionately high

number of species relative to the proportion of the

landscape they occupy. For example, riparian areas

in the mulga and south-western brigalow regions inQueensland (see appendix 4 of Neldner 1984)

contain the highest number of plant species (27%

of the total) compared to all other habitats, even

though they occupy a relatively small area (<10%of the total area). Soft mulga land types are the

next richest ‘broad’ habitat type, containing 20% of

the total number of species but occupying >20%

of the area. Similar patterns occur for flora andfauna numbers in other parts of Queensland

(Boyland 1984; McFarland 1992; Catterall et al.

1992; Crome et al. 1994) and, at least for bird

species, in other parts of Australia (Recher et al.1991; Loyn 1985; Gregory & Pressey 1982).

Though riparian zones have been extensively

cleared or degraded in many regions ofQueensland, significant areas of intact habitat do

remain (indicated by the status of riparianecosystem types). The importance of these zones

for the protection of biodiversity and other natural

resource values is increasingly being recognised

(Bunn et al. 1993).

Arthington et al. (1992) have summarised theimportance of riparian vegetation in the

development of linked habitat networks for regional

or catchment planning by:

• forming corridors that link bushland remnants

into sustainable regional networks• providing critical habitat refugia within which

species are maintained in time of drought or fire

• forming part of local habitat complexes whichsustain terrestrial wildlife

• representing unique lowland communities

subject to threatening processes.

The significance of riparian lands for wildlife is

such that they should be regarded as ecologicalarteries of the Australian continent, spreading as a

series of intricate interconnecting webs across the

landscape.Ecological benefits of riparian vegetationfor in-stream fauna

Important ecological processes in upland streams

are largely dependent on riparian vegetation.Proposed shading (by riparian vegetation) of 50%,

particularly in small catchments, will have a

significant improvement on ecological functions of

upland streams (Davies & Bunn 1999) andimprovements in upland streams (e.g. lower water

temperatures) may also protect downstream reaches.

Riparian vegetation provides an important source ofin-stream woody debris in the form of fallen logs

and trees. Woody debris can provide habitat for in-stream fauna, as well as increasing channel

roughness, and hence decreasing velocity and



58

associated stream power (Cohen 1999). Marsh et

al. (1999) showed that in the Albert River,Queensland, 78% of large woody debris (LWD)

pieces were associated with some form of habitat

scale morphological effect, whereas in Cooper

Creek system, morphological effects of LWD werelow (11%). This shows that in some systems,

particularly those with higher energy, LWD has a

vital role in habitat provision (this may be in the

form of forming a scour hole, forming bars,providing a bank scallop, etc.).

Loss of riparian vegetation has in part resulted in

the decrease in in-stream woody debris. For

example, existing levels on the lower

Murray–Darling basin may be only 15% of pre-European settlement levels. Appropriate levels of

coarse woody debris are crucial for the ecological

‘health’ of floodplains (MacNally & Parkinson 1999).

Riparian zone dimensions

Riparian zones vary enormously in size dependingupon their position within a river catchment (e.g.gully head versus a lower reach of a river system).

In lower parts of the catchment, the riparian zone

increases in size, usually incorporating wetlands

and significant areas of floodplains. Widths ofvegetation required in riparian areas will therefore

depend on the position in the catchment and the

functions that the riparian zone is required to

perform. Different functions will often requiredifferent widths of vegetation. These areas are very

productive and important wildlife habitat; they are

very important to grazing livestock as well.Research in Queensland (Catterall 1993) andoverseas (Spackman & Hughes 1995) indicates that

to be effective these corridors need to be of

substantial width, particularly for avifauna. As an

overseas example, for mid-order streams, minimumwidths of 75–175 m were needed to include 90% of

bird species (Spackman & Hughes 1995). In south-

east Queensland, corridors greater than 200 m

wide have been recommended (Catterall 1993).

Riparian zones should be multi-functioning, whichwill then necessitate the adoption of the widest

width recommendation and should:• include the ecotones between aquatic and

terrestrial ecosystems along streams andadjoining wetlands and lakes

• incorporate appropriate buffers to enable

protection of these ecotones from disturbance

from such factors as fire and weed invasion• be sufficiently wide to maintain stream bank

stabilising functions and to allow for natural

changes in watercourse positioning within its

floodplain• enable the reduction of sediment, nutrients and

other pollutants from overland flow beyond thesaturated zone

• contain sufficient ecological integrity to act aseffective wildlife corridors

• be sufficiently wide to ensure the viability of the

riparian zone buffer.

Accordingly, it is appropriate for buffer widthstandards to vary for gullies, creeks and rivers

rather than a set figure being applied, but the width

should be such as to ensure the viability of the

riparian zone buffer. Other factors that have to beconsidered are the impact of riparian zone

corridors on management practices (particularlymustering) and property operations (e.g. clearing of

declared weeds such as rubber vine (Cryptostegia grandiflora)), and access to water for stock and

agriculture right up to the high bank.

4.1.6.2 Wetlands

Queensland has the most diverse array of wetlands

in Australia, due mainly to the State’s climatic

variation and seasonal variability. The biologicaland hydrological values of natural wetlands are

recognised in a range of catchment and land

management strategies (e.g. Murray–Darling BasinCatchment Management Strategy). Areas thatcontribute to the conservation value of wetlands

can be protected under the Vegetation Management Act 1999 (Qld).

Although wetlands are most commonly thought

of as occurring where land and sea meet (e.g.mangroves and estuaries), natural wetlands occur

in a range of landscapes including basins (e.g.

lakes), flat lands (e.g. swamps), and floodplains

(e.g. billabongs), or where the watertable intersectsthe surface (e.g. springs).

Wetlands have been broadly defined as ‘areas of

permanent or periodically/intermittent inundation,

whether natural or artificial, with water that is

temporary or permanent, static or flowing, freshbrackish or salt, including marine areas the depth

of which at low tide does not exceed six metres’

(EPA 1999c).

For the purposes of vegetation management, other

researchers have taken a narrower view, forexample floodplain wetlands (Hillman 1997) or

coastal wetlands (Zeller 1998). Wetlands can, to a

very large extent, be viewed as ecotones, that is,transitional zones between terrestrial habitats anddeepwater aquatic systems (Boon & Bailey 1997).

Typically, wetlands include areas that show

evidence of adaptation of soils or vegetation to

periodic waterlogging (EPA 1999d). This providesfor areas subject to saturation through periodic or

seasonal rise in the watertable, as well as

depressions or channels filled from overland flow.

Such areas may be bare of vegetation, be coveredwith sedges or other aquatic vegetation, or be

forested, for example wetlands with Melaleuca spp.

or Eucalyptus coolabah woodland (e.g. EPA 1999a).



The values and functions of wetlands have been

documented by numerous studies (e.g. QueenslandGovernment 1999) and include:

• playing a key role in supporting the diversity and

abundance of wildlife

• contributing significantly to the economicproductivity of the State by providing water

resources for (primary) industry; vital breeding,

nursery and harvest sites for edible fish,

molluscs and crustaceans; and areas of pasturefor stock.

Away from the coastal delta and lowland wetlands,

floodplain wetlands become significant features in

the landscape, both ecologically and hydrologically.

For example, the arid river floodplain systems ofthe Lake Eyre Basin are geomorphically,

hydrologically and ecologically complex, and might

be described as a series of extensive and widely

dispersed, predominantly ephemeral wetlands,rather than as rivers in the conventional sense

(Morrish 1997). The diversity and values of inlandwetlands are discussed in ‘Wetlands of South-

Western Queensland’ (EPA 1999a).

The flood-pulse concept (Junk et al. 1989) hashighlighted the significance of floodplain

productivity in providing organic carbon for the

biota of lowland rivers (Hillman 1997; examples in

Timms 1997 and 1999; Puckridge 1997). Becauseof their distinctive aquatic biota, in comparison

with their river, and because their spatial and

temporal variability creates a mosaic of habitat

conditions, billabongs represent a significant

contribution to biodiversity to floodplain riverecosystems, and also contribute to biodiversity

beyond their boundaries (Hillman 1997). Briefly

inundated wooded swamps in inland Queenslandhave been documented as having significant

conservation values for bird life, frogs, fish and

mammals (EPA 1999a).

The major factors altering plant communities in

wetlands are water regime and grazing (Brock1997). There is surprisingly little detail on the ways

domestic stock and feral animals influence the

ecology of wetlands in Australia (Walker 1993;Bacon et al. 1994). However, it is clear that stockcan have direct impacts on wetland vegetation,

soils and water quality (Robertson 1997), and that

they impact directly on faunal communities and the

biogeochemistry of wetlands by altering habitatstructure and patterns of primary and secondary

production in and around wetlands (Robertson

1997). By altering wetland vegetation structure and

biomass, sediment chemistry and water columnnutrient concentrations, livestock and feral grazers

also contribute to shifts in the quantities and

chemical quality of materials available for transportfrom floodplains to rivers during flood periods(Robertson 1997).

Soil mobilisation, nutrient enrichment, and

controlled burning are obvious factors associated 59

with the pastoral industry. Other factors, such as

modification of pasture grasses (e.g. by thinningthrough grazing or planting of exotic grasses

(Bullen 1993)) and construction of ponded

pastures, can significantly affect the ecology or

hydrology of wetlands (Boland 1997). In addition,particularly on the eastern coastal plain, large

areas of freshwater wetlands have been lost or

degraded by clearing, draining, and exotic weed

invasion (Zeller 1998). For example, in coastalareas in the Johnstone, Moresby and Mulgrave-

Russell river catchments between 1952 and 1992,

forested wetlands and sedgelands decreased in area

by between 48% and 82%, due to clearing forgrazing and agriculture (EPA 1999b).

A significant factor in maintaining the ecological and

hydrological functions of a wetland is the provision

of a buffer zone of riparian vegetation, as for rivers

and watercourses. Appropriate widths for buffers orriparian zones vary depending on their purpose. For

example, a filtration buffer for water quality couldbe as little as 10 m (Karssies & Prosser 1999), while

buffers up to 2 km wide could be required tomaintain groundwater quality in certain situations

(Van Waegeningh 1981; Davies & Lane 1995).

4.1.6.3 Marine and adjacent coastalvegetation communities

MangrovesMangroves are trees and shrubs tolerant of

intermittent flooding by salt water, living in the

intertidal zone between Mean Sea Level and

Highest Astronomical Tide (HAT), bordering thebanks of estuaries and foreshores along protected

parts of the Queensland coastline (Zeller 1998).

Areas of deposition of silt and mud at the mouthsof rivers and creeks and in the lee of larger offshore

islands (e.g. Hinchinbrook, Curtis, Fraser or North

Stradbroke islands), protected from strong wave

action, support the most extensive mangrovecommunities (Dowling & McDonald 1982).

Saenger (1995) estimated 3424 km2 of mangroves

occurred in estuaries, while Galloway (1982)

estimated the total area of mangroves in

Queensland to be 4602 km2. Approximately 90% ofQueensland’s mangrove forests lie in the tropics

(Robertson & Alongi 1995).

In general, mangroves vary in height with rainfall

(MacNae 1966), and in species diversity withlatitude (Lear & Turner 1977), varying from over 30

species on Cape York Peninsula and the Wet Tropics

to seven in Moreton Bay. Queensland’s tropical

mangrove forests are among the most productive ofany mangrove system worldwide (Hutchings &

Saenger 1987) while, under certain conditions,

primary productivity of subtropical mangroves mayexceed that of tropical systems. A suite of factors(including soil pore salinity, nutrient supply and

water balance under dry weather conditions) may

cause variability in primary productivity between



60

locations and among mangrove species in the same

location (Clough 1992).

It has been estimated that 75% by weight of theQueensland commercial fisheries catch is derived

from species dependent on shallow marine habitats

(e.g. estuaries) for at least part of their life (Quinn

1992). Mangroves, seagrasses, and adjacentsaltpans and marine couch areas are all part of the

ecosystem that sustains this industry.The importance of the tidal wetland (mangroves,

saltmarshes and clay pans) and its connected

freshwater wetland (melaleuca wetlands, palmforests, sedges and lagoons) ecosystem, both for

fisheries and for shoreline protection, has been

widely acknowledged (Hamilton & Snedaker 1984;

Quinn 1992; EPA 1999d). However, extensiveclearing, draining and filling of these wetlands for

agriculture, industry or urban development, and

separation of estuarine systems from adjacent

freshwater or riparian habitats has had a major

impact on fisheries values in some areas (e.g.Tait 1994; Russell & Hales 1994; Zeller 1998).

Other coastal vegetationCoastal vegetation varies considerably in both

structure and species composition, depending onthe substrate and hydrological regime. Coastal

vegetation communities range from spinifex and

coastal she-oak communities on the foredunes, to

closed littoral forests usually in swales behindforedunes, to tall open forest, such as satinay

forests, on deep sands. Intertidal (mangrove)

forests, salt flats with chenopod herbfields and

marine couch grasslands, swamp oak andsedgelands, melaleuca forests, or sometimes closed

forest with palms, occur on heavier or poorly

drained soils.

Native vegetation in the coastal zone is important

because it:• maintains biological and ecological processes

• is biologically diverse

• provides habitat for protected wildlife and

migratory species covered by State legislation orinternational agreements

• maintains river and estuary bank stability andshades water bodies, reducing light and

temperature (factors in weed and algal growth)• minimises soil erosion, siltation and pollutant

run-off into waterways and estuaries

• maintains the watertable and catchment areas

that provide water suitable for domesticconsumption

• can assist in beach accretion on dunal areas

through trapping windblown sand (EPA 1999b).

Land clearing has affected most of Queensland’s

coastal zone to some degree. This clearing has beenfor agricultural purposes, but more recently for

urban and tourist development particularly in

south-east Queensland. Clearing constitutes a major

pressure on the biological resources of the coastal

zone and is continuing (EPA 1999a). Many of these

ecosystems rely on a healthy vegetation cover forstabilisation against wind or water erosion, invasion

by exotic weeds and subsequent degradation of the

system. Changes to vegetation cover are associated

with changes in hydrology, increased risk of duneinstability, wind erosion and tidal inundation, and

loss of natural values (EPA 1999b).

4.2 Land degradation 4.2.1 Tree decline and dieback

‘Dieback’ is commonly associated with general tree

death resulting from a wide range of causes. It is

symptomised by deterioration of the primary treecrown that may lead to total defoliation and

subsequent repeated bursts of epicormic regrowth

along the main branches and trunk (Landsberg

1990; Landsberg & Cork 1997). The plant’scarbohydrate reserves are reduced if these

subsequent flushes of secondary growth are lost,and death may ensue (Podger 1973; Gall &

Davidson 1981).

Tree decline relates to noticeable reductions in treepopulation health over time (Kile et al. 1980). The

term includes the more apparent problems of

dieback, senescence and mortality as well as the

inability of a tree population to effectivelyregenerate from seed stock or vegetative propagules

(Neale 1981).

Occurrences

Dieback symptoms have been recorded in a widerange of species with considerable regional

variation in relative susceptibilities (Landsberg et al.1990; Williams & Nadolny 1981). Most individuals

are eucalypts, but this may reflect the prominence

of the genus in the Australian woody flora.

Wylie et al. (1993) provide a detailed assessment of

the incidence of dieback in Queensland, andconclude, in part, that dieback in southern and

central Queensland was most severe in landscapes

where more than 50% of original tree cover had

been removed. Serious land degradation (erosionand salting) have also been recorded in areas of

high tree loss (Firth et al. 1984; Shaw et al. 1986;

Woods 1983).

Localised studies of dieback have been conducted

of riparian areas of the Condamine (Voller & Eddie1996) and Macintyre catchment (King 1995).

Fensham and Holman (1999) observed tree death

as resulting from drought in north Queensland.

Anecdotal reports of dieback associated with insect

plagues or unseasonal weather events have beenrecorded from inland areas of the State, while

incidence of patch death in rainforest areas of farnorth Queensland have been attributed to

phytophora root disease.



Causes

Many potentially damaging factors have been

suggested as possible causes of dieback, butrelatively few of these have been extensively

investigated (Landsberg & Wylie 1991). While it has

been possible to identify single causal agents in

some regions (e.g. Hughes (1984) showed thatdieback of many eucalypts in the Lockyer Valley was

due to secondary salinisation), single causal agentsare more likely to be the exception than the rule

(Landsberg & Wylie 1991) (see figure 4.4). Diebackdoes, however, appear to be particularly severe

where intensive farming production is the main land

use (Wylie & Johnston 1984). The recruitment of

native trees into these landscapes may be limited,where cultivation for establishing improved pastures

kills seedlings, and natural seedling regeneration is

prevented by associated increases in stocking rates

(Ford et al. 1993; Reid et al. 1998). In the absence ofnatural regeneration, sown pastures over the whole

of a property may result in either a perpetualcommitment to planting trees or the eventual loss of

trees from the landscape.

Insects

While many factors (including waterlogging andmistletoe infestation) probably cause localised

incidents of tree death, repeated defoliation by leaf-

eating insects is the single factor most frequently

cited in reports of rural dieback (Old et al. 1981;Wylie 1986, Landsberg et al. 1990; Reid & Landsberg

1999). For example, anecdotal accounts of severe

defoliation by cup moths in Charters Towers wereobserved in 1989–91 (J. C. Scanlan 2000, pers.comm., 13 April).

Dieback trees are often more heavily damaged by

insects than healthier nearby trees (Landsberg &

Wylie 1983; Landsberg 1988; Landsberg et al.

1990; Mackay et al. 1984). Control of insects ondieback trees (Mackay et al. 1984) or branches

(Landsberg et al. 1990) can lead to rapid recovery

or regrowth.

Detailed studies of insects and dieback have been

restricted to south-east Queensland and the NewSouth Wales tablelands (Wylie et al. 1993;

Landsberg & Wylie 1983; Mackay et al. 1984). Reid

et al. (1998) described the relationship between

insect population dynamics and dieback in NewEngland. They concluded that, while clearing

removed mature trees as a food source for insects,

pastures provided an increased food supply for

larvae. Increased insect populations subsequentlyconsumed epicormic regrowth, depleting tree

nutrient reserves (Reid et al. 1998).

Although insect damage is often associated with

dieback, this association is not universal. Where itdoes occur, there is some evidence to show thatchronic defoliation may be the ultimate cause of

61

dieback, but may have been accelerated by other

factors, such as climatic stress (Sutherst & Mo 1997)or human intervention (Wylie 1984).

Salinity

Salinity has frequently been associated with

dieback (Old et al. 1981). Tree death associated

with dryland salinity was first observed in valley

floors in south-eastern Queensland in the 1920s,

and has since been reported with increasingfrequency to affect a variety of eucalypt, Casuarinaand Callitris species in south-eastern and central

Queensland (Wylie & Bevege 1981).

Where dieback is associated with salinity, salt maybe a primary cause of dieback or predispose trees

to other agents, such as chronic defoliation by

insects. In the Mary River catchment, a close

association between the occurrence of salinity,dieback and insect damage was demonstrated

(Wylie & Johnston 1984; Wylie 1986).

Nutrient enrichmentPasture improvement has lead to substantial

increases in soil nutrient levels (Russell 1986).

Redistribution of nutrients by livestock throughmanure and urine can lead to very high

concentrations of nutrients near trees (Russell

1986). Insect-related dieback has been associated

with very high levels of soil and tree nutrients andenhanced growth of defoliating insects. Landsberg et

al. (1990) demonstrated a causal link between high

plant nutrients and the enhanced insect damage.

PathogensSeveral species of fungi have been implicated in stem

cankers and crown dieback in eucalypts (Davidson &

Tay 1983; Old et al. 1986; Shearer et al. 1987). Someof these fungi can spread rapidly in branches of

defoliated trees and are nearly always associated

with insect defoliated trees (Beckmann 1989).

Virulent soil borne pathogens such as Phytophoracinnamomi (Old 1979), armillaria (Kile 1981) and

leaf pathogens (Palzer 1981), have caused locally

severe and sometimes widespread dieback and

death of vulnerable species.

Senescence

Senescence could be a primary cause of dieback or

a predisposing factor towards it in some, but notall, dieback affected regions. Many of the trees left

after initial clearing are now old, and in areas

where regeneration is slow, dense pasture and

grazing can suppress regeneration, and wholestands of rural trees may now be senescent

(Landsberg & Wylie 1991; Voller & Eddie 1995). In

areas where natural recruitment of native trees is

no longer occurring, many of the extant treesinevitably develop apparent dieback symptoms as

the population ages.



62

Drought

Several very severe droughts have been associated

with leaf wilt, leaf shedding, bark splitting andsome death of severely stressed trees (Ashton et al.

1975; Palzer 1981; Pook et al. 1966; Fensham &

Holman 1998). Fensham and Holman (1999) used

extensive historical accounts of dieback and rainfallrecords to confirm extensive tree death following

past droughts in the Queensland savanna.Protracted dieback of drought-affected trees may

result if stem-boring beetles invade injured stems

(Hoult 1970). Landsberg and Wylie (1983) recordeda worsening of rural dieback in south-east

Queensland during a period of severe water stress.

If there is no insect infestation, full recovery of

surviving trees generally occurs in the followingwet season.

Mistletoe, arboreal wildlife

There have been localised occurrences related to

very high populations of mistletoes and or arborealwildlife such as brushtail possums (Pitman et al.

1977; Nadolny 1984; Loyn & Middleton 1981;Statham 1992; Voller & Eddie 1995).

planting ofexotic pastures

fertiliserapplication

ringbarkingand poisoning

increasedlivestock

production

improved

soil nutrition

loss of habitat

for predatorsand parasites

climaticfluctuations

soil

acidification

physical

damage tostems and roots

deterioration of

soil physicalstructure

increasedgroundwater

salinity

productionof epicormic

foliage

improvednutritionalquality oftree foliage

increasedpopulations

of root-feedinglarvae

increasedexposure ofremaining

tree canopies

sunlitfoliage

physicaldamage

chronic defoliation

competition

increased localpopulations of tree

feeding insects

dieback

intensification of land management

tree stress tree death

pathways based onthe results of research

more speculative

feedback pathways

feedback pathways

Figure 4.4 A conceptual model of the complex interaction of factors generally associated with tree death and decline. Adaptedfrom Landsberg & Wylie (1991).

Waterlogging

Waterlogging has also been posed as a cause of

initial tree decline, again facilitating insect attack.However, this theory has not been experimentally

tested, and evidence is mostly anecdotal (Reid &

Landsberg 1999). For example, tree decline has

been observed on the New England tablelandsfollowing tree ringbarking during the mid–late

1800s (Norton 1886, as cited in Reid & Landsberg1999) and tree death occurred following the 1974

Brisbane floods (Wylie & Bevege 1981). Reid andLandsberg (1999) suggest that, in the case of the

New England tablelands, tree clearing for pasture

improvement may have led to increases in soil

moisture where subsurface water flow created byan impermeable B-horizon in duplex soils resulted

in water saturation at lower slopes and valley

floors. In some cases, flooding increases the

establishment of woody species (e.g. coolibah andthe exotic weed Parkinsonia aculeata).

4.2.2 Pest invasionsThe management of woody vegetation has adramatic impact on associated organisms. (The

impact on native flora and fauna is generally



considered in section 4.1.) In this section, the

relationships between woody vegetationmanagement and the occurrence of undesirable

plants and animals (pests) are considered.

The best strategy to reduce the impact of pests is to

prevent their establishment initially. This requires

recognition of pest organisms, and action to removeany of these before establishment of a self-

sustaining population. The use of washdownfacilities for vehicles and machinery moving from

parthenium weed (Parthenium hysterophorus) areas isa good example of the prevention approach being

implemented in Queensland (Walton 1999).

The cost of rehabilitating areas infested with weeds

is often very high and, in many cases, the costs

exceed the value of the land on which the pests arelocated (Scanlan 1986). In some cases, attempts in

rehabilitation are sound and justifiable on simple

economic grounds, while in others it is not. For

example, the recent efforts in controlling Quilpie

mesquite (Prosopis velutina) can be justified on thebasis of protecting large areas lower in the

catchment, whereas it would never make economic

sense to control mesquite solely on the basis ofrecovering lost productivity (B. Toms 2000, pers.

comm. 21 February). At the other extreme, it is not

justifiable to make a large scale effort to control

Lantana camara in Queensland (other than bybiocontrol), because it has largely reached its

potential distribution (Swarbrick et al. 1995).

However, in many areas, the recovery of lost

production may exceed the cost of treatment and

could be justified.

Plants

Even apparently undisturbed native vegetation has

generally been disturbed to some degree or another.

The disturbance could take an indirect form (e.g. a

change to historical patterns of fire), or a moredirect form (e.g. grazing by domestic livestock). In

either case, a change in the composition of the

understorey vegetation may occur. For example, the

reduction in fire can lead to an increase inunderstorey Acacia spp. and an increase in size of

Eucalyptus spp. saplings (Burrows et al. 1990).Grazing can lead to a reduction in ground cover and

a great increase in the opportunity for herbaceousand woody species (either native or exotic) to

establish. The importance of grazing management

in the control of parthenium weed, an introduced

herbaceous species, has been acknowledged(Navie et al. 1996).

Managed forestry areas would initially appear to be

areas that do not have serious weed problems.

However, this is not necessarily the case,

particularly when there is not a full tree canopy. Insouth-east Queensland, areas of Pinus spp.

plantations are a major reservoir of the introduced

woody weed Baccharis halimifolia (Armstrong &

Wells 1979). However, dense shade under fully63

developed canopies can inhibit the development of

this weed (Panetta 1977).

Integrated management of native vegetation toreduce its susceptibility to invasion and enhance its

regeneration is required (Humphries et al. 1991).

Total clearing of tree cover provides an excellent

opportunity for weeds to establish. For this reason,many landholders have planted exotic pasture

species in an effort to get a rapid cover ofcompetitive species that are useful for grazing

purposes (DPI 1976). Buffel grass (Cenchrus ciliaris)is perhaps the most widely planted pasture species

that fits into this category. In cases where pasture

species have not become established, herbaceous

weeds can be serious (Anderson et al. 1983). Oneof the best examples was the dense stand of

parthenium weed that established in pulled

blackwood (Acacia argyrodendron) and gidgee

(A. cambagei) scrubs in the Clermont region ofcentral Queensland in the 1980s in cases where

buffel grass was not planted or did not establish(Anderson et al. 1984).

The planting of pasture provides another possible

source of weeds. There are two aspects of pastureplanting that must be considered—contamination by

known weeds and planted species becoming weeds.

Contaminated pasture seed brought into Australia

from the USA was the source of parthenium weed in

central Queensland (Navie et al. 1996). Currently,the federal legislation dealing with contaminants

specifies zero tolerance for seeds of plants known to

be weedy elsewhere or under active control in

Australia. Control of the movement of weeds inpasture seed is currently under consideration in the

review of the Rural Lands Protection Act 1985 (Qld).

Among the proposals being considered is that the

sale or movement of any product containing aserious weed that is not currently established in

Queensland will be prohibited. Also, the sale of

products containing an established weed will be

prohibited for selected weeds. There is also aproposal for a general duty of care to prevent the

establishment and spread of pests. Note that if

pasture seed is purchased interstate, the sale mustconform to the rules that apply within that State.Thus it is possible for seed to be purchased from

another State that has seeds of weeds that are

declared in Queensland, in it, provided it is legal to

sell the seed (with its contaminants) in that State.

A number of pasture introductions have becomeserious weeds, either in the agricultural sector

(Lonsdale 1994) or in natural ecosystems

(Humphries et al. 1991; Lonsdale 1994). Since

August 1998, all species proposed for importationinto Australia have been subjected to the Weed Risk

Assessment (WRA) system by the AustralianQuarantine and Inspection Service (AQIS). The

WRA utilises a series of questions to assess theweed potential of a species on the basis of

available information on its current weed status in



Pest management and tree clearing

Clearing of trees can alter the presence, absence

and demographics of individual faunal populations,creating pest problems. For example, the removal of

trees along watercourses and from the general

landscape has allowed grass to thrive in many

sugarcane growing areas. An unintendedconsequence of this has been that the cane rat

(Rattus sordidus) has greatly increased. The slashingof all accessible grassy areas and the replanting of

trees in such areas is being promoted as aneffective means of reducing the numbers of cane

rats. The removal of harbourage for rabbits (hollow

logs, blackberry (Rubus fruticosus)) is a vital aspect

of controlling their numbers in the Stanthorpe–Wallangarra area of southern Queensland.

Trees may also have to be cleared to assist in

removal of some pest weeds. Rubber vine

(Cryptostegia grandiflora) is a serious weed from both

production and environmental perspectives

(Humphries et al. 1991). This scrambling orclimbing shrub can grow up and over large trees

along watercourses in north Queensland (Tomley

1995). In some cases, the only practical controlinvolved clearing some of the native trees over

which it climbs. This may be by clearing or by

burning these areas at a time and in a manner that

can damage the trees amongst which rubber vinegrows (Vitelli 1992).

The management of pest plants and animals may

involve planting trees or the removal of trees and

shrubs. The complexities of each organism andeach vegetation–environmental combination mustbe considered before designing management

practices aimed at reducing or preventing the

impact of pests (Commonwealth of Australia 1997).

4.2.3 Tree removal: implications forsoil processes and acceleratedsoil loss

There is much anecdotal evidence to suggest that

the removal of trees results in the large-scale loss

of soil, or decline in soil processes. However,

evidence in the scientific literature is oftenconflicting with regard to these processes. There is

considerable evidence that tree clearing in itself

does not necessarily initiate the degradation cycle,but rather that inappropriate land management

practices are often the causal factors (e.g. Scanlan

et al. 1992). Quantifying and/or qualifying the rates

of soil loss or soil degradation across the State isvery difficult due to the complexity and diversity of

soil and plant interactions

Impact of trees on soil processes

Vegetation has an impact on soil fertility anderosion, along with other long-term processes such

as salinity and soil acidification. Vegetation

influences the soil fertility through nutrient releasevia litter fall and organic matter decomposition,64

other parts of the world, climate preferences and

biological attributes. Proponents are encouraged tosupply this information for their candidate species.

A generally increased awareness of unintended

consequences of plant introductions should greatly

reduce this avenue of weed introduction.

An area that is often overlooked is the impact ofinfrastructure development and housing on the

establishment and spread of pests. Weeds like theexotic creeper Thunbergia grandiflora, grow up trees

on the edges of rainforests in northern Queensland.This plant can smother crowns of trees up to 40 m

high and can progressively destroy rainforest,

moving from the edge inward (Humphries et al.

1991). These edges commonly occur along roadsthat have been built through the rainforest. In

south-east Queensland, there are woody vines

(e.g. cat’s claw creeper (Macfadyena unguis-cati) and

Madeira vine (Anredera cordifolia) (Swarbrick 1999))that thrive on ‘edge vegetation’ caused by

infrastructure development. Invasive trees, such ascamphor laurel (Cinnamomum camphora) and

Chinese celtis (Celtis sinensis) may also gainfootholds on the edges of clearings.

An emergent effect of the clearing of vegetation has

been the increased fragmentation of remnant

vegetation, which increases its vulnerability to weed

invasion. While most weeds may be restricted tothe outer edges of remnants, edge effects are

particularly prominent in small remnants that have

high edge:area ratios (see section 4.1.2). Vegetation

corridors are particularly difficult to protect from

weed invasion (Panetta & Hopkins 1991). Remnantsclose to population centres may be subjected to

high levels of disturbance from human activity

(Matlack 1993), which can lead to degradationabove and beyond what occurs at remnant edges.

Animals

Animals (e.g. pigs) can become pests as a direct

result of land management in a similar manner as

weeds, but usually less dramatically. Some

introduced animals appear to have established andspread rapidly, irrespective of the type of land

management, for example rabbits (Oryctolaguscuniculus) (Williams et al. 1995) and cane toads

(Bufo marinus). Also, many introduced herbivorousmammals have become feral (goats, deer and horses

(Braysher 1993)), especially in semiarid areas where

large property sizes preclude their removal.

Land management practices have increased the

numbers of some native species although, ingeneral, the impact of European settlement has

been to greatly reduce native mammals. An oft-

quoted example is that of macropods in inland

areas. Their numbers are generally acknowledgedas having increased due to the provision of

permanent water and the encouragement of good

pastures for domestic livestock (Newsome 1975;

Poole 1978).



addition of nitrogen through fixation, acidification

via the secretion of acids from roots, and thedepletion of soil nutrients via plant uptake

(Anderson & Bell 1995). Enhanced soil fauna

populations associated with vegetation roots

perform a critical function in the cycling ofnutrients. Both macrofauna and micro-organisms

play a critical role in organic matter decomposition,

mineralisation and subsequent release of nutrients

(Swift et al. 1979; Morgan et al. 1989). Debateexists as to whether the soil fauna populations vary

between pasture and natural forested ecosystems.

Erosion of soil occurs as a result of a transport

agent (wind or water) passing over or imparting a

force on the soil surface, or indirectly when waterhas weakened the soil structure resulting in mass

movement (landslides and mudflows) (Rose 1993).

Tongway and Ludwig (1997) suggest that the

spatial redistribution of materials across thelandscape is influenced by terrain and vegetation.

Greater soil surface roughness (in the form ofperennial grass and hummocks) may allow greater

storage of soil water than smooth sites dominatedby ephemeral vegetation. Slope also influences the

transporting capacity of overland flows, with a

sudden decrease in slope causing slowing and

ponding of water and subsequently deposition ofmaterial. Sudden increases in slope will increase

flow and mobilise soil particles. Aeolian (wind)

erosion is minimised with the presence of a

vegetative cover. A cover in the form of trees,pasture and/or a litter layer, increases the surface

roughness resulting in an increased friction velocityof wind (McTainsh 1993). This creates a boundary

layer that pushes the erosive wind higher from thesoil surface. In mulga lands, cover levels above

34% reduced wind erosion losses to 0.2 mm of soil

per year compared with bare trampled ground

which suffered from wind erosion losses exceeding6 mm per year (Miles 1993). Thus the extent of

wind erosion is closely related to residual grass

cover levels.

Important factors controlling fluvial (water) erosion

at a point-scale are soil moisture status, amount

and intensity of rain, the soil’s water holdingcapacity and infiltration rate, and the level of

surface cover. Management practices such as

grazing, fire and vegetation clearing can affectsurface cover and soil properties (e.g.

macroporosity) that control infiltration rate, thereby

potentially changing run-off. Also, changes to

vegetation can change the water use (e.g. timepattern and depth of drying) and soil moisture

status, potentially affecting run-off. At a landscape

scale (e.g. hillslope and stream) run-off may be the

product of the point-scale run-off, and/or ofinfiltrated water that returns to the surface/stream

via lateral subsurface or groundwater flow. Lateral

subsurface flow or groundwater may also create

wet zones in the lower parts of the landscape,which then produce run-off during rain. 65

In their natural condition, most landscapes are

covered by vegetation that protects the soil fromerosion. Bache and MacAskil (1984) identify the

principal effects of vegetation in reducing erosion as:

• the interception of the raindrops so that their

kinetic energy is dissipated by plants, rather thanimparted to the soil

• increasing the frictional losses associated with

surface flows, and thereby reducing the erosive

potential and the transport capability• increasing the infiltration capacity of the soil,

thereby reducing the probability of overland flow

• the physical restraint of soil movement.

Despite these protective mechanisms provided by

vegetation, few studies in Queensland haveinvestigated comparisons between uncleared and

cleared land systems. Data that is published

highlights the spatio-temporal variation

encountered by researchers. Those thatinvestigated the effects of removal of trees generally

found an increase of run-off as a result of theclearing. However, researchers who investigated the

run-off rates of a forested block compared to apasture block often found that the pastures were

more efficient in minimising run-off.

Measurements of small catchments in Gayndah in a

silverleaf ironbark – black speargrass community

on a granite duplex soil showed no significantdifferences in run-off following clearing (Prebble &

Stirk 1988). Yet in small catchment studies of a

brigalow community in central Queensland,

clearing of brigalow scrub on fertile clay soils and

establishing buffel grass pasture was demonstratedto increase run-off by 21 mm/year. Using historic

rainfall data in the PERFECT simulation model,

Littleboy et al. (1992) estimated that run-offdoubles from 3 to 6% of the annual water balance

with clearing (Lawrence et al. 1993).

A combination of neutron moisture meter studies

and simulation modelling by Williams et al. (1993)

predict that there would be an increase in run-off iftrees were cleared on neutral red duplex and red

earth soils in north Queensland. This is supported

by Dilshad and Jonauskas (1992), working onsimilar soils in the Northern Territory. However, itis contrary to the data collected by McIvor et al.

(1995), and the simulations of Scanlan and

McIvor (1993).

In a study of small plots in semiarid tropical

savannas of north Queensland, McIvor et al. (1995)showed that soil loss from areas with native

pastures under trees was higher than for other

pasture systems (cleared areas, with or without

sown pasture). The soil loss from these pasturesystems were from 13 to 56% of that measured

from native pastures with live trees. Scanlan andMcIvor (1993), in simulation studies in the same

area, showed a reduction in soil loss of between53% and 85% when trees were removed from

native pastures, with the actual figure being

dependent on stocking rate.



Investigating cover percentages as a controller of

erosion, Miles (1993) found that the average soilloss due to water erosion for soft mulga was

4.16 t/ha/yr with 20% cover, compared with

1.1 t/ha/yr when cover was 40%. Comparable

figures for hard mulga were 6.57 t/ha/yr and0.65 t/ha/yr.

A large proportion of rainfall intercepted by trees is

released again as large ‘gravity drops’. Moss andGreen (1987) found that these drops average about

5 mm in diameter making them more erosive thanalmost all raindrops. Gravity drops from a height

range of 1.0 to 2.5 m reach a potential to cause

erosion with a gradual increase in erosive power

occurring up to 6 m of free fall. Protection fromgravity drops is best provided by vegetation on the

soil surface. Under natural conditions, forested

areas have a proportion of ground cover and forest

litter that minimise overland flow and enhancerainfall infiltration. Pressland et al. (1991), Scanlan

et al. (1996), and Silburn et al. (1992) showed thatcover was able to reduce both run-off and soil loss

in grazed woodlands of north and centralQueensland respectively.

Soil cover, be it leaf litter or low vegetation, is

accepted by researchers as an important

component in minimising fluvial erosion. Soil

erosion and deposition models such as UniversalSoil Loss Equation (USLE) (Rosewall 1993)

incorporate surface cover as a subfunction of the

model. The USLE computes estimated soil loss from

a given site as the product of six factors whose

values at a site can be expressed numerically. Theequation is as follows:

A=RKLSCP

Where

A = Average annual soil loss in tonnes per hectareR = Rainfall erosivity factor

K = Soil erodibility factor

L = Slope length factor

S = Slope steepness factorC = Management factor

P = Support practice factor

The model demonstrates the interaction of thesedifferent factors in soil loss. Table 4.2 highlights

how changes made in the percentage soil coveralters the level of management control (C factor)

required to minimise soil losses. The C factor is

defined in the USLE as the ratio of soil loss from

land managed under specified conditions to thecorresponding loss from continuous tilled bare

fallow cultivation (Roswell 1993).

Slope also has a dominant influence on

susceptibility to erosion. Mass movement or

landslips may occur on steep slopes. Soil erosionbegins when intense rainfall breaks down

aggregates on the soil surface into small particles.

These small particles may be splashed into the air,

and on steep slopes this results in a net movementof soil downslope. The steeper the slope, the

greater the risk of erosion. Velocity of overland flow

increases on steep slopes, and run-off is more

likely to concentrate and increase its erosive power.In addition, the run-off rate is likely to be higher on

steep land. Slope length and slope gradient have

substantial effects on soil erosion by water. In some

landscapes, the slope steepens adjacent to drainagelines, making such areas especially vulnerable to

soil erosion. Using the USLE, recommendations for

slope limits on development can be made to avoidexceeding an acceptable level of soil loss (forexample, table 4.3 provides slope limits based on

the USLE to avoid average losses greater than

12 t/ha/yr).

The effect of trees on soils and pasture produce

contrasting effects on run-off and erosion inwoodland situations. The reduced pasture

production observed in eucalyptus woodlands of

northern (Gardener et al. 1990), central (Scanlan &

Burrows 1990), and southern Queensland (Walker

et al. 1972) would suggest that run-off and erosionmay be higher in grazed woodlands than in cleared

areas. This may be due to the lower pasture cover

in the former areas; however, the presence of treeleaf litter can complicate this, as there tends to be

some buffering of the system. More trees may lead

to less pasture but increased leaf litter (Burrows et

al. 1990). Silburn et al. (1992) and Yee Yet et al.(1999) found run-off was similar from pasture with

good cover and from under trees where cover was

mainly leaf litter. The surface porosity and depth of

the A horizon also tends to be higher under trees

(Dowling et al. 1986). Infiltration rates also tend toincrease below tree cover (Johns 1981), increasing

the amount of rainfall held in the soil, and therefore

not contributing to run-off.

Some researchers have found that it is the level of

litter cover that is important, and not tree cover

that minimises fluvial erosion. In central

Queensland (Silburn et al. 1992), run-off and soilloss were both highly related to the proportion of

on- or near-ground cover, decreasing exponentially

with increasing cover, with only minor differences

between cover types (e.g. grass or tree litter) or soiltypes studied. Annual soil losses from degraded

pasture were 15–25 t/ha, equivalent to about 2 mm

depth of soil lost per year. Silburn indicated that

dense tree cover greatly reduced grass growth andfavoured poorer, shorter grasses that were not

favoured by stock. This absence of grazing enabled

soil cover to remain greater than 50%, thereby

offering protection to the soil. The tree canopycover of 20–40% offered by the dense groves of

ironbarks was not considered to reduce erosion as

a result of gravity drops. Ironically, the 50% soil

cover that offered the erosion protection was due toleaf litter from the trees. Tree litter may not persist

under heavy grazing. Simulation studies by Scanlan

and McIvor (1993) indicated that run-off was

reduced by between 37 and 60% when trees were66



cleared from native pastures (at the same stocking

rate). The stocking rate had reduced the soil coverin the simulations with trees to the point where

removal of gravity drops reduced erosion.

By contrast, in the Upper Burdekin River catchment,

McIvor et al. (1995) found that stocking rate had

little effect on reducing run-off. They demonstratedthat run-off was 50 to 70% lower under treatments

that were cleared (with either native or sown

pastures) compared with timbered areas (with

Eucalyptus crebra and Eucalyptus erythrophloia).

Mass movement can be triggered by such activitiesas road works in mountainous regions or by

removal of trees from steep land, thus influencing

the water balance. Once the soil profile becomes

wetter than normal, the strength of the soil isreduced, resulting in either a slow creep or rapid

movement of potentially vast quantities of soil

downslope (Rose 1993). Removal of trees from theseland systems can also result in long-term hazardssuch as salinity and acidification. These issues are

dealt with in more detail in subsequent sections.

Management influences on trees andsoil loss

The method of clearing will affect the susceptibility

of soil to erosion. If trees are thinned by chemical

treatment, there will be minimal disturbance to thesurface vegetation thereby minimising the erosion

risk. Clear felling, however, initially exposes the

soil surface to higher surface temperatures thatbreak down organic matter and reduce aggregatestability. Any associated mismanagement (such as

overgrazing), combined with raindrop impact, may67

lead to high surface strength of soils impeding

seedling establishment (Arndt 1965; Bridge et al.1983).

Heavy grazing may cause sheet erosion irrespective

of the presence of trees (Gardener et al. 1990), as

soil erosion in pasture land is greatly influenced by

the extent of surface cover on or near the ground

(Ciesiolka 1987; McIvor et al. 1995). The treecanopy (>1–2 m high) does not necessarily

provide good cover for erosion control, due to the

formation of gravity drops (Moss & Green 1987).Densely timbered areas may have either more or

less total cover of understorey plants and tree leaf

litter than a cleared site, depending on the species

involved (see figure 4.5). Trees compete directlywith grass for water and nutrients and, in all but

the monsoonal zones, this usually results in less

herbaceous cover under trees than in cleared areas

(Mott & Tothill 1984). Tree litter complicates this

effect. For example, in Eucalyptus populneawoodlands (see figure 4.5a), there is a decline in

total ground biomass (tree leaf litter plus pasture),

as tree density increases due to the overridingnegative effect of increasing tree density on grass

cover. In Acacia harpophylla communities (see figure

4.5b), however, the highest total ground biomass is

at the highest tree densities due to the higherrelative production of tree litter. Ground cover is

further modified by the interaction of grazing

pressure, tree cover, use of fire and rainfall amount,

intensity and distribution, and the interactions

between these create a complex set of erosionresponses. Therefore, generalisations about tree

cover and surface soil erosion are not possible.

4.2.4 Soil structure

The physical condition of soil is a major

determinant of land condition, with immediate,

direct and indirect impacts on the potentialproductivity of land for cropping, grazing and

timber production. Maintenance of soil physical

condition is vital if the productive capacity of land

is to be maintained.

The principal determinant and descriptor of soilphysical condition is soil structure. The negative

state of structure condition is structure

degradation, often termed ‘soil compaction’.

Table 4.2 Hypothetical example of management factors (C) for pasture lands with varying levels of canopy and surface coverbased on the USLE.

Canopy cover Cover in contact with soil surface

Per cent soil cover

Type and height Per cent 0 20 40 60 80 95+cover C factors

No appreciable canopy cover 0 0.45 0.20 0.10 0.042 0.013 0.003

Tall weeds or scrub. Average drop fall height of 0.5 m 75 0.17 0.10 0.06 0.032 0.011 0.003

Appreciable scrub. Average drop fall height of 2 m 75 0.28 0.14 0.08 0.036 0.012 0.003

Trees with no understorey. Average drop fall height of 4 m 75 0.36 0.17 0.09 0.039 0.012 0.003

Note: Assumes that cover at the surface is grass or a compacted organic layer.

Table 4.3 Slope limits (percentage) on pasture developmentto avoid average soil loss rates exceeding 12 t/ha/yr basedon the Universal Soil Loss Equation. Source: Roswell (1993).

Rainfall erosivity 9000 7000 4000 2000 850

Low soilerodibility K=0.015 18% 20% 30% 11% 19%

Medium soil

erodibility K=0.03 12% 14% 20% 7% 13%High soilerodibility K=0.055 8% 9% 14% 4.5% 8%

Soil cover Pasture Pasture80% cover 40% cover



Structure degradation is one of a recognised suite

of land degradation types, commonly considered

ubiquitous to the world’s cropping and grazinglands. Structure degradation has been ranked as

the greatest problem in terms of damage to

Australia’s soil resource (Williams 1998). It has avery real impact on land profitability. As a cost

example, Fray (1991) states that soil structure

degradation alone has caused $144 million worth

of damage in the Murray–Darling basin.

Soil structure refers to the size, shape and degree ofdevelopment of soil units that are composed of

primary soil particles (sand, silt and clay), and the

arrangement of these units with the spaces (pores)

within and between them. Good soil structure,typified by many interconnected spaces, is

important for the movement of water and gases in

the soil system and the proliferation of plant roots,

and is the prime regulator of water and nutrientsupply to plants. It is the loss of this pore space,

especially the interconnected pores, through

compression and shear, that best defines soil

structure degradation.

Soil structure degradation, as discussed here, solelyconsiders human-made degradation caused by

machinery and animals. Some soils do naturallyself-compact with no (or little) additional human

input, for example, hardsetting and crusting soils.McGarry (1993) presents a schema of differences

between human-induced and inherent structure

degradation. Because of the inherent, negative

physical properties of the hardsetting and crustingsoils, the historical intensity of their use, and the

expectations of their cropping or grazing potential

have been relatively low (McGarry 1993, 1997).

Vegetation clearing, however, will put physicalpressure on these soils that are inherently,

physically fragile. So the potential for degradation,

even from low intensity usage, is high.

In terms of vegetation clearing, there are two

distinct management areas with strong potential tocause soil structure degradation. The first is the

actual clearing process, most often with bulldozers

pulling either chains or subsoiling tines (for sucker

and root cutting). Then, the subsequent increasedstocking rates of sheep or cattle will give far greater

pressure on the soil physical environment,

particularly the all important topsoil layer. With

each, the level of negative effect is determined bythe soil water content at time of trafficking,

cultivating or trampling; moist to wet soil beingmost vulnerable to structure degradation.

Though tree clearing will continue for land

development, sufficient knowledge on the causesand processes of structure degradation exists that

preventative management strategies can be

implemented.

Considerable literature exists on the recognition

and management of soil structure degradation.Most is from cropping land and timber plantations,

rather than native timbered land. However, the

underlying processes, effects, recording and

monitoring techniques, and preventativemanagement techniques are common.

Identification, diagnosis and rationalisation of

structure degradation are firmly based on the

description and measurement of soil structure

through soil profile description. The same set ofdescriptive and/or quantitative assessments can be

employed to monitor and define subsequent

improvements in soil structure state with altered,

better management systems.

Extent and locationDifficulties surround the precise definition of theextent and location of structure degradation. The

reason is that structure degradation principally

occurs in the upper subsoil and is hidden from view.

As a result, structure degradation is blamed formany soil and crop problems that have no

immediately obvious cause. Conversely, many crop

failures due to structure degradation are wrongly

blamed on other factors, for example, root diseaseand soil pathogens. With structure degradation,

most crops fail because their roots are unable to

penetrate a physical barrier. There may well be rootdisease, but it is caused and exacerbated by thewaterlogging and poor root performance from


68

B i o m a s s ( k g / h a )

1500

00 100 200 400

Trees/ha

pasture

total

tree leaf

2500

1000

2000

500

300

B i o m a s s ( k g / h a )

4000

00 100 200 400

Trees/ha

pasture

total

tree leaf

6000

2000

300

a

b

Figure 4.5 Biomass of tree leaf and pasture within (a) poplarbox and (b) brigalow communities in Queensland. Source:Scanlan et al. (1992) with data from Burrows et al. (1990)and Scanlan (1991) respectively.



In terms of data collection toward defining the

extent and location of structure degradation, thereis currently no better method than visual

recognition of the phenomenon in a spade or

backhoe pit. Such observations are the basis of

SOILpak, a soil management decision-supportsystem (Daniells et al. 1996; McKenzie 1998).

Contributing factors

Soil water content at the time of traversing orcultivating a soil is the principal determinant of the

severity and extent of soil structure degradation.

Tractor and caterpillar loads, implement design,animal stocking rates, speed, and tyre size, type

and inflation are all important, but soil water

content is the prime determinant (Kirby & Blunden

1992). Soil water content at key times isparticularly important, for example during tree

clearing and when stocking rates are high, and the

water content at those times depends on climate

and current weather patterns.

Soil type is important in determining andrationalising the severity of structure degradation.

This is for two different reasons. First, different

soils hold water for varying lengths of time. Some

soils remain more plastic, hence more degradable,than others at similar times after similar amounts

of rain or irrigation. Clay soils tend to stay wetter

for longer as their fine particles hold more water,

more tightly than a sand or loam. Critical to theinterrelation of soil type and the potential for

structure degradation is a soil’s plastic limit water

content (PL). PL is the water content of a soil abovewhich it will compress and shear when loaded, thatis, the soil is in a ‘plastic’ state and is prone to

structure degradation. Soil cultivated drier than PL

will fracture rather than smear so structure

degradation will not occur. Second, some soils areinherently, physically fragile. In particular, soils

with large proportions of fine sand (but still with

enough clay to bind them) and low organic matter

contents tend to naturally hardset and form surfacecrusts. With human inputs like tree clearing or

increased stocking rates, organic matter declines

further. Together with increased energy inputs(animal hooves) this causes bonds betweenparticles to disintegrate—leading to a worsened

physical condition.

The level of management awareness is potentially a

major contributor to the occurrence of structure

degradation. Imperfect understanding is the keyand occurs at many different levels. Especially up

to the late 1970s, primary producers lacked an

understanding and awareness of the physical frailty

of soil structure. There had been a Europeanparadigm for cultivation—repeated, deep,

cultivation of soil close to field capacity. Earlyfarmers, unknowingly, had assumed Australian

soils were as physically robust as European soils.

69

Adding to the problem, Australian farms are large.

This necessitates large machinery, gives inflexibilityin timing of cultivation, sowing and harvesting,

generally on a wide range of soils with different

levels of robustness. The problem is not that

farmers knowingly have over-used the soil, ratherthey were unaware of the high level of care needed

to maintain the resource.

Though best for the soil, there are severalconsiderations that preclude cultivating and

trafficking at optimal (i.e. sub PL) soil watercontents. Specific to vegetation clearing, if large

areas are to be cleared to tight schedules, then

clearing will continue even after rain, despite the

soil being in a most vulnerable condition. The sameis true if stocking rates are raised after clearing.

After rain, animals cannot be removed from wet

fields, so they trample and puddle the wet topsoil.

This not only kills pasture but also seriouslydegrades the physical condition of the topsoil,

causing problems with water infiltration andpasture regeneration.

The impact of structure degradation

Soil structure degradation only increases the

potential for productivity reduction. The wordpotential is stressed as crops and pastures can

grow well in structurally degraded soil, if there is

frequent irrigation or rainfall. The crop grows

almost hydroponically. However, when rain isscarce, crops in structurally degraded soil will fail

long before crops in well-structured soil.

There are potentially high costs involved in bothforming soil structure degradation and then

initiating repair and control strategies. Cultivation,traffic and animal hooves cause structure

degradation. Yet, on many occasions the aim of the

cultivation was to alleviate soil structure

degradation, or to open up land for improvedpastures. However, if the soil was too moist or wet

at the time of the cultivation, structure degradation

ensues. So the farmer is paying threefold: the cost

of the cultivation and traffic, and the cost ofnegative responses (yield loss, increased irrigations,

poor seedbeds, etc.) that then require morecultivation (with traffic) to repair—again running

the risk of producing more structure degradation.This is a typical ‘downward spiral’ associated with


As with some other land degradation (e.g.

accelerated soil loss), post-clearing activities may be

more significant in contributing to soil degradationthan tree clearing per se. In the case of soil

structure degradation, the impact of animal hooves

in new pasture may cause structural degradation.

For example, severe degradation of the soil surfacewas located in a sown pasture on a shallow blackearth west of Moura in central Queensland (photo

in McGarry et al. 1999). The grazier reported poor

rain infiltration and poor pasture growth at this site,



despite the deep chiselling operation that preceded

sowing of the pasture. The cattle had trampled therecently loosened soil by walking on wet or moist

soil, following rain. The outcome was poor water

infiltration and water ponding. In turn, this caused

the soil surface to remain wet for long periods oftime, so increasing the potential for structure

degradation as the cattle traversed wet soil.

A second example is presented in Proffitt et al.(1995), where the strong negative impact of sheep

trampling is shown (figure 4.6). Sheep tramplingeffectively reduced the aeration in the topsoil to

zero, as evident in figure 4.6a, where there is

massive soil structure degradation (white in the

image) to at least 100 mm. This, in turn, severelyreduced water infiltration and subsequent pasture

growth. Where the sheep were removed after every

rain event, there are many interconnected, faunal

holes to facilitate water infiltration (figure 4.6b).

Repair and prevention of structuredegradation

Once structure degradation is located, then repair

and control measures can commence. It isimperative that soil management and crop

problems are correctly linked to the recorded

presence of structure degradation before repair and

control practices are begun. Location, with spade-dug holes or soil pits, needs to be at different

scales: parts of fields, across fields, across farms,

etc. Location in the soil profile is also important to

correctly choose the best repair strategy. If the

problem lies in the top 0.1 m, there is no need tocultivate to 0.4 m. Deep cultivation is expensive

and has strong potential to produce adverse effects

by inducing deep-soil smearing and compaction,and bringing subsoil with poor chemical properties

to the soil surface.

Repair, where required, can either be biological or

mechanical, or a combination of both. Biologicalmethods are preferable, as they not only remove

the possibility of further damaging the soil by

mechanically removing the structure degradation,

but also are more sustainable and have minimum

costs. Current biological options include rotationcrops, pasture phases (with carefully controlled

stocking, especially in wet years), earthworms and

green manures. These activate natural soilprocesses of swelling and shrinking, the production

of natural soil pores, and organic matter

improvement. It is recognised that the potential for

these in grazing lands is minimal, but graziers needto be aware of potential repair strategies that may

be enacted when possible.

Different soils as well as different degrees of

structure degradation vary in their response torepair practices. Generally, cracking clays respondwell to repeated wet and dry cycles under rotation

crops (Pillai & McGarry, 1999), whereas non-

swelling soils react better to increases in earthworm

activity and root-hole formation (McGarry et al.

2000), and additions of organic matter. Mechanicaloptions of ripping and cultivating must only be

done after digging pits to ensure the soil (to a depth

below the intended cultivation zone) is drier than

PL. This will ensure brittle failure of the soil ratherthan plastic flow (which would give further

structure degradation).

Before initiating prevention practices, carefulconsideration should be given to repairing any

inherent soil structure degradation. The initialremoval of degradation is particularly important if

the degradation is severe or the soil has little,

inherent self-repair ability (it is not a cracking soil)

or if zero till will be practised in the new system.Under zero till, even a strongly cracking soil will

take several seasons to repair degradation through

biological means. Initial improvement of structure

degradation kick-starts the new prevention systemin which all future traffic is controlled, and the

need for future deep cultivation is removed.Subsoiling, deep ripping or square ploughing are

potential devices for the initial degradation repair,but must only be used in soil below PL, where a

problem has been identified (spade holes or

backhoe pit) and its location in the profile noted.

Currently, prevention measures include controlled

traffic, minimum tillage and flotation tyres.Vegetation clearance may be able to incorporate

flotation tyres (minimising tyre impact in wet soils),

but few other prevention strategies.

In the example described previously, the black clay

at Moura has potential for moderate swell/shrinkwith wet/dry cycles under a crop. However, the

immediate problem is the lack of a seedbed, as the

degradation occurs from the immediate soil surface.

Shallow cultivation in dry soil is needed to preparea seedbed, then subsequent crops should initiate

cracking of the compacted subsoil. Critical,

however, is that the soil must not be trampled

while moist or wet, or the problem will return.Fencing is required to better control stock

movement. Thought should be given to the creation

of a ‘sacrifice’ paddock where stock are kept andhand-fed in wet times, to save the soil structure onthe remainder of the farm.

Discussion

There are difficulties and challenges to the true

enactment of the above management strategies

across all cropping systems. With vegetation

clearing, in some years it will be difficult tocultivate and traffic only dry soil. There will also be

strong economic problems associated with moving

animals around to protect wet, fragile soils. Also,

certain soils, especially the hardsetting and crustingsoils, are so fragile that some degree of physical

damage and organic matter decline is inevitable.

The build-up of organic matter is vital to structure

optimisation in such soils, but even under optimal70



conditions this can be a most slow process. Other

difficulties arise where several soil types occur inone field, as one part of the field is sufficiently dry

to traffic or graze without damage, but the other

soil remains too wet. If possible, fencing should be

used to separate such soils. The use of flotationtyres on tractors should also help reduce damage.

4.2.5 Nutrient cycling

For many years, scientific literature has recognisedthat vegetation exerts a considerable influence onboth the nature and amount of organic matter in

soils (Spain et al. 1983). Previous studies have

found that the processes whereby trees improve

soil fertility are numerous and difficult to separate,although the positive benefits of trees on nutrient

cycling processes are often reported in the

literature (Young 1989; Prinsley 1991; Noble and

Randall 1998).

The role of trees in influencing (generally

increasing) soil nutrient status has beendemonstrated for phosphorus in Eucalyptus populneacommunities (Ebersohn & Lucas 1965), nitrogen

and sulphur (Dowling et al. 1986). More recentstudies have shown that the nutrient availability is

improved beneath eucalypt canopies (Wilson et al.

1990a), giving rise to a heterogeneous soil nutrient

environment. Trees have been described as nutrientpumps, exploiting and redistributing nutrients from

depth in the soil profile and laterally from areas

beyond the canopy, depositing them via litterfall

and canopy leaching (Noble & Randall 1998). A

consequence of clearing is that this spatialvariability and patchiness is greatly reduced. This

can be attributed to the reduced size of the plant

patches that are using and redistributing the soilnutrients (grasses versus trees), which can

potentially have a large impact on nutrient losses

(Ludwig et al. 2000).

The relatively deep root systems of trees allow

them to access nutrients deep in the soil, bothlimiting leaching potential and making otherwise

unavailable nutrients accessible to shallow-rooted

pasture species. However, plants often compete by

depleting resources required by neighbours, andtrees must acquire water and nutrients that the

pasture understorey would otherwise attain.

Elevated nutrient status under trees generally does

not increase pasture productivity at the communitylevel (Beale 1973; Walker et al. 1986; Scanlan &

Burrows 1990), although exceptions exist (Christie

1975; Belsky et al. 1989, 1993). Belsky et al. (1989,

1993) found increased herbaceous-layer productionbeneath canopies associated with lower soil

temperatures and greater soil fertility. Work in low

fertility, semiarid areas indicates a growth response

in pasture under mature poplar box (E. populnea)(Ebersohn & Lucas 1965; Christie 1975; Silcock

1980). It is suggested that in these situations

enhanced pasture growth resulted from nutrient

build-up beneath older canopies. 71

Figure. 4.6 Binary images of topsoil structure condition inthree sheep grazing treatments: (a) traditional grazing—pasture grazed continuously for 17 weeks, (b) controlledgrazing—sheep removed after all rain events, and (c)ungrazed—where the pasture was mown only. All sampleswere taken at the end of the grazing period. In the images,black areas are the soil pores (air) and white is the soilsolid. All samples are 100 mm x 100 mm in real life. Source:Proffitt et al. (1995).

Sheep hoof imprint

Surface faunal pores

Faunal pores

a

b

cSurface faunal pores

Faunal pores



and any decline in soil organic matter will impact

on nutrient availability. Gillman (1976) foundsignificantly higher carbon and nitrogen levels in

krasnozem soil types under rainforest in north

Queensland than under adjacent eucalypt forest.

Teakle (1950) suggested that after removing therainforest from north Queensland krasnozem soil

types, organic carbon content could be halved after

about 20 to 30 years under Paspalum dilatatum

pasture.

Graham (1978) found in studies of solodizedsolonetz and sodic soils that in 8 out of 17 paired

sites, a significant decrease in organic carbon

occurred post clearing. The period since clearing in

these instances ranged from 7 to 27 years with apercentage change from 17 to 41% of original levels.

Isbell (1966) found that brigalow (Acacia harpophylla)forests had substantially higher organic carbon than

adjacent grasslands in northern central Queensland,

both communities being on very similar grey and

brown clays. Recent observation of strip-clearedbrigalow confirm Isbell’s observation, with Chilcott

(forthcoming) finding five times higher soil nitrogen

in retained tree strip compared to adjacent treelessgrazed pastures. However, Ahern and Turner (1993)

showed that surface organic carbon and total

nitrogen were similar for vertisols of the Mitchell

grass downs and adjacent open gidgee woodlandsin western Queensland. Dowling et al. (1986)

showed that organic matter was much higher

beneath tree canopies than in associated grassed

interspaces in a brigalow–Dawson gum

(A. harpophylla–E. cambageana) woodland. However,in naturally fertile brigalow soils nearby, soil organic

matter did not decline in a five-year period after

clearing and planting to buffel grass (Cenchrusciliaris). An adjoining cropped catchment lost 19% of

soil organic matter over the same period. Total

nitrogen followed the same pattern. Data collected

by Lawrence et al. (1993) in these cleared brigalowcatchments showed a short lived flush of plant-

available nitrogen (N), phosphorous (P) and

potassium (K), but that within three years of

clearing, soil organic carbon and total nitrogen

under buffel grass had returned to preclearing levels.

Chilcott (2000) found significantly higher organic

carbon, soil nitrogen and plant available

phosphorus levels beneath trees than in interspaces

in eucalypt woodlands in the Northern Tablelandsof New South Wales. Associated with this was

higher microbial activity and biomass beneath tree

canopies in the woodland. A fertile island was

observed beneath tree canopies as a result ofhigher levels of organic inputs. Chilcott (2000)

attributed this to:

1) higher root and litter biomass pools resulting inan accumulation of organic matter on or nearthe soil surface

2) the presence of better quality substrate beneath

trees than in the canopy gaps.72

In the more fertile cleared brigalow communities,

there is also a reduction in the availability of soilnutrients as the time since clearing increases

(Graham et al. 1981). This can be related to the

increase in root biomass that tends to immobilise a

large proportion of the available nutrient pool(especially nitrogen). No measurable decline in the

total nutrient pool size has been recorded in these

circumstances.

Trees also contribute more above-ground litter than

pastures (Frost 1985), and soil fertility has beendemonstrated to improve through increased litter

and soil organic matter return beneath trees

(Christie 1975, Campbell et al. 1988). Litter

decomposition rates can be improved directly byproviding litter of better quality (higher in nutrient

content), and indirectly by altering the habitat for

the soil mesofauna and soil microbes (Chilcott

2000; Young 1997). Retention of a diversity ofvegetation promotes a range of different qualities of

litter through a mixture of woody and herbaceouslitter. This has direct consequences on the soil

biota that mediates litter decomposition processes.The presence of trees provides a steadily decaying

nutrient store of organic matter (Young 1997).

Trees may also enhance the nutrient status of soil

by providing shade for livestock camping (Chilcott

2000; Belsky 1994; Taylor & Hedges 1984) thatconsequentially concentrates nutrients from the

grazed paddock, and may enhance local nutrient

cycling (Georgiadis 1989).

Tree canopies can also act as an effective trap for

atmospheric dust, with the nutrients contained inthe dust being washed from leaves during rain,

and accumulating in the subcanopy soils

(Szott et al. 1991).

Leguminous shrubs (those that fix atmospheric

nitrogen, e.g. some Acacia spp.) have been found toincrease pasture production under canopies by

elevating soil nutrient status (Scrifes et al. 1982).

Some individual tree species are recognised as

providing functional roles in nutrient fixationthrough microbial associations. The genus

Casuarina has been documented to fix atmosphericnitrogen through bacterial nodulation (Torrey

1981). It is likely that most Australian plants,including acacia, eucalyptus, melaleuca and others,

are mycorrhizal. Most mycorrhizal studies have

pointed to the crucial role of mycorrhizas in

phosphorus uptake but they also appear to improvethe availability of poorly mobile ions of zinc,

copper, molybdenum, and possibly ammonium

(Turnbull 1986).

Effect of tree removal on soil nutrient

statusEvidence that trees are important in nutrient

cycling leads to concern about the removal of trees,nutrient losses and rundown (Ludwig et al. 2000).

Many nutrients are associated with organic matter,



In the mulga lands, the concentration of topsoil

nutrients and organic carbon (from highest tolowest) is found under mulga, grass, turkeybush,

bare ground, and eroded ground (Miles 1993).

Chilcott (2000) found that clearing Eucalyptuslaeviopinea woodlands resulted in an initial flush

organic C and total N. Following clearing, a readilyavailable supply of organic carbon for microbial

growth resulted from decomposition of fine rootsand harvest trash. Increases in water availability

and temperature following clearing stimulateddecomposition, contributing to increased soil

organic C initially following clearing. However, soil

organic C and nutrient levels will decline in the

long-term if natural tree regeneration is suppressed,as readily available nutrients are leached from the

system. Kauffman et al. (1993) investigated effects

of deforestation on tropical dry forests and reported

significant losses of C, N and P from the soil,estimating that it would require a century or more

to reaccumulate those nutrients and carbon lost.Phosphorus is a very important element, but it is

not a mobile element within the soil profile. Losses

can be expected where soil erosion is significant. Ifleaching and soil erosion losses are excluded, then

the only loss from grazed communities will be in

the form of livestock (meat and wool). The amount

removed will depend on stocking rate and soilfertility level. Burrows (1993) asserts that the

removal of phosphorus by livestock is not a

significant contributor to phosphorus dynamics in

the medium- to long-term in grazed woodlands.

4.2.6 Soil acidification

In Queensland, more than 2 000 000 ha of

agricultural lands have soils that are naturally acidic(pH in water <6.5) as a result of leaching processes

in a humid environment, and from previous climatic

conditions (White 1997a; Aitken et al. 1998). Acid

enters the ecosystem naturally as carbonic acid inrainfall, sulphuric and nitric acids produced by

biological processes, and as organic acids (White

1997a). However, the development of a strongly acid

soil (pH in water <5.5) results in poor plant growth

as a consequence of one or more of the followingproblems: aluminium toxicity, manganese toxicity,

deficiencies of calcium, magnesium, phosphorus

and molybdenum, and reduced microbial activityleading to a reduction in the cycling of nutrients

such as nitrogen. In 1998, 90 000 000 ha of land in

Australia was considered to be acidic, withapproximately 35 000 000 ha highly acidic and

55 000 000 ha moderately or slightly acidic (see

table 4.4). Queensland has the second highest rate

of highly acidic soils, with 8 400 000 ha affected.

Any change in land use may cause accelerated soilacidification, with the rate of acidification being

dependent on the particular land use and thesusceptibility of the soil. Accelerated acidification is

often associated with intensive agriculture andhorticulture, and in grazing lands where tropical

legumes have been introduced (Commonwealth of

Australia 1996; Aitken et al. 1998; Noble et al.

1997; Noble et al. 1998). Some soil types havebeen identified as being vulnerable to acidification.

Accelerated acidification of soils is due to increases

in the losses of products of acid reactions in the

biological carbon and nitrogen cycles (Noble et al.

1997). The main mechanisms of acidification of soils

in the agricultural setting have been identified as:• application of acidifying fertilisers (usually

nitrogen fertilisers) or elemental sulphur in

intensive agriculture• nitrogen fixation by legumes (in oversown

pastures) increasing soil nitrogen which is

subsequently nitrified and leached

• removal of plant and waste products higher inresidual alkalinity and redistribution of nutrients

through grazing animals (DEST 1996; Cregan &

Scott 1998).

Effect of clearing on soil acidificationUnder native vegetation, acidification is minimal

because nutrients are efficiently recycled from thesoil back through the vegetation, and there is no

removal of plant material off-site. Land clearing is

an acidifying process. Following clearing of trees,

there is a large release of nutrients as windrowedwoody vegetation decomposes (or is burnt).

Leaching of these released nutrients causes soil

acidification. Soil acidification is also caused by

removal of timber off-site, as occurs with logging.This occurs because the removal of vegetation that

has been produced on-site leaves behind residualacidity in the soil. Studies in Victoria showed that

50 years after clearing eucalypt forest for timberand allowing regrowth to occur, the amount of

acidity generated was equivalent to 2.25 t/ha of

lime (Prosser et al. 1993).

73

Table 4.4 Extent of acid soils in Australia (ha x 106).Extracted from Cregan and Scott 1998.

State Highly acidic Moderate acidity Slight acidity(pH Ca<4.8) (pH Ca<4.9–5.5) (pH Ca<5.6–6.0)

New South Wales 13.5 5.7 5.1

Victoria 3.0 5.6 5.5

Western Australia 4.7 4.7 n/a

South Australia 2.8 n/a n/a

Queensland 8.4 32.0 n/a

Tasmania 1.0 n/a n/a



their liming program is counteracting the

acidification caused by their production system. Inparticular, light-textured soils should be targeted for

regular pH monitoring. It is likely that soil

acidification rates will be greater in areas receiving

more than 500 mm annual rainfall because of theenhanced possibility of leaching in this environment.

Planting perennial, rather than annual, grass and

legume species will reduce accelerated soilacidification by maintaining an established root

system throughout the year for nutrient and wateruptake, thereby reducing nutrient loss by leaching.

Reforestation of cleared areas will arrest further soil

acidification by re-establishing ‘closed’ nutrient

cycling, and reducing nutrient leaching by

increasing evapotranspiration.

In summary, the following management strategieswill minimise accelerated soil acidification:

• regular monitoring of soil pH, particularly that of

light-textured soils

• implementing a regular liming program• avoid clearing light-textured soils

• use of perennial pasture species

• reafforestation of cleared areas.

4.2.7 Hydrology

The removal of deep-rooted woody vegetation and

its replacement by shallow rooted grass species,

leads to alteration of hydrological relationshipswithin catchments. Generally, the removal of trees

increases the deep drainage component of the soil

water balance, while heavily grazed pasture

systems can result in large increases in surfacerun-off from cleared land systems (Miles, 1993;

Silburn, et al. 1992). If cleared land is then brought

into cultivation, further increases in drainage below

the root zone and surface run-off can be expected(Wockner & Freebairn 1991). Often, changes in

water-balance components are a result of changes

in water-use patterns as well as depth of water

extraction by plants. The mobilisation of saltpreviously distributed in deeper subsoil and

substrate layers that accompanies alteration of the

hydrology and the associated salinity problems isdiscussed in section 4.2.8. Specific studies of otherchanges relevant to Queensland follow.

It should be noted that for most parts of

Queensland (other than coastal and subcoastal

areas and high rainfall areas of Cape York),

potential evaporation exceeds precipitation by afactor of 2 in any month. As a result, groundwater

recharge is a small and irregular component of

water balance. This is in strong contrast with the

situation in southern and south-western Australia,where recharge is a regular feature of the water

balance, due to rainfall commonly exceedingevapotranspiration potential in winter months, and

resultant salinity problems are widespread.However, in Queensland, sporadic heavy rainfall

events are important in overall recharge rates.74

Effect of land use on soil acidification

Land uses which are particularly acidifying are

those where (a) there is a large removal of harvestedproduct (e.g. sugar cane), (b) large amounts of

ammonium-based fertilisers are applied (e.g. many

horticultural crops, dairy pastures), or (c)

introduced legumes are part of the land use (e.g.stylosanthes pastures). Unfertilised pastures of low

productivity cause minimal acidification. Noble etal. (1997) examined paired ‘developed’

(stylostanthes-dominated pasture) and‘undeveloped’ (grass-dominated pasture) between

Rockhampton, Queensland, and Katherine, Northern

Territory, to estimate the impact of stylostanthes on

rates of soil acidification. In this study the extent ofacidification, whilst significantly more acid in six out

of seven sites, ranged from no measurable change to

severe subsurface acidification extending to over

70 cm and demonstrated considerable variationamong sites. In a comparison of leucaena-based

and nitrogen fertilised and irrigated sites, Noble etal. (1998) found for both systems a decline in pH

since sampling was taken in 1960. However, theextent of acidification was much greater under the

more intensively managed fertilised and irrigated

sites than the leucaena system (Noble et al. 1998).

Management of soil acidification

Under extensive production systems where clearing

is to be undertaken to enhance pasture production,it is important that producers are aware of the

possible long-term consequences. Remediation of

acidification through conventional avenues (i.e.application of liming sources) is uneconomic inthese systems. Consequently, the producer is left

with assessing the potential risk associated with

clearing. On soils that have a high internal

buffering capacity (i.e. black alkaline crackingclays), the long-term impact of increased

acidification would be low, since the soil has the

ability to resist any downward pH trends. However,

on light texture sandy soils that have a low internalbuffering capacity, the consequences of accelerated

acidification associated with clearing may be

significant. Therefore, if tree clearing is to beundertaken for extensive pasture production, areasof high risk, as outlined previously, should be

avoided or appropriately managed.

In the intensively managed production systems,

landholders can initiate a liming program

appropriate to their production system. Such astrategy will minimise the risk of soil acidification

becoming a production constraint, and will protect

the long-term productivity of the soil resource.

Soil acidification is detected by a gradual decline in

soil pH. This decline will be more evident in light-textured soils than in clayey soils, because the

former have a low ability to ‘buffer’ or counteract

the effects of acidity on soil pH. Landholders should

monitor soil pH by annual sampling to ensure that



Differences in water use can be demonstrated

between native grasses, introduced shrubbylegumes and Eucalyptus spp. in a north Queensland

red earth (Gardener et al. 1990). Trees extracted

water to a depth of at least 4 m, whereas grasses

mainly used water from less than 1 m of the soil. Adetailed examination of water use in a planted

flooded gum (Eucalyptus grandis) agroforestry

experiment showed that, at higher tree densities, a

greater proportion of soil water was extracted fromdeep within the soil profile (Eastham & Rose 1988,

1990; Eastham et al. 1988, 1990a, 1990b).

Impact of clearing trees

There is substantial evidence that removal of trees

disturbs the hydrological regime, often resulting in

expression of salinity (see section 4.2.8). A one-year study by Williams et al. (1993) in north

Queensland showed increased deep drainage once

trees were cleared—from 9 to 86 mm for a red

earth, from 118 to 238 mm for a sandy red earth,

and from 72 to 115 mm for a yellow podzolic.When these results were extrapolated for 100 years

using the PERFECT (Littleboy et al. 1989) and

SWIM (Ross 1990) models, increased deep drainagefollowing clearing was from 15 to 74 mm/year for a

red earth and from 1 to 8 mm/year for a neutral

red duplex soil. This change in groundwater

recharge, in conjunction with soil salt levels of0.4 mS/cm and groundwater salinity levels of

1500 to 5000 mS/L, present a potential salinity

hazard after clearing.

There are, however, some studies in Queenslandthat have presented different results. Lawrence andSinclair (1989) reported that the clearing of

brigalow (Acacia harpophylla) in central Queensland

and planting a crop or pasture did not alter the

annual catchment water balance. The meanrecharge rate measured by Lawrence et al. (1993)

rose from 7 mm to 28 mm per year after

establishing a buffel grass pasture, but this was due

to one very wet period (April–May 1983). Apartfrom this period, groundwater recharge had been

the same under buffel grass and brigalow. Clearing

Eucalyptus laevopinea woodlands (northern NewSouth Wales) caused a significant increase in soilmoisture profiles, with soils remaining saturated or

near-saturated for 12 months following clearing

(Reid et al. 1998). This (coupled with the clearing

disturbance) resulted in a substantial shift inpasture species composition from previously

palatable grasses to unpalatable sedges and rushes

(Chilcott 2000). Pressland (1976a) demonstrated

that cleared mulga areas had up to 77 mm lessevapotranspiration compared with an area thinned

to 640 trees/ha.

An important consideration in hydrology is thatwoody plants re-establish or regrow in areas that

are cleared, particularly when pulling, chaining orstem injection is the method of clearing. This is

reported for eucalypt (Walker et al. 1972; Anderson

et al. 1983; Burrows et al. 1988a), brigalow

(Anderson et al. 1984), gidgee (Reynolds & Carter1993) and tea-tree (melaleuca) communities

(Anderson et al. 1983). The regrowth may support

the same leaf area as uncleared woodlands, and

therefore the hydrological regime may not differgreatly between intact woodlands and ‘cleared

areas’ with woody regrowth. A factor of major

importance will be the depth of rooting of mature

trees versus regrowth. Unfortunately, no studieshave compared these aspects.

The return of woody vegetation (approximately

10% of total paddock area) into previously cleared

grazing lands resulted in more thorough and rapid

drying of soil profiles beneath five- to six-year-oldtrees. Reid et al. (1998) concluded that

appropriately located woody vegetation has a role

in mitigating waterlogging and dryland salinisation

in upland temperate pastures.

Catchment level effects of water-use patterns have

been difficult to detect in some short-term studiesdue to between-catchment variability and between-

year variation in rainfall in southern Queensland

ironbark–black speargrass woodland (Prebble &Stirk 1988). Changes in water balance components

have been clearly shown in studies at the 1 ha

scale on cultivated cracking clays (Freebairn et al.

1986; Wockner & Freebairn 1991). Maintenance ofhigh levels of stubble or crop cover reduced run-off

volumes by 40% and peak discharge rates by

70–85% compared to bare soil. These changes at

the small scale are not easily demonstrated at the

large scale (e.g. 1 000 000 ha) even when a largeproportion of a catchment is modified.

With the application of water-balance models and

appropriate physical measurements, we now have

the capacity to estimate changes in water-balancecomponents of different land uses and management

options. These models allow us to explore long-term

scenarios and alternative management options at

the point or paddock scale (PERFECT—Littleboy etal. 1992; APSIM—McCown et al. 1996). These tools

need to be linked to landform, land use, geology and

groundwater maps to determine risk profiles.4.2.8 Salinity

With dryland salinity reportedly affecting nearly

2 500 000 ha Australia wide in 1996, and potential

for this figure to grow to over 12 000 000 ha,salinity has become a major natural resource

management issue (Hayes 1997). Impacts of

dryland salinity include retarded plant growth,

degraded soil structure, limitations on water use byplants, subsequent loss of productivity,

infrastructure damage, loss of biodiversity, impacts

on water quality, and disruption of ecologicalprocesses in wetlands and riverine ecosystems(SalCon 1997; MDBC 1999). Estimates of the

known impacts (largely infrastructure damage) put

the annual cost at $270 million, including75



and some of the issues involved in this are

discussed here. Considerable development in thedetection of salinity risk has emerged recently.

These tools are essential in Queensland in order to

plan for development and anticipate future salinity

risks, and will also be reviewed here.

Identification of salinity risk potential

Improvement of the predictive capability of salinity

hazard assessment to avoid inappropriate treeclearing or development requires a thorough

understanding of the processes contributing to

salinity and sodicity problems. SalCon (1997)identified the following factors that can provide

information on current and potential salinity levels

and processes:

• landform features and geology in the catchment• vegetation species and communities, and specific

responses to salinity or ion toxicity

• local climate and rainfall patterns

• soil properties, salinity and sodicity levels

• water characteristics, salinity and sodicity levels• land use records.

(For a comprehensive discussion of these

attributes refer to the Salinity Management Handbook, SalCon 1997.)

Methods to determine the risk or potential for

salinity problems usually involves a combination of

measuring and modelling a combination of these

characteristics to produce an informed prediction ofthe likely consequences of different management

scenarios. However, a major impediment to the

broader identification of salinity risk is thelimitation of existing spatial datasets. In areaswhere dryland salinity is an expression of localised

hydro-geomorphic features (such as the Eastern

Downs), datasets in the order of 1:100 000 scale or

better are required to fully delineate high-risksubcatchments.

Soil properties

Investigations of soil properties can be used to

determine hydrologic processes, history of

waterlogging and salting, and guidelines for the

potential of the soil under cropping, pasture ortrees (SalCon 1997). Properties such as soil pH,

concretions, clay content, mineralogy and soil

salinity can all indicate something about salts in

soils. Examination of the soil salinity profile can beinterpreted to determine whether recharge or

discharge may be occurring at a specific location

(SalCon 1997). Modelling software has been

developed to use a number of parameters of the soilprofile incorporated in SALF software. It predicts the

soil leaching fraction6 and salinity within the root

zone under different irrigation regimes, to then

predict the effect of growing different crops (SalCon1997). Utilising these techniques, Gordon and

Claridge (1997), in a recent investigation of the

Upper Dawson River catchment, combined soil

characteristics, SALF soil profile modelling software76

$130 million in lost agricultural production

(LWRRDC 1997; PMSEIC 1999).

The incidence of salinity-affected areas inQueensland is smaller and more scattered, with

10 000 ha5 of land estimated to be affected by

dryland salinity (Gordon 1991). However, salinity is

considered an emerging issue, with potential forsignificant areas of Queensland’s agricultural lands

to be affected over the next 10–30 years (Gordon1998).

Approximately 5.3% of Australian soils naturally

contain soluble salts (Northcote & Skene 1972).The presence of these salts is commonly attributed

to deposits of oceanic salts by rainfall or wind, but

may also result from chemical weathering of rock

minerals and marine sediments (SalCon 1997). It isgenerally accepted that the main cause of dryland

salinity is inappropriate clearing of deep-rooted

perennial vegetation and its replacement with

shallow-rooted crops or pastures or with urban

development (RIRDC 2000). The resulting alterationof the hydrologic regime increases recharge and

mobilises salt previously distributed in deeper

subsoil and substrate layers. These thenaccumulate in vulnerable parts of the landscape

(Loveday & Bridge 1983; SalCon 1997) accelerating

the salinity process (House et al. 1998). Because

the hydrological processes that affect ground watermovements are complex, it may take many years

before any evidence of salinity becomes apparent

(Oliver et al. 1996).

Although the proportional distribution of naturally

occurring saline and sodic soils in Queensland issimilar to other States (Shaw et al. 1994; SalCon

1997), current rainfall patterns, geology, soil types,

and extent and duration of land clearance result in

lower rates of saline-affected areas in Queensland(House et al. 1998). With the majority of

Queensland’s rain falling in summer, evaporation

mostly exceeds rainfall, so the soil profile is rarely

fully saturated and recharge only occurs where asuccession of wet periods prevent the soil from

drying out (Hobson & Carey 1994).

With high rates of tree clearing in Queenslandcontinuing for land development, there is an

opportunity to implement preventative managementstrategies to prevent expansion of salinity and

sodicity problems observed in other States (Gordon

1998). For example, there is some scope under the

recently enacted Vegetation Management Act 1999(Qld), for statutory controls on tree clearing to

strategically avoid the expression of salinity in the

landscape. The Act provides for the development of

Regional Vegetation Management Plans, whichpotentially may anticipate the long-term

consequences of tree clearing on groundwaterhydrology, and plan tree-clearing restrictions in

vulnerable catchment areas.

There is a considerable body of literature that

addresses management of saline-affected areas,



and electrical conductance of the top 6.0 m of soil

to demonstrate the potential of a large proportion ofthe area studied for use in irrigated cropping. This

use, however, was conditional on following certain

criteria for selection of crops, and volume and

method of irrigation. The risk of developing asalinity hazard for areas where a highly permeable

soil exists above a less permeable soil (in this study

a light Sodosol above a heavier Vertosol were

highlighted).

Climate and rainfall

Certainly an important factor in predicting salinityhazard potential in Queensland is average annual

rainfall characteristics. In Queensland, watertable

salting is mainly restricted to areas with between

600 and 1500 mm per annum rainfall, and hencerestricted largely to the eastern and northern

portion of the State (figure 4.7). Further, use of

moving average rainfall pattern allows comparison

of historic rainfall patterns to determine whether acurrent expression of salinity may potentially

increase or decrease depending on predicted

rainfall trend (SalCon 1997).

Landform

Information about landform and geology can provide

useful information about sources of salt, areas likelyto be susceptible to salinity expression, and

geological structures controlling water movement.

77Figure 4.7 Zones of salinity hazard in Queensland, based on annual rainfall and evaporation patterns. Source: SalCon 1997.

salinity hazard

moderate 600–700 and 1100–1500 mm/yr

high 700–1100 mm/yr

low <600 and >1500 mm/yr

Brisbane

Cairns

Townsville

Rockhampton

Charleville

Mount Isa

Mackay

Emerald



A number of recent Queensland studies have begun

using GIS to assist the process of developingsalinity hazard prediction (Bui 1997; Williams et al.

1997; Searle & Baillie 1998; Bourke et al. 1999) The

Queensland Department of Natural Resources

(DNR) adopted the HARSD (Hydrogeomorphicanalysis of regional spatial data) methodology to

quantify groundwater-level trends in the

Murray–Darling Basin (Bourke et al. 1999). These

trends have been used to predict the area ofgroundwater discharge over the next 100 years

(Bourke et al. 1999).

By classifying the landscape into discrete,

hydrogeomorphic units of similar aquifer properties

and recharge/discharge behaviour, a linearregressional relationship was developed to create a

baseline water elevation surface for each discrete

unit. From this, a groundwater level map for the

Queensland Murray–Darling basin was developedin a GIS environment. The predicted water

elevation surfaces for 2020, 2050 and 2100 weregenerated to determine salt loads, and estimates of

land area with high watertable, areas with salt loadmobilised to the surface, and river salinity for each

of the future years (Bourke et al. 1999).

Further pilot work by the Department of Natural

Resources has explored the use of a linear additive

method within a GIS framework to automaticallyidentify subcatchments at potential risk of salinity

(Searle & Baille 1998). GIS layers used in the

analysis included soils, geology, climate, vegetation

and topographic indices. Each data layer was rated

with a separate salinity hazard rating, based on adefined set of decision rules. When overlaid, the

total of assigned ratings were used to map areas

along a continuum from low to high salinityhazard. The results of the modelling were reflected

in the experience of field staff, and Searle and Baille

suggest this modelling represents a fairly accurate

means of assessing salinity hazard at the landscapelevel. They suggest that further development of this

model would necessarily include a more rigorous

method of ground truthing, testing the sensitivity of

the model to different weightings of the layers, and

improving the way in which conceptual landscapesalinity processes are represented in digital models.

Bui (1997) has similarly developed a GIS-based

salinity risk assessment model for north

Queensland. The risk of salinity hazard after treeclearing was assessed based on information about

climate, vegetation cover, position in the landscape,

depth to groundwater, rate of recharge and

presence of salt in the groundwater. As a result ofthis study, it was recommended for the study area

that recharge areas should not be cleared in

watersheds where unconfined aquifers are presentand where soils with per cent TSS>0.25 occur,although where intermediate recharge areas are

cleared, the introduction of deep-rooted improved

pasture species may control recharge (Bui 1997).

Bui identified the need for more detailed78

Vegetation

Observation of plant communities, as well as

specific physiological responses in individualplants, can indicate areas of current or recurrent

salinity, and demonstrate the need for more

comprehensive salinity investigation.

At a broader scale, vegetation patterns,

demonstrating variations in density, species

composition, and changes over time, using remotesensing images, can provide more detailed

information about salinity risk and expression.

Remote sensing methods can collate information ona number of the features reviewed previously in this

section (i.e. landform, soils, vegetation, and land

use) to estimate and map the mass and extent of

salt in the landscape. These methods of mappingcan be used to identify areas of potential salinity

hazard and salt loads likely to be mobilised under a

wetter equilibrium.

Salinity mapping can also be carried out using

ground-based geophysical methods. Mostcommonly, electromagnetic induction (EMI) is used

for site surveys and regional reconnaissance

(SalCon 1997). By inducing a magnetic field within

the soil, the electrical conductance of the soil (EC)can be measured at various depths. These

measurements are indicative values, as the readings

are of the bulk soil at given water content, and the

instrumentation is sensitive to clay content andmineralogy, soil water content, and the depth of

bands of more conductive material within the soil

profile (SalCon 1997). There is considerableinformation available in the literature thatquantifies the likely significance of EMI readings

with respect to different profile effects, and other

factors. SalCon (1997) recommends the use of

ground truthing by the taking of soil samples toverify EM readings.

Salinity hazard investigations inQueensland

An investigation of salinity hazard following tree

clearing in north Queensland (Williams et al. 1997)

using a simulation model, demonstrated asubstantial increase in deep drainage following thereplacement of woodland with native grassland

across a number of different soil profiles. Whilst

introduction of a perennial legume lessens the

increase in deep drainage, the effectiveness of thisvegetation is strongly dependent on nutrient status

and, subsequently, tree clearing may well release

water, but this may not be converted into dry

matter and water use if nutrient and other edaphiclimiting factors remain. Williams et al. (1997)

highlighted the need to develop routine tools for

assessing the risk of salinity hazard at sites wheretree clearing is planned, to predict ground waterresponse and hill-slope watertable developments

that can mobilise salt in the landscape.



hydrogeological information to give more certainty

to the results.

It should be noted that most approaches tomapping salinity are ‘static’ tools and do not allow

an assessment of catchment water balance. Whilst

‘high risk’ catchments can be identified, the

number of trees that need to be retained cannot.Catchment characterisation and catchment water

balance (using flow tube modelling) is being testedwithin the National Land and Water Audit to

provide a quantitative framework for salinitymanagement (Coram et al. 2000). Unfortunately,

this work is focused on remedial action in southern

and western Australia.

Management

The management of shallow saline watertables to

reverse the process of secondary salinity isproblematic because of a number of factors. These

include:

• the complex interaction between land use andmanagement, landscape hydrology,geomorphology, historic salt loads, and

socioeconomic and environmental factors

• the slow hydrological response, that is,

secondary salinity often becomes worse before itgets better even where remediation is

implemented

• the cost to manage may be greater than the

economic benefit• and the site of the cause of salinity (recharge

areas) are often separated from the site of

expression.Direct management of saline-affected areas can be

carried out in a number of ways. Strategies includealtering hydrological processes, improvement of

water efficiency where irrigating, and direct

management of saline-affected land (SalCon 1997;

Thorburn 1999). Direct management of saline-affected land may include establishing salt-tolerant

plant species with production benefits. A

comprehensive review of management strategies

and their application is available in the Salinity Management Handbook (SalCon 1997).

Altering hydrological processes

Strategies to alter hydrological processes can

operate to reduce salinity by:

• reducing recharge

• intercepting water in transmission area• increasing water use in discharge areas.

This may be achieved in a number of ways,

including revegetating catchment areas to lower the

watertable and implementing engineering options

(drainage). Engineering solutions such as deep

drainage or pumping of saline-affected lands caninvolve the difficulty of disposing of saline water.

Traditional engineering solutions (pumps and

drains) are generally viewed as uneconomical, andare becoming less popular as the downstream

79

impact on other water users and the environment

are becoming more apparent. (Clarke et al. 1998;Thorburn 1999). Alternatively, manipulation of the

hydrologic cycle by revegetation strategies has

become increasingly popular. Revegetation can act

to reduce recharge or maximise discharge (RIRDC2000). Reduction of groundwater recharge is

achieved by interception of rainfall by vegetation.

Transpiration by the plants causes a water-

potential gradient throughout the plant, drawingwater from the soil. Selection of species with

appropriate leaf area and canopy structure are

important considerations for planting to reduce

recharge (RIRDC 2000). However, Scholfield (1990)argues that the effectiveness of trees in capturing

water in the unsaturated soil zone depends on

whether recharge occurs largely from the slower

matrix flow of soil water that trees can effectivelycapture or the faster preferential flow, which

recharges groundwater before trees are able to

transpire. There is some evidence to suggest native

vegetation is able to transpire significantly morerainfall than crops or pasture (McFarlane et al.

1995) because trees are able to use water from

deeper in the soil profile although again, leaf area,

canopy structure and physiological features areimportant (Morris & Thompson 1983).

Revegetation or regeneration to enhance

groundwater discharge has been widely promoted

since several studies demonstrated the reversal of

rising groundwater levels under these strategies(e.g. Bari & Scholfield 1992). It should be noted,

however, that as much as 70–80% of a catchmentmay need to be revegetated to significantly reduce

the level of the watertable and salinity (Bari &Scholfield 1992; George et al. 1999). A potential

limitation of the use of vegetation in saline areas is

the accumulation of salts in the root zone over

time, limiting transpiration and growth of theseplants (Thorburn 1996; Thorburn 1999). As plants

take up water from or near a watertable, the

groundwater flowing towards the roots carries

salts, which accumulate in this way. Evaluation ofthe effectiveness of such strategies has been

undertaken by:• direct measurement of uptake

• indirect measurement• predictive modelling.

Careful planning and knowledge of the catchment

hydrology, geology and so forth, is essential to

avoid these problems. House et al. (1998)

recommend planting concentrated on transmissionand recharge areas of the catchment. It should be

noted that a great deal of work has focused on

revegetation strategies and their effectiveness,

particularly in the southern States of Australia. Forthe Queensland situation, it may be possible to

derive some guidelines as to the appropriate

retention rates from this body of work (Ian Gordon

February 2000, pers. comm., 6 March).



4.3 Management and production aspects

4.3.1 Crop production

Apart from naturally treeless areas (parts of Darling

Downs and central Queensland bluegrass), allcropping in Queensland is conducted on cleared

lands. These range from highly fertile alluvial soils

which may have been well-grassed, to rainforestareas to brigalow lands and poplar box woodlandsthat supported a high woody biomass before

clearing (see Weston et al. 1981 for assessment of

potential cropping in Queensland). Cropping has

been used as a means to control regrowth of treesand shrubs following clearing (Johnson 1964). This

was particularly used in the early phases of the

brigalow development (DPI 1976). Only a few

woody species can survive in a cropping situation,for example Alstonia constricta, Eremocitrus glaucaand Atalaya hemiglauca, because of their deep root

system and their ability to shoot from severed roots(Anderson 1984).

There is often a long-term decline in productivity asthe time since initial clearing and development

increases (Graham et al. 1981). Long-term

monoculture of grains leads to decline in yields and

grain protein content, with the rate of declinedepending on soil type (Dalal & Mayer 1996). This

occurs on naturally open clay soils as well as

cleared loam and clay soils. In part, this is due to the

high nutrient conditions that prevail in the first few

years after initial development. However, continualcropping will reduce soil organic matter, particularly

in light textured soils (Graham et al. 1981, Dalal &

Mayer 1996) and result in lower crop yields withoutthe input of fertilisers or ley pasture rotation.

High-value horticultural crops may require some

form of protection from wind, but this is usually

provided by planted windbreaks, rather than

natural vegetation. The use of shelter strips incropping systems is uncommon in Queensland, and

observations indicate that native vegetation on the

margins of cropped areas generally decreases crop

height, and presumably yield, around the perimeterof the cropped areas. This has resulted in many

cropping paddocks having any buffer strips of trees

removed. While this may have reduced the

competition with the crops, it may also haveresulted in loss of the benefits of having retained

trees (e.g. windbreaks).

Windbreaks can be particularly important in high-

value crops, where the physical damage due to

wind can be a source of serious production losses(Snell & Brooks 1999). Windbreaks may also help

control spray drift, which is becoming anincreasing concern where insecticides are used on

cotton farms adjoining beef production areas. Innorth Queensland the growth, morphology and

yield of maize, potatoes and peanuts were

measured over a four-year period at increasing80

Direct management of saline areas

In southern Australia, it is acknowledged that in

many catchments that are affected by salinity, totalremediation will not occur, and opportunities for

the productive use of saline land and water need to

be considered. Considerable efforts have been

directed toward improving the productive capabilityof saline lands, with vegetation such as grasses and

shrubs for grazing, and the use of trees and shrubsfor other wood and non-wood products (Barson &

Barrett-Lennard 1995; Marcar et al. 1995; House etal. 1998). Considerable effort has also been devoted

to determining suitable species to plant in saline

areas, particularly those that offer a production

benefit. The Queensland Forestry ResearchInstitute, in field trials, has tested the performance

of individual tree species for a range of salinity

classes and, subsequently, provided a guide to the

suitability, planting and management of thesespecies (House et al. 1998). Successful trials of a

number of native and exotic salt-tolerant forageplants for summer rainfall areas are summarised in

Fisher and Skerman (1986).

Various combinations of pasture and trees,particularly fodder trees, have been trialled to test

production and salinity management. Clarke et al.

(1998), in modelling revegetation strategies for the

Western Australian wheat belt, demonstrated thatreplacing annual pasture with deep-rooted

perennial pasture, or pristine native vegetation,

prevented the onset of salinity. However, by

combining remnant native vegetation, 60 m spaced

tree belts and deep-rooted perennial pasture(mostly in upper mid-slope bays), the expression of

salinity was reduced to 10% of the cleared area (as

opposed to 40% under the current land use)(Clarke et al. 1998). Alternative industries,

including salt harvesting, aquaculture and solar

ponds, are currently being investigated.

Most authors agree that, at the property level, a

whole-farm approach to salinity management isessential, with consideration of economic and

production issues, which are also consistent with

catchment hydrological behaviour (SalCon 1997;White 1999). By the nature of the hydrologicalimpact of activities that accelerate salinity, the

problems crossover property boundaries.

Consequently, management options are often

more successful where the expression of salinityis localised and only one or a small number of

properties form the ‘at risk’ catchment. Approaches

to dealing with salinity problems and potential

hazards must necessarily consider broader scaleplanning.



distance from windbreaks (Snell & Brooks 1999).

The results suggest that windbreaks increased yieldof field crops such as potatoes and peanuts.

Increased potato yield was attributed to reduced

wind damage to leaves, while a combination of

lower water stress and leaf damage (during theinitial stages of crop growth) increased peanut

yield. Expected yield increases in high-value crops

(such as potatoes and peanuts) can offset the loss

of productive land on which the windbreak isgrowing, and yield reductions due to tree–crop

competition. Snell and Brooks (1999) suggest the

evidence pointing to reduced leaf damage by wind

can be extended to orchard crops (such asmangoes, avocados, lychees and macadamias),

where fruit quality may be improved by reducing

wind damage in orchards.

In southern Australia, shelter belts, while reducing

crop yields adjacent to the tree line, can lead toincreases in production to a distance of up to 25

tree heights, due to moisture savings, higher CO2,higher soil temperature and less wind damage (Bird

1984). In the temperate climates of the southernStates, pasture and crop yields were increased by

up to 30% in a downwind zone extending to about

ten times windbreak height (Breckwoldt 1986;

Bird 1984).

Recent simulations of crop performance behindwindbreaks by Meinke et al. (in press) used

micrometeorological data collected at Hermitage

(Queensland) and Esperance (Western Australia) to

predict yield improvements in wheat. They

predicted an average yield increase of between 3%and 13% for maximum shelter conditions. The

authors conceded the real impact of natural shelter

will be considerably less given the impossibility ofproviding maximum shelter to a field crop over a

large distance, and that most winds blow obliquely

to the shelter. Further simulations by Carberry et

al. (in press) at 17 sites across Australia predictedan average 10% yield advantage for protection from

winds in any direction, with the largest yield

advantage in Australia expected at Dalby. The

overall conclusion of the simulation experiments

was that for cropping ‘microclimate impacts alonecannot justify the planting or maintenance of tree

windbreaks on farms. Such justification needs to be

the result of a combination of benefits in additionto an expected crop yield increase, for example the

production of saleable wood, protection from

damaging winds, assistance in lowering

watertables, increasing the biodiversity or simplyvaluing the trees for their aesthetic appeal’

(Prinsley 1998).

4.3.2 Animal production

Tree clearing is listed as one of the main reasons

for increased livestock production in Queensland

(Gramshaw & Lloyd 1993). O’Rourke et al. (1992)

provide a detailed analysis of beef productionsystems in Queensland. In a review of the benefits

and problems arising from reducing woody plant

competition with pasture in savanna grazing lands,Burrows (1993), cites the following reasons for

clearing trees:

• improved livestock handling

• improved groundwater supplies• better dietary choice for animals

• improved habitat for some (author’s emphasis)

wildlife

• enhanced augmentation of pastures withlegumes

• the planting of useful fodder trees.

Burrows (1993) also lists the disadvantages of

removing trees and shrubs as:

• loss of browse and drought reserves• increased salinisation in susceptible areas

• increased erosion hazard in susceptible areas

• promotion and growth of undesirable woody

weeds and regrowth• reduced shade and shelter for domestic stock

• a more extreme microclimate• fragmentation of wildlife habitat

• less sequestration of carbon in long-lastingorganisms

• loss of useful timber.

Burrows (1993) notes the justification of tree

clearing must be economic and must allow for

greater production than would be achieved byalternative land-use practices.

Substantial production benefits to graziers have

been demonstrated over most of Queensland with

management of plant populations, especially in

southern and central parts of the State (Burrows1990). There can be financial benefits to individual

landholders, especially in the short-term, arising

from applying woodland management and control

of shrub species (Harrington et al. 1984b; Rolfe1999; Gillard et al. 1989). This has resulted in this

production practice being almost universally

implemented throughout the grazing lands as

evidenced by the high degree of clearing, especiallyin coastal and subcoastal Queensland (DNR 1999b).

In systems grazed by domestic livestock, animal

production is strongly related to the availability ofyoung plant material (e.g. Ash et al. 1982,

McLennan 1988) and controlled by environmentaland plant characteristics. Grazing history, burning

and tree management have a major impact on both

the quantity and quality of pasture production, and

hence on diet quality (Ash et al. 1995). Even inthose cases where management practices like tree

clearing produces more pasture of the same total

quality, animal production may increase due to the

enhanced ability of the domestic animals to select adiet higher in leaf and/or green material.

The whole basis of setting safe stocking rates in

Queensland is based on the principle of safe

utilisation (Wilson et al. 1984; McKeon et al. 1990;

Scanlan et al. 1994; Johnston et al. 1996). Underthis approach, the animal requirements on either 81



when protected by an efficient wind break. Survival

rates of lambs and sheep were also higher duringextreme conditions (Breckwoldt 1986; Bird et al.

1984). The large increases in sheep production

were due to reduced stress and less energy

expenditure (Lynch & Donnelly 1980; Bird 1998).

Despite the introduction of heat tolerant cattle, mostlandholders see tree retention as desirable at least

for stock shade and shelter. Shade may enable cattleto graze longer during the day and may extend

pasture usage to areas well away from wateringpoints. At least half the calf losses in north-western

Queensland can be attributed to heat stress,

particularly in the first week of life and in calves

born away from shade. Heat stress also reducesfertility (Daly 1984). Dupont (1998) recorded an

average reduction in temperature of 1–2ºC with a

projected foliage cover ranging from 25% to 60% in

19 sites from Warwick to Quilpie. An increase inminimum temperatures was also observed. In areas

prone to frosting, tree retention results intemperatures 2–4ºC warmer than if vegetation had

been cleared (McIvor 1990a). Chilcott (forthcoming)observed a 4.5ºC decrease in summer maximum

temperatures beneath brigalow in central

Queensland compared with temperatures in an

open paddock during summer (December–March)1998. The difference was greater for days where the

temperature in the open was greater than 35ºC,

being 7.2ºC cooler on average. Lack of shade

causes increased lamb mortality in the naturallytreeless Mitchell grass land in north-western

Queensland. It has been reported that the provisionof shade during the last weeks of pregnancy and

during the lambing period increases lamb markingby 20% (Roberts 1984). Shade is required from an

animal welfare perspective as well as from animal

performance (e.g. Daly 1984).

In a study in the New England tablelands in New

South Wales, Reid et al. (in press) compared openfertilised paddocks, to treed, fertilised paddocks

and showed that there were significant gains in

sheep production with the presence of trees. Treed

paddocks had 34% more sheep, which grazed

more (and were heavier) and thus the paddocksustained a grazing rate 42% higher. As a

consequence, the paddocks cut 32% more wool,

the wool was of a higher quality and the paddockreturned 55% more income. Shelter from strong,

cold winds is a consideration in parts of southern

Queensland especially for newly shorn sheep.

Beekeepers are an active group in rural Queensland

who have pointed out the necessity to retain treesfor their industry. Some well recognised honey-

producing timbers, for example yellow box

(Eucalyptus melliodora) have largely been cleared insouth-east Queensland (Blake & Roff 1988), whileothers previously considered are under threat of

clearing, for example yapunyah (Eucalyptusochrophloia) in south-west Queensland.

82

an annual or seasonal basis are compared with the

growth over the same period. A number of studieshave shown that annual utilisation rates of 20%

(i.e. 20% of annual growth is actually consumed by

domestic livestock) of native pastures would result

in satisfactory production per head (compared withthe maximum possible from that pasture system in

that environment) and would ensure that pastures

were maintained in good condition. This system

forms the basis of restructuring in the South WestStrategy and has been shown to be appropriate for

the South Burnett and Upper Burdekin areas (Hall

et al. 1998).

Fodder

Retention of native vegetation for the provision of

fodder from trees and shrubs is often quoted as anexample of good management practice. Top fed

species are an important component of grazing

systems in western Queensland (Turner &

McDonald 1993). In Queensland, this applies

primarily to the mulga country ( Acacia aneura) asmulga leaf is an important dietary component

under all conditions, and is extensively used for

drought feeding. However, this has a downside inthat it enables stock to be retained in paddocks

long after the herbaceous species have been

severely grazed. During drought, when herbage and

grasses are absent, many other species such as Acacia stenophylla (belalie) and Acacia shirleyi(lancewood), which otherwise are seldom eaten,

become major components of the diet (Turner &

McDonald 1993). During the initial growth phasefollowing rain, the presence of high stock numbers

can result in severe damage to regrowing pasture

(Harrington et al. 1984a). Thus if livestock are

maintained on pasture during drought by using treefodder species, overgrazing of grasses occurs

following the first rains and long-term pasture

deterioration can occur.

The importance of forage supply on domestic stock

production was emphasised by Harrington et al.(1984a), who said that the two most important

factors in maintaining animal production in

semiarid woodlands of Queensland and New SouthWales were maximising forage potential andcontrolling the biomass of shrubs (for a discussion

on the impact of grazing on vegetation see section

4.1.4). Animal production was lower in areas with

a dense woody layer because of increasedpredation losses due to harboured predators,

especially feral pigs, and increased losses from

flystrike because of the difficulty of carrying out

complete musters under these conditions.

Benefits from tree retention

Livestock and crop production can be increased byusing remnant vegetation for shade and shelter in

some environments. In northern New South Wales,

wool production increased by up to 31% and sheep

were on average 6 kilograms per head heavier,



4.3.3 Pasture production

Approximately 87% (173 000 000 ha) of

Queensland is covered by native pastures (Westonet al. 1981). There are about 60 000 000 ha of

grazed woodland communities (Burrows et al.

1988b) and about 16 000 000 ha of national parks,

State forests and timber reserves which supportmoderate to dense woodland or forest cover. The

original cover of forests, woodlands and shrublandsin the State is estimated to have been about

100 000 000 ha (Burrows et al. 1988a). Apart frommulga, the shrubby dominants in these

communities are generally not palatable to

domestic livestock.

Non-leguminous trees and shrubs normally

decrease pasture production within their projectedtree canopies and beyond (House & Hall 1999).

Documentation of higher pasture production in

open areas compared with woodlands of

Queensland include Eucalyptus crebra in north

Queensland (Gillard 1979; Gardener et al. 1990;McIvor & Gardener 1995); Eucalyptus spp. in central

Queensland (Walker et al. 1986; Scanlan & Burrows

1990); Acacia harpophylla in central Queensland(Scanlan 1991); Eucalyptus populnea (Walker et al.

1972) Callitris columellaris (Wells 1974) in southern

Queensland; and Acacia aneura (Beale 1973) in

south-western Queensland. Shrub species that havealso been reported as decreasing pasture production

include Acacia nilotica in north-west Queensland

(Burrows et al. 1990); Eremophila mitchellii in Central

Queensland (Scanlan 1991); and Eremophila gilesii in

south-western Queensland (Burrows et al. 1990).Dodonaea viscosa and Cassia nemophila in north-

western New South Wales also show similar trends

to shrubs in Queensland (Noble 1997b).

Detailed field experiments in the Charleville (Beale1973), Dirranbandi (Walker et al. 1972),

Mundubbera (Tothill 1983), Gympie (Walker et al.

1986), Dingo (W. H. Burrows 25 April 2000, pers.

comm.), Duaringa (Scanlan & Burrows 1990) andCharters Towers (McIvor & Gardener 1995) districts

have demonstrated that initial pasture production is

improved two- to four-fold when woody plantcompetition is removed from grazing lands (seefigure 4.8). These studies are generally conducted

over 5–10 years in southern and central parts of

Queensland. Much less is known about longevity of

responses in poorer areas such as those describedby Rae (1990). Some studies have indicated that

planting exotic pasture species may be more

economic than tree clearing (Gillard et al. 1989).

Safe stock-carrying capacity on treated areas can

be increased proportionately while still retainingthe same utilisation. Alternatively, the increased

pasture gives the landholder the flexibility to loweroverall property grazing pressure and so improve

individual animal performance. Increases of two tothreefold are recorded in cattle liveweight gain per

hectare after removal of eucalyptus species 83

competition (Tothill 1983; Rae 1990). The extra

pasture may also lower the risk of soil erosion (by

increasing ground cover), provided the overallutilisation levels (pasture eaten as a proportion of

pasture grown) are reduced. McIvor and Gardener

(1995) conducted a study on the effect of pasture

management options (including stocking rate) onyield and botanical composition of pastures.

Basically, they found that legume-based pastures

have a higher carrying capacity and support higher

annual growth rates than native pastures. However,productive native pastures that are predominantly

perennial grass could be maintained, providing

stocking rates were not excessive

(<0.2–0.25 steers/ha), so fewer destocking periodswould be required. Killing trees to increase herbage

production can increase carrying capacity of native

pasture and plots with live trees required

destocking for longer periods. Thus clearing mayincrease livestock numbers per unit area, but

decrease the impact of those animals on pasture.

However, when extensive clearing is undertaken,

consideration must be given to potential problemswith salinity, loss of habitat for wildlife, regrowth

and costs of clearing.The relative decrease in pasture production due to

the presence of trees is greatest in semiarid regions(Walker et al. 1972; Beale 1973). In mulga areas, a

tree basal area of only 1 m2/ha reduced pasture

yields by 50% (Beale 1973). In central Queensland,

Scanlan and Burrows (1990) showed that theimpact of trees on production was greatest in areas

with lower potential. In central Queensland, a

reduction in pasture production of 50% occurred at

5 to 15 m2/ha, depending on fertility (Scanlan &Burrows 1990; Walker et al. 1986). In the tropics,

soil fertility is relatively low, soil moistureavailability during the growing period is generally

high and the tree density is generally lower than insouthern parts of the State (Mott & Tothill 1984;

Holmes & Mott 1993). Under these circumstances,

G r a s s y e i l d ( k g / h a )

Narrowleaf ironbark—dry

Silver-leaf ironbark

Narrow-leaf ironbark—wet

Poplar box

1500

00 5 10 20

Tree basal area (m2/ha)

2500

1000

2000

500

15

2000

Figure 4.8 Relationship between tree basal area and grassyield in eucalypt woodlands of central Queensland. Providedby J. C. Scanlan, based on Scanlan & Burrows (1990).



temperature, humidity, soil physical and chemical

properties, and infiltration properties of the soil.The tree also has competitive effects on the

understorey due to light interception, rainfall

interception, and soil, water and nutrient usage.

What is observed around and individual tree is thenet result of the counteracting effects. By

considering the relative strength of these

counteracting effects, the landscape-level

consequences of increasing tree density can besimulated. If the net result is a decrease in

understorey production due to the presence of a

tree, the landscape-level response is that there is a

negative concave relationship between understoreyproduction and tree basal area. This is the

commonly observed situation in most eucalypt

communities in Queensland. If the net result is

increased understorey production, the landscape-level response is an initial increase in understorey

production as tree basal area increases, followed by

a decline in production. At high tree basal area

values, the understorey production is less than theproduction in the absence of trees. The reason for

this is that the stimulation of understorey

production reaches a maximum (e.g. the maximum

possible nutrient-use efficiency) and the addition ofmore trees cannot increase production any more.

However, the competitive effect of trees (e.g. water

use) continues to increase. The overall effect is that

understorey production decreases from themaximum as tree basal area increases.

Trees generate islands of increased fertility beneath

their canopy (Scholes & Archer 1997), with thedegree of soil change related to the period that

trees have occupied the site. In some countries,human activity has caused woody composition

changes e.g. in Africa, areas of human inhabitation

during the Iron Age now support a woody

vegetation that is quite distinct from surroundingareas (Blackmore et al. 1990).

There are several important situations where trees

have been reported as improving pasture growth.

Christie (1975) noted that only 6% of an area was

covered by the canopies of individual Eucalyptus

populnea in central-western Queensland, but thatthis area produced about one quarter of the total

pasture growth if sown to buffel grass. Lowry

(1989) also noted increased growth beneath Ziziphus mauritiana in north Queensland, while

Cameron et al. (1989) claimed no effect of young

Eucalyptus grandis trees soon after establishment on

growth of setaria-based pasture. Where trees areplanted in existing cleared areas, there is often no

effect of these trees or even a slight improvement.

At least part of this is associated with the

disturbance and/or fertilisation of the young trees.When these trees increase in size (i.e. are no longer

seedlings), the competition they exert on pastures

increases (Cameron 1990). Some interesting results

are being obtained in areas where regrowth is beingleft in narrow strips during blade ploughing

trees appear to have less effect on pasture

production in north Queensland (Scanlan & McKeon1993). McIvor and Gardener (1995) reported large

increases in pasture production on fertile clay soils

in north Queensland for 12 years following the

removal of trees during a period of both belowaverage and above average rainfall years.

Moisture competition is the most often cited reason

for reduced growth of pastures within woodlands,and therefore Mott and Tothill (1984) suggest that

trees will have relatively less effect in areas wherethere are fewer dry periods (soil–water stress

conditions) during the growing season. Recent

simulations using GRASP (McKeon et al.1990) have

indicated that rainfall distribution and soil depthhave a large impact on the degree of competition

between pastures and trees (Scanlan & McKeon

1993). Arguably nutrient competition is also vitally

important and should be considered in anydiscussion of tree–grass interactions. The two

factors are very closely linked, as trees take upnutrients in the transpiration stream. The relative

contributions of these two factors can be examinedin models. However, the construction and

assumptions of models can have an impact on the

relative importance of these factors. See House et

al. (forthcoming) for a comparison of four modelsof tree–grass interactions.

An associated factor is that the total tree basal area

tends to be lower in northern parts of the State

than it is in comparable areas to the south. This

has been attributed to: the length of the dry season

causing mortality of young trees, leading to asparse woodland; and/or the widespread use or

occurrence of fire in tropical woodlands. Recent12C/13C ratio work suggests that the woodlands ofnorth Queensland were previously much more open

than at present (Burrows et al. 1998). The

reduction in fire frequency observed since the

1960s will tend to reinforce any long-term increasein density of these woodlands. However, Fensham

and Holman (1999) consider whether the fluxes in

woodland density are caused by a change in the

fire regime, normal climatic cycles, changes in

cattle grazing (hence changes in the proportion ofwood and grass) or to carbon dioxide fertilisation

(see section 3.3).

Individual trees can have a variety of impacts on

pasture growth beneath their canopy and beyond(Belsky et al. 1989; Belsky et al. 1993). These

effects vary from net increase, to no effect, to net

decrease (Scanlan 1992). When considering the

effect of trees at a landscape or paddock level,there are a corresponding variety of relationships

that would be expected. Simulations from a model

developed by Scanlan (1992) include the conceptsof the stimulatory and competitive effect of treesand produce the relationships shown in figure 4.9.

An individual tree produces some stimulation

effects on understorey species due to altered84



85

operations (C. Chilcott 2000, pers. comm.,

12 January). In these areas, it will be important toseparate the direct effect of trees, the effects of the

disturbance during the ploughing operation and the

indirect effects of any management actions. It willalso be interesting to note any changes that may

occur as the regrowth increases in age and size

and requires more water and nutrients for growth.

Higher biomass yields under tree canopies than in

the open have been reported for Panicum maximum(Kennard & Walker 1973; East & Feller 1993) and

buffel grass (Christie 1975; Shanker et al. 1976). In

Africa, Stuart-Hill et al. (1987) believed that the

shade of the canopy and leaf litter compensated forboth reduced rainfall beneath trees and soil moisture

competition, so that the net effect was enhanced

grass production. Also in Africa, Belsky et al. (1989,

1993) found that increased herbaceous-layerproduction beneath canopies was associated with

lower soil temperatures and greater soil fertility.

It is undeniable that in most situations tree clearing

promotes increases in livestock production;however, the long-term effects (both on- and off-

farm) may not be apparent. The presence of

canopy cover can result in apparent lower levels ofpasture biomass, but this may not equate to loweranimal production (Walpole, 1999; Chilcott et al.

1997). Few studies have considered that shifts in

species composition towards more productive

grasses (higher digestibility and protein) may beinduced by trees. Canopy cover afforded by trees

reduces soil and air temperature, lowers

temperature extremes and reduces

evapotranspiration (Lynch & Donnelly 1980; Birdet al. 1984; Young 1989; Dupont 1998). The lower

light environment and increased soil fertility can

lead to shifts towards more productive species inthe composition of the herbaceous layer. Higherlevels of woody litter beneath trees may also act as

a physical barrier to growth of large tufted grasses,

to favour more prostrate, smaller grasses and herbs

(Chilcott et al. 1997). This was shown

experimentally where more favourable (higherprotein) grasses were found beneath trees when

compared to interspaces on similar soils in

eucalyptus woodlands in the Northern Tablelands

of New South Wales (Chilcott 2000).

Little is known of the effect of trees on understoreyplant nutrients or on plant digestibility. Reductions

in soil and air temperature through shading havebeen shown to increase growth and nitrogen uptake

of rundown, green panic pasture on brigalow claysoils (Wilson et al. 1986). Minson (1990) has

shown experimentally that grass quality (e.g.

digestibility) increases when temperature

decreases, while Wilson and Wild (1991) showshade effects on the nitrogen content of pastures.

Dupont (1998) found that 25% foliage projective

cover reduced air temperature by 1.30C across

central Queensland. This could lead to an increasein grass digestibility of 1.3% and protein by 0.3%,

which could equate to an increase in liveweightgain of approximately 30 kg/year (based on the

equations of Hendricksen et al. 1982).

Tree–grass interaction may vary with tree age andclimatic fluctuation. Therefore trees may have net

facilitative effect on grasses in some years and a

net competitive effect in other years (Scholes &

Archer 1997). Current tree–grass competitionmodels do not account for this, although the

capacity to predict variation in seasonal conditions

does exist. Predictions in GRASSMAN (Scanlan &

McKeon 1993) that estimate the impacts on grass

and animal production do not account for anygrass quality variation between wooded and

un-wooded systems. Further, benefits to animal

production from shade and shelter are notaccounted for, nor is the value of retaining timber

for harvesting and other environmental services.

Apart from increased animal production, advantages

from clearing woodlands and associated

management for livestock may include: lower overallgrazing pressure (lower stock numbers per unit of

forage produced); improved livestock handling

(Harrington et al. 1984a); and improved conditionsfor some wildlife, for example, kangaroos arebelieved to have increased since European settlement

(Newsome 1975; Poole 1978). There have been

substantial increases in pasture biomass production

from the introduction of exotic pasture species intocleared areas—especially cleared Acacia spp. scrubs

(brigalow, gidgee and blackwood).

4.3.4 Improved pastures

Native pastures occupy most of northern Australia’s

land area offering forage and protection against

erosion (Gramshaw & Lloyd 1993). Native grassesare suitable for extensive low cost production butmay be used in conjunction with another source of

feed to enable animals to meet increasingly strict

market specifications (Gramshaw 1995). In some

P a s t u r e p r o d u c t i o n ( k g / h a )

1500

0 0 10 20 50


1000

2500

500

30 40

2000

Figure 4.9 The herbaceous production (relative to that inopen areas) in simulated tree communities in which isolatedtrees have a net stimulatory effect (top line), no net effect(middle line) and a net competitive effect (bottom line).Adapted from Scanlan (1992). Note that at high tree basalareas, herbaceous production is reduced even whereindividual isolated trees would stimulate production underand near its canopy (top line).



86

potential for expansion of these systems. They have

the added advantage of restoring most of theecosystem processes to levels analogous to those

originally in place in the original brigalow

community. Although it should be noted that

because they are expected to become naturalisedand self-sustaining populations under grazing

pressure, leucaena, as with other introduced

grass–legume pastures, is susceptible to becoming

weedy (Low 1999). While this is desirable forproduction purposes, it can have implications for

non-production areas (see also section 4.2.2).

Investigations have been made into planting

individual or scattered ‘useful’ trees such as Indian

siris ( Albizia lebbeck) into pasture land. Fodder treeslike these have potential for improving quality (e.g.

Lowry 1989). However, the scale of feasible

planting is limited and care must be taken to

protect individual young trees from stock or fire.

Augmenting native grasses with legumes

Cattle on native pastures grow rapidly in earlysummer for 2–4 months, until the grass starts to

flower or exhausts the available nitrogen in the soil

(McLennan et al. 1988). Thereafter, feed quality

declines rapidly and cattle frequently lose weightduring the winter. The animals’ diet can be

improved with protein-rich leaf from forage

legumes that may be oversown into the existing

native pasture after a fire (Miller et al. 1988).

The existing native pasture often occurs with intactwoodland in the north of the State, and where trees

have been thinned or removed in the south. Gillardet al. (1989) suggested that augmenting native

pasture with a legume was likely to produce greaterfinancial gains than tree clearing in north

Queensland. Cook and Grimes (1977) reported that

trees have a relatively minor impact on the

establishment and yield of introduced pasturespecies. By contrast, Cook and Ratcliff (1992)

showed that live trees depressed the establishment

of siratro (Macroptilium atropurpureum) in south-east

Queensland.

Unlike the phosphorus-demanding temperatelegumes (Trifolium and Medicago species) used in the

southern states, those sown in the tropics and

subtropics are hardy species (especially Stylosanthesspp.) that can produce and persist in soils of low Pstatus (Partridge & Miller 1991). While they will

respond to the application of superphosphate, this

is rarely economical, and the cattle obtain the

mineral directly from supplements (McCosker &Winks 1994). Because the general fertility and

stocking rates are lower than in the south,

production of nitrous oxide by the legume is lower,

and less fertility is transferred to cattle camps undershade trees.

Nitrogen fixation by the legumes’ root nodule

bacteria can make soils more acid, especially on

light soils (Noble et al. 1998). This effect is likely to

regions, climate or soil are adequate for an

improved pasture based on replacement of theexisting species or augmentation with a legume

(e.g. McIvor et al. 1991).

Replacing species

GrassesIntroduced grasses generally need reasonable soil

fertility to persist, and the soil must be cultivated to

remove existing competition for satisfactoryestablishment (Partridge et al. 1994). This

competition would come from a dense tree

overstorey, for example, in the brigalow ( Acaciaharpophylla) lands or rainforest (DPI 1976), or from

established perennial native grasses, for example

black speargrass (Hacker et al. 1982).

Introduced grasses are planted in fertile soils, as in

the brigalow lands, or in soils of lower fertility butwith higher rainfall. In the latter case, high stocking

rates can be used to justify fertilising (Mott &

Tothill 1984). Historically, rainforest and softwoodscrub were cleared to establish oversown pasturesfor dairy production, as in coastal lands or on the

Atherton Tableland.

Similarly, most of the State’s brigalow lands have

been cleared, and introduced pastures such as

buffel grass, Rhodes grass and green panic sowninto the tree ash after a fire (Johnson 1964; DPI

1976). Following clearing, an influx of brigalow

regrowth can impact on pasture growth and may

make cattle management difficult (Anderson et al.1984). Most brigalow regrowth can now be

controlled by blade ploughing (Scanlan & Anderson1981). This has the added advantage of disturbing

the soil to release nitrogen and restore fertilitywhile allowing new pasture seed to be sown (e.g.

Blacket & Thompson 1992).

LegumesOn brigalow lands, soils have remained fertile

enough to maintain production of pure grasspastures even though at a reduced level (Graham et

al. 1981). Nitrogen run-down can be alleviated

temporarily with soil disturbance (Robbins et al.

1986), or more permanently, by sowing a legumeable to tolerate the heavier soils.

A more recent approach has been to replace the

original brigalow species that is unpalatable to

domestic livestock, with a productive palatable

species (Leucaena leucocephala subsp. globata).Leucaena is a tall shrub or small tree with foliage of

exceptional quality; its deep root system allows

green leaf to grow into the dry season, long after

the shallow-rooted grasses have ceased growing(Wildin 1986; Partridge 1989). Tens of thousands of

hectares of leucaena have been planted in rows in

brigalow and downs country in central Queenslandto provide one of the most productive grazingsystems in the State (Gramshaw & Lloyd 1993;

Pengelly & Conway 2000). There is considerable



87

be most serious in legume-dominant paddocks and

least serious in unfertilised and grazedgrass–legume paddocks. Noble et al. (1998)

reported decreases in pH under Leucaena spp. over

a 20-year period, but the decrease was not as great

as that in nitrogen-fertilised pastures.

Coates et al. (1997) demonstrated a markedpreference by cattle for green grass in pastures

oversown with Stylosanthes spp. during the wetseason. They also demonstrated that while

increases in stocking rate (without loss of animalcondition) could be made on those oversown

pastures in some cases, (depending on initial

stocking rates), excessive pressure may be placed

on perennial grasses where the species (such asnative tussock grass) are not tolerant of heavy

grazing pressure. The loss of perennial grass invites

ecological instability and increases the risk of soil

erosion (Mott & Tothill 1984). The grass–legumebalance is influenced by management (McIvor &

Gardener 1998) such as the rate of stocking, use offire, fertiliser application and timber treatment.

4.3.5 Regrowth management

The method of clearing and the regenerative

mechanisms of cleared vegetation will influence the

consequences of clearing.

Acacia harpophylla is a vegetative reproducer, andthe most common method of initial clearing is by

pulling a chain between two bulldozers (Johnson

1964; Scanlan 1988). This snaps most plants off at

ground level (unless the soil was very moist)

resulting in regrowth from roots or broken-offstumps. If the initial clearing includes a ploughing

operation that kills most of the original plants, then

there is little regeneration in the future aspropagation from seed is uncommon among these

plants (Johnson 1964; DPI 1976).

Within eucalyptus communities, a common method

of tree treatment is to kill individual trees with stem

injection of a picloram-based aboricide (Scanlan1988; Robertson & Beeston 1981). This allows for

selective treatment and retention of desirable trees.

The understorey population of seedlings and multi-stemmed suckers are left untouched. Under thesecircumstances, there can be considerable growth of

these previously suppressed plants (see figure 4.10).

This may require a follow-up treatment on a regular

(10–15 year) basis to maintain pasture production(Burrows et al. 1988a). Increased use of chaining in

these communities can lead to rapid regrowth as

few, if any, plants are actually killed during the

chaining operation (Anderson et al. 1983).

The mulga lands of south-western Queensland area case where disturbance by grazing, mainly by

sheep, with some cattle, a period of rabbitinfestation, and a lack of regular fires have resulted

in a landscape that is becoming increasinglydominated by understorey shrubs (Burrows et al.

1985; Howden et al. 1999).

Any increase in woody plant density and biomass

in woodlands is potentially detrimental in pastoralproduction terms. This increase can arise from

‘disturbance’ to the ground layer in uncleared

woodlands, leading to an increased density

(‘thickening up’) of existing populations (Burrows etal. 1997); regeneration from seedlings and/or root

suckers, following mechanical or chemical control

of overstorey plants (Anderson et al. 1984); and

invasion of existing areas by native or exoticspecies which did not occur there naturally

(Scanlan 1988; Robertson & Beeston 1981;

Harrington 1979). Such increases in woody plant

cover alter the structure and functioning ofecosystems, for both production and conservation.

N u m b e r / h a

150

00 25 35

Size

50

200

55 65

100

4515S MS 5

Figure 4.10 Size class distribution (basal diameter cm) for aeucalypt woodland in central Queensland. (S=seedling;MS=multi-stemmed plant). Source: J. S. Scanlan.

Average basal area growth rates of 0.135 m2/ha/yr

in intact eucalypt woodlands (Burrows 1995) wouldhave little additional depressant effect on

understorey pasture production as it is already

greatly reduced by mature tree competition (see

figure 4.9 for greater than 10 m2/ha). Conversely,regrowth rates following tractor pulling

(0.46 m2/ha/yr for poplar box) can reduce pasture

production by 50% within 11 years (figure 4.11).

Untreated brigalow suckers can reduce pastureproduction to negligible amounts within 5 years of

pulling when tree basal area approaches 2m2/ha

(Scanlan 1984—figure 4.12).

The reduction in pasture production per unit of

regrowth tree basal area is greater than per unit ofmature tree basal area. This is related to tree

allometry, where more leaf is supported per unit of

tree basal area for small trees than for larger trees

(Scanlan 1991). The amount of tree leaf is directlyrelated to sapwood basal area—the cross-sectional

area of tree stems that is directly involved in

conducting water to the leaves. As trees mature,

the proportion of tree basal area made up ofsapwood decreases.



88

G r a s s y i e l d ( k g / h a )

L o s

s o f p a s t u r e ( % o

f o p e n a r e a s )

4000

00 4


1000

5000

10620

20

40

60

80

100

% of open areas

pasture yield

2000

3000

8

Figure 4.12 Tree–grass relationships in brigalow regrowth ona clay–loam surfaced duplex near Theodore, Queensland.Data from Scanlan (1991).

G r a s s y i e l d ( k g / h a )

L o s s o

f p a s t u r e ( % o

f o p e n a r e a s )

1500


500

2000

1000

% of open areas

pasture yield

00 10 20155

0

20

40

60

80

100

Figure 4.11 Tree–grass relationships in mature woodlands incentral Queensland. Data for poplar box from Scanlan andMcKeon (1990).

4.3.6 Fire

Most vegetation communities in Queensland

experienced regular fires prior to the establishmentof a grazing industry, due to lightning strikes and

use of fire by Aboriginal people (Kimber 1983).

Bowman (1998) provides a good review on

evidence of Indigenous burning). Rainforests, andsome arid community types, would have been the

exceptions, but even in these cases, historically,high-intensity fires would have occurred

infrequently (Harrington et al. 1984b). Fire differsfrom many other environmental stresses in that it

can occur infrequently (e.g. 5–50 years apart) and

irregularly, for only a short period, is self-

propagating, and can also kill all above-groundparts of a plant. Fire has an effect on plant ecology,

the extent of which depends on fire intensity,

frequency and the season of occurrence. Individual

species may be adapted to particular combinationsof these three variables (fire regimes). The

interaction between an adaptive trait and a regimemay facilitate survival or reproduction (Gill 1975).

Fire is valued in different ways by the community.Scientists may be concerned with its effect on the

ecosystem, whereas the recreationist may be

concerned with amenity.

Fire can be a useful management tool in grazing

lands. Demonstrated benefits include:

• An increase in liveweight of stock of 0.3 kg/hacan be obtained initially after burning. This gain

may be lost later in the growing period as the

burnt pasture matures, resulting in a lowerdifference in liveweight gains between burnt andunburnt pasture overall (Ash et al. 1982).

• Determining pasture composition: it has been

long recognised that the black speargrass lands

of coastal and subcoastal Queensland are

encouraged or maintained by burning (Tothill1971). Recent studies by Orr and Paton (1997)

have shown the importance of the combination

of burning and grazing to the restoration of

species composition from Aristida- to Heteropogoncontortus-dominant pasture.

• Reducing the impact of native and exotic woody

shrubs and plants: these plants may be killed by

burning , for example, rubber vine (Cryptostegia grandiflora) (Vitelli 1992; Bebawi et al. 2000;Grice 1997) or scorched or burnt to ground level

by fire—most eucalyptus species (Scanlan 1988).

Landholders’ attitude to the use of fire as a

management tool changes over time, and varies

with vegetation community type. This has beennoted as follows:

• In semiarid areas, the standing fodder is

regarded as a ‘bank’ of forage, which can beconsumed until the next growth period (Partridge

1999). This attitude prevails even on propertieslarge enough to allow for a burning regime to be

implemented with little risk. There is a

reluctance to burn this forage as this could

impose ‘drought conditions’ if rain during thenext ‘growing season’ is minimal. A related

concern is that in some areas, once a fire hasstarted, it can be very difficult to stop. Both these

issues are a major factor in the Mitchell Grass

Downs communities of western Queensland

(Scanlan 1980). Furthermore, in the more aridlandscapes, the long-term effects of fire are

uncertain and it is believed fire could adversely

affect some vegetation communities (Turner &

McDonald 1993).

• In tropical parts of the State, where rainfall ismore reliable, burning is still a common feature

of property management (Partridge 1999).

Pasture growth is rapid and nutrient levels of

soils are often low and these combine to produce



bulky, low quality feed for stock. Fire removes

the large bulk of dry matter and allows easieraccess to green feed.

• In coastal and subcoastal parts of the State, the

attitude to fire has changed considerably since

the 1960s. Prior to that period, fire was used

extensively to remove dry forage of low qualityallowing access to green feed; and to help

control ticks; to help keep regrowth in check(Mott & Tothill 1984). With the advent of

brahman-infused livestock and supplements, dryforage became a useable resource and the

frequency of burning decreased. A direct

consequence of this has been the increase in

density and size of native species that werepreviously controlled by regular burning regimes

(Anderson et al. 1988). An associated

consequence has been the increased survival of

cattle with increased body weight leading toincreased demand for dry matter (McKeon et al.

1990). This increases pasture usage, therebydecreasing the opportunity to burn off, even

when the landholder is not averse to using fire.

4.3.7 Timber production and farmforestry

Maintenance of a supply of useable timber is aconcern to many landholders in Queensland. Many

millions of tonnes of timber were burned during the

time of the Brigalow Development Scheme in central

Queensland, because at that time there was nocommercial use for the timber (Johnson 1964). The

same situation exists with much of the clearing ofeucalypt woodlands at present. The benefit of

retaining and managing native vegetation for itstimber and other commercial values is only now

beginning to be realised. Farm forestry has been

defined as ‘the growth and management of trees onfarms, as part of the farm enterprise, for the purpose

of producing wood and/or non-wood products’

(NAFI 1997). Farm forestry includes wood and non-

wood production from both native forests andplantations and offers a commercial incentive for the

sustainable management of this vegetation (Greening

Australia 1996). Investment in farm forestry hasbeen projected to provide a significant boost toregional economies. For example, in Victoria,

modelling studies estimated that farm forestry would

increase regional income by 4.8%, or $302 million,

and create 5748 new jobs (RIRDC 1998).

Based on the National Forest Policy definition of‘forest’7, Queensland has around 49 000 000 ha of

native forest, or 28% of the State’s total land area.

The vast majority of this area is in some way

managed by the private sector, where 49% is

private leasehold and 35% is privately owned. Theremainder of the State’s forest is about 8% public

forests that are managed for timber production, 6%

within conservation reserves, and 2% is otherCrown land (DPIE 1998a).

89

For timber management purposes, most

commercial native forests may be simply classifiedas wet or dry sclerophyll eucalypt or and cypress

pine forest (Taylor & Nester 2000). The commercial

log productivity of these forests ranges from less

than 1 m3/ha/yr for most cypress and drysclerophyll forest types, to more than 3 m3/ha/yr in

wet sclerophyll forests (Taylor & Nester 2000).

Across all private native forests this productivity

has a recorded yield of about 200 000 m3/year(Parsons 1999). This has declined from a peak of

about 600 000 m3/year since 1950 (Parson 1999).

Appropriate silvicultural treatment provides the

opportunity to increase the productivity rates in allforest types (Henry, in Taylor & Nester 2000). New

perspectives on commerciality, markets and

productivity are emerging as non-traditional

owners of wood and non-wood resources,particularly in western Queensland, begin to

develop new markets and products (Fairbairn

2000). The aim of the Western Queensland

Hardwoods project is to develop a new resourcefrom an area of native vegetation previously

regarded as having a lesser value.

The production of millable timber tends to

dominate discussions on forest management,

however, a substantial volume of other wood fibreproducts is harvested such as: sleepers, power

poles, landscape timbers, firewood, fencing timbers

and woodturning timbers (see Taylor (1994) for a

general coverage of forestry in Queensland, andsection 4.3.8 Alternative products). A significant

operation also revolves around honey productionand the flower, gumnut and leaf markets (Anderson

1993). For example, in the 111 000 ha of the DPIForestry Beerburrum district, foliage harvesting

licences return approximately $100 000 per annum

and the 523 registered apiary sites generate over

$27 000 annually. All of these products requireplanning for their sustainable use and management

to maximise grower returns. The use of farm timber

for fencing, yard building and other infrastructure

is an important use for tree products. Thisimportance is recognised in the Land Act 1994 (Qld)

(and its predecessor), where timber forconstruction purposes is regarded separately in

terms of the permit application process forleasehold land.

The wet/dry sclerophyll forest distinction also

indicates aspects of the ecology of the forest types

that influence native forest silvicultural practices.

These differences in species composition, seedgermination, seedling establishment, presence of

lignotubers, gap-phase behaviour, competition and

fire responses affect selective tree marking,

harvesting operations and stand-managementpractices employed in each forest type (Taylor &

Nester 2000). Early research in these forest types

on Crown land saw the development of ‘silvicultural

systems’ for their sustainable management. These



Some research has been conducted into

agroforestry (e.g. Cameron et al. 1989), but only asmall area in the State is managed as agroforestry.

In grazing lands, there can be considerable damage

done to young tree saplings and this more than

outweighs the financial benefits of grazing theseareas while trees are young and are having a

relatively small impact on pasture production. Once

trees become large and the tree canopy approaches

closure, pasture production in the understorey isreduced and potential animal production decreases.

Farm forestry and the sustainable management of

native forests are supported at a State and national

level by various policy initiatives and funding

programs. International factors include:

• Global Markets—global market conditions seemto indicate a positive scenario for wood fibre

production (CIE 1997). Australia and Queensland

are both currently significant net importers of

forest products. In 1994–95 Australia’s net deficit

was about $1.7 billion and Queensland’s balancewas $287 million of which 47% was paper and

paper product imports (DPI 1998). In broad

terms, there may be opportunities to supplyinternationally competitively priced products to

meet the domestic demand for a range of

traditional forest products.

• Carbon Trading—there is some expectation that

carbon trading will provide additional income tosome areas of farm forestry with an as yet

indefinite value (Francis 2000). It is also possible,

but less certain, that these benefits will apply to

managed areas of regrowth native forest.

• Montreal Process—As a signatory to theMontreal Process Australia agreed, in 1995, to

adopt the use of a comprehensive framework for

monitoring the conservation and sustainable

management of its native forest (AFFA 1997).The Ecologically Sustainable Forest Management

principles used for this process are embodied in

Queensland in the Code of Practice for Native

Forest Timber Production (DNR 1999c).

systems have been refined over time to produce

‘multiple use’ management objectives. Theseprinciples of management, such as selective

harvesting and silvicultural treatment, have largely

been adopted on private land, however, with

varying results. The simplified aims of private nativeforest managers, of wood production principally,

have led to the development of more intensive

silvicultural regimes. The production of pasture in

association with timber, and landowners’requirements for a more regular income than the

State system delivers, has led to a shorter

harvesting interval and more intensive thinning.

With some selective overstorey removal, possible

regeneration fires and judicious removal of poorstems, the growth rates of selected retained stems

can be improved and hence the return period

shortened. In cypress pine (Callitris glaucophylla)

areas, seedling establishment can be at such adensity that some thinning should be carried out to

ensure that the remaining trees grow and formuseable timber (Johnston 1975). Cypress pine

seedlings may require only a low intensity fire tokill them, as they are particularly susceptible to fire

(Johnston 1987). In other woodland communities,

the unwanted timber may have to be removed by

chemical means in order to reduce competition andallow adequate growth rates. See table 4.5 for

spotted gum (Corymbia citriodora) and cypress pine.

Note that individual tree production is greatest at the

lowest density (widest spacing) but that productionper hectare is greatest at moderate to high tree

densities. Therefore, the appropriate density oftrees to retain will depend on the type of product.

These results show that by effectively managing a

forest, the volume of wood produced on a perhectare basis can be substantially increased. This

increase is then available for harvest to maintain

productivity.

90

Table 4.5 Effect of tree spacing on individual tree growth (dbh—diameter at breast height) and forest growth (volumeincrement per area). Data from Department of Primary Industries Forest Service western experiments.

Spacing regime Cypress pine Cypress pine Spotted gum Spotted gumdbh cm/yr m3/ha/yr dbh cm/yr m3/ha/yr

Unmanaged 0.07 0.17 0.18 0.3

Bulloak removal 0.21 0.87

4 x 4 0.23 2.4

5 x 5 0.27 2.2

6 x 6 0.28 2.0 0.41 0.7

7 x 7 0.31 1.8

8 x 8 0.57 0.710 x 10 0.59 0.5

12 x 12 0.74 0.5

14 x 14 0.83 0.5



• Certification and Labelling of Forest Products—international pressure is growing for the

development of a certification and labelling

scheme that enables buyers of forest products to

be aware of how the sustainable production of aparticular product is in comparison to other

products on the market (Fortech 1997). These

developments may provide a useful marketing

opportunity for promoting products derived fromsustainably harvested and managed native

forests and plantations.

At a national level, a number of policy documents

may affect the development of farm forestry. In

1992, the Federal, State and Territory governmentssigned the ‘National Forestry Policy Statement—A

new focus for Australia’s forests’. This statement,

which describes a nationally agreed set of objectives

and policies for Australia’s public and privateforests, has been the founding policy document for

the development of farm forestry. Under 11 national

goals with numerous specific objectives, it has setthe development of public and private forests withinthe context of ecologically sustainable development

and recognises the need to develop the forestry and

wood production industry. It has seen the

implementation of the Comprehensive RegionalAssessment process and the development of a

number of Regional Forest Agreements, which aim

to provide resource security for native forest

dependent producers, while ensuring there is anecologically sustainable system of reserves

established (Commonwealth of Australia 1992a).

The South East Queensland Regional ForestAgreement was achieved in 1999. It is expected that

this agreement will promote the rapid expansion ofhardwood plantations in south-east Queensland.

Key elements of the agreement include:

• a transition to plantation forests for hardwood

supply over 25 years• no logging of old growth or wilderness and no

clearfelling

• an end to all logging in Crown native forests in

south-east Queensland by the year 2024• government will facilitate and provide incentives

for ecologically sustainable management of

forests and timber resources on private land.

In contrast to Western Australia, South Australia,

Victoria and southern New South Wales, the focusof plantation farm forestry in Queensland has been

on a range of local native hardwood species rather

than on exotic pine or non-local eucalypt species.

The Queensland Forest Research Institute (QFRI)lists 17 hardwood species for attention in their

Private Plantations Initiative (Lee et al. 2000) and

recent publications advocate the use of a range of

‘best bet’ species (Sewell 1997), most of which arelocally native species. If plantation farm forestry

does become a common land use on suitable

cleared land in rural Queensland using a wide

range of locally native species, this may help in the

partial restoration of threatened ecosystems andthe buffering of remnant vegetation.

Traditionally plantations in Queensland have been

government-owned and funded monoculture

plantings using exotic and native pine species. The

development of landholder-driven farm forestry, thescope of the Private Plantations Initiative (Lee et al.

2000) and expressed landholder preferences(Harrison et al. 1997) for mixed native species

planting, clearly indicate that a significantly largerrange of locally native species are likely to be used

in the future. The broadscale replanting of the

preclearing dominant tree species on cleared land

provides for a partial reintroduction of thevegetation communities of regional ecosystems.

This partial restoration can be enhanced by the use

of an appropriate range of mixed species in the

plantation or a number of small monoculture plotsof different locally endemic species.

The strategic placement of plantations adjacent orclose to remnant vegetation can remove or reduce a

number of the threats to remnant vegetation, such

as reduced edge effects and improved firemanagement. Long, thin or scattered remnants can

effectively be aggregated into much larger, less

vulnerable areas with sympathetically developed

and managed native hardwood plantations. Otherecological threats to remnants, such as weed and

feral animal pests, may not necessarily be reduced

by the proximity of such plantations.

Carr and Jenkins (2000) have presented a

revegetation model that includes plantations andargue that there are a range of compromises which

can be made to capitalise on the multiple benefits

of revegetation activities. Table 4.6 illustrates a

range of common revegetation activities practicedin Australia and shows some of the compromises

which can be made.

Lamb (1997) has identified several opportunities for

broadscale biodiversity restoration with long

rotation sawlog plantations:• use of native species instead of exotic species

• embedding of monoculture plantations in amatrix of intact or restored forest

• use of several species and creation of a mosaicof monocultures across the landscape instead of

a single plantation

• use of species mixtures instead of plantation

monocultures• fostering and management of the diverse

understoreys that often develop below the

canopy of plantations.

These more biologically diverse plantations can

continue to be managed for biodiversity beyond thelife of the first rotation. Management options

include:

• the use of selective harvesting to recover the

plantation cost and then manage for biodiversity91



• Allowing the dormant understorey species to

grow and join the plantation canopy andmanaging the result as a mixed species forest

• Using the plantation as a means of accelerated

successional development—do not harvest and

manage for biodiversity (Lamb 1997).

While many private native forest areas areprincipally managed for wood, grazing or non-

wood production, there is also the potential for theapplication of ecologically sound remnant

vegetation management principles to maximise theconservation outcomes from the native forest area.

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Lower establishmentcosts, cheaper fencing,better tree form, higherreturns, easier

management. Usuallylarge area >40 ha

Lower establishmentcosts, cheaper fencing,better tree form, higherreturns, easiermanagement andharvest. Usually largearea >40 ha

1. Exotic speciesplantation on farm (fortimber, fodder, firewoodetc.)

2. Native speciesplantation on farm(for timber, fodder,firewood, cut flowers,foliage, bushfood,oil, etc.)

Positive: greenhouse gasuptake, some habitat value,may reduce recharge ofgroundwater, may intercept

nutrients

Negative: may attract exoticfauna, may displace existingecosystem, temporary,suppressed understorey, weedpotential

Positive: CO2sequestration,

more habitat value thanmodel 1, corridor potential,may reduce recharge andintercept nutrients

Negative: may displace existingecosystem, risk of geneticpollution, temporary

Positive: some shelterand shade, lowestcrop–tree interface

Negative: reducedpasture, changes rurallandscape aesthetics

Positive: somewindbreak and shelterbenefit, lowest crop–treeinterface

Negative: reducedpasture, changes rurallandscape aesthetics

Use native or locallyindigenous speciesWide spacingIncorporate habitat

blocksPlace on cleared ordegraded land

Use locally indigenousspeciesWide spacingUse a mix of speciesPlace on cleared landPlant annually

Timber production maybe reduced, species bestadapted for localconditions, optimummethods applied forgrowth

3. Locally indigenousspecies plantation onfarm (for timber, fodder,firewood, cut flowers,foliage, bushfood, oil,etc.)

Positive: CO2 sequestration,greater habitat value thanmodels 1 and 2, corridorpotential, may reduce rechargeand intercept nutrients

Negative: may displace natural,age-diverse stands, temporary

Positive: somewindbreak and shelterbenefit, lowest crop–treeinterface, blends intorural landscape better

Negative: reducedpasture

Use best performing seedfamilies of localprovenancesPlace on cleared landWide spacing

Positive: quality timberproduction, able to coverlarge areas, lesscompetition betweentrees

Negative: compromise insilviculture (more

thinning and pruning),poorer tree form onedges

4. Timberbelts andshelter belts

Positive: corridor potential(depending on species), CO

2

sequestration, habitat potential,maximum nutrient andgroundwater interception

Negative: may draw wildlifeout of habitat areas, weed or

genetic pollution potential asfor plantations depending onspecies, increased edge effects

Positive: high windbreakand shade effect, utilisesexisting fences, followsnatural and man-madefeatures (creeks,contours, roads), spreadsrisk

Negative: high crop-treeinterface, high fencingcosts

Use temporary electricfencingUse local species forshelter and timber rowsPlant outer rows withshelter speciesChoose species whichcompete less withadjacent pastures andcropsCan have shelter ortimber emphasis

Table 4.6 The effects on commercial revegetation, natural resource conservation and farm enhancement in a range ofrevegetation models and some possible modifications to allow the capture of multiple benefits (Carr & Jenkins, 2000).

Revegetation model Commercial Natural resource Farm Possiblerevegetation conservation enhancement modifications

Positive: existingresource, large logs,lower managementrequirements, noestablishment costs

Negative: slow growthrates, compliance withnative vegetationlegislation, greaterharvesting cost

5. Managed nativeforest

Positive: high habitat andwildlife values, diversity ofspecies, can be managed toimprove biodiversity, forestmanaged, rather than cleared

Negative: management canreduce diversity and habitatvalues, increased fire frequency,spread of weeds throughdisturbance

Positive: blends intoexisting landscape,shelter and shade values,some grazing value

Negative: greater firerisk, pasture competition,potential for regenerationin agricultural productionareas

Remove less treesRetain understoreyManage for wildlifePrune best treesThin to increaseproductionFence out livestock



4.3.8 Alternative products

Retaining, replanting or rehabilitating native

vegetation may offer ecological and economicbenefits through new crops, diversified agriculture

or alternative products such as:

• timber

• bushfoods

• ecotourism

• oils, gums and resins

• tannins and dyes

• medicinal and pharmaceutical compounds

• bee keeping and honey production• landscape and horticultural materials and

products

• native seed production

• integrated pest management agents

• gene improvement and breeding programs

• cultural and heritage products and services.

The incorporation of native vegetation alternative

products into production systems and practices

may simultaneously provide conservation benefits.

Table 4.7 summarises some of the current andpotential alternative products from nativevegetation. It is by no means exhaustive, but is to

be seen as a starting point.

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Positive: noestablishment costs—turns a problem into aresource

Negative: no control onspecies, high

management costs, slowgrowth rates (depending

on species), large wastecomponent

6. Managed nativeregeneration

Positive: increased species andage diversity, can be managedfor increased understorey,regrowth managed, rather thancleared

Negative: seedlings not

naturally selected, decreasingtree density may disadvantagesome species of flora and fauna

Positive: can bemanaged for increasedpasture, increased shelteras stands are opened up,reduced clearing costs

Negative: thinnings may

be a fire hazard

Encourage diversityThin for timber orpastureAllow grazingExclude grazingFertilise trees

Positive: fast growthencouraged

Negative: not in optimalareas for timberproduction, pruning andthinning regime may bedifferent

7. Salinity or erosioncontrol planting

Positive: increased biodiversityand habitat, corridor potential

Negative: species variety maybe limited in discharge zones

Positive: cheapcompared withengineering solutions,long-term, slows thedecline of agriculturalland

Use salt tolerant speciesUse commercial speciesCan easily include localshrubs and trees

Positive: best trees canbe pruned for timber,seed source

Negative: slow growthrates, may not beoptimal timber species

Positive: low competitionbetween trees

Negative: high pruningcosts, no competition toforce trees to growstraight

8. Habitat planting

9. Wide-spacedagroforestry

Positive: CO2

sequestration,increase wildlife numbers andresilience, maintain biodiversity,

reverse tree decline, aestheticsNegative: may harbour feralanimals and weeds if notmanaged properly

Positive: CO2

sequestration,nutrient recycling, habitat forsome species

Negative: Poor habitat for mostspecies, relies on exotic species

Positive: Pest control,shelter for pastures,crops and stock,

contributes to stability ofagricultural ecosystems,aesthetics

Positive: highest pasturecomponent of all designs,good stock shade andsome shelter

Negative: high treeprotection costs

Incorporate some localcommercial speciesHarvest logs of high

value speciesManage weeds and feralanimalsSell seed

Utilise select plantingmaterial,Stagger plantingsFence whole paddockuntil trees establish

Table 4.6 Continued.

Revegetation model Commercial Natural resource Farm Possiblerevegetation conservation enhancement modifications

4.4 Other values of native vegetation

4.4.1 Non-value benefits

Benefits from retaining native vegetation clearly fallinto two categories—measurable shorter term

economic benefits to the landholder and the

community, and desirable medium to long-term

benefits that are not easily measured, or impacteither on the farm or beyond the farm gate.

Benefits to the whole of society include aesthetic

and amenity benefits. Little research has examined

these, although efforts to quantify such benefits are

discussed in section 5.2. Implicit to manyarguments for vegetation retention for this purpose,

are discussions on ecotourism (see section 4.3.8).

Section 4.3 examined in detail some of the on-farm

benefits of native vegetation for production,

including income diversification and alternativeproducts. Section 5.2 explores further economic

quantifications of these values. At the property

level, vegetation has a number of other values that

are more difficult to quantify, including ecosystemprocesses (nutrient retention, nutrient cycling, and

the maintenance or enhancement of soil fertility

and biological status; see also section 3.2) and

scenic and amenity values. Implicit in thearguments for retention of native vegetation in

agro-ecosystems, is the need to maintain ecosystem

services. Retention of vegetation provides benefits



94

Table 4.7 Alternative products from native vegetation

Product Reference/s and resources Comments and uses

Timber

1) ‘wood’/timber, value-added resources

Forest Facts (2000) WA - CALM

Anderson (1993); Bulman et al. (1998);Fairbairn (1999): Australian NationalUniversity (1998); Sewell (1997)

1) Examples: timber, charcoal, fuelwoodbroombush (Melaleuca uncinata)

2) Specialty timbers 2) Fairbairn (1999) 2) Uses: fine furniture, cabinet making; parquetry flooring;veneering ; musical instrument/s or components ofmusical instruments; carbon-storage potential; decorativewooden objects (such as vases, lamp shades, pens,serviette holders, coasters, wine goblets, platters, bowls,potpourri bowls, wooden toys, canisters and clocks);gun-stocks, knife handles, lidded boxes; wood carvingsmade from western timbers; wood pieces for turning(hobby); architectural fittings and souvenir items

Oils, gums and resins Anderson (1993); Archer (1997); Murtagh(1998); Plummer & Considine (1997)

Essential oils (eg Backhousia citriodora andMelaleuca alternifolia)

Medicinal andpharmaceutical products

1) Herbal Medicines Research and EducationCentre, Sydney

other: Anderson (1993); Parnell (2000);Purbrick (1998)

1) Herbal medicines; anti-cancer drugs;antioxidant-action mechanisms;cardiovascular drugs

FloricultureWildflowersCut flowersFoliage etc.

1) Export Flora Australia2) Flower Export Council of Australia Inc.3) Other: Johnson (1996); KaringalConsultants (1994)Plummer & Considine (1997); Sedgley &Horlock (1998)

1) Australian native plants: products and services2) Fresh and dried native flowers, foliage etc.

Native/bushfood products

1) Bark and cork

2) Leaf

3) Flowers

4) Fruits

5) Nuts

6) Seeds

7) General8) Extracts, spices, foods

and oils

1) Anderson (1993)

2) Anderson (1993); Phelps (1999b)

3) Anderson (1993)

4) Anderson (1993); Flynn (2000) eg riberryPhelps (1999b)

5) Anderson (1993)

6) Anderson (1993); Phelps (1999b)

7) Anderson (1993); Flynn (2000)Graham & Hart (1998)

8) Rayner (2000); McCarthy (1995)Phelps (1999a)

Beekeeping and honeyproduction

Anderson (1993); CAST (1999); Parnell (2000)

Landscaping andhorticultural materials andsources

1) Eg ‘Blue Grass’ Themeda australis var.Mingo (Burke’s Backyard Fact Sheet 2000)

2) Rayner (2000)

1) Native gardens and groundcovers

Cultural and heritageproducts and services

1) Indigenous culture andheritage

2) Farm and home-staybusinesses

3) Historical and landscapeheritage

Schmitt (2000)

Integrated pest management Tilman and Duvick (1999)

Gene improvement, breedingprograms, scientific research

Brown (1997); Tilman & Duvick (1999)

Roadside revegetation,transport and utilitycorridor rehabilitationand revegetation

Brown (1997)

Tourism and ecotourism Industry Sciences Resources (1999)Queensland Tourism and Travel Corporation

(1998); Tilman & Duvick (1999)



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the introduction and spread of exotic species.

However, remaining remnant vegetation can behighly significant.

Management of the tree clearing issue in the south-

east Queensland coastal zone has been a

significant environmental issue for at least the last

decade (Catterall & Kingston 1993). Many parallelscan be drawn between the planning initiatives that

have been developed during the last ten years andthose being considered now in rural environments.

Analysis has shown that, while the south-eastQueensland region has not lost the same absolute

area of land from tree clearing as rural

environments, it has placed a considerable amount

of the region’s biodiversity values at risk and stillthreatens many of the more stable ecosystems,

species and populations that remain (see box 6.2).

Values of vegetation in urban areas can include

shade for public and private recreation areas,

landscape amenity, visual pollution barriers,

catchment protection and control of soil degradation.

for the conservation of biological diversity, for

example, through the provision of habitats absent intreeless landscapes (Chilcott et al. 1997).

The value of property may be enhanced with the

retention of remnant vegetation. Premiums of up to

20% on the value of properties in the central wheat

belt of Western Australia are expected forproperties with elaborate investments in

windbreaks, fodder shrubs and perennial pasturesfor wind erosion and salinisation control (Kubicki et

al. 1993). Similar premiums may be available forproperties with a high proportion of native

vegetation in over-cleared parts of south-eastern

Australia (Reid 1997).

Many desirable aspects of retaining natural

vegetation revolve around benefits to the whole ofsociety as well as to the long-term sustainability

and health of the property itself. In an environment

of economic survival, many landholders make

individual decisions that may be beneficial

(essential) to them in the short-term, but whichmay be disadvantageous on the property and to the

wider community in the longer-term. Salting from

clearing of vegetation in recharge areas resulting inrising watertables and expression of salinity, is an

extreme example in this regard. However,

landholders generally accept that these major

impacts are counter-productive (e.g.VirtualConsulting Group and Griffin nrm 2000).

The maintenance of species diversity (flora and

fauna), achieved by retaining native vegetation, is

highly desirable for bioregions, the community, and

as an essential element of State and nationalobligations. In some cases, landholders consider

that this has limited direct benefit for them

individually, and that, in fact, it may reduce

potential agricultural or grazing productivity in theshort term. Thus there is a perception that there is

little incentive to manage lands for biodiversity

purposes, especially if there is an associated

negative impact on production or management.However, some grazing companies are effectively

working with conservation agencies in a

cooperative, mutually beneficial manner (WimBurggraaf—keynote presentation at KatherineRangeland Conference 1994).

4.4.2 Urban and peri-urban

The primary focus of this review has been on ruralland use and management, but it is important to

note urban and peri-urban uses of vegetation.

Vegetation clearing in urban and peri-urban areas

is still a key threat to the State’s biodiversity. Many

urban areas are developed in highly diverse,productive areas, particularly lowland coastal

areas; and this can have devastating impacts onlocal fauna and flora. Urban development usually

involves complete destruction or high levels ofmodification and fragmentation of vegetation, and



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The following is a summary of the tree-clearing issue in Brisbane City over the past 100 years.

• Initial clearing of the central city and inner suburban area, followed by clearing of patches of rainforestalong the Brisbane River and waterways, for timber extraction and for agricultural purposes was mostly

complete by the 1870s. Most of Brisbane’s lowland rainforest (closed forest) was cleared by 1900 and

most of the lowland eucalypt open forest by 1946. Most of the melaleuca woodland/wetland was

cleared by the1960s.

• Clearing and thinning of eucalypt forests across the city for hardwood to be used in the construction ofnew homes was mostly complete by the 1930s. Facilitation of economic development and urban growth,

at the expense of natural area loss was to remain an overriding priority for the remainder of thecentury. There were some early examples of visionary thinking about the need to protect a ‘green belt’

around the city by individuals such as the former Lord Mayor, William Jolly.

• Expansion of the city and middle suburbs and the consequential clearing of intact and thinned forestsand further thinning of outlying areas was mostly complete by the 1950s. Clearing, draining and land

reclamation of much of the city’s low-lying areas containing most of the freshwater wetlands, melaleuca

woodlands and open forests (primarily for airport construction, but also housing and other

infrastructure) was mostly complete by the 1960s. Quarrying sites were developed across the city inforested foothill localities. At this time, a decline in the abundance and diversity of species and their

habitats was largely unrecognised by the community except for specialist interest groups and

individuals.

• Expansion of clearing into areas of steeper lands, such as Mt Coot-tha. Rapid expansion of the citynorth and south into areas of former cleared land and remnant bushland with few planning or otherconstraints. There was the growth of a high speed network of roads across and out of the city. The

introduction of new varieties of ornamental plants in gardens was strongly promoted, many with

unrecognised weed potential (‘sleeper weeds’), cane toad numbers were steadily increasing and the

growing of native plants in gardens was becoming popular, partly in response to rapid loss of bushland.There was growing community concern about the rapid loss of habitat in the Greater Brisbane area. All

this was well under way by the 1970s.

• Implementation of the Brisbane Wildlife Survey, Brisbane City Council (BCC) and community

involvement in 1981. Publication of the results and a book; the Brisbane Wildlife Survey represented amilestone in community environmental education. Clearing of 50% of koala habitat took place in the

Leslie Harrison Dam catchment during the 1980s for rural acreage development. BCC land with

bushland value was sold for residential development. Studies and reports by BCC all came to the same

basic conclusion: half the city’s bushland and wetland was in private ownership, none of the existingmeasures were likely to be effective in protecting it, and there was a strong community mandate to

introduce new bushland protection measures.

• There was strong community opposition to residential development pressure and clearing of privately

owned bushland on the face of Mt Coot-tha; Council refusal of development, and commencement of the

Bushland Acquisition Program (BAP) in 1989. Since 1991, there has been a progressive adoption ofelements of a comprehensive bushland protection strategy; the acceleration of the BAP, retention of

Council land with bushland value, strengthening of town planning measures and vegetation protection

laws, initiation of community participation in bushland management and environmental educational

programs, and introduction of initiatives and incentives for owners of privately owned bushland, a

combination which contributed to a slowing in the rate of bushland and habitat loss. Creation of anumber of major natural area reserves and achievement of interim planning protection goals by the end

of the 1990s.

• At present there is continuation of the above protection initiatives, mixed level of commitment by

different levels and sections of government and community to considering biodiversity beyond theimmediate, growing recognition of the need to coordinate efforts with south-east Queensland councils at

a regional level, monitor progress and anticipate emerging management issues (such as fire, ferals and

weeds), and apply the ‘precautionary principle’. There are changing conservation priorities including the

need to promote ‘duty of care’ by all landholders to better manage environmental values on ‘off-reserve’land with high habitat value.

Box 4. 2 Case study: history of tree clearing issue in Brisbane City



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5 Social and economic issues

Contributors

Rural social issues

Lyn Aitken, Department of Natural Resources

An economic analysis of broadscale tree clearing in Queensland

John Rolfe, Central Queensland University

return to contents

http://start.pdf/



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Summary In this section, the social and economic dimensions

of native vegetation management are discussed.

Some of the most critical barriers to natural

resource management are social and these arediscussed under the headings of socioeconomic

issues, values, social issues and sustainability,

community involvement issues and communication

and partnerships in section 5.1. Section 5.2provides an economic analysis of broadscale tree

clearing in Queensland.

Social issues

1. Socioeconomic issues related to nativevegetation management include:

• the costs and benefits to society of differentmanagement options for remnant native

vegetation management

• identification of effective market and non-market

mechanisms or systems to assist landholders toretain native vegetation on private land

• off-site effects of clearing native vegetation and

on-farm effects of maintaining native vegetation.

2. Issues connected to values include:

• the role and importance of non-commercialvalues of remnant native vegetation in the

retention and management of vegetation

• the range of values—non-commercial forest

values include intrinsic values, spiritual values,ecological values, community values and

existence values.

Values must be considered if balanced decisionsabout natural resource management are to bemade. Such considerations can be complex, as

values can sometimes be a source of contradiction

and dilemma. For example, there are dilemmas

between a nation’s history of equating clearingwith development, and valuing the ethos and

features of the bush as intrinsic to our national

identity. Other apparent contradictions arise when

there is a disjunction between conservation beliefs,and pro-environmental behaviour, as some studies

suggest that pro-conservation attitudes were not

necessarily being translated into pro-conservation

behaviour on-farm (Goldney & Watson 1995).

3. Social issues and sustainability

As the topic of sustainability broadens, a greaterrange of social issues emerges. As a result, the

focus changes from individual landholder’s actions

to the links between the local and the global, and

from forest tenure to forest management.

4. Community involvement issues

• Policy and projects explore arrangements for

enabling community participation in naturalresource management generally, and in

vegetation management in particular. Such

arrangements, considered in consultation withlandholders, may include long- and short-term

leases, wardens, custodians, local and remote

management committees, conservationcovenants and heritage agreements.

• As the value of participation is largely accepted,

a contemporary issue is not whether it should be

sought or encouraged, but how it should be

achieved.

• Summits and strategy papers confirm that

sustainable resource management requires astrengthening of partnerships between all levels

of government, communities and individuals.

• An important issue centers on where support is

provided—whether to activities, or to thestructures that in turn would support activities.

5. Communication and partnerships

• Communication is needed to address the poor

understanding of the value of remnant vegetation

among land managers.

• A study of natural resource management

programs shows that partnerships areconsidered crucial to success. Community and

government partnerships are developing through

community-based natural resource management

programs and through the development ofregional strategies.

6. Other issues

• These concern the links between systems, for

example, those between remnant native

vegetation and agricultural production.

Economic issuesIn this section, the economic analysis of both thebenefits and the negative consequences of tree

clearing is discussed as one mechanism for

assessing the preferences of society between

development and preservation options. Points in thediscussion are:

• The analysis deals with both the direct and

indirect effects of clearing.

• Past difficulties in such analyses include limited

data on production gains and poor

understanding of the longer-term consequencesof tree-clearing activities.

• Net overall clearing benefits are outweighed in

some situations by the negative consequences

(e.g. salinity). Comparison of these costs

(marginal analysis) for different vegetation typeswill have varying outcomes.

• Cost–benefit analysis is commonly used in

economic analysis for assessing preservation and

production choices in determining likely trade-

offs.

• Historically, the emphasis has been on the socialbenefits of production. Greater emphasis is now

placed on social costs in assessing land

degradation issues. These social costs cannot be

priced through normal markets, and a range ofspecialised economic valuation tools are used.



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5.1 Rural social issues A major provider of natural resources management

research funds prefaces its new Social and

Institutional Research Program information with thestatement that:

More than ten years experience in funding naturalresource R&D has demonstrated to the Corporationthat the most crucial barriers to improved use ormanagement of natural resources are social and

institutional factors and not a lack of scientificknowledge. (LWRRDC 1999)

In the past, tree clearing was linked to productivity,and it followed that discussions about minimising

tree clearing considered whether production would

be adversely affected, and what the follow-on

effects would be for surrounding communities. Thecontemporary approach is to consider long term

maintenance, which means sustaining vegetation

while still sustaining agricultural industries and

rural communities. A number of issues arise, andwill be addressed in the following sections:

socioeconomic issues related to native vegetation

management; values; social issues and

sustainability; and community involvement issues.

5.1.1 Socioeconomic issues relatedto native vegetationmanagement

Many important social issues relating to native

vegetation management were identified by a Land

and Water Resources Research and DevelopmentCorporation (LWRRDC) project examining the

socioeconomic aspects of maintaining nativevegetation on agricultural land (Price 1995). The

project held a national workshop to consider thesocioeconomic, policy and related aspects of

managing native remnant vegetation, and the project

report records the background papers, discussions

and outcomes. The working group identified anumber of priority issues including:

The costs and benefits to society of differentmanagement options for remnant nativevegetation management.

A major concern for landholders is how to linkpreservation of native vegetation to agriculturalproductivity, as there are differences in

understanding the costs and benefits There are few

economic models available that include native

vegetation management, although Charles Sturt

University’s Johnstone Centre is making availablereports on the economics of conserving remnant

native vegetation management in the

Murray–Darling basin (Lockwood & Walpole 1999;

Walpole & Lockwood 1999).

Identification of effective market and non-marketmechanisms to assist landholders to retain nativevegetation on private land

The working group argues that landowners do notalways have the ability to take the long-term view

of economic benefit associated with nativevegetation management. They comment that there

is little analysis of the costs of clearance and the

establishment of farming systems, compared with

the profits and benefits of retention of nativevegetation. However, there are real costs in

managing native vegetation in terms of capital,

opportunity and recurrent costs. ‘Many farmers see

neither economic incentives to retain remnantnative vegetation nor effective ways to protect and

manage bushland’ (Price 1995). In the same vein,Hussey (1995) comments that ‘cost for no

perceived return’ is the most common reason citedfor clearing or not managing native vegetation, and

is therefore an important social issue.

If the idea of ‘cost’ and ‘return’ is broadened

beyond a narrow financial, market-related

meaning, then Furze et al. (1996) provide furthersupport for the necessity to positively link

conservation effort and benefit to achieve results.

They analysed 50 conservation and development

case studies from around the world and theycomment that their analysis

Highlights the importance of explicitly linkingindividual and local community benefit toconservation programs. If conservationists stick tothe old paradigm, that development andconservation are antithetical and natural resourcesare for preservation, not use, then our review ofcase studies holds out little hope for realconservation gain. (Furze et al.1996)

The LWRRDC project (Price 1995) also reports onissues not directly described as economic, such as

the clarification of the roles, rights andresponsibilities of stakeholder groups, and the

establishment of methods for collaboration betweentiers of government. Before such dynamics can be

worked out, it is important to identify scale

(national through to paddock) related to the

• Analysis of the on-farm benefits of tree clearing

in Queensland shows low returns from clearingand development. Clearing may be conducted to

maintain or improve viability levels for individual

producers.

• Estimates are made of the indirect external

impacts of tree clearing such as carbonemissions, although it is noted that more work is

needed to quantify carbon losses.

• Public values of vegetation are discussed, with an

example of the willingness of Brisbane householdsto pay for different preservation options.



100

different tiers of government, rural industries,

community groups and landholders, to help identify

key stakeholders for each scale level.

At the biophysical and managerial level, theLWRRDC working group also comments on the

disparity between management units such as

paddocks and stands of trees, and the scale on

which action is needed to retain native vegetation

for ecological purposes, such as ecosystems andlandscapes. Another issue arising in this category

is the poor integration of native vegetation

management in catchment and regional planning.

Off-site effects of clearing native vegetation andon-farm effects of maintaining native vegetation

The social issues that arise in relation to native

vegetation management often involve a diversity of

interests in regional areas. For example, landmanagers may argue that their viability depends on

their capacity to increase their areas of production.

However, such an increase can have negative

effects on other regional interests. Tree clearing inone area can result in salinisation hundreds of

kilometres away on other properties and in regional

towns where buildings and roads become affected.

Increased soil and nutrient run-off, affectinginterests such as eco-tourism can also degrade

catchments.

Black et al. (1999), in their review of literature on

rural social issues, comment that ‘Land continues

to be cleared for agriculture in Australia as farmersrespond to new opportunities without having to

calculate the effects beyond their own enterprises’.

However, such information is being collected. A

recent report by Walpole and Lockwood (1999)

(table 5.1) lists the off-site costs of remnant nativevegetation clearance as:

• cost to local government

• cost to non-farm businesses

• costs to urban households• cost of carbon dioxide release following clearing.

ValuesA colloquium on Sustainable Forests—GlobalChallenges and Local Solutions (Bouman & Brand

1997) was held to identify non-commercial forest

values. The consensus was that they include

intrinsic, spiritual, ecological, community andexistence values. As an outcome of the colloquium,

the Ontario Ministry of Natural Resources now

recognises the importance of non-commercial

values and that methods are needed to incorporatethem when making decisions about forests.

In the retention and management of remnant nativevegetation, the role and importance of its non-

commercial values are important issues. TheLWRRDC national working group (Price 1995)

identifies conflict over the intrinsic value of remnant

native vegetation. To some, the benefits of remnant

native vegetation are seen as symbolic rather thansubstantive. There are dilemmas between a nation’s

history of equating clearing with development, and

valuing the ethos and features of the bush as

intrinsic to our national identify.

Table 5.1 Summary of estimated off-site costs of land degradation associated with tree clearing. Walpole and Lockwood (1999).

Type of Location Cause of cost Year of Annual Referenceimpact estimate cost

Soil erosion Eppalock catchment, Maintenance costs for roads, 1974–75 $15 000– Dunn & Gray (1978)Victoria bridges and water supply $30 000

Stream Loddon catchment, Damage to household equipment 1980 $4.40/ha Greig & Devonshiresalinity Victoria (1981)

Salinity Victoria Downstream water quality effects 1990 $7.3m Dumsday & Oram (1990)

Salinity Northern and Damage to household equipment 1984 $2.9m Salinity Committee (1984)

western Victoria

Salinity South Australia Damage to household equipment 1984 $7.2m Peck et al. (1983)

Salinity Bendigo, Ballarat and Damage to roads 1983 $1.1m Salinity Committee (1984)Horsham area, Victoria

Salinity Public utilities in Damage to bridges and roads, 1983 $10.7m Barter (1986)New South Wales restoration of coastal sand drift

Soil erosion Coorong and district, Public infrastructure maintenance 1997 $0.4m CDLAPSC (1997)South Australia

Salinity/ Queensland Damage to urban water supplies, 1988 $31.3m Russell et al. (1990)soil erosion drainage maintenance, silt

removal, dredging

Soil erosion Murray–Darling basin Repairs and maintenance 1993 $8.2m Oliver et al. (1996)of infrastructure

Salinity Loddon and Campaspe Damage to household equipment 1995 $0.67/ Lubulwa (1997)catchments, Victoria household

Salinity Loddon and Campaspe Damage to non-farm business 1995 $26/ Whish-Wilson & Shafroncatchments, Victoria equipment business (1997)

Salinity Loddon and Campaspe Cost of reduced agricultural 1995 $19.6m Whish-Wilson & Shafroncatchments, Victoria production attributable to salinity (1997)



101

The working group also considers there are

dilemmas between valuing the bush for what it is,

and what its use can be, or seeing it as an obstacleto other land uses. The failure to give remnant

native vegetation a ‘book value’ as an asset with

potential to change value, or generate income or

expenditure, in the way that an area of cleared landis given a book value for marketed properties, was

identified by the group as such an obstacle.

5.1.2 Social issues and sustainability

Framing the issues

The development of land for production was ofprime importance in earlier decades. Consequently,

decisions were made with the goal of getting

greatest use from the land, and that meant clear-

felling to increase areas for production. As manyare aware, such practices have led to major

problems. Rural producers often point to the

requirement by governments of the time, that land

be cleared (as a condition of occupancy), and thattherefore the State must take some of the

responsibility for past rounds of what is now

construed as ‘destruction’. But what of continued

tree clearing? Decisions are still often made withthe intention of getting greatest use from the land,

despite the fact that the goal of production is now

being challenged by that of sustainability.

As Furze et al. (1996) comment, the focus on

sustainability has broadened the focus from theindividual landholder’s actions to the links between

the local and the global. They note that Local

Agenda 21—from the Rio Summit—sets out a

framework for local government, recognising theneed to mobilise resources at all levels from the

local to the global, forging a partnership between

local, regional, national and international

stakeholders. In their view, the linkages are acritical focus.

No policy aimed to support localconservation/development initiatives can work if itignores the steamrolling impact of the globaleconomy. International trade, the growth imperative,global marketing and communications,

instantaneous pricing of commodities, bonds,currencies as well as the power of centralgovernments all provide a context for localprocesses. (Furze et al. 1996)

They agree with Scherl et al. (1994) who argue for

a pluralistic planning approach.

There is an urgent need to link local concerns, localneeds and local actions to the national andinternational government structures designed toconserve and manage the global environment.(Scherl et al. 1994)

Ensuring sustainability is a complex juggling act, as

indicated in the findings from a five-yearconsultation process to develop national guidelines

for rangeland management. The process began in

1994 with the release of the Rangelands Issues

Paper. Submissions were invited, with 182

responses received, and 30 workshops held around

Australia. The report, released in 1999, states

among its findings that

The challenge is to balance the diverse economic,cultural and social needs of rangelands residentsand users with the need to maintain [therangelands’] natural resources and conserve ourbiological and cultural heritage. (ANZECC &ARMCANZ, 1999)

Achieving sustainability involves keeping a numberof goals in mind, and in balance. In the past, the

economics were weighed to make decisions. Buchyand Hoverman (1999) note that until recently forest

conflicts centred on issues of forest tenure, rather

than forest management. In the present, and for the

future, as one of the principles for rangelandmanagement states:

A wide range of values (social, cultural, economic,aesthetic and ecological) needs to be considered inmaking balanced decisions about the rangelands;financial analysis alone is an inadequate tool for

this purpose. (ANZECC & ARMCANZ 1999)

The importance of aesthetic and other values was

recognized in the Regional Forest Agreement

process (Lennon 1998). The place given to

community involvement is an important part of thisbroadening of the issue of vegetation management.

5.1.3 Community involvement issues

Population diversity in relation toecological mapping

Social dynamics will differ according to the

ecological, political and socioeconomic context.The variety of ecological and social circumstancesand ownership has seen bodies such as the

International Union for Conservation of Nature and

Natural Resources (IUCN) develop six

classifications of protected areas; from strictwilderness reserve to managed resource protected

area. Additionally, UNESCO has proposed the

concept of a Biosphere Reserve—a protected area

with a core for conservation, a buffer zone forresearch, recreation and tourism, and a transition

zone for agriculture, settlements and other human

uses of natural resources (Borrini-Feyeraband

1996). Such artificial divisions (artificial becausethe lines often blur) give clues to the diversity of

populations in areas where natural resource

management issues become highly visible, and

such diversity is reflected in efforts towardcommunity involvement.

Community involvement in vegetation management

is a social issue that is gaining primary importance

in policy and practice. A number of research

projects have been exploring arrangements for

enabling community participation in naturalresource management generally, and in remnant

native vegetation management in particular. For

example, in the southern wheat belt, researchersare investigating community involvement in



102

participation in decisions affecting regional

Australians and the broader Australian community.

The summit also recognised that the increasing scale

and scope of environmental challenges are beyondthe capacity of regional Australians alone to respond

to; sustainable resource management requires a

strengthening of partnerships between all levels of

government, communities and individuals. Morerecently, the discussion paper emanating from

Agriculture, Fisheries and Forestry–Australia entitled‘Managing Natural Resources in Rural Australia for a

Sustainable Future’ is replete with references to‘community’, ‘empowerment’, and ‘capacity

building’ as part of the emerging ‘self help’ approach

to regionally-based natural resource management.

Lawrence (2000) has argued that to ensure that

real empowerment occurs, a project of sustainableregional development should be enacted

throughout the nation. Permanent regional

structures with statutory powers are viewed by

Lawrence as being more effective in naturalresource management than the work of a plethora

of voluntary ‘self help’ organisations. He advocates

policies that provide strong economic incentives to

regional citizens to embrace sustainable regionaldevelopment, and for the Federal Government to

provide leadership in establishing new forms of

regional organisations with clear environmental

responsibilities. Currently, the Federal Governmentis viewed as having no overall ‘vision’ for regional

communities, with their fate being left up to

uncertain and polarising market forces—and to the

knee-jerk reactions of populist politics (Gray &Lawrence, forthcoming). The aim of the new

regional bodies would be to pursue the integration

of environmental management, social and

community development, and economic growth.Statutory powers would help to ensure that

regional structures are not controlled by the Federal

and State governments (Dore & Woodhill 1999;

Gray & Lawrence, forthcoming).

Communication and involvement

Partnerships require mutual understanding of the

problems being addressed. An issue identified bythe LWRRDC working group (Price 1995) involves

making available appropriate information for

remnant native vegetation management. A numberof issues connect with this identified need for

communication.

• There is a poor understanding of the value of

remnant vegetation among land managers andadvisers and inadequate communication of

knowledge about the status of remnant

vegetation. On the ground there is a paucity of

knowledge, skills and guidelines and a lack ofpersonnel for remnant vegetation management.

The range of stakeholders is also

underestimated.

managing remnant native vegetation through

arrangements such as short- and long-term leases,

wardens, custodians, local and remote management

committees and conservation covenants andheritage agreements (National Vegetation Initiative

1997). A Queensland government project is also

currently investigating appropriate arrangements

through workshops with regional communities.Collaboration between communities and

government agencies is considered to be the wayforward (see AFFA 1999).

Treeby (1999) notes in a paper presented to the

1999 Tsukuba Asian Seminar on AgriculturalEducation, that research is confirming that

participation is important to environmental

outcomes. He comments that, for instance, there

are indications that farms involved in broadercommunity and district approaches place a higher

priority on environmental outcomes than do

landholders who act in an individual capacity.

Participatory approaches are important to mostaspects of NRM, and some of these includeinstitutional issues such as the right mix of

decision-making powers and the integration of

disciplines; scales of decision making from the

national level to property and personal level, andthe integration of participation across scales.

There has been an increase in activity and interest

related to participatory approaches because

‘participation in natural resource management’ is

viewed by governments both as a means of

promoting greater democracy through community‘ownership’ of natural resource issues, and as a

means of generating ‘self help’ solutions to regional

problems. A contemporary issue is not whetherparticipation should be sought or encouraged, but

how participation should be achieved, as its value

is largely accepted.

There are a number of important imperativesdriving this increasing clarity of focus.

• International policy forums, research and local

on-ground experience tell us that our natural

resource problems are escalating, and that our

stewardship efforts must increase.

• Stewardship implies restoration, protection andmaintenance, and it is recognised that

stewardship cannot be left to one sector of

society alone. While

in the past, governments may have had primaryresponsibility for resource management, the

activity currently recognised as necessary for

effective stewardship also involves landholders

and communities.

The recent Regional Australia Summit held on 27–29

October 1999, confirmed the importance of thoseimperatives as it demonstrated the increasing call by

citizens for involvement in decision making through

partnerships based on respect. It was agreed thatsuch partnerships would involve comprehensive



management for its conservation. This refers back

to the emphasis placed on linking production and

conservation.

Participatory approaches are important to mostaspects of NRM, and some of these include

institutional issues such as the right mix of

decision-making powers and the integration of

disciplines; scales of decision making from national

level to property and personal level, and theintegration of participation across scales.

5.1.4 Partnerships

In their in-depth study of three cases (includinglandcare), among other findings, Furze et al. (1996)

conclude that partnership is a crucial common

factor in the success of all three programs. Such a

finding accords with the call from the RegionalAustralia Summit: explicitly, a partnership based on

respect. Their work also accords with the LWRRDC

national working group study contributions that

highlight the need for a greater understanding ofthe links between conservation of native vegetation

and agricultural production.

Community and government partnerships have

been developing through programs such as

landcare and bushcare, and monitoring programssuch as Waterwatch, Pasture Watch, Saltwatch and

Grass Care. Other consultation mechanisms include

social impact assessment through the Regional

Forest Agreement process and the Water AllocationManagement Plans.

Consultation is also taking place through thedevelopment of regional strategies. Property

management planning is another forum for

developing partnerships between government andlandholders. Such developments are based on the

widespread realisation that sustainable production

is dependent on protection of our environment.

As regional communities become more diverse,production becomes a part of broader regional

activities. Sustaining the regions depends on

maintaining the diversity of communities, just as

sustaining the environment depends on maintaining

the diversity of its biology and ecology. The focus isnow on sustainable communities, with production a

significant part of community activity, but with

other interests also needing to be addressed (Dore& Woodhill 1998; Lawrence 1998).

5.2 An economic analysis of broadscale tree clearing in Queensland

5.2.1 Introduction

Broadscale tree clearing in Queensland has beenassociated with large increases in agricultural

production, particularly in the beef and grain

industries. However, clearing has also beenassociated with some negative consequences,

Other issues are concerned with the links between

systems, for example:

• between remnant native revegetation andagricultural production. The appreciation of this

linkage is considered by one of the authors to be

the key to assessing ecological values

• between remnants and the maintenance of bioticdiversity, and how communities are drawn into

understanding these linkages

• Thomas (1995), in a background paper for theworkshop, writes that ‘the first law of successfulnatural resource management is where

community interests and private interests

coincide’.

Changes in rural demographics

The demographic profile of farmers is changing

through ageing and structural adjustment. Thefarming population of the future needs to be

identified so that the fact that sustainable

management can be effectively integrated with

production systems can be demonstrated andcommunicated.

Partnerships and communication go some way to

involving rural communities in resource

management, including native vegetation

management. A benefit of such involvement is theincrease and exchange of knowledge, which is

important to enable informed, as opposed to

passive, vegetation management.

Many landholders and landcare groups areembarking on projects without the benefit of

scientific particularly ecological, input, which isprobably undermining considerable amounts ofwell-intentioned work. (Thomas 1995)

Goldney and Watson (1995) identify gaps in the

knowledge base such as ‘What is the optimal area

and positioning of bushland on farms, incatchments and across landscape to maximise

agricultural production?’ They also note a

disjunction between farmers’ pro-environmental

beliefs and their conservation action. They write:

Our survey suggests that, while farmers were indeedresponding positively to global environmental

concerns, including those that bear directly uponthe conservation of remnant bushland, they werenot translating those beliefs into action torehabilitate and conserve bushland on their farms,and a significant proportion were open to furtherclearing, should circumstance warrant.(Goldney & Watson 1995)

Goldney also comments that in Cary’s analysis,

farmers’ beliefs about remnant bushland for

farmers are best described as ‘symbolic’ and seemlargely unrelated to actual and intended

management behaviours. Their findings also

suggested that the establishment of moresubstantive beliefs about remnant bushland, onwhich behaviour would be based, might rely on

improved technical information about the

characteristics of remnant bushland and103



104

including the loss of biodiversity, and in some

cases, indirect impacts such as salinity and land

degradation (Conacher & Conacher 1995; Gretton &Salma 1996). In the cases where environmental

damage leads to production losses, there is little

disagreement about the need for remedial action,

but there is wider disagreement about who shouldbear the costs of such action. There are other cases

where there are direct trade-offs between

production and environmental factors, and oftenmore substantial disagreements about resource use.

An economic framework offers one mechanism forassessing the preferences of society between

development and preservation options. In this

approach, the costs and benefits of different

options are assessed in monetary terms. Thesecosts and benefits can be classified into three broad

groups. The first relate to the direct uses attached

to production and conservation options. In relation

to tree-clearing activities, these are mainly

associated with commercial benefits from theincreased production of grain, beef and wool.

The second broad group is associated with the

indirect effects that might be associated with

clearing activities. Examples of these might bepotential losses from increased risks of salinity,

land degradation and greenhouse gas emissions. In

some cases there may also be benefits from

reduced erosion or land degradation impacts as aconsequence of development activities. The third

group are the preferences that groups in society

might hold for particular options, independent of

whether they bear any direct or indirect effects.These are the preferences that people might hold

for protecting biodiversity, and for protecting the

livelihood and ethos of people in rural regions, even

if they have no direct association. Suchpreservation values are termed non-use values.

It has been difficult in the past to conduct a full

economic appraisal of tree-clearing activities. This

is because of limited data about production gains, a

poor understanding of the longer termconsequences of clearing, and almost no

information about the protection values that thewider community might hold for vegetation

preservation and/or for rural communities. The lackof information about values that the wider

community might hold for protecting vegetation

(and biodiversity more generally) in regional areas

of Australia is a particular deficiency.

There is often confusion about the economicanalysis of natural resource management issues.

This is because an economic analysis is more

inclusive than one focusing on commercial viability.

As well as assessing the direct uses (commercial

benefits and costs), an economic analysis willinclude the various spillover effects that are

represented by the indirect and non-use costs

and benefits.

In economic terms, the major reason why

disagreements about tree clearing arise is that the

costs and benefits arising from vegetation clearing

fall unevenly across different groups in society. Theproduction benefits that result from clearing and

development are largely commercial benefits that

accrue directly to landholders. In making choices to

clear vegetation, landholders balance these benefitsagainst the financial costs that they will incur, as

well as their own perceptions about other costssuch as salinity risks and biodiversity loss.

Many of the potential losses that result fromclearing and development are borne by other

groups in society. If clearing results in indirect

losses, such as land degradation and salinity, these

costs tend to be borne by future generations oflandholders and those on downstream or

neighbouring properties. If clearing results in

biodiversity loss, the impacts will tend to be borne

by the wider State and national community who

place a value on preserving such factors. If clearingresults in increased levels of greenhouse gas

emissions, these impacts will have global effects.

Vegetation clearing activities that impose costs on

wider communities than the groups making theclearing decision are examples of what economists

term spillover effects, or externalities. In making the

decision to clear vegetation, landholders do not

always take into account the wishes of the broadercommunity. In a sense, the problem is one of a

missing market. Landholders receive signals from

society, in the form of prices and income, to

produce more beef and wool, and so they clearland to meet those needs, but do not receive

corresponding financial signals about the wishes of

society to preserve biodiversity and reduce

greenhouse gas emissions. Relying on commercialproduction benefits to allocate natural resources is

not always efficient because it does not account for

the broader wishes of society.

In recent decades, there has been a large shift in

community values associated with vegetationclearing. There is widespread knowledge now of

many of the indirect effects of clearing on landquality and greenhouse gas emissions. There are

increasing community values for vegetationprotection, partly because of rising income and

diminished levels of remnant vegetation (Hone,

Edwards & Fraser 1999). There is also awareness

by the community of subsequent impacts ofclearing on ecosystem functioning and other biota.

These impacts have meant that there is increasing

divergence between the commercial gains from

clearing and the associated community lossesrepresented by indirect and non-use values.

Governments generally have a role in correctingexternality problems, and there is increasing

recognition of externality issues in natural resource

management in Australia. There are a variety of



Governments have traditionally acted to balance

the wishes of society in relation to both production

and preservation issues. The prime example of thisrole is where the Government has reserved some

land from production areas in the form of National

Parks. The complexity and diversity of natural

resource management issues means thatgovernments are involved on a number of fronts to

establish where trade-offs might occur and to set

the framework for production goals to be pursued.

The production benefits that can be gained from

clearing native vegetation are rarely uniform. Thebest quality agricultural land, with high production

benefits per hectare, tends to be cleared first. As

this land becomes scarcer, attention turns to lower

quality land where some commercial benefits arestill available from clearing. This pattern can be

seen in Queensland, where clearing activities have

moved from high rainfall and fertile soil areas,

westwards into the scrub and then to the woodland

vegetation types. Falling real costs of development,as well as new production techniques (e.g.

introduced pastures) have also aided this process.

The preservation values per hectare of native

vegetation are also rarely uniform. People in societygenerally place most importance on unique and/or

endangered species and ecosystems (Rolfe, Blamey

& Bennett 2000). As a species or ecosystem moves

from plentiful and widespread towards beingrestricted and endangered, the preservation values

attached to an average unit or hectare are likely to

rise substantially.

correction mechanisms available (AFFA 1999),

largely directed towards making those responsible

for resource use consider the wishes of a more

encompassing group in society. A first step is toquantify the differences that might exist between

commercial gains and other impacts on wider

groups in society. To develop some understanding of

how the benefits and costs relating to tree clearingin Queensland may be viewed in economic terms, a

number of different concepts are discussed below.

5.2.2 Marginal costs and benefitsof clearing

While many clearing activities have provided net

overall benefits to Australia, there are some

situations where the increased production andother benefits of clearing may be outweighed by the

negative consequences. There are examples in

Australia (Walpole & Lockwood 1999), where

clearing has continued past the point where the

benefits from increased production have beenbelow the subsequent environmental costs and

long-term production losses. In some cases, such

as in dry-land salinity areas, it has occurredbecause of limited knowledge about the long-term

and indirect effects of clearing actions. In other

cases, such as in endangered vegetation

communities, it occurs because landholdersrespond to the commercial pressures for increased

production and do not receive signals about the

wider community’s wishes for biodiversity

protection.

105

Table 5.2 Social costs and benefits of tree clearing.

Impacts Benefits Costs

Property level

Direct, medium term Income from increase in carrying capacity, animal Cost of clearing trees, cost of pasture establishment,performance OR Increase in land values as a result of maintenance of cleared land, extra investment inthe net increase in annual income livestock, extra investment in fencing, water, yards,

extra running costs such as labour and repairs

Indirect, longer term Savings in costs/increased output from possible reduction Increase in costs/decrease in output from reduced treein grazing pressure on rest of property cover (e.g. shade, shelter, nutrient recycling)

Savings in costs/increased output from improved access Increase in costs/decrease in output from on-propertyfor mustering salinity and erosion

Enhanced aesthetic value of cleared landscape Pastoralists own value for biodiversity lossDiminished aesthetic value because of reductionin tree cover

External impacts

Land quality Savings in costs/increased income from possible Increase in costs/decrease in output from off-propertyreduction in land degradation on some properties salinity, erosion

Cost of greenhouse gases Reduction in economic welfare from increase ingreenhouse gas emissions

Biodiversity Reduction in economic welfare from biodiversity loss

Aesthetics Non-pastoralists’ enhanced aesthetic value of Non-pastoralists’ diminished aesthetic value becausecleared landscape of reduction in tree cover

Rural communities Increase in welfare of rural communities frommore profitable agricultural sector

Source: ABARE (1995); Rolfe, Bennett & Blamey (2000).



106

These changes in both the marginal benefits and

costs of vegetation clearing provide a powerfulexplanation of development history in Queensland.

When European settlement commenced and most

vegetation types were abundant, preservation

values per hectare would have been low, andpotential production benefits high. With the values

of (European) society at the time emphasising the

social objectives of closer settlement and

development, it was appropriate for the governmentto promote development outcomes. The arguments

about resources in the first 100 years of settlement

tended to be about competing uses (e.g. forestry or

agriculture), rather than development versusprotection.

As widespread clearing has occurred, particularly

over the last 50 years, governments have moved to

emphasis conservation and protection goals as well

as development ones. This has been partly becauseof rising concerns in the community about

biodiversity protection. It is also because, as clearingin vegetation communities extends towards the last

remaining units, the extra gains in production tendto fall below the values for preserving those

vegetation communities. As a vegetation community

becomes more extensively cleared, the additions to

total production tend to fall (because the betterquality land tends to be cleared first), while the

preservation values tend to rise (reflecting the

limited amount of biodiversity remaining).

When the costs and benefits of clearing are

considered for each additional area of a vegetation

type (marginal analysis), the overall outcome islikely to vary. At low levels of development, the

production benefits from clearing are likely to

outweigh other costs, such as biodiversity losses.At some more intensive level of development, the

additional production benefits from clearing may be

outweighed by the associated losses, particularly in

an affluent country such as Australia where valuesfor protecting biodiversity tend to be high. The

policy shifts at the Commonwealth Government and

State Government levels over the past 20 years

reflect this logical outcome.

5.2.3 Assessing the costs andbenefits of clearing options

The diversity of vegetation types and production

opportunities means that the balance betweenproduction and preservation goals might vary

widely across different vegetation communities and

choices. For example, society may benefit from

having high clearing rates in areas that have low

preservation values and high production values.This may help to explain past high clearing rates in

agricultural areas. The maximum benefits to society

might come from clearing vegetation types for highvalue uses (such as new roads or other

infrastructure developments) but preserving them

against other development opportunities (such as

low value agricultural development).

To minimise the decision costs (transaction costs)involved in establishing where the trade-offs should

apply in each case, it is generally preferable to

group the potential trade-off choices into easily

comprehensible and enforceable rules. Biologistsand ecologists advise on how risks of biodiversity

loss may be conveniently related to remnant

vegetation as a function of area, extent of clearing

and other factors. This advice may be codified intoguidelines for use by landholders, communities and

governments to help determine where the

appropriate trade-offs between production and

protection exist.

The standard tool that economists use for assessingpreservation and production choices is cost–benefit

analysis (CBA). This technique operates byassessing how people in society value the benefits

and costs that flow from a particular resource-usealternative. If the benefits outweigh the costs, the

project is assumed to be worthwhile or desirable

(economic), and vice versa. In this way, economists

can provide advice to decision makers in societyabout how the preferences of society sum-up over a

particular issue. While the technique relies on some

particular assumptions (notably accepting the

current distribution of income in society), it providesa powerful mechanism of assessing the weight of

preferences for particular resource-use alternatives.

Table 5.3 Individual business summaries by region. Source: DPI (forthcoming).

Northern Central Central west Maranoablack Queensland Mitchell grass brigalowspeargrass brigalow

Business assets (land, stock and equipment) $2 292 206 $3 628 100 $2 237 700 $2 056 200

Business liabilities $436 000 $544 215 $378 432 $185 000

Cattle sales $313 770 $342 261 $235 633 $149 000

Variable costs $87 487 $50 966 $49 309 $15 265

Total gross margin $226 283 $291 295 $186 324 $133 843

Fixed costs (including depreciation) $117 000 $114 600 $85 380 $53 250

Unpaid family labour $40 000 $40 000 $40 000 $40 000

Return to total capital $69 283 $136 695 $60 944 $40 593

Return on total capital 3.02% 3.77% 2.72% 1.97%

Asset turnover ratio 13% 9% 10% 7%



There are a large number of factors that need to be

considered in a complete CBA approach. This is

because an economic analysis of a resource use

option is much broader than a correspondingfinancial summary. While estimates of potential

production benefits can usually be gained from

market data, indirect and non-use costs and

benefits have to be estimated in different ways.

Pastoralists generally respond to direct-use benefitswhen they clear trees, in the expectation that the

returns from increased carrying capacity will

outweigh the cost of clearing, pasture development

and subsequent maintenance. Pastoralists mightalso factor in their personal preferences for items

such as biodiversity conservation, the aesthetics of

tree cover, and the risks of longer-term impacts

such as salinity. However, there are a range of costsand benefits that may not be considered by

pastoralists, including community values for

biodiversity, indirect effects on greenhouse gas

emissions, and off-farm costs of land degradation.A summary of the costs and benefits of tree

clearing is presented in table 5.2.

In the absence of government intervention, tree

clearing occurs where landholders balance the

benefits and costs at the property level andperceive that higher returns are available from

pursuing clearing options8. Some landholders may

consider only the benefits and costs of development

in the short term, while others may be inclined tofactor in a variety of medium to longer term

considerations that they consider important. This

means that among landholders, there will be somediversity in the balance that they strike betweenproduction and preservation alternatives.

The external impacts of tree clearing activities can

be both positive and negative. In the past,

governments have emphasised the social benefits of

increased production and have encouraged treeclearing through taxation incentives, lease

conditions and other mechanisms. This has

occurred in part because there has been little

knowledge about some of the external and indirect

costs of clearing (such as salinity and greenhousegas emissions),and because when native vegetation

was in abundance, it is likely that the marginal

social benefits from further clearing outweighed themarginal social costs.

Social benefits are likely to be increased where

tree-clearing and production increases help to

address land degradation issues and enhance the

viability of rural communities. Social losses arelikely to result when tree clearing increases land

degradation, increases greenhouse gas emissions,

or reduces biodiversity.

The categorisation of costs and benefits outlined in

table 5.2 provides one framework for assessingwhere trade-offs between production and

preservation should be made at a regional or

property level. In summary, the issue to be 107

R a t e

o f r e t u r n

6

-6Years

-2

8

0

4

2

-4

1995 1996 1997

Cattle numbers vs rate of return

<300 cattle

300–550 cattle

550–1000 cattle

1000–2800 cattle

2800–5500 cattle

>5500 cattle

Figure 5.1 Rates of return by establishment herd size inQueensland. Source: ABARE (1998, 1999).

determined is whether the net returns from tree

clearing at the property level (the items in the first

half of the table) are outweighed by the net external

impacts (the items in the second half of the table).

The external (or off-farm) impacts of tree clearingare not priced in normal markets, in contrast to the

physical outcomes such as increased supplies of

beef or grain. A range of specialised economic

valuation techniques are available to estimate whatvalue may be placed on external impacts, (Sinden

1994). To assess the value of indirect impacts such

as salinisation and greenhouse gas emissions, cost

pricing and other techniques are available. Forexample, Walpole and Lockwood (1999) summarise

a list of Australian studies that estimate off-site

costs of land degradation associated with tree

clearing. The only Queensland example is fromRussell et al. (1990), who estimate that the annual

cost of degradation in damage to urban water

supplies, drainage maintenance, silt removal and

dredging costs is $31.3 million.

To assess the non-use values associated with theexistence and protection of biodiversity, and the

stated preference of rural communities, techniques

such as contingent valuation and choice modelling

need to be employed. These have not been widelyapplied in Australia, and there has been some

controversy about the use of the contingent

valuation method (Bennett & Carter 1993). There are

few applications of non-market valuation techniquesassociated with vegetation protection issues in

Australia, as the following summary illustrates.

Bennett (1984) estimated, with the use of theContingent Valuation Method (CVM), that the

average value per adult in Canberra for preservinga particular woodland area in the Australian



108

Capital Territory was $20. Hundloe et al. (1990)

used CVM to report that the environmental benefits

of banning logging on Fraser Island were in excessof $5 billion. The Resource Assessment Commission

(1992) used CVM to estimate that in Victoria, New

South Wales and the Australian Capital Territory,

households were willing to pay $43.50 to preservethe south-east forests (Bennett & Carter 1993).

Windle and Cramb (1993) used CVM to estimate

values for preserving bushland in Brisbane, andconcluded that these were positive.

More recently, Lockwood and Walpole (1999) havereported on a benefit–cost analysis of remnant

native vegetation conservation in north-east

Victoria and the Murray catchment in southern

New South Wales. The costs of conservationoptions were first assessed in terms of the

economic costs to landholders in terms of

production foregone and other factors. This was

then compared with the benefits of conservation

options, which included impacts on mitigatingdryland salinity, reducing greenhouse gas

emissions, and the protection values held by the

State populations. These values, estimated usingthe Choice Modelling technique, were estimated at

$60.7 million for north-east Victoria, and

$75.6 million in the Murray catchment.

That study indicated that there were 113 313 ha of

remnant vegetation remaining on private lands innorth-east Victoria and 203 429 ha in the New

South Wales Murray catchment. The protection

values on a per hectare basis are thus $535/ha in

the Victorian area, and $372/ha in the New SouthWales Murray catchment. The study concluded that

the benefits of conservation outweighed the

opportunity costs, and that governments could

spend up to $29.8 million in north-east Victoria and$40.5 million in the Murray catchment on vegetation

protection to maximise community values.

5.2.4 Net on-farm benefits from treeclearing in Queensland

The draft Integrated Beef Industry Strategies (IBIS)

report (DPI, forthcoming), provides a summaryof financial returns and productivity indicators of

beef enterprises in four major regions (Tables 5.3

and 5.4).

Table 5.4 Productivity Performance Indicators. Source: DPI(forthcoming).

Performance Northern Central Central Maranoaindicator black Queensland west brigalow

spear- brigalow Mitchellgrass grass

Beef sold(kg/beast area) 106 132 86 142

Cost/kgbeef ($) 0.77 0.64 0.81 0.98

Gross margin($/ha) 7.54 40.06 10.34 38.24

Gross margins represent the difference between

gross income and variable costs. They aretraditionally used as an economic indicator to

compare enterprises because they minimise

comparative differences. The data in table 5.4

shows that the annual gross margins associatedwith beef production in brigalow country (which

has largely been cleared and developed) are much

higher than in speargrass or Mitchell grass country

(which is largely in its original state).

In Queensland, the commercial production benefitsavailable from tree clearing vary widely according

to the vegetation type and production

opportunities. After the initial clearing, there is a

spike in pasture production, followed by declinescaused by falling soil fertility and competition from

regrowth. ABARE (1995) quotes Burrows (1990) as

indicating that the removal of trees can increase

initial pasture production 2–7 times. Treatment ofregrowth can be used to maintain pasture

production above the preclearing levels.Burrows (1999) reports that the net present value

of clearing in the poplar box woodlands of central

Queensland ranges from $40–$64/ha, according todifferent timber treatments and allowing for a 20%

retention rate. In the Desert Uplands bioregion

further to the west, Resource Consulting Services

(RCS 1999) report from two case studies that thenet present value of developing ironbark and wattle

country is $12.34/ha, and $28.31/ha for ironbark

and box country.

In each of these cases, overhead expenses, unpaid

family labour and a return on capital invested inland and equipment have not been included in the

estimation of net returns per hectare. At the

property level, where landholders may be

considering additional clearing, this exclusion maybe commonplace. However, when these additional

costs are included to develop an overall picture of

net returns per hectare, the returns are likely to be

much lower. This is because these additional costsare a substantial proportion of inputs (see table 5.3).

Net property returns are analysed in Rolfe and

Donaghy (2000), who report that for many beefproperties across Queensland, net returns are very

low or negative. This is shown in figure 5.1, wherethe rates of return (incorporating overhead costs,

unpaid family labour and return on capital

invested) are reported by herd size over time. The

results show increases in the rates of return overtime (as seasons and market conditions improve),

but that, on average, enterprises running less than

1000 head do not meet long-term viability

standards. Approximately two-thirds of specialistbeef producers have less than 1000 head of cattle

(see table 5.5).



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Table 5.5 Queensland specialist beef producers by herd size.Source: ABARE (1998, 1999).

Herd size Number of Number of producers in producers in

1997–98 1998–99

<300 2 415 2 032

300–550 1 154 1 304

550–1000 787 804

1000–2800 1 131 1 2622800–5500 429 438

>5500 250 325

This summary shows that there are two importantreasons why beef producers are likely to be

involved in tree-clearing activities. The first is that

if only operating costs and returns are considered,

the returns from clearing and pasture developmentare attractive. If all costs and inputs are considered,

the returns from clearing and development are

lower. The difference between gross margins and

total returns suggests that landholders will oftenfind it profitable to develop an additional paddock

(on an ongoing incremental basis), but not

necessarily attractive to develop an entire property

immediately.

The second reason why clearing activities may beimportant to landholders is that they may be trying

to maintain or improve viability levels. Given the

substantial number of beef enterprises that fall

below long-term viability criteria (Rolfe & Donaghy2000), this may be a very important consideration

for individual producers. However, for a number of

smaller producers, it is very unlikely that clearingand development options on virgin vegetation areaswill be enough to redress viability issues.

5.2.5 Indirect external impacts fromtree clearing

There are several indirect impacts from tree

clearing that might be considered in a CBA

framework, such as those that reduce landdegradation. Examples of positive outcomes might

be clearing and pasture development measures that

reduce soil erosion, and that in some cases,address vegetation thickening and soil degradationimpacts. ABARE (1999) report that 63% of beef

producers surveyed in Queensland have declining

pasture productivity as a result of vegetation

thickening. This thickening is a widespreadphenomenon in Queensland, and in Australia more

generally, due to grazing pressure and suppressed

fire management since European settlement

(Flannery 1994; Burrows et al. 1997). The widercommunity may view favourably measures that

restore pre-European landscapes and production,

although as Burrows (1999) notes, there is somedebate about whether such clearing is restorationor development.

Clearing might also lead to land degradation

impacts, and thus invoke overall costs. In somecases, such as soil erosion, it is often not the initial

clearing that is directly responsible, but the

subsequent stocking pressures and management

activities. In other cases, such as impacts relatingto dryland salinity, clearing is directly associated

with indirect losses.

The impacts of many indirect effects of landclearing, such as dryland salinity, have been

generally poorly anticipated in Australia bylandholders, scientists and regulators. There is

increasing evidence that dryland salinity problems

associated with tree clearing may be more

substantial in Queensland than had previously beenconsidered (Williams et al. 1997; CSIRO 1999),

although areas affected by salinity remain at low

levels compared with those in States such as

Western Australia (Gretton & Salma 1996). Thissuggests that for some clearing options, the risks of

salinity impacts will need to be considered carefullyin any CBA.

One of the indirect impacts of tree clearing is the

subsequent release of greenhouse gases, principallycarbon in the form of carbon dioxide9. The major

release is likely to be from the burning and rotting

of above-ground vegetation once it has been

cleared. Other releases are likely to come from therotting and burning of below-ground biomass (e.g.

roots), and from changes in the organic carbon

levels in soils. At the same time, there may be

offsetting carbon sequestration effects, largely

through carbon taken up in increased pasturelevels, and in some cases, improvements in soil

carbon levels.

The overall loss of carbon from clearing activities is

difficult to quantify for a number of reasons(Burrows et al. 1997). The amount of biomass

varies across sites according to vegetation type, soil

type and climatic influences. The measurement of

carbon levels is imprecise because the developmentof the appropriate modelling relationships is in its

early stages and there is a limited amount of data

available. These difficulties are more pronounced forbelow-ground biomass and soil carbon levelscompared with those for above-ground biomass.

Carbon releases from different sources also occur at

varying rates, and both release and sequestration

patterns are confounded with seasonal fluxes. Theestimation of the actual areas of each vegetation

type is also imprecise, making it difficult to

extrapolate site data to aggregate amounts.

Given these uncertainties, some broad estimates ofthe amount of carbon that might be released from

tree clearing in some areas can be made. Burrows

et al. (1997) report that for the grazed woodlandsof northern Queensland, the average basal area ofall woody plants is 9.62 (+– 0.95)m2/ha. They also

report that the mean above-ground biomass of



110

eucalyptus trees (the dominant genus type in these

woodland regions) is 4235 kg of matter per m2 ofbasal area, or approximately 40.74 tonnes/ha10. At

approximately 46% carbon, the total mass of

above-ground carbon is 18.7 tonnes/ha.

To this estimate for above-ground carbon must be

added the below-ground stock (approximately 30%of above-ground stocks to a one metre depth) and

soil carbon levels. (Burrows, W. H. 2000, pers.comm., 25 April) suggests that net below-ground

and soil carbon stocks remain relatively unchangedafter tree clearing because below-ground biomass

decays tend to be balanced by pasture and soil

carbon increases. If this is the case, then the net

carbon loss from tree clearing in the northerneucalypt woodlands can be estimated at the above-

ground biomass of 18.7 tonnes per hectare. While

this estimate, is approximate it will give some idea

of the external losses associated with this factor oftree clearing.

Trade in carbon offsets is an emerging market, withmany initial trades occurring in the region of

around $10 US/tonne of carbon. Rolfe (1998)

summarises a number of international forestrycarbon offset programs as costing between $1.50

and $12.50 Australian11. Within that range, the

indirect losses associated with greenhouse gas

emissions from tree clearing in woodland regionsappear to lie between $28 and $233 per hectare.

Lockwood and Walpole (1999) selected $10/tonne

of carbon dioxide as an appropriate benchmark,

which converts to approximately $2.70/tonne of

carbon. At this price, the value of the loss ingreenhouse gas emissions from tree clearing in the

northern eucalypt woodlands is approximately

$50.50/ha.

More work is needed to quantify carbon lossesfrom tree clearing at the property level and to

estimate appropriate price levels.

5.2.6 Non-use values

The other category of external impacts to consider

is public values for biodiversity protection and thehealth of rural communities. Data on the value of

these impacts in Queensland is limited, but Rolfe,

Bennett and Blamey (2000) report some exploratory

estimates within an economic analysis of treeclearing in the Desert Uplands bioregion of central-

western Queensland.In that study, the Choice Modelling Technique was

used to estimate the preservation values that

households in Brisbane had for protecting bothenvironmental factors and the livelihood of people

in rural communities. The results can be illustrated

in a number of different options for increasing

vegetation protection, as shown in table 5.6. Thisindicates how much Brisbane households are

willing to pay for further restrictions on tree

clearing with different policy outcomes.

The results indicate that there are substantialpreservation values associated with options givinggreater protection to biodiversity in the Desert

Uplands region. The values are sensitive to impacts

on regional income and job losses, but are not

completely negated by these effects unless they arevery high (as in option E). The preservation values

do not correlate linearly with increases in

protection levels, but are weighted heavily towards

some increase in protection levels above thecurrent standard, and towards the protection of

endangered species.

Rolfe, Bennett and Blamey (2000) compared thenon-use protection values with the production

opportunities in the Desert Uplands to concludethat for slight to modest increases in vegetation

protection, the values of biodiversity protection

would outweigh both subsequent social impacts

and potential production losses. For moresubstantial levels of protection, the latter tended to

outweigh the former. However, the value of possible

greenhouse gas emissions may still make many

tree-clearing activities in the region uneconomicfrom the viewpoint of society as a whole.

Table 5.6 The amount that Brisbane householders are willing to pay for different preservation options.Source: Rolfe, Bennett & Blamey (2000).

Attribute Change from Change from Change from Change from Change fromcurrent trends current trends current trends current trends current trends

Option A Option B Option C Option D Option E

Jobs lost in the region 10 30 50 50 180

Regional income lost $5 million $10 million $5 million $10 million $10 million

Additional speciespreserved in area 2 10 2 2 2

Additional % ofnon-threatenedspecies preserved 30% 45% 10% 10% 10%

Additional area of uniqueecosystems preserved 10% 20% 30% 30% 30%

Amount $76 $88 $80 $74.50 $0



5.2.7 Measures to reduce tree-clearing activities

The evidence from the cost–benefit approach

outlined is that there are likely to be some

situations where tree-clearing activities are not

economic from a social perspective. However, theymay still be commercially attractive to the

landholder because landholders do not receive

signals about the indirect and non-use impactsof clearing decisions. In the presence of theseexternalities, policy makers have firstly to consider

whether the costs of those externalities outweigh

the production benefits, and secondly, whether it is

economic to change the situation.

It is not always worthwhile to correct externalitiesbecause of the administrative and transaction costs

involved, and the difficulties in achieving balanced

outcomes. For this reason, policy makers are

sensitive to the size of remedial costs, and to thesearch for the most efficient solutions to reduce

social losses. It is rare that a solution satisfies every

affected group in society, and more likely that a

solution (or group of solutions) will address only themajor losses caused by an externality. In applying a

potential correction measure, the policy maker has

to determine whether the benefits of the correction

outweigh the costs of the corrective measure.

There are a number of corrective measures that maybe employed to address externalities caused by

tree-clearing activities. Many of these have been

listed or reviewed by AFFA (1999). For example,

regulatory measures have advantages in that theyare compulsory, but may be inflexible, have high

compliance costs, and impose losses on some

groups. Improvements in knowledge can help

landholders to reduce short-term behaviour thatincurs long-term production losses, but may offer

little incentive to reduce public losses. Incentive

payments, in the form of biodiversity credits,

stewardship payments or carbon offsets may offersome flexibility in pursuing protection options, but

may be difficult to administer and audit.

The process of developing solutions to externality

problems can also be evaluated in economic

outcomes. Solutions that have low compliancecosts and are accepted by all affected groups tend

to minimise the transaction costs involved in

moving to different resource allocation rules.

Processes that give stakeholders and thecommunity some role in resource allocation may

appear expensive and difficult to develop, but

ultimately reduce subsequent transaction costs.

The involvement of stakeholder groups in regional

planning processes and negotiated settlements in

natural resource management often generatessubstantial economic benefits in terms of reduced

transaction and compliance costs. Among the

recommendations of AFFA (1999), are thatauthority relating to natural resource management

should be devolved to regional and catchment

areas, and that partnerships should be builtbetween all relevant parties to improve

management. There is an increasing role for social

scientists (e.g. economists, sociologists and regional

planners) in identifying and in negotiatingagreement between stakeholders about resource

management issues.

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112



113

6 Planning and monitoring native vegetation management

Contributors

Vegetation management planning


Richard Johnson, Environmental Protection AgencyBruce Wilson, Environmental Protection Agency

Rod Fensham, Environmental Protection AgencyMonitoring

Peter Johnston, Department of Primary Industries

Andrew Franks, Department of Natural Resources

Anne Kelly, Department of Natural ResourcesTeresa Eyre, Department of Natural Resources

Geoffrey Smith, Department of Natural Resources

return to contents

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114

Summary • Planning is the process by which individuals or

groups determine outcomes and strategies. Early

planning theory advocates a centralisedapproach in which it is instigated by government

agencies. More recent approaches advocate a

political process of bargaining and negotiating

among competing interests.

• Planning activities occur in a range of contexts(e.g. catchment or rangelands), and in association

with other planning activities. Collectively, these

make up planning systems. The ability of asystem to achieve sustainability and equity

depends on the collective understanding of natural

resource management problems, institutional

support for stakeholders in negotiating the issues,and capacity of these groups to participate in

inherently political processes.

• Regional approaches to planning are suitable for

dealing with problems of environmentaldegradation, conservation and sustainability. Inparticular, planning at this level can use the

dynamic approach of landscape ecology, and its

description of flows in ecosystems.

• Regional ecosystems, which can act as a

surrogate for biodiversity, offer a system onwhich to base biodiversity planning approaches

to sustainable vegetation management.

Bioregional planning systems should include

ecological links that reflect natural processes.

• Problems identified in a review of currentregional planning methods were: difficulty of

integrating information; different approaches to,

and practicalities of, problems; failure of

technical information to meet decision-makingneeds; inability to achieve full public

participation; and lack of integration in policy

and legislation.

• There are many opportunities for integrated

planning and community participation ineffective regional planning. However, a number

of principles and guidelines are recommended

including: ensuring that all elements are adaptive

and adequate, and are applied in a way that issustainable, equitable, accountable, integrated,

effective and efficient.

• Regional vegetation management plans (RVMPs)may provide opportunities to plan for sustainable

native vegetation management and integrationwith other natural resource management

initiatives. RVMPs may be guided by the

principles of planning systems theory to

contribute to the development of an improvedregional planning system.

• Property planning is used by landholders to

achieve a variety of outcomes. It can be used to

secure the long-term viability of a property and

to maintain ecosystem health, integrated pest

management and production values. Applicationsfor tree-clearing permits must be accompanied

by a property management plan.

• Property planning should consider the retention

of remnant vegetation for biodiversity andproduction. Recommendations for the amount of

vegetation to be retained will depend on the

planned land use. Retained areas can be in the

form of strips and clumps.

• Monitoring and modification of managementstrategies help ensure that planning systems

remain robust. Monitoring requires effectiveindicators of sustainability, and can be

conducted at various levels for a variety ofpurposes. There are a number of monitoring

tools and resources available. It is essential that

the objectives of any monitoring program be

clearly defined at the outset.



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Marsh (1998) describes a number of activities that

are conventionally associated with environmentalplanning (see table 6.1). He notes that the methods

and techniques used in environmental and

landscape (regional) planning are no different from

those in other areas of planning. These categoriesof planning are currently used in a number of

aspects of vegetation management.

Why plan?Dale and Bellamy (1998), in their review of the

evolution of regional planning theory, highlight the

debate in the literature between those who viewplanning from a technical perspective and those

who view it as a forum for negotiating across

conflicting agendas. The former advocates a

centralised planning approach whereby planning isinstigated by government agencies, the latter a

political process of bargaining and negotiating

among competing interests (Dale & Bellamy 1998).

Dale and Bellamy (1998) highlight that the focus of

the literature revolves around physical factors (eg:infrastructure development), resolving intra- and

international economic inequities and the

application of GIS and decision-support systems bycentral planning agencies. More recent approaches

in planning theory acknowledge that the planning

environment can be better described as ‘a complex

web of bargaining and negotiation among pluralinterests (including community, industry and

government)’ (Dale & Cowell 1999). These more

recent approaches to planning offer an opportunity

to use planning as a framework for negotiationamong diverse interests in land-use outcomes.

Changes in the economic, ecological and

sociological disciplines have converged towards a

system view of interactions and the relationships

between system components—in essence, agrowing acknowledgment that nothing happens in

6.1 Vegetation management planning

Unprecedented population pressure and the

demands of society are increasing the degradation

of resources and threatening ecosystem stabilityand resilience. The role of integrated planning to

meet these pressures has been highlighted by the

Commission on Sustainable Development (ad hoc

Working Group on Integrated Planning andManagement of Land Resources and Agriculture

2000). Traditional planning theory has evolved from

rational approaches towards communicative and

adaptive forms of planning. Dale and Cowell (1999)suggest that emerging landscape ecology concepts

are based on systematic and adaptive perspectives,

and that this shift in theoretical perspective, if

combined with the recent emphasis onsustainability concepts, can refocus planning for

sustainability. Vegetation management is integral to

land use and environmental change. This reviewhas highlighted the functional role of vegetation inthe landscape. Planning has frequently been used

in the past to manage native vegetation sustainably,

both formally (e.g. Tree Management Plans under

the Land Act 1994 (Qld)), and less formally (e.g.landholder property planning). In this section, the

challenges and opportunities of planning for

sustainable native vegetation management at a

number of levels in Queensland are examined.

6.1.1 Planning defined

Planning may be defined as ‘the coordination ofhuman activities with both natural and humanresources’ (Ramsay & Rowe 1995). It can be a

process used by individuals, groups or collectives of

groups to determine an agreed vision, a set of

objectives, or to determine strategies and monitorand evaluate outcomes (Dale & Cowell 1999).

Table 6.1 Conventional activities associated with landscape planning. Adapted from Marsh (1998).

Activities of landscape planning Description

Environmental inventory catalogue and description of the features and resources of a study area

Discovery of opportunity and constraints searching the environment for those features and situations that wouldfacilitate/deter a proposed land use

Site assessment providing environmental profiles of site/s

Land capability, carrying capacity, determining what types of use and how much use the land can accommodatesustainability planning without degradation

Hazard assessment and risk management identifying dangerous zones in the environment and building strategies andcontingency plans for coping with hazards

Forecasting impacts identifying changes required and evaluating the type and magnitude ofenvironmental impact

Special environments analysing and evaluating special environments (e.g. wetlands)

Restoration and planning assessing environments that have been degraded and require restoration

Site selection and feasibility studies assessing locations usually based on economic, more recently environmentalconsiderations, or determining the most appropriate use for known site

Facility planning siting, planning and designing installations that depend on structural and mechanicalsystems (e.g. sewerage plants, airfields)

Master planning may include all of the above, providing a comprehensive framework to guide landchange

Management planning providing comprehensive ongoing control to ensure sustainability throughcompatibility with greater land use



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isolation and that activities are nested withincontexts, either biophysical or social. Brunkhorst

(1995) suggests that these areas of research have

identified a previous failure by planning and

management to ‘produce practical information fordecision making and planning that meets

socioeconomic needs while conserving and

respecting the limits of biophysical resources’

(Brunkhorst 1995).

The response in planning theory has been theexploration of planning systems. Planning has been

largely viewed as discrete activities undertaken by

an agency or organisation. However, in reality, in

any given region (e.g. catchment) or context (e.g.rangelands) there are many planning activities

occurring which collectively comprise the planning

system (Dale & Cowell 1999). The system approach

identifies which units in the landscape are linkedand what activities impact on others. Essentially,

planning systems are the sum of activities at

different times and spatial scales, involve multiplestakeholders and seek to achieve value-basedobjectives (Dale & Cowell 1999).

An important aspect of this developing body of

natural resource management planning theory is

the greater expectation by the community of public

involvement in decision making and greateraccountability for environmental protection (Dale &

Bellamy 1998). This has resulted in the emergence

of a resource management paradigm based on

integrated ecosystem management and collaborativedecision-making. The health of the planning system

(i.e. its ability to achieve sustainability and equity)depends on the collective understanding of natural

resource management problems, institutionalsupport for stakeholders negotiating the issues, and

the capacity of these groups to participate in

inherently political processes.

6.1.2 Regional approaches toplanning

In dealing specifically with questions ofenvironmental degradation, conservation and

sustainability, planning is often inextricably linkedto concepts of ecological theory. For example,

planning for ecological networks owes itstheoretical foundations to the island biogeography

theory (MacArthur & Wilson 1967) and

metapopulation theory (Levins 1969). A great deal

of current ecological study acknowledges the needto look at environmental processes at the landscape

level (Barbault 1995; Tongway & Ludwig 1997).

Landscape ecology is a recently emerging discipline

that looks at environments on a ‘whole landscape’

scale to develop an integrated understanding of

these systems. In essence, it recognises that alllandscapes are mosaics of different habitat types,

and focuses on spatial patterns within these

mosaics, the influence of these patterns on

ecological processes, and how landscape mosaics

change over time. It also acknowledges that the

movement of animals, plants, water and wind, and

the flow of materials, energy and nutrients that aretransported in this way, are all central to the

functioning of the landscape and to its ecological

sustainability (Bennett 1999). Importantly, it

acknowledges the impact of both human-inducedand natural changes (McAlpin 1999). Landscape

ecology attempts to couple biodiversity, ecosystemfunction and larger scale processes (Brunkhorst

1995) and allows an opportunity to explore theecological function of habitat fragments in

developed environments.

In the same way that modern planning theory takes

a systems approach, so too does the ecological

study of landscape ecology. The importance oflinking these two disciplines lies in ensuring

landscape or regional approaches. There is

increasing recognition that ecologically sustainable

management and conservation of natural resourcescannot be tackled on a ‘site-by-site’ basis, but

needs to be dealt with at the landscape scale

(Kitching 1996; Sattler et al. 1997). Regional

planning can utilise the dynamic approach ofecology to understand and plan for the variability

and change that landscape ecology emphasises.

Landscape ecology provides the concepts and

techniques for conserving biodiversity and solvingland-use management problems.

Landscape planning (cf: land-use planning) is

concerned with resource allocation at the macro

scale where it was previously based on politicalboundaries, watersheds or other landmarks(Cook & van Lier 1994). Landscape or regional

planning seeks to meet the goals of ESD, aesthetics,

recreation and tourism, economics, human health

and ecological conservation, while satisfying theneed for complex inter-agency, multi-level planning

and management strategies that cross

anthropogenic or political boundaries (Cook &

van Lier 1994).

Biodiversity planning requires information on the

distribution of ecosystems, species and geneticvariation (section 3.2). While all biological surveys

are expensive, species and genetic surveys are

particularly time consuming and typically sampleonly a very small proportion of the total area of a

region and its species or species groups

(e.g. mammals and birds may be relatively well

sampled, but not invertebrates or lower plantspecies). This patchy nature of species and genetic

data is often addressed by using surrogate

measures of species distributions (Resource

Assessment Commission 1993; Wessels et al.

1999). Types of surrogates used in Australia forbiodiversity planning include mapped land classes

(vegetation and land systems) environmental

classifications derived from numerical analysis of



117

environmental attributes (e.g. terrain and soils) and

modelled species distributions. Recent work on theeffectiveness of surrogates for biodiversity suggests

that a range of the commonly used surrogates do

predict species distributions although the

effectiveness varies with type of surrogate, speciesgroups and regions (Ferrier & Watson 1997).

In Queensland, a system of defining regional

ecosystems has been developed (Sattler & Williams1999). They are defined as vegetation communities

in a biogeographic region, which are consistentlyassociated with a particular combination of geology,

landform and soil. They are widely used as a

biodiversity planning tool in Queensland in

conjunction with information on the distribution ofindividual species over much of the State. The

integrated nature of regional ecosystems is believed

to provide a robust classification for biodiversity

planning that maximises their use as a surrogate forother levels of biodiversity (Sattler & Williams 1999).

Regional ecosystems generally provide an effectivesurrogate for biodiversity. The use of this

classification can be justified on the grounds that

they are derived in a systematic way based onsound ecological principles and that they can be

mapped. Maps are advantageous in biodiversity

planning because the definition of the status (e.g.

intact or reservation ) and the distribution of ourbiota, are critical The regional ecosystem

classification is used to define the range of

ecosystems needed to provide habitat for the full

range of species-level biodiversity.

The use of the bioregional or regional classificationof ecosystems is often referred to in the concept of

‘bioregional planning’. Powell (1996) notes that the

application of the term ‘bioregional’ in the context

of planning in Australia ‘emphasises the supremacyof natural units over other jurisdictional areas,

including political divisions’. Powell maintains that

the process not only includes the importance of

ecological entities, but also expands spatial visionand promotes public participation in the process.

The Global Biodiversity Strategy defines a bioregion

as being:• large enough to maintain the integrity of itsbiological communities, habitats and ecosystems

• having cultural identity and a sense of home to

its local residents

• containing a mosaic of land uses• having components which are dynamic and

interactive (Lambert & Elix 1996).

Brunkhorst (1995) asserts that a strategic

bioregional framework for planning and

management should reflect nature and society. Hesuggests that it should be ‘multi-stakeholder groups

that are striving to establish cooperative programsthat address ecological, cultural and economic

issues at the scale of the regional landscape’. Healso recommends that the management paradigm

be ecologically sustainable use, strongly supported

by research and monitoring, core protected areas,

rehabilitation, and the reduction and managementof human impacts.

Historically, conservation of biodiversity has been

restricted to protected or reserve areas, but their

establishment has generally been opportunistic.

Such areas continue to play a role in conservation,but it is increasingly acknowledged that the reserve

system is not in itself the solution. Brunkhorst(1995) suggests that the function of reserves should

go beyond protection, as they represent areas forrehabilitation of environments, nutrient sinks,

landscape stability, and the replenishment of

species assemblages and recruitment. The

recognition of the need to connect these reserveswith outside areas has led to the inclusion of

ecological links in bioregional planning, and reflects

the concepts developed in landscape ecology.

Brunkhorst (1995) asserts that ‘these connectivitiesalready exist in nature—we need human

management systems which reflect these naturalprocesses—a bioregional planning framework could

help achieve these common goals.’ Dale andBellamy (1998) note however, that regions are far

more frequently based on administrative and

economic factors than bioregional considerations.

On a geographically lower level than bioregional

planning, there has been the evolution of strategicplanning, at metropolitan and local levels (Neilson

1996). Neilson defines strategic plans as a means

of addressing the broadly-based, forward planning,

economic, social, cultural and environmental

aspects of development as well as the social andeconomic infrastructure.

The Department of Natural Resources (DNR

1999e), in providing guidelines for the development

of regional strategies, describes regional planningas the linking mechanism between bottom-up

community planning (i.e. property and catchment

planning) and top-down principle-based

institutional planning (e.g. internationalagreements, national and State-wide natural

resource management strategies). They emphasise

the need for this intermediate level to integrate wellwith surrounding levels of planning.

Opportunities and limitations of regionalplanning

Dale and Bellamy (1998) argue that while there hasbeen substantial regional planning, its effectiveness

has been limited. They note the following issues

hindering implementation of integrated regional or

landscape planning schemes or strategies:• The practical problems of integrating information

that is disparate across time, space and

academic boundaries, thus inhibiting theintegration and sharing of information.

• The difference in the character of the problem

and the available analytical approaches or

institutional arrangements.



Box 6.1 Principles for regional resource-use planning.Source: Dale & Bellamy (1999).

6.1.3 Planning for vegetationmanagement

This review has examined in detail many of thescientific arguments for how and why native

vegetation in Queensland should be managed. This

section has demonstrated both the opportunities

and the limitations of planning in sustainablenatural resource management, particularly at

regional scales. In considering Queensland’s

substantial native vegetation resource, it is evident

that planning certainly has a role to play inaddressing the threats and opportunities involved

in securing its sustainable management. As

highlighted in section 2, a number of legislativeinstruments have adopted planning approaches tomanaging natural resources, for example in the

Integrated Planning Act 1997 (Qld) and in particular

managing native vegetation, for example, Tree118

• Sustainability—planning needs to achieve

sustainable outcomes in natural resource

management, although measurement anddefinition of sustainability are vexacious, and

there has been limited integration of economic,

social and ecological sustainability.

• Equity—is closely associated with an

individual’s overall judgement of the inherent

fairness of the planning process, and willdetermine willingness and commitment to the

outcome.

• Accountability—those planning activities must

be accountable to the stakeholders, and thisreflects governments’ accountability to their

constituents.

• Integration—poor integration between planning

disciplines, activities and institutional

arrangements has previously caused planningproblems This has resulted in inefficiencies and

inequities, favouring economic rather thansocial and environmental objectives.

• Adequacy—checks that negotiatory and

participatory elements are working, and askswhether interventions are being applied at

appropriate levels to get the job done.

• Effectiveness—means checking that planning

activities result in meaningful and effective

outcomes.

• Efficiency—represents outcomes achieved frominputs to the planning process, and must not

be considered in isolation from thoseoutcomes.

• Adaptiveness—planning systems must

demonstrate the capacity to make strategic andoperational change.

• The fact that there is often a mismatch between

the available technical information and decision-making needs.

• The inability to gain full public participation in

the decision-making process because of

ineffective institutional arrangements.• The lack of comprehensive integration of

legislation, administrative responsibilities and

operational management that would reflect the

complexities and interrelatedness of the variouselements of the natural and human resource

systems.

An integrated approach to environmental planning

and management is an important and emerging

element of regional planning. Dale and Bellamy(1998) report that much of the conceptual

development and experience in Australian regional

planning relates to catchment management.

However, these concepts have proved difficult toimplement in practice because integrated

environmental management is a developing conceptand lacks a well-defined body of guiding principles.

They also argue that ecological theory has beenpoorly integrated into the planning literature. If

resource use planning is to occur in Australia, then

facilitators will need to craft their own approach to

meet the political context. They recommend thatthe following three core elements are required for

regional planning:

• effective application of technical information (in

the biological, social and economic sciences) andappropriate information technologies to assist in

structuring frameworks for negotiation amongstakeholders and to better inform the negotiation

process• structuring, operating, institutionalising,

implementing and monitoring regional planning

in a way that facilitates active negotiation among

stakeholders within the planning arena• processes which ensure that stakeholder groups

involved in the planning negotiations are able to

represent their constituents through appropriate

participatory methods, giving credibility to theagreements negotiated as a result of the regional

planning process.Dale and Cowell (1999) argue that in order to

improve the health of the planning system at a

regional scale it is necessary to :• build regional sectoral capacity

• establish a better institutional basis for

structured negotiations at the regional scale

• ensure that each stage of the process is wellinformed by technical information.

Dale and Bellamy (1998) argue that there are key

principles that should underpin such activities, and

be used to assess the effectiveness of regionalplanning. These include ensuring that all elementsare adaptive and adequate, and are applied in a

way that is sustainable, equitable, accountable,

integrated, effective and efficient (see box 6.1).



Management Plans under the Land Act 1994 (Qld).

With the introduction of the Vegetation Management

Act 1999 (Qld)12, there are further opportunities to

manage native vegetation through planning and

strategic processes both on the property and at

regional scale.

In particular, the Vegetation Management Act 1999

(Qld) provides for the development of regional

vegetation management plans (RVMPs) by regionalcommittees.

In essence these regional committees will:

1. Prepare a regional vegetation management plan

for a given region that will include:• outcomes for vegetation management

• a code for the clearing of vegetation on

freehold land under the Integrated Planning Act

1997 (Qld) which achieves the purpose of theState code

• local guidelines for tree clearing on leasehold

and State land under the Land Act 1994 (Qld)

• other actions proposed to achieve theoutcomes.

2. Formalise guidelines for achieving best practice

vegetation management in the region.

3. Prepare a spatial representation of the RVMP.

4. Develop and implement consultation and

communication strategies for the formulation ofthe RVMP.

It is possible that the RVMP process, or associated

regional strategies, may facilitate the following :

• the integration of the RVMP and vegetationmanagement with other natural resourcemanagement initiatives in the region

• monitoring, reviewing and evaluating the RVMP

• the regional delivery of sustainable native

vegetation management services, includingincentive programs for landholders

• the identification of areas to be declared as

having high nature conservation values or as

vulnerable to land degradation.

Development of RVMPs presents the opportunity touse the processes developed in landscape ecology

and the concepts of participatory approachesdeveloped in planning theory. Up-to-date

information on the extent and conservation statusof native vegetation is available through the

Queensland Herbarium’s Regional Ecosystem

Mapping project (see section 1.2) and offers an

ecological basis for vegetation planning, rather thanboundaries based on social or administrative

considerations. By basing plans on regional

information, generic State-wide guidelines can be

refined locally, and regional land degradation riskscan be assessed. It is important that these

opportunities and limitations are considered in

developing RVMPs. A planning systems approach

would specifically argue that RVMPs should not beexpected to solve a region’s problems, but could

constructively contribute to the development of an 119

improved regional planning system. It would thenrecommend some clear parameters for use in

conducting the RVMP process.

Lambeck (1999) has described an approach to

regional biodiversity conservation in agricultural

areas that uses an evaluation of the conservationneeds of at-risk plant and animal species as a

template for planning vegetation retention and

configuration. Information of this kind can be usedas a basis for regional vegetation planning.The challenge for government agencies and

community groups is how to develop methods of

implementing regional plans through actions at the

property level. While legislative changes willprovide an impetus, successful vegetation

management is likely to depend on fostering a

sense of ownership of the issue among landholders

and successful facilitation of an integratedecosystem approach.

6.1.4 Property planning

Landholders use a variety of formal and informal

plans to manage their properties for production.The Department of Land and Water Conservation,

New South Wales (1995) describes property

management planning as the process of analysis

and then planning property operation frompersonal, physical and financial perspectives.

Planning the management of vegetation in

particular can help to:

• secure the long-term viability of a property• protect biodiversity and prevent soil erosion and

salinity• protect catchments and keep them healthy

• control pests using integrated pest management• provide production values such as shade and

shelter.

Under both the Land Act 1994 (Qld) and theVegetation Management Act 1999 (Qld), applications

for a permit to clear trees must be accompanied bya property vegetation management plan (PVMP)13,

which details the type, area and location of

vegetation proposed to be cleared.

Formalising PVMPs may assist landholders byincreasing awareness of vegetation on the property,

identifying areas vulnerable to degradation that

should be retained and identification of areas of

degradation. The general principles of planningapply at this level of planning as they do to other

levels.

6.1.5 Configuration of remnantvegetation

The trend has been to clear the most productive

elements within a landscape completely and to

leave surrounding, less productive areas with thevegetation intact. While this may ensure that a

large area of the property or paddock remains

covered in woody vegetation, it reduces habitat

diversity. To maintain and conserve biodiversity it is



120

recommended that 30% of each regional

ecosystem is retained (see section 4.1).Importantly, the mix of land uses should be

considered and threshold parameters taken into

account. For example McIntyre et al. (1999)

recommend a mix of 30% retention of woodyvegetation, 10% of the area managed specifically

for wildlife and a maximum of 30% used

intensively (cropping, exotic pastures). These, in

combination with other thresholds, are required tosupport the bulk of plant and animal species in

grassy woodlands in south-east Queensland.

The most appropriate configuration of retained

vegetation will depend on the planned land use.

For example, where potential salinisation is aconcern, intake areas should support native woody

vegetation; where shelter from cold winds is

required, south and south-western slopes should

be left covered by trees. Where trees encouragegrowth beneath their canopy, some scattering of

trees may be beneficial. Scattered trees may alsoreduce temperature extremes and in tropical to

subtropical environments this may be sufficient toprevent frosting of pastures (McIvor 1990a).

Retained vegetation can be in the form of strips or

clumps. Clumps are more effective in that a greater

proportion of the total retained area is natural

(minimal edge effect) compared with strips (seesection 4.1.2). The wider the strip, the larger the

natural habitat area for the same reserved area.

Strips should also interconnect with large

undisturbed or natural habitat (clumps or

reserves). Clumps must be large enough to supporta viable population of wildlife and should be joined

to other native vegetation areas to allow movement

between major reserved areas (Bennett 1999). It isimportant to diversify structure (i.e. a combination

of strips, clumps and patches) to allow greater

resilience to disturbances.

Another option for retaining some woody vegetation

and increasing livestock carrying capacity is to thinthe existing stand, leaving a savanna landscape.

This has aesthetic appeal, but in most situations a

savanna is undesirable. Problems may include: 1)the habitat for native fauna and flora isdramatically altered (unless the original vegetation

was a savanna and the density had markedly

increased); 2) that remaining trees are likely to have

a shorter lifespan, and are more prone to insectand disease attack, and to fire damage; (see section

4.2.1 Dieback); 3) that pasture production is often

lower from a savanna landscape than from an area

in which the equivalent number of trees wereretained in undisturbed habitat while the

complement of the area was cleared (Burrows et al.

1988a); and 4) the mature remaining trees are seedtrees that ensure a seed source to re-establish newtrees, thereby creating an inherent regrowth

problem. As few as 40 trees/ha, each 10 m high,

can result in three-quarters of an area being subject

to seed rain, whereas the same number of smallertrees potentially impacts a mere 10% of the area.

However, a savanna landscape can be desirable

where the canopied zone is more productive than

the interspaces. Reasons for this include increased

total soil nutrient levels (Dowling et al. 1986;Ebersohn & Lucas 1965), and indirect effects of

shade (Wilson et al. 1986; Wilson et al. 1990a).However, this situation occurs in very limited areas

within Queensland.

6.1.6 How do the different layers ofplanning relate?

The emphasis of these initiatives on decisionmaking at the property level is understandable,

given that the individual property is the unit for

resource use decisions. However, approaches to

resource management based solely at this level donot always adequately address the wider-scale

issues involved. The geophysical and ecologicalinfluences of soil, water and vegetation use operate

at scales well beyond the borders of individualproperties. Hence, a broader perspective is required

for long-term, ecologically-based, rational resource

use. Incremental degradation of resources is a well-

known phenomenon. At the same time, land tenureis a fundamental part of the management

environment and broader objectives cannot be met

without the involvement of all resource users.

There is a need to combine regional issues andmanagement strategies with the implementation of

actions at a property scale that collectively

addresses these issues. Over the last decade or

two, the development of the landcare movementand integrated catchment management has been a

positive response to this need. For example, the

goals of the Queensland Decade of Landcare (DNR

1997) include the minimisation of adverse effects ofland use and the integration of production and

nature conservation, assessing needs on a regional

rather than an individual farm basis. Similar

strategies have been identified by numerous other

community-based, resource management groups.Various legislative instruments (see section 2.0),

and other institutional arrangements (e.g.

catchment and property management plans)operate to provide a wide range of planning

activities in the regions. The Broadscale Tree

Clearing Policy (1997)14 incorporated regional

issues such as protection of riparian areas andconservation of threatened plant communities, but

still primarily addressed these issues through

prescriptions at the property level. RVMPs offer the

opportunity to plan ‘upwards’ from the property,

bringing the details and experience at this level upto the regional approach, and incorporate already

established regional strategies and plans to develop

an integrated, and improved planning system.



6.2 Monitoring The use of adaptive management is an important

aspect of regional planning (Iles 1996; Dale &

Bellamy 1998). Adaptive management is anapproach to environmental policy that treats policy

measures as experiments to be learned from

(Iles 1996). By monitoring the results of policy or

planning, modification of management and

strategies can be made via a feedback loop. Thisapproach contrasts the traditional, centralised, top-

down, static framework for management and

acknowledges the dynamic nature of ecosystems.Monitoring requires that there be effective indicators

of sustainability to measure. These indicators may

monitor productivity and ecosystem health.

Medium to long-term monitoring of the effects ofmanagement is vital because:

• it is important to keep a record of impacts within

a remnant after any management action, so that

an understanding of the effect of a range ofmanagement prescriptions can be constructed

• repeated observations and monitoring are

necessary to assess whether adapted land-

management practises are having the desiredeffect. If not, they can then be altered accordingly

to allow for the amelioration of impacts.

Monitoring at the property scale includes those

managerial functions that are necessary to

measure the performance of a property withrespect to its progress toward achieving the goals

and objectives established during the planning

phase (Stuth et al 1991). There are two maincomponents to monitoring:• gathering and maintaining information

• analysis and interpretation of this information to

measure performance and diagnose problems.

The monitoring of livestock numbers, livestock

productivity (growth rates, wool returns,reproductive rate, livestock sales etc.) are generally

the most useful indicators of productivity and

economic status (Wilson et al. 1990b). However,

animal productivity is not always a good indicatorof resource condition, as animal production can be

maintained for some time after pasture

deterioration has occurred (Beale et al. 1984). It is

important to recognise that no single measure orstandard technique will describe the ‘condition’ of

the land resource. The type of land use and the

objectives of management will define the specific

attributes that should be measured and the way inwhich they are measured (Wilson et al. 1990b).

The purpose of monitoring land resources

For pastoral enterprises, the major source of

income is from the production of livestock. The

long-term viability of a property therefore depends

on maintaining the condition and vigour of thevegetation on which livestock graze (Muir 1992).

It therefore makes sound business sense to monitor

the condition of the major resources of theenterprise (vegetation, water and soils).

Monitoring the productivity of vegetation primarily

involves measuring changes in vegetation, and

subsequent effects on livestock production and soil

erosion. Vegetation is easier to measure, can beinterpreted in terms of its effects on potential

productivity and soil protection and is a moresensitive indicator of ecosystem change than

livestock are (Wilson et al. 1990b). Monitoringchange in vegetation condition can therefore

enable adjustment of land management practices

(Bonham 1989).

It is traditionally accepted that remnant size, shape

and proximity to other areas of native vegetation arecritical variables affecting the persistence of native

species and the invasion by exotic species (Saunders

& Hobbs, 1991). Other factors affecting the condition

and functioning of remnants include the type and

intensity of disturbances that the remnant has beensubject to, and the vegetation types, which vary in

their levels of natural resilience and resistance to

change. Despite these influences, degradedremnants are still valuable in the landscape in terms

of property productivity and regional conservation,

although it is assumed that remnants with a higher

degree of naturalness are better able to providethese values across the landscape.

Monitoring of remnant vegetation allows anevaluation of existing land-management practicesand assesses the potential impacts on the condition

and long-term viability of the remnant patch orstrip. (Dallmeier & Comiskey 1998)

At present there are few published studies in

Queensland that deal specifically with remnant

condition and function in terms of community

structure, impacts of disturbance and habitat values.

The effective long-term management of remnantvegetation requires adequate property-level,

baseline data to enable better informed

management decisions. From a landholder

perspective, the simplest and most effective method

of monitoring is to record all observations andmanagement actions affecting remnant vegetation.

Photographs of the remnant may be included for

future comparisons, especially as evidence ofthickening of the understorey shrub layer, or of

degradation of vegetation condition over time.

Photographic records are an effective means of

assessing change over time or as a means ofcomparing the condition of similar forest types that

have been subject to varying management

practices. A property map including locations of

remnant strips and patches of native vegetation will

be useful in providing baseline data.

121



Endnotes1 Under the Vegetation Management Act 1999 (Qld), ecosystem

status is assessed using criteria relating solely to habitat loss asindicated by the preclearing and remnant area. This differs fromthe ecosystem conservation status in Sattler & Williams (1999),which includes criteria relating to other threatening processessuch as grazing degradation. (See table 1.6.)

2 Note the impact of Mabo and Others v. Queensland (No. 2)175 CLR 1. Since European settlement, land administration inAustralia has been based on the traditional doctrine thatAustralia was terra nullius (land belonging to no one) at the timeof European settlement. The decision in Mabo (No. 2) establishedat common law that native title may have survived where it hadnot been lost or extinguished. Where native title has been lost orcompletely extinguished there are no rights remaining to berecognised. Where native title continues to exist, the commonlaw recognises the rights of the native titleholders in a similarway to the recognition of the rights of ordinary titleholders.

3 Note that this is currently under review.

4 Department of Primary Industries recommendations of 20% areretention levels beyond ‘vulnerable’ areas, (e.g. steep slopes,riparian zones etc.).

5 This estimate, made in 1991 (Gordon 1991), was based on asurvey of regional extension staff. At the time, Department ofNatural Resources extension staff estimated that 10 000 ha were

severely affected and approximately 75 000 ha were at risk. Thisfigure may now be an underestimate, as the area at risk in theMurray–Darling basin within Queensland has recently beenestimated at 600 000 ha (MDBC 1999).

6 This is the proportion of applied water required to drain throughthe root zone to maintain soil salinity at an acceptableconcentration.

7 ‘Forest’ is an area, incorporating all living and non-livingcomponents, dominated by trees having usually a single stemand a mature or potentially mature stand height exceeding twometres, and with existing or potential crown cover of overstoreystrata about equal to, or greater than 20%. It is also sufficientlybroad to encompass areas of trees that are described aswoodlands (DPIE 1998a).

8 Some clearing may also occur for other reasons, including

experimentation with pasture development on ‘new’ landscapetypes; making the area easier to muster; and responding to therisk that governments might impose further clearing restrictions.However, the dominant expectation is that clearing will increaseoverall returns.

9 The material in this paragraph and the following four paragraphson carbon emissions has been taken from Rolfe et al. (2000).

10 W. H. Burrows (2000 pers. comm., 25 April) reports thatestimates of above-ground biomass for eucalypts in northernQueensland are being revised upwards, and may beapproximately 6 tonnes per m2 of basal area.

11 Prices for carbon offsets are likely to fall further as newopportunities for offsets are found and markets continue todevelop.

12 Not yet proclaimed, at the time of publication.

13 Referred to under the Land Act 1994 (Qld) as a treemanagement plan.

14 Replaced in 1999 by A Broadscale Tree Clearing Policy forLeasehold Land.

There are many vegetation and soil monitoring

tools available in Queensland. These range fromintensive procedures used by researchers

examining specific ecosystem processes to simple

techniques used by land managers to visually

monitor trends in vegetation. Detailed descriptionsof the steps to consider when developing a

monitoring program can be found in Brown 1954;

Bonham 1989; Wilson et al. 1990b; DNR 1999d;

and Forge 1997.

For land administrators who are interested in aregional perspective, some major tools are

available. Firstly, the TRAPS and QGRAZE network

of vegetation monitoring sites established across

Queensland. Secondly, the remote sensingmonitoring conducted by the Department of

Natural Resources in the Statewide Landcover and

Trees Study (SLATS).

It is essential that the objectives of any monitoring

program be clearly defined at the outset. This will

greatly assist in determining what will be measuredand how it will be measured. It is essential to focus

on the plant, water and soil characteristics that can

be monitored to detect change at a scale relevant tothe level of management.

122



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Appendixes

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124

The dominant land use of the region is cattle

grazing on native pastures. The region is sparselypopulated. Pastoral leases cover most of the region

and stocking levels are reasonably low. The only

broadacre clearing has occurred in the south,

where gidgee ( Acacia cambagei) communities have

been cleared, mainly on clay soils.

3. Cape York Peninsula

The Cape York Peninsula bioregion extends fromthe northern tip of Queensland to Cooktown on its

southern border.

The region receives a high, though strongly

seasonal (summer) rainfall. Much of the region is

dominated by gently undulating plains and plateauswith sandy earth, relatively deep, but low nutrient

status soils. The dominant vegetation is ‘savanna’

woodlands; typically Darwin stringybark (Eucalyptustetrodonta) and related Eucalyptus spp. with a tallgrass understorey. Lower lying areas often support

paperbark (Melaleuca viridiflora) woodlands. Closer

to the coast there are estuarine and alluvial plains

supporting a range of mangroves, wetlands, vineforests, fringing woodlands, grasslands and a

diverse array of other coastal formations. Mainly

sandstone, but also older volcanic geologies form

ranges and low hills supporting various Eucalyptusspp. and Corymbia spp. woodlands and scattered,

mixed species vine forests.

Pastoral leases, conservation reserves and Deed ofGrant in Trust (Aboriginal land) cover most of the

region. The region is considered to be in a relativelynatural state with the dominant land uses being

cattle grazing on native pastures, tourism, nature

conservation, support for traditional Aboriginal life

and some mining. Broadscale clearing for moreintensive agricultural management is not

appropriate.

4. Mitchell Grass Downs

The Mitchell Grass Downs bioregion occurs in a

horizontal band across the largely semiarid centralwest of Queensland. The region is dominated by

undulating plains with deep, heavy, clay soils

formed from the underlying Cretaceous shales.These areas support mainly Mitchell grass ( Astreblaspp). tussock grasslands (the ‘downs’) sometimes

with a low tree layer of gidgee ( Acacia cambagei)and other species (the ‘wooded downs’).

The undulating plains are drained by several river

systems, south into the Channel Country bioregion

or north to the Gulf Plains and the ocean. The

associated floodplains support a range of coolibah(E. coolabah) woodlands and grasslands–forblands.

Low, dissected, deeply-weathered residuals with

shallow soils supporting a range of sparse acacia

or cassia shrublands are also scattered across theregion.

The bioregions of Queensland group the State into

areas with broadly similar landscape patterns.These areas provide a useful context for assessing

the natural resources of the State. Following is a

general overview of the regions including major

geology, landform, soils, the characteristic native

vegetation and ecosystems and the dominant landtenure and use that the regions support

(summarised from Sattler & Williams 1999).

1. Northwest Highlands

The NorthWest Highlands bioregion lies in the far

north-west of the State adjoining the Northern

Territory border. The region is characterised bystony hills and ranges, often formed from old,

heavily folded sediments or limestone. The

dominant vegetation type is the ubiquitous snappy

gum (Eucalyptus leucophloia) in open woodlands

with a spinifex Triodia spp. ground layer. Sandsheets overlying older rocks occur at the foot of the

ranges, particularly along the south-western edge

of the region. These areas support E. leucophloiaand other eucalyptus open woodlands. Rivers, and

associated sandy and clayey floodplains drain the

region south into the Mitchell Grass Downs, or

north into the Gulf Plains, and support a range ofopen woodland shrublands and open

grass–forblands. Areas of gidgee ( Acacia cambagei)shrubland occur scattered across the region on

alluvium or clay soils derived from underlying

Cretaceous sediments.

The major land uses within the NorthWest

Highlands are mining and extensive cattle grazing.

The region is sparsely populated. Due to the low

and erratic rainfall, trees are cleared mainly forroutine management purposes.

2. Gulf Plains

The Gulf Plains bioregion extends around the

southern and eastern shores of the Gulf ofCarpentaria, between the Northern Territory border

and the Mitchell River. The region is characterisedby the extensive alluvial plains of the large river

systems that drain the area to the northerncoastline. These areas support mainly blue grass

(Dichanthium spp). grasslands and various open

woodlands dominated by species such as coolibah

(E. microtheca), guttapercha (Excoecaria parviflora),Corymbia spp., gidgee ( A. cambagei), paperbark

(Melaleuca spp). and bauhinia (Lysiphyllumcunninghamii).

Along the coast are extensive estuarine areas and

floodplains supporting mangroves, sedgelands and

grasslands and providing important wetlandhabitat. Gently sloping sandstone tablelands along

the eastern margin of the region support a variety

of eucalyptus woodlands and lancewood( A. shirleyi) low, open forests.

Appendix 1 Overview of the bioregions of Queensland



125

Most of the region is used extensively for grazing of

sheep and cattle production. Land tenure is mainlyleasehold, with freehold occurring commonly in the

south-east of the region.

5. Channel Country

The Channel Country bioregion occurs in the aridsouth-west corner of Queensland. The region is

characterised by the Channel Country—the vast

(often 10–50 km or more wide) braided floodplainsof the Georgina, Eyre, Cooper and Diamantinarivers and creeks, which supply most of the water

in the land locked Eyre Basin to the south-west.

These river systems support a range of herbfields,

grasslands, terminal swamps, claypans, lakes andfringing eucalypt woodlands.

Wetlands in these areas provide important

ephemeral habitat for enormous water-bird

populations. The floodplains are surrounded by

undulating gravel or stone (gibber) covered plains

supporting Mitchell Grass ( Astrebla spp.) grasslandand forblands. Further away are low dissected

residuals, which support a range of acacia–senna

sparse shrubland communities. In the south-westof the region, but also scattered across it, are sand

dunes and plains supporting sparse spinifex

hummock grasslands and an arid desert flora

and fauna.

The dominant industry in the region is cattlegrazing, with smaller areas used for mining and

tourism.

6. Mulga LandsThe Mulga Lands bioregion occurs in the semiarid

central south of Queensland. The region is

dominated by flat, to gently undulating plains, with

low nutrient status red earth soils derived fromQuaternary deposits. These areas support mainly

mulga ( Acacia aneura) shrubland and woodlands.

Low, dissected, highly-weathered hills with shallow

stony soils support Acacia spp. shrublands. Poplarbox (Eucalyptus populnea) woodlands occur on

lower-lying alluvial areas or in the eastern parts of

the region, across the surrounding plains as a

co-dominant with mulga. More fertile and moistareas supporting coolibah (E. coolabah) woodlands

and Mitchell Grass ( Astrebla spp.) herb grasslands

are scattered across the region, associated with the

floodplains of major rivers and smaller drainagelines. Brigalow ( Acacia harpophylla), in the east, and

gidgee ( Acacia cambagei) woodlands or shrublands

are also scattered across the region, occurring on

alluvial soils or soils produced from underlyingCretaceous shales.

Most of the land in the region is used for cattle and

sheep grazing. Intensive land clearing is morecommon in the eastern parts of the region. Land

tenure is mainly leasehold, although freeholdtenures are more common towards the eastern part

of the region and the Warrego River floodplain in

the central south.

7. Wet Tropics

The Wet Tropics bioregion is situated along the

tropical east coast of northern Queensland. Theregion is dominated by rugged mountain ranges,

which include the highest mountains in

Queensland. These areas are formed from granites

and other old sediments and meta-sediments. Themountains, and some of the associated lower hills

and undulating plains, which receive a high andconsistent rainfall, often support an extremely

diverse array of the lush, complex, tropicalmesophyll rainforest and vine forests which

characterise the region.

Above the mountains, along the western edge of

the region, are extensive plateau areas with basalt-

derived, fertile, soils that support both rainforestsand eucalyptus forests. Below the mountains are

low-lying coastal plains that support eucalyptus

and melaleuca woodlands. Mangroves, samphire,

beach vine forests and other communities occur on

the saline estuarine plains and adjacent coastallandscapes.

Clearing is largely restricted to the plateau areas

where small cropping and dairying are the major

land uses, and to the coastal lowlands, where sugarcane production is the major industry. Tourism and

nature conservation are major land uses for the

World Heritage listed rainforest areas of the region.

8. Central Queensland Coast

The Central Queensland Coast bioregion is centred

upon the high rainfall coastal lowlands, hills andranges around Byfield in the south, and

Carmilla–Proserpine in the north. Subcoastal andcoastal rugged ranges and lower hills support

broad-leaved evergreen, rain and vine forests or a

range of eucalyptus and corymbia forests and

woodlands. The lower-lying coastal and alluvialplains support a series of melaleuca and

eucalyptus dominated woodlands. Adjacent to the

coast, mangroves and samphire occur on saline

estuarine deposits. Eucalyptus, banksia andmelaleuca woodlands and wetlands occur on

coastal sand and dune complexes.The major land uses include sugar cane on the

lower lying alluvial and adjacent plains and cattle

grazing. Flatter parts of the region have beencleared extensively for agriculture.

9. Einasleigh Uplands

The Einasleigh Uplands bioregion straddles theGreat Dividing Range in inland north-east

Queensland. The region is mainly undulating to

hilly, with some rugged ranges and plateaus. Most

of the region is covered in eucalyptus woodlands;

common species include E. drepanophylla, E. crebra,E. microneura, E. cullenii and E. brownii. Low hills

and ranges support bendee ( A. catenulata)

lancewood ( A. shirleyi) open forest, or eucalyptus



126

low open woodlands. Tertiary lava flows are a

distinctive and common component of the southernhalf of the region. These areas support ironbark

woodlands, vine thickets and smaller but distinctive

lake and seasonally flooded vegetation communities.

Most of the region is leasehold land, although areas

of freehold are widespread in some parts such asthe area near Charters Towers. The major land use

is extensive grazing, although cropping is locallysignificant. Clearing is largely restricted to freehold

land, usually for cropping or horticultural purposes.

10. Desert Uplands

The Desert Uplands bioregion lies in central

northern Queensland, straddling the Great Dividing

Range between Blackall and Pentland. The region isdominated by sand plains supporting eucalyptus

open woodlands; widespread dominant species

include E. similis, E. whitei, E. melanophloia and

E. populnea/brownii. Low sandstone ranges carry a

variety of eucalyptus woodlands and lancewood( Acacia shirleyi) and bendee ( A. catenulata) low,

open forests.

More fertile clay soils derived from alluvium,

Cainozoic clay deposits or underlying Cretaceoussediments support gidgee ( Acacia cambagei), black

gidgee ( A. argyrodendron) and some brigalow

( A. harpophylla) and Mitchell Grass ( Astrebla spp.)

grasslands. Large, ephemeral lake systems and theirassociated surrounding dunes support fringing

coolibah (E. coolabah) woodlands, shrublands,

sedgelands and grasslands. These wetlands provide

important seasonal waterbird habitat.

Extensive cattle grazing is the dominant land use of

this region, although clearing for more intensive

cattle production is becoming more widespread.

Clearing has focused on the heavier soils carryingacacia communities. However, clearing has recently

extended into the eucalypt woodlands on the

infertile sand plains in the south-east part of the

region.

11. Brigalow Belt

The Brigalow Belt bioregion covers much of the500–750 mm per annum rainfall country that runs

in a subcoastal belt between the Queensland–NewSouth Wales border and Townsville. The region

encompasses a wide range of geologies and

associated landforms. As its name suggests, the

region is characterised by the main area ofdistribution of the leguminous tree brigalow ( Acaciaharpophylla), which occurs on flat, to undulating

plains, with deep clay soils derived from Cretaceous

sediments, more recent Cainozoic deposits andolder volcanic rocks.

A wide range of other ecosystems and land formsalso occurs in the region. Ironbark (Eucalyptuscrebra) and a range of other species, and

bloodwood (Corymbia spp) forest and woodlandsoccur on the rugged ranges and hills formed from

sandstone or older folded sediments that crisscross

the region. Cypress pine (Callitris glaucophylla)woodland and/or poplar box (E. populnea), and

silver-leafed ironbark (E. melanophloia) woodlands

are common on slopes and plains with sandy or at

least texture-contrast soils. Grasslands occur onflat plains with clay soils derived from alluvium,

Cretaceous sediments or basalts. Alluvial plains

with clay or sandy soils support a range of

eucalypt woodlands. Softwood scrub (dryrainforest) communities and heathlands are found

in scattered pockets across the region. Estuarine

plains with mangrove forest and samphire

communities occur in parts of the region adjacentto the coast.

The Brigalow Belt is a major agricultural and

pastoral area and tree clearing has been a

widespread practice, particularly as part of land

development schemes since the late 1950s, and isstill substantial in the region (see section 2.0).

12. Southeast QueenslandThe Southeast Queensland bioregion extends from

the New South Wales border, north to Bundaberg.The region contains a wide range of habitat types.

Perhaps the most common are hilly to mountainous

areas supporting spotted gum (C. citriodora) and

Eucalyptus spp. open forests and woodlands.Basalt-derived rugged ranges and hills

characteristically support complex notophyll and

araucarian microphyll rain forests and tall open

forests. The lower lying coastal plains include large

areas of marine, alluvial and the very distinctivelarge sand areas (Fraser, Moreton etc). These areas

support a range of communities including

heathlands, banksia woodlands, mangroves andsedgelands, paperbark (Melaleuca quinquenervia)

open forests and blackbutt (E. pilularis), scribbly

gum (E. racemosa) and other eucalyptus woodlands

and open forests.

The region is highly populated and has been

extensively cleared for agriculture and urban

purposes. Most of the region is freehold. Small

areas of leasehold land used for agricultural

purposes occur in the north and west of the region.

13. New England Tableland

The New England Tableland bioregion is

distinguished by its high altitude (>800 m) andgeology (predominantly granite and ‘traprock’—

Devonian and sedimentary, often metamorphosed,

rocks). The main landforms are mountains,

tablelands and hills separated by broad valleys.Vegetation is mainly eucalyptus woodland and

open forest with localised montane heaths and

swamps. Common dominant tree species include

New England blackbutt (E. andrewsii), tumbledowngum (E. dealbata), New England peppermint

(E. noveahollandiae), yellow box (E. melliodora) and

ironbarks (E. crebra) and (E. sideroxylon).



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The major land uses of the region include fruit and

vegetable production, wool growing, cattle grazingand tourism. Horticulture has resulted in the

retention of a greater proportion of natural

vegetation cover. Most of the flatter country has

been cleared and much of the remaining naturalvegetation occurs along the ridgelines.



128

Weston et al. (1981) have produced a map of native

pasture that is widely used in Queensland to make

general assessments about capability, degradationand other land resource related issues. A brief

statement is given here on each of the 14 nativepasture communities. The characteristic ground

cover grasses and the dominant tree species areindicated.

1. Pastures sparse or absent

Closed forests and two coastal communities,

namely rainforest, littoral and heath, are groupedtogether because they have limited usefulness for

animal production in the natural state. The total

area they cover is 4 400 000 ha. Rainforest has few

grasses until cleared when Melinis minutiflora,

Pennisetum clandestinum, Paspalum dilatatum and Axonopus affinis may become naturalised.

Although the littoral areas contain a rich ground

flora, pastures of Spinifex hirsutus have a low

productive value. The exception to this is on sometidal flats where valuable seasonal grazing is

obtained from Sporobolus virginicus. The sedge

Schoenus sparteus occurs as a characteristic species

on the heath of Cape York Peninsula.

Prominent soils in the rainforest areas are friableearths and fertile loams; in littoral zones they are

plastic clays and texture contrast soils with gleyed

clayey subsoils; and in heath areas, infertile earths.

2. Bladygrass

A composite of northern and southern sandy

coastal lowlands, these open forest and woodland

communities cover an area of only 2 700 000 haand generally receive more than 1100 mm of rainfall

annually. The major trees in the north are

Eucalyptus platyphylla, Corymbia dallachiana and

bloodwoods; and in the south, E. signata,bloodwoods and Melaleuca spp. The characteristic

grasses are Themeda triandra and Imperata cylindricawith Heteropogon triticeus associated in the north and

A. affinis in the south. Intensive use is not possiblein the absence of expensive land development.

Soils are infertile, mostly with a shallow A horizon

and an impervious B horizon in the duplex profiles.

3. Black speargrass

Black speargrass (Heteropogon contortus) is the mostextensive native pasture community in the humid

and subhumid zones. It occupies 25 000 000 ha

and for the most part receives between 700 mm

and 1200 mm of rainfall annually. Woodlands andopen forests of Eucalyptus spp. (E. crebra,

C. citriodora, E. tereticornis, and C. tessellaris) occur in

coastal and subcoastal areas along the eastern

seaboard from Cooktown to the Queensland–New

South Wales border. Induced by management

practices, H. contortus is the most characteristicspecies, although Bothriochloa bladhii and T. triandra

are dominant in some parts of the community.While black speargrass occurs on almost all soil

types, 70% of its area is confined to infertile

texture-contrast soils and earths. The remainderoccurs on more fertile soils (duplex, loam, and

clay) and is thus subject to replacement by sown

pasture species or crops.

Most areas in the south have been cleared to some

extent, some extensively, by tree ringbarking andpoisoning.

4. Queensland bluegrass

Dichanthium sericeum grasslands occur on limited(2 400 000 ha) areas of fertile cracking clays in

southern (Darling Downs) and central (Central

Highlands) Queensland. Rainfall averages between

600 mm and 700 mm annually.

Characteristic species in southern Queensland areD. sericeum, D. affine and Aristida leptopoda, while

Bothriochloa erianthoides, D. sericeum, D. affine, A. leptopoda, A. latifolia and Astrebla spp. occur in

the Central Highlands.

Much of this grassland community is cultivated

for crops.

5. Brigalow pastures

Flat, to gently undulating brigalow forests, and

open forests occupy 8 700 000 ha of largely fertile,sometimes gilgaied heavy clays that occur to the

west of the black spear grass in central and

southern Queensland. The dominant tree in this

area is Acacia harpophylla, which is associated withseveral other trees. Casuarina cristata is often

co-dominant and on some soils it may be

dominant. Although clearing by axe was started

around 1900, accelerated development hasoccurred over only the past 40 years with the use

of heavy machinery for land clearing.

Pasture species (Paspalidium spp.) were sparse before

clearing. Following tree removal, and in the absence

of species introduction, native pasture communitiesbased on Chloris, Paspalidium, Dichanthium,

Sporobolus and Eragrostis spp. developed.

Sixty per cent of brigalow pasture soils are uniform

clays of moderate to good fertility. A further 27%

are texture contrast soils of moderate fertility. Very

high levels of production immediately followingdevelopment have declined in brigalow pastures,

but these pasture systems remain productive

compared with others in the State. Long-term land-use trends in this native pasture community are

Appendix 2 Description of land types (native pasture communities)



129

towards greater areas of cultivation at the expense

of sown and native pastures, especially on claysoils and in southern areas. The use of leucaena

(Leucaena leucocephala) is providing a significant

boost to animal production in the northern half of

the zone.

6. Aristida–Bothriochloa pastures

This community is a composite of eight types in

which either Aristid a or Bothriochloa spp. areprominent. It occupies 33 500 000 ha of semiaridwoodlands that surround, and in places form a

mosaic with brigalow in central and southern

Queensland. It occurs as an unbroken community

in north Queensland. Infertile earths, texture-contrast and sandy soils comprise 89% of the area.

In many pastures, Aristida has been a major

increaser. Land use is predominantly sheep and

cattle grazing at relatively low stocking rates,except in the granite–traprock area where rates are

higher. The small proportion of better soils (11%)

have potential for forage cropping.

The component vegetation zones are:

• Western slopes of Einasleigh uplands: woodlands

of E. microneura developed on infertile sandy soilswith Aristida spp. and Chrysopogon fallax prominent.

• Paperbarked tea-tree: (Melaleuca spp.) low

woodlands occurring on infertile earths andduplex soils with Aristida spp. and C. fallax as

characteristic grasses. Low grazing pressures

have left these pastures in good condition.

• Lancewood: woodlands of Acacia shirleyi with a

very sparse ground cover of Triodia pungens and Aristida spp. occupying dissected plateau areas

with skeletal soils. The level of use is low.

• Dissected sandstone hills: a range of forest or

woodland communities occurring on dissected

sandstone hills. Eucalyptus spp. form layeredwoodlands with grasses such as Cymbopogonrefractus, Aristida spp., Themeda triandra,

Arundinella spp. and Triodia mitchellii. Acacia open

forests with A. catenulata and A. shirleyi have

Aristida caput-medusae, Cleistochloa subjuncea,Dimorphochloa rigida, Cymbopogon refractus and

Arundinella spp. as characteristic grasses.

Aristida spp. increase with disturbance.

• Poplar box-mulga: woodlands of E. populnea withan understorey of Acacia aneura, Geijera parvifloraand sometimes Eremophila mitchellii occur on

deep red earth plains. Grasses commonly

encountered are Aristida spp. and Thyridolepismitchelliana. Sheep and cattle grazing have

promoted the increase of Aristida and probably

contributed to increased densities of woodyplants.

• Semiarid woodland plains and low hills:

woodlands of Eucalyptus populnea and Eremophilamitchellii with G. parviflora develop on alluvial

material and are often associated with drainage

lines. Soils are duplexes of moderate fertility.

Chloris spp. are important grasses, and withdevelopment and use, Bothriochloa and

Aristida spp. become prominent. Heavy sheep

and cattle grazing in the past has promoted

Aristida spp. and probably contributed toincreased densities of woody plants.

• Southern sandy country: there are two distinct

community types contained in this vegetation

zone. The first is the open forest of Callitriscolumellaris and Casuarina leuhmannii that occurson infertile sandy duplex soils (solodics) and

contains a native pasture of Aristida and

Eragrostis as characteristic genera.The second

is the temperate woodland community thatextends northward from New South Wales into

the southern Darling Downs and is locallyknown as the granite–traprock country. It

contains a large range of eucalyptus species.While subtropical woodland grasses such as

Bothriochloa decipiens and B. macra occur,

temperate grasses such as Stipa scabra and

Danthonia spp. are also prominent.

• Cypress pine: deep, sandy, duplex soils supportCallitris glaucophylla woodlands with a variety of

Eucalyptus spp. and sometimes with Allocasuarinaleuhmannii. Native pastures are very sparse and

contain Aristida spp. and Cymbopogon refractus as

characteristic grasses. Densities of cypress pinehave increased considerably in the absence of fire.

7. Gidgee pastures

A total area of 4 800 000 ha probably

underestimates the extent of gidgee ( Acaciacambagei) and Georgina gidgee ( A. georginae). As

rainfall decreases, gidgee replaces brigalow on theheavier soils and scattered occurrences on the

margins of both brigalow forests and Astrebla spp.

grasslands may not be recorded as distinct

communities. Gidgee stands in the latter grasslands

have increased in density and in area in recentdecades. Georgina gidgee is restricted to north-

west Queensland.

Dense stands of Acacia cambagei in the central west

had only a sparse ground flora until modified byland clearing. Subsequently, stands of Cenchrusciliaris thrive on high available nitrogen and even in

the long term appear well adapted. They support

greatly increased stocking rates of sheep and cattle.Characteristic native grasses are B. ewartiana and

Dichanthium affine while Astrebla spp., Eragrostis

setifolia, E. parviflora and Chloris pectinate occur inlow, open gidgee woodlands in the south-west.Woodland communities of Acacia georginae support

species of the astrebla grasslands.



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While most commonly occurring on clay soils,

gidgee pastures are also found on loams, earthsand duplex soils.

8. Mulga pastures

The semiarid woodlands give way to mulga ( Acaciaaneura) woodlands and shrublands on the poorerand lighter soils. Both summer and winter rainfall

appear necessary to maintain mulga and the plant

is absent from semiarid regions with regularsummer or winter drought. Structurally, mulgaassociations range from open forests to sparse, tall

open shrublands. They occupy 19 100 000 ha of

south-west and central western Queensland.

Characteristic genera are Aristida, Thyridolepis,

Eriachne, Digitaria and Eragrostis, not necessarilyoccurring in the same communities. The presence

of Acacia aneura as a drought fodder has been

invaluable for the maintenance of stock, but has

contributed directly to the over-utilisation of native

pasture species.Eighty per cent of soils are infertile earths, texture-

contrast soils, or sands.

9. Mitchell grass

The astrebla grasslands are the most extensive and

the most valuable of Queensland’s inland native

pastures. They occupy an area of 29 500 000 ha

between the 250 mm and 500 mm isohyets. Onsuitable soils receiving less than 250 mm of annual

rainfall in the far west, astrebla occurs only during

sequences of high rainfall years. These areas are

more frequently occupied by chenopod herbfields.In flooded areas, Eucalyptus coolabah and

E. camaldulensis fringe drainage lines.

Four Astrebla spp. ( A. lappacea, A. elymoides, A. pectinata, and A. squarrosa) are widespread and

occur as tussock grasslands of low basal cover(2–4%). The interspaces are occupied by a range of

annual grasses and forbs (Iseilema, Dactyloctenium,

Brachyachne, Amaranthus, Salsola, and Portulaca spp.).

The astrebla grasslands occur on heavy textured

soils, 90% being cracking clay and the remainder

fertile duplex soils. High temperatures and the lackof shade are husbandry problems. The spread of

the introduced woody weed, prickly acacia ( Acacianilotica) onto 6 000 000 ha of these grasslands hasled to serious management problems in northern

areas. Other species causing similar concerns

include mesquite (Prosopis) and parkinsonia

(Parkinsonia aculeata), and the native mimosa(Mimosa farnesiana) (Reynolds & Carter 1993).

10. Spinifex

Triodia, Eriachne and Zygochloa are characteristic

species of 21 200 000 ha of poor quality,hummockh native pastures occurring as grasslands

and under acacia and eucalypt (Eucalyptusmelanophloia and E. leucophloia) woodlands. Soils

are sands, loams and duplex soils and are

consistently infertile.

Many spinifex pastures are grazed only inconjunction with better-quality associated land

systems. Alternatively, they are reserved for

drought grazing with the aid of supplements.

11. Channel Country pastures

The broad network of channels and enclosed flatsof the Diamantina, Georgina and Bulloo Rivers and

Cooper and Eyre Creeks form the Channel Country

of the south-west. The area involved is5 400 000 ha of clay soils with Eucalyptus coolabahand E.camaldulensis fringing the main channels.

Muehlenbeckia cunninghamii is associated with

depressions.

Valuable forage appears after flooding of thechannels and flats. The genera Echinochloa,Chenopodium, Trigonella, Iseilema, Panicum,

Sclerolaena, Dactyloctenium and Atriplex are common

depending on when flooding occurs.

12. Bluegrass–browntop

The treeless plains of the lower Gulf of Carpentaria

support 5 600 000 ha of Dichanthium fecundum–Eulalia aurea grasslands. Associated

genera are Astrebla, Sorghum, Aristida, Chrysopogonand Iseilema. The community occurs between the

500 mm and 800 mm isohyets and rain falls mainlyin the summer. Cracking clays predominate, but

these differ from the fertile grey and brown clays of

the astrebla grasslands in their lower fertility and

low percentage of plant-available water capacity.

13. Schizachyrium

The lands of Cape York Peninsula are the least

developed for pastoral use in the State. This is a

reflection of the poor quality of the available forage.

Ground cover species vary throughout the area.The most widespread community is Eucalyptustetrodonta open forest that supports Heteropogontriticeus, Schizachyrium fragile, Panicum mindanaenseand Eriachne stipacea.

In the central north, woodlands of E. tetrodontasupport Sorghum plumosum pastures while

H. triticeus, Rhynchospora longisetis,Pseudopogonantherum contortum and Bothriochloabladhii occur, but are less abundant.

Melaleuca viridiflora is conspicuous in the lower treestratum in some forests and woodlands and is the

dominant tree species in low, open woodlands on

the western peninsula. In this community, the bulk

of the ground cover consists of annual grasses( Aristida spp., Eriachne burkittii, Schizachyrium spp.

and Ischaemum baileyi).

Low eucalypt woodlands on the eastern peninsula

have ground cover of H. triticeus, E. glauca, S. fragileand Thaumastochloa spp. or H. triticeus and Sorghum plumosum. The heath communities of the



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north–east have Schoenus sparteus as the common

ground species.

More than 90% of soils are infertile earths, duplexsoils, sands and loams.

14. Native sorghum

Extending over 1 000 000 ha of E. tetrodontawoodlands in the northern part of Cape York, the

native sorghum community provides one of thebetter grazing lands of the Peninsula. Annual

rainfall of 1200 mm is reliable.

Sorghum plumosum is the common grass species,

though H. triticeus, Rhynchospora longisetis,Pseudopogonantherum contortum and Bothriochloabladhii occur, but are less abundant.



Area of Queensland covered byregional scale vegetation/ecosystemmapping

By June 2000, preclearing and 1995–1997 remnantecosystem mapping will be completed for most of

the Brigalow Belt, Desert Uplands, Queensland

Central Coast, Southeast Queensland, the south-

eastern Mitchell Grass Downs, Mulga Lands east ofthe Warrego River floodplain and some of the

Einasleigh Uplands bioregions. In addition,

preclearing vegetation and regional ecosystem

mapping is available for Cape York Peninsula, theChannel Country and most of the Mitchell Grass

Downs and the Mulga Lands regions.

Mapping Methods

Preclearing vegetation

Preclearing vegetation communities are delineatedon 1960s aerial photos with the aid of any available

land system, geology, soils and other land resource

mapping. These aerial photos are used as they

constitute the earliest uniform State-wide coverage.This lessens the amount of disturbance to photo

patterns compared with present day photos.

Photo interpretation is followed by extensive field

sampling, ground truthing and collection of

quantitative site data. This information is thencollated and analysed and photo patterns are

attributed with vegetation and ecosystem types.

Where it is evident from the aerial photography that

vegetation has been substantially cleared,extrapolations are made from remnant vegetation to

cleared areas using landform and photo patterns. If

available, other land resource maps, older air photos

and old land survey–property records held by theDepartment of Natural Resources are also used.

Remnant vegetation

An unambiguous definition of remnant vegetation isdifficult because there is a continuum between

remnants, regrowth, thinned and cleared

vegetation. For example, one definition of regrowthvegetation is ‘all lignotubers, suckers, re-sprouting

stumps, seedlings etc. of woody vegetation that

develops in response to removal of the woody

canopy by clearing and/or thinning by humans(i.e. not through storms, fires etc)’. This definition

would include areas that have received partial or

light thinning or logging, or areas that had been

cleared or thinned many years ago and which have

regrown to their original height and cover. Suchareas are likely to have biodiversity and other

values equal to those of ‘remnant’ vegetation that

has never been logged, thinned or cleared. Another

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definition (New South Wales Department of Land

and Water Conservation 1997) which uses set age

and/or height cut-offs to define remnant vegetation,

does not allow for the fact that different vegetation

types will regrow at different rates, and attaindifferent height canopies.

Therefore, the Queensland Herbarium has defined

remnant ‘intact’ vegetation as that which has at

least 70% of the height and 50% of the cover of thedominant stratum, relative to the normal height and

cover of that stratum. Normal vegetation is

generally considered to be vegetation that has not

been subjected to gross mechanical or chemicaldisturbance of the dominant stratum. These

threshold figures were based on the variation of

height and cover of remnant vegetation around the

mean height and cover figures (as indicated fromsite data and field survey). Vegetation that has

been cleared in the past, but now has canopy

height and cover above this threshold, appears to

generally possess much of the structural andfloristic diversity of other remnant vegetation that

has been subjected to an otherwise similar grazing

and management regime. However, it should be

noted that non-remnant vegetation may also havehigh habitat and biodiversity values (section 3.2).

Remnant vegetation is mapped using the latest

Landsat imagery (1997 at April 2000) supplied bythe Department of Natural Resources State

Landcover and Tree Study (SLATS) project, inconjunction with recent aerial photography and

ground truthing. In practice, remnant vegetation is

defined in the field by locating vegetation,

observation or quantitative survey sites inundisturbed areas, often on stock routes and

reserves or areas where there has been no obvious

mechanical or chemical disturbance to the

dominant stratum. These areas are used as abenchmark for determining remnant thresholds in

the field and are related to Landsat image andaerial photo patterns to enable extrapolation of

remnant vegetation within each vegetation typeacross the landscape. Areas that show as cleared

on 1960s photography and have subsequently

regrown, are also used to indicate non-remnant

vegetation, particularly in western Queenslandwhere growth rates are relatively slow. Mapping of

remnant and non-remnant vegetation is also

related to scale. Areas less than the minimum

mapped area (< 5 ha) mapped by the QueenslandHerbarium, which have less than 50% canopy

cover or 70% height, may be mapped as part of alarger remnant as the height and cover of the

overall remnant is greater than that of thethreshold.

Appendix 3 Queensland Herbarium vegetation and regionalecosystem survey and mapping program



133

The finalised remnant map is overlaid with the

preclearing ecosystem map to attach the ecosystemtypes to the remnant cover. This is then inspected

by botanists to re-allocate proportions to each

component of mosaic polygons (areas mapped as a

combination of two or more ecosystems) to takeinto account clearing that has occurred

differentially across the components of a mosaic

(Fensham et al. 1998).

Limitations, ongoing refinement and useof survey and mapping

The ecosystem–vegetation maps are extrapolations

from site data, observations and remotely sensed

imagery. The line work is generally accurate to1:100 000 scale mapping that is within 100 m of

where it should be on the ground. For preclearing

mapping, the minimum size of an area mapped is

20 ha, while for remnant land cover mapping, theminimum size is generally 5 ha clumps or 100 m

linear features (except for south-east Queensland

where the minimum area mapped is 20 ha). In

addition, time and budget constraints mean thatdetailed sampling may be at 1:250 000 scale (about

100 detailed sites per map sheet). Variations in the

condition of vegetation within remnant areas are

not mapped.

The survey and mapping aims to achieve a greaterthan 80% accuracy of preclearing and remnant

coverage across Queensland. Accuracy will vary

from area to area and vegetation type to vegetation

type. While the mapping gives a good regional

perspective on the distribution and status ofecosystems, it is expected that property level

inspections and property vegetation management

plans will be used progressively to update themapping. This information will be combined with

monitoring of ongoing clearing to periodically

update ecosystem statistics, distribution maps and

the conservation status of regional ecosystems.

Native Vegetation Management in Queensland

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