Electronic edition, 2005 - NZES · and J.S.C.Begg B.J. Wills, W.T. McDougall and J.S.C. Begg 59 62...

Electronic edition, 2005

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2

VEGETATION CHANGE IN TUSSOCK GRASSLANDS,

WITH EMPHASIS ON HAWKWEEDS

Record of a workshopof the New Zealand Ecological Society,

Cass Field Station, Canterbury,3-6 October 1991.

Edited byG.G. Hunter, C.R. Mason and D.M. Robertson

New Zealand Ecological SocietyOccasional Publication No.2

1992

ISSN 0114-8028

ISBN 0-9597949-2-1

Published by:The New Zealand Ecological Society (Inc.)P O Box 25178Christchurch, New Zealand

First published 1992

Suggested reference to articles in this volume:

Author, 1992: Article title. In, Hunter, G.G.; C.R. Mason; D.M. Robertson (Editors), Vegetationchange in tussock grasslands, with emphasis on hawkweeds, pp. xx-zz. Occasional Publication No.2,New Zealand Ecological Society, Christchurch.

CONTENTS

Preface

Editors' note

List of participants

Session One: Plant sociological issues

Concepts and methods in assessing vegetation trends

Inconsistencies between the scale of the hawkweed (Hieracium)problems and the methods used for investigating it

Changes in grazed and retired fescue tussock grasslands,Harper-Avoca catchment, Canterbury, 1965 - 1990

The influence of ground cover on hawkweed establishment infescue tussock grassland

A review of characteristics of mouse-ear hawkweed (Hieraciumpilosella)

Session One: Discussion

Session Two: Case studies from vegetation monitoring programmes

Trends of mouse-ear hawkweed (Hieracium pilosella) in theSouth Opuha catchment

Effects of burning on Otago tussock grasslands ÖGlenshee K.B. Duuan 31StationHawkweeds in Otago - distribution, ecology and management N.S. Harris and A.F. Mark 32

Hawkweeds and vegetation monitoring in the Rabbit and Land K. Colhoun, B.D. Foran and 35Management programme W.D. Ross

Monitoring changes in non-forest ecosystems: case studies from K.J.M. Dickinson 39Molesworth Station and the Mackenzie (Waitaki) basin

Regeneration after fire on the Leibig Range, Mount Cook H. Wilson 44National Park; the role of hawkweeds (Hieracium spp.) duringthe first 20 years

A preliminary assessment of the effects of management on R.B. Allen, W.G. Lee and 45mouse-ear hawkweed (Hieracium pilosella) establishment in A.F. Marknarrow-leaved snow tussock (Chionochloa rigida) grassland,Lammermoor Range, East Otago

Time segment analysis of permanent quadrat data: changes in D. Scott 45hawkweeds (Hieracium spp.) in the Waimakariri in 24 years1

King devil hawkweed (Hieracium praeallum) in wet, alpine, talltussock grassland, Hopkins Valley, South Canterbury'

Session Two: Discussion

1 Paper not presented at workshop

v

vi

vii

G.G. Hunter 50

52

D.Scott 3

12

13

14

15

24

M. Treskonova

A.B. Rose, K.H. Platt and C.Frampton

P.R. Espie

T.A. Jenkins

J. Cuff 29

Session Three: Case studies from plant introduction, agronomic and grazing trials

Hawkweed control and residual effects of oversowing,overdrilling and herbicide in Otago

Plant introduction trials in hawkweed communities on GallowayStation, Upper Manorburn

Long term climate records - can they assist real-timemanagement decisions in our tussock grasslands?

A paddock based survey of management factors relating tomouse-ear hawkweed (Hieracium pilosella) dominance inCentral Otago

Management effects on hawkweeds - the Stony Creekexperience

Response of mouse-ear hawkweed (Hieracium pilosella) in threelong term manipulative agricultural trials

Interaction between some pasture species and two hawkweed(Hieracium) speciesl

Long term effects of pastoral management on improved tussockgrassland vegetation

Rabbit and sheep grazing in Mackenzie tussock grasslands:vegetation change 1991

Studies of hawkweeds in the diet of sheep in New Zealandtussock grasslands

Nutrient mass balances in pastoral high country

Session Three: Discussion

G.G. Cossens 57

B.J. Wills, W.T. McDougalland J.S.C.Begg

B.J. Wills, W.T. McDougalland J.S.C. Begg

59

62

B.D. Foran, J. Bates, P.Murray, G. Heward and D.Pickens

C.R. Mason

64

69

D. Scott 71

Session Four: Development of simple models relating hawkweed performance toenvironmental and management conditions

A general model of past and likely future vegetation changes ingrazed and retired tussock grasslands of the Harper-Avocacatchment, 700-1400 m altitude, 1200-1500 mm annual rainfall

Temporal changes in the indigenous vegetation pattern of Otago,eastward from the lakes district

Working group report: development of simple models ofhawkweed performance in tussock grasslands.

Requirements for urgent research into hawkweed (Hieraciumspp.)

Annotated bibliography on hawkweeds (Hieracium spp.)

1 Paper not presented at workshop

A.B. Rose 81

compiled by D.Scott, T.A.Jenkins and P.R. Espie

93

D. Scott and B.L. Sutherland 72

73B.E. Allan and R.J. Doney

74P.R. Espie and C. Meurk

75K.F. O'Connor and N.Covacevich

K.F. O'Connor and P.SHarris

76

77

A.F. Mark 82

85

91

compiled by G.G. Hunter

compiled by A.F. Mark

v

PREFACE

Hawkweeds (Hieracium spp.) are associated with a widely-acknowledged concern about degradationof tussock grasslands in the South Island. Resource managers, affected communities and scientistsshare concern for the future sustainability of tussock grassland based production and conservationsystems.

In 1990 a series of workshops and committees, convened by New Zealand Mountain Lands Institute,considered implications of the 'hawkweed problem' to land management and made recommendationsfor action. A clear outcome from these deliberations was that the status of hawkweeds was not widelyunderstood in terms of the underlying interactions between vegetation, environment and management.

It was recognised, however, that the findings of a substantial pool of research effort relating to thesegrasslands, when integrated in a 'hawkweed context', would increase our understanding and providea more objective basis on which to evaluate the status of the grasslands and hence to formulatemanagement strategies. .

Accordingly, in October 1991, the New Zealand Ecological Society convened a workshop to bringtogether people with key scientific information and understanding of hill and high country tussockgrassland ecosystems to provide this integration. Participants included scientists and resourcemanagers from Department of Conservation, DSIR, Forest Research Institute, High Country Sectionof Federated Farmers, Land Corporation Ltd., MAFTech, regional councils, Mountain Lands Instituteand universities.

Various scenarios regarding the role of hawkweeds have been put forward; the aggressive invader,the stress-tolerant indicator of long-term ecosystem decline, and the opportunist responding to shorter-term disturbances or stresses such as those related to climatic fluctuation (e.g., drought) andmanagement effects (e.g., grazing). The challenge for this workshop was to critically evaluateavailable evidence and to advance best-bet explanations for the tussock grasslands changephenomenon. The measure of a successful workshop was seen as "what does available informationtell us about what is happening in the tussock grasslands", rather than simply "what information dowe have?"

Aims of the workshop were:

• To consider quantitative information on condition and trends in vegetation composition andcover in tussock grasslands, especially those containing hawkweeds.

• To develop, as far as possible, simple models of trends in tussock grasslands, with emphasison causes of change and the role of hawkweeds.

• To improve understanding of the ecology of hawkweeds in tussock grasslands.• To identify future research requirements.• To identify management implications, from an ecological perspective.

The initial papers at the workshop set the scene by outlining plant sociological issues in the tussockgrasslands. The biology of mouse-ear hawkweed (Hieracium pilosella) was reviewed. Case-studiesset out the evidence of vegetation change and vegetation-environment-management relationships intussock grasslands from ecological investigations, grassland monitoring programmes, plantintroduction and management trials, and from investigations of grazing animal-vegetation interactions.The working groups were structured to integrate this evidence and to clarify current understanding.Emphasis was placed on reaching consensus on the processes of change where possible, and on theidentification of areas of disagreement and on areas for which insufficient information is available.

vi

The working groups also developed a broad schedule of priorities for research requirements fortussock grasslands.

The workshop recognised that timely and appropriate reporting from the workshop would include:a summary of the main findings for media release, a record of the material presented together withthe associated discussions and working group reports, and specific submissions to appropriate agenciesand Ministers of Government.

Contributors were encouraged to present even interim results, and to be speculative rather thanconservative with their interpretations. Consequently interpretations in this record may be modifiedas more information becomes available, and as results are more fully evaluated within the wider bodyof evidence.

A feature of the workshop was the high level of cohesion and mutual understanding developed by theparticipants who were drawn from diverse production and conservation systems perspectives. We wishto record the willingness of the scientific and resource management community to contribute to thisworkshop. We believe that this attitude reflects their level of concern on this issue and theircommitment to contributing to solutions.

We thank Barney Foran, Kath Dickinson and Alan Mark for directing the workshop sessions whichintegrated our understanding and for crystallising the outcomes of the workshop. We also thank DianaRobertson (Land Corporation Ltd.) and Graham Hickling and John Hunt (Forest Research Institute)for their contribution to the smooth running of the workshop.

Caroline Mason, Grant Hunter & Chris KerrWorkshop Convenors

EDITORS' NOTE

This publication provides a record of papers presented at the workshop. Some papers are produced infull, while others have been summarised, and may be subsequently reported in full in formal scientificpublications. Three papers were circulated but not verbally presented at the workshop. Discussionsfollowing presentation of the papers (sessions 1-3), and a summary of the workshop sessions ondevelopment of simple models (session 4) are reported. While every attempt has been made toaccurately and fairly reflect discussions and conclusions arising from the workshop, we recognise thepotential, and accept responsibility, for any misinterpretation and I or over-simplification of comments.

The report from session 4 also includes recommendations for future research requirements that arosefrom the workshop, and which have been circulated to workshop participants, appropriate Ministers ofGovernment and agencies.

Many people have contributed to the production of this publication. We would particularly like to thankDavid Scott, Alan Mark, Kath Dickinson, Alan Rose, Pat Garden, Barney Foran and Chris Kerr forcomments. Facilities for editing and page layout were kindly provided by Land Corporation Ltd.

Grant Hunter, Caroline Mason & Di RobertsonEditors

vii

LIST OF PARTICIPANTS

Dr Bruce Allan1

Dr Ralph Allen2

Dr Les Basher2

Dr Peter Clinton3

Ms Joy ComrieDr Gordon CossensDr Nilo CovacevichMr Jeromy CuffDr Gavin DalyDr Kath DickinsonMr Kevin DugganDr Peter EspieMr Barney Foran2

Mr Pat GardenMr Neil HarrisMr Grant Hunter2

Mr Tim JenkinsMr Chris KerrProf Alan MarkMs Caroline MasonDr Colin Meurk2

Mr Jon MoenMr Phil MurrayMr Alan Nordmeyer3

Prof Kevin O'ConnorMr Tony PerretMr Alan Rose2

Dr David Scott1

Mr Ron SutherlandMs Kristin SvavarsdottirDr Marta TreskonovaDr Morgan WilliamsDr Peter Williams2

Dr Barrie Wills2

Mr Hugh Wilson

MAFTechDSIR Land ResourcesDSIR Land ResourcesFRI (Forest & Wildlands)Department of ConservationMAFTechChilean Government, Lincoln UniversityCanterbury Regional CouncilLincoln UniversityVictoria University of WellingtonOtago Regional CouncilFRI (Forest & Wildlands)MAFTechHigh Country Section, Federated FarmersOtago UniversityDSIR Land ResourcesDSIR GrasslandsMountain Lands InstituteOtago UniversityLand Corporation Ltd.DSIR Land ResourcesUniversity of Umea, SwedenLand Corporation Ltd.FRI (Forest & Wildlands)Centre for Resource Management, Lincoln UniversityDepartment of ConservationForest Research Institute (Forest & Wildlands)DSIR GrasslandsNelson/Marlborough Regional CouncilPlant Science Dept. Lincoln UniversityCentre for Resource Management, Lincoln UniversityMAFTechDSIR Land ResourcesDSIR Fruit & TreesFreelance Botanist, Research Associate,DSIR Land Resources

1 NZ Pastoral Agriculture Research Institute Ltd (as of 1/7/92)2 Landcare Research New Zealand Ltd - Manaaki Whenua (as of 1/7/92)3 NZ Forest Research Institute (as of 1/7/92)

SESSION ONE

PLANT SOCIOLOGICAL ISSUES

N.Z. Ecol. Soc. Occ. Pub. No. 2

CONCEPTS AND METHODS IN ASSESSING VEGETATION TRENDS

3

D. ScottNZ Pastoral Agriculture Research Institute Ltd.

P. O. Box 60, Lincoln, CANTERBURY

SummaryWith the emphasis on vegetation as an indicator ofecosystem condition, a brief review is made of theconcepts and methods used for vegetationassessment used by different groups, and theconsequent assumptions they make in assessingthe present trends of hawkweed species in NewZealand high country.

IntroductionIt is often said that ecology is more a way oflooking at things than an exact science. At thestart of this symposium on hawkweeds (Hieraciumspp.), it may be as well to have a quick look atthe way different people view vegetation and itstrends. Note the tenor of this opening comment.The most important paper at the recentInternational Rangeland Conference emphasizedthat there is probably no real world, only differentpeople's perception of it, and the ideas andconcepts that they use to try and share thatexperience (Russel and lson 1991).

Vegetation, environment and timeUsing the theme of hawkweeds, there are at leastthree initial components or concepts - vegetation,environment and time. It is relatively wellingrained in the psyche of people at this meetingthat vegetation is a good measure of the status orcondition of a particular ecosystem, and I onlyneed to point to the widespread habit in NewZealand of including vegetation surveys as part ofland capability and other resource surveys. Here,and throughout the paper, these approaches andconcepts will be given in their more extreme formto make the point that people do have differentperceptions.

New Zealand probably inherited its emphasis onvegetation from USA rangeland and Europeanphytosociology ethos. We have embraced it sowell as a measure of ecosystem condition that Iam going to assume its relevance for the rest ofthe paper in considering different concepts ofvegetation. But there are many other ways of

looking at ecosystem condition ego economic,landscape values, and natural conservation values.

In looking at landscapes or ecosystems ourobjective is to understand the vegetation changesin terms of environmental changes over time. Thepresumed intention is that we may be able tointervene to change the direction to some stateconsidered more desirable. In such discussions itshould be recognised that most attitudes are of the'seat of the pants', 'wise men', or 'accumulatedexperience' type, with detailed measurement andanalysis using the particular concepts often onlysecondary. In particular the treatment of the threecomponents is very uneven. The major emphasisis given to the description of vegetation as it is atone point in time. Much less emphasis is given tothe description of the environmental factors in anyprecise or detailed manner, and most of themeasures used, come from extrapolation fromsome distant source. There are relatively fewstudies which measure either vegetation orenvironment over time, and almost none thatmeasure both. Such lack of factual data meansthat discussion is very much influenced by theconceptual and analytical approaches used, andhence the need to briefly examine them. To keepthe discussion relevant, a hypothetical site will beused which in its present state could either bebeech forest, short tussock grassland, hawkweedmat, vegetation characteristic of bare soil, or adeveloped fertilised pasture.

Climate climaxThe prevailing concept in North America is theclimax concept of Clements (Weaver andClements 1938) which sees vegetation developingtowards the highest type that can be supported bythe climate of the area. That climax is seen as adesirable state with range or ecosystem conditionbeing measured by how close the particularvegetation is to the climax (Fig 1). There is acontinuum of the intermediate states, eitherdetermined by insufficient time to reach theclimax, or the presence of disturbance factors like

Record of a workshop of the New Zealand Ecological Society on “Vegetation change in tussock grasslands, withemphasis on hawkweeds”, Cass Field Station, Canterbury, 1991.

4

grazing or fire. Associated concepts havedeveloped like 'decreasers', 'increasers', and'invaders' to describe the behaviour of vegetationcomponents, and for identification of 'indicator'species and 'range condition'. This concept seesecosystem condition as being defined by referenceto the climax of the site, which may have to beextrapolated from geographic considerations. Theclimate is also seen to be stable over millennia.This concept had difficulty in accommodatingsubsequent work which indicated that Americanrangelands were as much determined by pastgrazing or fires as climate.

These concepts are moderately prevalent in NewZealand but probably never applied in theirextreme form. The difference probably relates tothe earlier recognition in New Zealand thatvegetation is very dynamic, that environmentvaries greatly over short distance and time, andfor tussock grasslands many of the dominantspecies are not agricultural species. In ourhypothetical example, the short tussock,hawkweeds and bare ground communities wouldbe seen as successively poorer 'range conditions'from the climax beech forest. In applying theconcept, all the possible vegetation communitieson a particular type of site would have to bearranged in a single continuum which would thendefine 'range condition'. Environmental factorsand time would be an explanation of the sequencebut not an integral part of the concept. Theconcept would have difficulty in accommodatingimproved pasture, unless it was seen as an earlierstage of some hypothetical fertilised forest.

Ball and cupA recent development of the climax conceptincorporates the observation that some vegetationcommunities in a supposed continuum of types arevery stable, and if disturbed will tend to return tothat type rather than another (Laycock 1991). Inthis, the even slide of the climax concept (wherethe actual position is seen as an equilibriumbetween competing forces as the climate factorsdrive the vegetation towards the climax and thecompeting disturbing factors drive it away), isreplaced by a switch back in which there aredepressions in which a vegetation will tend to stayuntil there is some major change to shift thevegetation over the hill into the next depression(Fig 1). I believe this concept has good support


from the observed log I linear relationshipbetween abundance and rank of species in avegetation which results in species tending toform themselves into communities of relativelyfixed composition across gradients ofenvironmental factors or time. The other climaxconcepts and limitations probably translate acrossto the ball and cup concept.

The concept has not been used in New Zealandyet, though it does raise the possibility thathawkweeds may be a stable state, even if notdesirable. The concept would have difficultyaccommodating the improved pasture option alongwith other vegetation types.

Transition statePartly to overcome limitations found in theprevious concept, Laycock (1991) has made afurther suggestion that the 'ball and cup' shouldnot be seen as a single sequence but a range ofassociated hills and depressions where movementbetween depressions depends on particularcombinations of environmental factors. Theanalysis technique of transition matrices wouldhave particular relevance to this concept.

This concept could accommodate all the types inthe example - the conversion of beech forest toshort tussock due to the environmentalcombination of Polynesian fire and low intensitygrazing, short tussock to improved pasture byfertiliser and species introduction, and hawkweedto bare ground by continued nutrient degradation,drought and grazing. The attraction of thisapproach is the inclusion of environmental factorsto explain particular changes. The rate of changeor time scale does not form part of theseconcepts.

SynusiaThe dominant concept in early European ecologywas to see landscape as a series of distinctvegetation types, synusia or associations, based onfloral composition, each of constant composition.A synusia was conceived as tending to act as aunique organism at a hierarchical level above thatof their constituent species (Braun-Blanquet1932). Variation between samples or 'rei eves' ofthe same 'synusia' were probably regarded asexperimental error even if they were initially usedto help define them. Each synusia is regarded as


N.Z. Ecol Soc. Occ. Pub. No. 2

unique and much effort is given to identifyingunique or 'indicator' species as compared withthose that are present in several communities.This concept has difficulty with ecotones. Theunique organismic view of the synusia alsoimplies that they could be defined by vegetationcharacteristic alone, and that environmentalfactors were descriptive rather than explanatoryvariables. There was also an implication that thesesynusia were stable over long periods so timetrends were not important. Their uniqueness alsoimplied that the relationship between them wasnot an important consideration.

Gradient analysisThe second concept originating from NorthAmerica is based on the recognition of the closerelationship between species and environment (forspecies Gleason 1917, Hanson 1958, and forvegetation Whittaker 1952, 1956). This conceptsees the landscape as the response of individualspecies to individual environmental factors, withthe particular vegetation being the sum of theresponse of the species that make up thatvegetation. The implication is that there could beinfinite environmental factors and gradients toconsider and an infinite variation in vegetationcomposition. However the concept becomespractical where one or a few environmentalfactors dominate a particular situation (Fig 1). Toaccommodate situations where the vegetation is ofdifferent types, the species importance isgenerally given in relative rather than absoluteterms. In this concept a vegetation type is seen asbeing a particular position on some environmentalscalar rather than a value judgement of itscondition relative to some desirable state. Thegradients used can be those appropriate to theparticular situation and need not have anyuniversality. The gradient could be time as wellas environmental factors.

The concept is moderately prevalent in NewZealand and may even have independentlydeveloped here from the early recognition of therelationship between soils; vegetation andenvironment because of our very steep Climategradients. The attraction of the concept is thecombination of both environmental and vegetationconsiderations. The hypothetical example couldsee beech forest, short tussock, hawkweed andbare ground communities as all part of some

5

degradation gradient. The difficulty is to definethe gradients in some objective way, or to includeother gradients like fertility, to take account of thepasture option, or to include time so that thetrends or rate of changes can be considered.There is also the need to include value judgementof what is desirable so that 'vegetation condition'can be assessed.

Environmental factorisationWhile recognising the importance of plant /environment interactions there is a multitude ofpotential plant species and a multitude of potentialenvironmental factors. This has led to the attemptto see plant species or environmental factors interms of fewer attributes that may have a degreeof universality. There is almost universalrecognition that the environment must supply thelight, temperature, water and nutrients requiredfor plant growth and that species will differ intheir ability to compete for these in particularsituations.

One approach was to change Jenny's soil conceptto an emphasis on vegetation (Major 1951), ie.that vegetation was a function of the generalfactors of rock parent material, soils, climate andtime. It included the useful concept that to studythe effect of one of the factors it was necessary toselect or design situations where the other factorswere constant.

C-S-R plant strategyGrime in the UK has developed concepts whichsees the environmental factors which affectvegetation in two broad categories with thespecies and vegetation response to these as threecontrasting evolutionary strategies. These conceptsare best explained by direct paraphrasing fromGrime et al.(1989).

The first category (called 'stress' factors), consistof environmental factors which restrictproduction, such as shortage of light, water,mineral nutrient or suboptimal temperatures. Thesecond category (referred to as 'disturbance~factors) are factors associated with partial or totaldestruction of plant biomass from herbivores,pathogens, cultivation, drought, frosting,flooding, fire etc.. When the four permutations ofhigh or low stress and high or low disturbance are


6

examined it is apparent that only three are viableplant habitats. The extremes are 'competitors'exploiting conditions of low stress and lowdisturbance, the 'stress tolerators' associated withhigh stress and low disturbance, and the 'ruderals'characteristic of low stress and high disturbance.There are other combinations of plant characterssuited to exploiting various intermediateconditions corresponding to particular equilibriabetween stress, disturbance and competitionfactors in the environment. These can bedisplayed in a triangular ordination diagram,which can also be used to indicate the strategicrange of various life forms (Fig 1). The C-S-Rmodel proposes that the vegetation which developsin a particular place and at a particular time is theresult of an equilibrium which is establishedbetween the intensities of stress (constraints onproduction), disturbance (physical damage to thevegetation) and competition (the attempt byneighbouring species to capture the same unitresource).

The thesis of the concept is that there has beenevolutionary specialisation in different taxatowards similar physiological and morphologicalcharacters in the three different modes of plantresponse. Species suitable for competitiveenvironments favour genotypes in which highmorphological plasticity facilitates escape fromresource depletion zones, in order to sustainresource capture and maintain reproductivefitness. In stress environments, both survival andreproduction depend crucially upon the capacityof the plant to remain viable through long periodsduring which little growth occurs. This mayconfer selective advantages upon species whichuncouple growth from resource intake. Indisturbance environments, selection is likely tofavour those genotypes in which rapid growth andearly reproduction increase the probability thatsufficient offspring will be produced, mostly in adormant stage like seed, to allow the survival andre-establishment of the population.

Environmental gradientsAnother concept, principally developed toaccommodate the range of both natural andmodified (oversown and fertilised) New Zealandtussock grasslands, gives emphasis to the plant /environment interactions and sees them in termsof four composite factors (Scott 1979). These are


temperature, moisture, soil fertility, and a fourthrelated to the interaction of growing points andanimal management. The concept is akin to theother species gradient concepts. It has no timecomponent and would have difficultyaccommodating disturbance or stress factors.

In the hypothetical example, this concept wouldsee beech forest, short tussock and the bareground communities as being three differentenvironments differing in moisture regime, andwould have difficulty if they were time phases onthe same site. The example might also suggestthat hawkweed is a moderate fertility phase of theothers. It easily accommodates improved pastureas being a high fertility phase.

Physiological modellingThe alternative to trying to condense plantresponses and/or environment into a few universalfactors is to go the other way using the power ofmodern computers to model all the components interms of their known complexity. The attractionis that it can potentially synthesize all the knowninteractions, either determined directly, or fromextrapolation from other studies. The other mainattraction is that it can simulate the dynamics ofprocesses and hence give a time frame of potentialchanges. An example of this is White's (1984)transcription of the USA prairie biomeprogramme to the New Zealand tussock grasslandsituation.

To date this approach has not lived up toexpectation (Hansen et aI1985). In my view thisis because of the complexity of detail, withdifferent emphasis in different research groups,with only a few people knowing the full details ofany particular model. Probably the main limitationhas been because the details are not available formost real life range land problems. The degree towhich parameters have to be estimated or'guessed at' does not engender confidence amongthose not directly involved in the model. It wouldbe doubtful if there were enough base data toattempt this approach for the examples given.

Probably more progress could be made if modelswere only used to do preliminary estimates of the'what in' type questions. Thus the trend has beentowards simpler models of the 'expert' type which



are different from the concept of physiologicalmodels as used here. As has been remarked, itseems we may have become involved with largecomplex systems, but have not learned to usesome of the universal properties of complexsystems ego for vegetation, the possible universalapplication of the 3/2 thinning law or the log /linear relationship between abundance and rank.

In the subsequent sections of the paper theemphasis is as much on techniques as the conceptsthey imply.

Cluster analysisFor vegetation, this is a general term foranalytical techniques which attempt to groupsamples of field data into like kinds (Fig 2).There can be considerable debate about whetherthere are real groups in which variability in fielddata can be regarded as experimental error, orwhether clustering is just a utilitarian grouping ofa continuum for the purpose of showingrelationships or summary. A wide variety oftechniques have been developed for this purposeapplicable to nominal, ordinal and quantitativevegetation data.

However clustering only looks at vegetation inone time frame and implies nothing about itsdynamic or environmental relationships, thoughthese may be appended as descriptive information.Thus in the present context, cluster analysismethods may only serve as a prelude to furtheranalysis.

Component analysisIf the concept of vegetation is as a continuum andif the vegetation data are quantitative, thenalternative concepts and analytical techniques areto seek the major trends between two classes ofdata. Principal component and factor analysis aretwo such statistical techniques, and there has beendevelopment of several non statistical techniqueswithin plant ecology.

These methods make no prior assumption as towhat the trend may be, and leave the data tospeak for themselves. This can be regarded as afault or virtue depending on whether the observerhas a prior concept as to what the trends are. Thetechniques only work well for unimodal speciesdata and have difficulty with multi-modal species

7

data or multi-species in different domains. Likecluster analysis, component analysis only dealswith vegetation in one time frame withoutreference to time or environment, and would onlybe useful,as a prelude to other analyses. As thediagram indicates, there are many similaritiesbetween cluster and component analysis,especially if one regards the clustering tree as a'mobile' which can be variously rotated in spaceto correspond with the component diagram.

Correspondence analysisOne method of considering vegetation /environment interactions is by doing componentlike analyses separately on both the vegetation andenvironmental factors and to then superimposethem and note their correspondence. Canonicalcorrelations and twinspan analysis are two suchanalysis methods. These, and similar techniques,are probably just more sophisticated approaches tothe 'eye balling' or 'seat of pants' approachimplied when environmental descriptors are addedto vegetation data.

Transition matrixOne method of considering vegetation / timeinteraction is that of transition matrix or life tableanalysis. In this, vegetation data from permanentquadrats monitored at regular intervals is firstclassified into nominal vegetation types, and theninto tables giving the empirical probabilities of aparticular vegetation type changing to anotherwithin a certain time period (Van Hulst 1989). Inthe hypothetical example, hawkweed dominatedquadrats have an 80 % chance of remaininghawkweed dominant for one year, 12 % chance ofchanging to bare ground types, 6 % to pasture,1.9 % to short tussock, and 0.1 % to beechforest. Actual tussock grassland examples aregiven in Scott et al (1990). The main features ofthe matrix can also be shown in diagrammaticform.

The method is probably the most useful andpowerful technique currently available forstudying vegetation time trends. It depends onregular repeated measurement on permanentquadrats, and vegetation defined in qualitativeterms. It does require a large database to getreliable estimates of probabilities. There can besome debate on whether there is an implied


8

concept that dynamics of the vegetation aredetermined by the vegetation itself, or whetherthey represent a response to environmentalchanges. If the former, then environmental effectsare essentially disregarded. If the latter, then thetransition matrix needs to be developed for eachset of environmental conditions, or the matrixderived from several years data, as being thegeneral trend after year to year variation has beenremoved. The approach can be used forextrapolation. Application of the method to somedeveloped and undeveloped tussock grasslandsdata has given the clear impression that vegetationadjusts to new environmental conditions muchmore rapidly than commonly supposed - usuallywithin a decade.

Black box correlationThis tenn is introduced to cover the wide range ofapproaches that seek correlation between variableswithout implying, or being unable to clearlyprove, causality. This applies to all of thevegetation I environment I time interactions. Agood example is the wide spread use of altitude,aspect and slope descriptors to vegetation data —these are factors which per se have nophysiological basis for effect on plants. Again asthe example shows this is not to decry theirusefulness - only that it must be realised that theyare only correlations. The approach is justifiableif it works and gives realistic results, but must bedumped when a more mechanistic I physiologicalapproach is available.

The concept, virtues and criticisms are morewidespread than the simple example. It is inherentin most measurement of environmental factorsappended to vegetation data, to most statisticalanalysis and many of the simpler, more robustmodels. There is seldom sufficient experimentaljustification or proof of the variables we choose tomeasure and probably most are in the category of'it is well known that..'.

There may even be virtue in this approach in thatit may allow extrapolation from a well basedconcept, or direct application of principlesestablished in other situations. Also in thecomputer analysis or modelling sense it may allowapplication of 'unifonn subjectivity' across largedata sets.


Regression analysisWhere species, vegetation, environment and timevariables have been measured in quantitativeterms, then multiple regression is the mostcommon form of analysis for determiningempirical quantitative relationships between thevariables. If the requirement is only a quantitativeempirical relationship of the 'black box' type,then there is considerable latitude in choice ofvariables, selection procedure for variables,curvilinear relationships, and determination ofrelative significance or importance of explanatoryvariables.

However, in light of the previous section, if theanalysis is also intended to imply causalmechanistic / physiological relationships thenmuch care is needed in the initial selection ofvariables, the transformation of these variablesand the form of the assumed function. Thecommonly assumed linear additive relationshipbetween vegetation and environmental variables isunlikely to reflect biological reality. Also,multiple regression is a two stage process (Fig 2),with the response or dependent variable on onegroup and the various independent or explanatoryvariables in the other; again unlikely to reflectbiological reality.

There are a number of difficulties in dealing withtime, of which only two will be mentioned at thisstage. The first is that in the study of vegetationtrends, one will invariably be trying to predictoutside the range of the data. One would need tobe very sure of the variables and the form of thefunction to make this extrapolation with anydegree of certainty. A second difficulty is that thebase of data usually come from repeatedmeasurement of permanent quadrats whichviolates the statistical requirement ofindependence of samples.

Path analysisThe multi-stage interactions between variablescharacteristic of ecosystems is more realisticallymimicked in the statistical technique of pathanalysis or simultaneous regression analysis. Ihave described this technique using New Zealandexamples (Scott 1973, 1977). While the techniqueis conceptually useful in its diagrammatic form inshowing the expected relationships betweenvariables, it is seldom applicable in its statistical



analytical form in that it requires simultaneousquantitative measurement of all variables ofinterest. The technique would have difficulty indealing with time.

Time series analysisIt has been suggested that time trends invegetation should be suited to the econometricstatistical technique of time series analysis. Thebasic assumption in time series is that theresponse in the-current period is partly dependenton the response in the previous period (unlikeregression analysis) as well as other cyclical orgeneral trends and random effects. The analysisattempts to determine that magnitude of differentcomponents and make prediction about futurevalues. Vegetation changes are likely to have thesame features.

However there are some major limitations to thetechnique for analysing vegetation trends. Themost likely is that it requires a series of at leastthirty measurements, preferably at equal timeintervals. Probably the most successful applicationof time series to vegetation data has been in treering research. There is also the concept in severalof the aspects of time series analysis, that thebehaviour is determined by intrinsic properties ofthe series, and not external factors, and wouldthus have difficulty in interpreting time trends invegetation in terms of environmental factors.

Segment analysisThe final concept is my as yet unpublishedanalysis technique for determining time trends invegetation data that are normally available. Thesedata tend to be quantitative measurements frompermanent quadrats at irregular time intervals;where there is marked variation between quadrats,where the response at each quadrat is reasonablywell defined, and the time scale of themeasurements is short (relative to the totalvegetation change). It is suggested that these smallchanges within individual quadrats can beconceived as being possible segments of a muchlonger 'mean trend' and the only requirement isto place them in their correct sequence. It wasfound that a scattergram of the mean and gradientof these individual segments formed a distinctivepattern according to the likely long term patternand could be used to show that pattern. In anexample from the long term Waimakariri data

(Scott et alI988), segment analysis showed thatonce hawkweed appeared on a plot an exponentialincrease followed.

DiscussionThis brief review paper has tried to make severalpoints.· Where factual information is limited, as in the

role of hawkweed in New Zealand tussockgrasslands, decisions are going to be swayedby concepts. Therefore there is a clear need toexamine these concepts and their background,and to be aware how much they influence ourattitudes. You are reminded that each of theconcepts was given in their more extremeform to illustrate the diversity.

· The objective is to determine the condition andtrend of a particular group of ecosystems thatmake up the New Zealand tussock grasslands.My impression is that we do not have verygood criteria for assessing condition, but thatmajor emphasis is being given to the state ofthe vegetation.

· Using the above approach there are three maincomponents — vegetation, environment andtime. My impression is that we are reasonablywell endowed with concepts and analysistechniques to describe variation in vegetationin a status quo, one off time frame. There aresome concepts and analytical techniques forconsidering environmental factors and theircorrespondence with species or vegetation,however the clearest deficiency is in thetreatment of the time concept. While it isalmost universally recognised as being thedimension in which the interaction of the othertwo components must be seen, there is a lackof specific concepts and analysis techniques toinclude time.

· Finally while concepts may provide usefulguidelines, they must only be a prelude to, andsubservient to, detailed factual information onhawkweed and its dynamic, physiologicalinteraction with other tussock grasslandcomponents.

AcknowledgementsTo Mr. J. Poff for diagram preparation.


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ReferencesBraun-Blanquet, J. 1932. Plant Sociology.

(translated by G.D. Fuller and H.S. Conard).McGraw Hill 439 pp.

Gleason, H.A. 1917. The structure anddevelopment of the plant association. Bulletinof the Torrey Botanical Club 43: 463481.

Grime, J.P.; Hodgson, J.G.; Hunt, R. 1989.Comparative plant ecology — a functionalapproach to common British species. UnwinHyman, London 742 pp.

Hanson, J.D.; Parton, W.J.; Innis, G.S. 1985.Plant growth and production of grasslandecosystems: a comparison of modellingapproaches. Ecological Modelling 29: 131–144.

Hanson, H.C. 1958. Principles concerned in theformation and classification of communities.Botanical Review 24: 75126.

Laycock, W.A. 1991. Stable states and thresholdof range condition on North Americanrangelands - A viewpoint. Journal of RangeManagement 44: 427–433.

Major, J. 1951. A functional, factorial approachto plant ecology. Ecology 32: 392412.

Russel, D.B.; Ison, R.L. 1991 (in press). Theresearch — development relationship inrangelands: An opportunity for contextualscience. I V t h International RangelandCongress.

Scott, D. 1973. Path analysis: a statistical methodsuited to ecological data. Proceedings of theNew Zealand Ecological Society 20: 79–95.

Scott, D. 1977. Plant ecology above timberline onMt Ruapehu, North Island, New Zealand. I.Site factors and plant frequency; II. .Climateand monthly growth of five species. N e wZealand Journal of Botany 15: 255–310.

Scott, D. 1979. Potential pasture production inthe hill and high country. T u s s o c k .Grasslands and Mountain Lands Institute


Special Publication No. 16: 171–193.

Scott, D.; Dick, R.D.; Hunter, G.G. 1988.Changes in the tussock grasslands in thecentral Waimakariri River basin, Canterbury,New Zealand, 1947–1981. New ZealandJournal of Botany 26: 197–222.

Scott, D.; Robertson, J.S.; Archie, W.J. 1990.Plant dynamics of New Zealand tussockgrassland infested with Hieracium pilosellaII. Transition matrices of vegetation change.Journal of Applied Ecology 27: 235–241.

Van Hulst, R. 1989. On the dynamics ofvegetation: Markov chains as models ofsuccession. Vegetatio 40: 3–14.

Weaver, J.E.; Clements, F.E. 1938. P l a n tecology (2nd edition) McGraw Hill, London601 pp.

White, E.G. 1984. A multi species simulationmodel of grassland producers andconsumers. Ecological Modelling 24: 241–-262.

Whittaker, R.H. 1952. A consideration of climaxtheory: the climax as a population andpattern. Ecological Monographs 23: 41–78.

Whittaker, R.H. 1956. Vegetation of the GreatSmoky Mountains. Ecological Monographs26: 1–80.


N.Z. Ecol Soc. Occ. Pub. No. 2 11

Figure 1: Concepts in assessing ecosystem conditionfrom vegetation characteristics. F=beech forest,T=short tussock, H=hawlcweed, B=species associatedwith bare ground, P=oversown developed pasture.


Figure 2: Vegetation analysis techniques used inassessing ecosystem condition and trends.

12 N.Z. Ecol. Soc. Occ. Pub. No.2

INCONSISTENCIES BETWEEN THE SCALE OF THE HAWKWEED (HIERACIUM) PROBLEMAND THE METHODS USED FOR INVESTIGATING IT.

Marta TreskonovaP. O. Box 56

Lincoln University, CANTERBURY

The problem of hawkweeds (Hieracium spp.) hasreached ecosystem dimensions. It needs to beunderstood at an ecosystem scale. Usually, smallscale empirical experiments have been used toinvestigate the large scale and complex problemof infestation by hawkweeds. Contemporaryvegetation science offers an ecosystem approachwith techniques which are able to detect causesunderlying complex processes.

Depending on the approach used, aspects of thehawkweed problem can be interpreted in differentways. From a species-centred perspective, thedistribution of hawkweeds appears to be chaotic.Patterns can only be recognised when observingthe wider grassland ecosystem. Within a widerperspective the patterns of human-induced andnatural disturbances, both of which facilitatedistribution of species of hawkweeds, becomeclearer.

From a small scale experimental approach,hawkweed-dominated vegetation may appear to bea relatively stable stage. On a larger scale,considering grassland succession, hawkweeddominant stages are relatively short-term andunstable. Under the prevailing environmental andmanagement conditions, hese stages are subject tofurther degradation.

Measurements in a permanent trial may appear tobe the only reliable method to determine temporalrelationships. However, the sequence of stagescan only be established from ecosystem data,representing larger areas and longer time spans.It then becomes evident that a space for spread ofhawkweeds has been pre-empted beforehawkweeds occupy it.

Even detailed measurements of vegetation changeon a small scale would be insufficient todetermine the composition of grasslands which areresilient to invasion by hawkweeds. Thatdetermination needs to come from successionaltrends in grasslands in a variety of conditions.

Hawkweed species, from a non-ecosystemperspective, are unwanted alien plants. Within anecosystem context they fulfil a role of soilconservation in depleted grasslands, as well as arole of initiation of natural revegetation. Nosatisfactory management decision can be madewithout understanding the role of hawkweeds ingrassland ecosystems. Categorical proclaiming ofhawkweeds as a pest, similar to rabbits, ismisleading. Whereas rabbits and sheep areremoving biomass, hawkweeds are restoring thedamage at faster rate than indigenous species andcurrent management is able to achieve.

An understanding of these complex relationshipsis essential if application of biological control ofhawkweeds is to be considered.


N.Z. EcoL Soc. Occ. Pub. No.2 13

CHANGES IN GRAZED AND RETIRED FESCUE TUSSOCK GRASSLANDS,HARPER-AVOCA CATCHMENT, CANTERBURY, 1965 -1990

A.B. Rosel, K.H. Platt, C. FramptonLandcare Research New Zealand Ltd - Manaaki Whenua

P.O. Box 31-011, CHRISTCHURCH1Present address: Marlborough Research Centre

Private Bag 1007, BLENHEIM

On permanent transects in the Harper-Avocacatchment, vegetation changes over the last 25years indicate a widespread and continuing trendaway from fescue tussock grassland towardsvegetation dominated by exotic grasses andhawkweeds. This period was characterised bymarked expansion of mouse-ear hawkweed(Hieracium pilosella). tussock hawkweed (H.lepidulum) and browntop (Agrostis capillaris),with associated declines in hard tussock (Festucanovae-zelandiae), other native species, andpreviously abundant exotic species.

Such change was most advanced in the relativelydry lower-valleys (1200 - 1300 mm annualrainfall). However, a slow increase in exoticspecies further up-valley (1300 - 1500 mm)suggests this process is spreading. Fluctuations inspring-early summer rainfall did not appear totrigger periods of rapid hawkweed spread, butmay be more important in drier areas.

On north-aspect, lower valley slopes the rate andextent of invasion by mouse-ear hawkweed wassimilar in grasslands still extensively grazed bysheep and in those retired from grazing in 1968.This may be interpreted as indicating that the twocontrasting grazing histories had no influence onthe susceptibility of the grasslands. It couldequally be argued that by 1965 all lower-valleygrasslands were predisposed by the effects of c.100 years of extensive grazing. Althoughprolonged sheep-grazing appeared to predisposethe tussock grasslands to early invasion bybrowntop and tussock hawkweed, these speciesare now also increasing in retired grasslands.

Exotic species are also becoming increasinglydominant on grazed and retired south-facing lowervalley slopes, where the main hawkweed involvedis tussock hawkweed.

Even in the absence of exotics, the grasslandswould continue to change as woody vegetationand snow tussocks (Chionochloa spp.) invade.

The essentially seral, culturally induced fescuetussock grasslands are predisposed to ongoingvegetation change and eventual demise over muchof their range. Researchers and land managersmust:

• accept the inevitability of such decline in orderto develop appropriate and sustainable goalsfor nature conservation or production

• apply appropriate management to achieve thesegoals

• monitor management outcomes to gauge theirsuccess

• be prepared to revise management goals asnew information becomes available.


14 N.Z. Ecol. Soc. Occ. Pub. No. 2

TIlE INFLUENCE OF GROUND COVER ON HAWKWEED ESTABLISHMENT INFESCUE TUSSOCK GRASSLAND

P.R. EspieForest Research Institute

Present address: 29 Woodford Tce, CHRISTCHURCH 5

How ground cover affects hawkweed (Hieraciumspp.) establishment in tussock grasslands is poorlyunderstood, but has important implications forland management. This study investigated theinfluence of ground cover, site preparation andsoil fertility on hawkweed establishment andflowering from 1982 to 1990.

The trial site is located in the mid-Waimakariribasin on a fluvioglacial outwash terrace with aninfertile Craigiebum high-country yeIlow-brownearth soil. Vegetation is undeveloped fescuetussock grassland. Mean annual precipitationvaries between 850 and 900 mm (Espie 1987).

Three site treatments; cultivation, oversowingafter glyphosate herbicide pre-treatment, andoversowing alone were applied factoriaIly withthree legumes; Maku lotus (Lotus pedunculatuscv. Maku), birdsfoot trefoil (L. corniculatus cv.Maitland), white clover (Trifolium repens cv.Huia). Two phosphate (P) levels (12.5 and 50.0kg P/ha) were applied once at sowing. Calcium,magnesium, potassium, molybdenum, and sulphurwere supplied as basal fertiliser. Control plotswere undeveloped fescue tussock grassland. Plotsize was 2 m with five replicates per treatment ina randomised block design. Hawkweed percentagecover and flowering were measured in February1990.

Mouse-ear hawkweed (Hieracium pilosella) wasthe only hawkweed present in the grasslands in1982, occurring at low density (less than oneplant per 64 m ). By 1990 king devil ( H .praealtum) and tussock hawkweed (H. lepidulum)had colonised by seed from populations outsidethe study area and hawkweed cover increased to3%, almost entirely comprised of king devil.Establishment of mouse-ear establishment in thetrial was minimal.

Establishment of king devil was greater inherbicide-treated grassland than in cultivated soil

or intact grassland (P<0.07). Legumes and Phad no significant effect on king devil cover orflowering.

There was a linear relationship between king devilrosette area and number of flowering culms(P<0.0001; R2 0.985), biologically indicative ofan early stage of population expansion and littledensity stress (Bishop and Davy 1985).

The implications for management are that seed isimportant in establishment of new hawkweedpopulations and that spring and early summergrazing may reduce hawkweed expansion rate byremoving flowering culms and limiting seeding.King devil appears to establish better with someground cover than on bare soil, so removingundeveloped grasslands from grazing is unlikelyto prevent or decrease spread.

ReferencesBishop, G.F.; Davy, A.J. 1985. Density and thecommitment of apical meristems to clonalgrowth and reproduction in Hieraciumpilosella. Oecologia 66: 417-422.

Espie, P.R. 1987 (unpublished). Edaphic ecologyof Festuca novae-zelandiae, Lotuspedunculatus and Trifolium repens onCraigieburn high-country yellow-brown earthand related soils. Ph.D. thesis, LincolnCollege, University of Canterbury. 313 pp.

Record of a workshop of the New Zealand Ecological Society on "Vegetation change in tussock grasslands, withemphasis on hawkweeds", Cass Field Station, Canterbury, 1991.

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N.Z. Ecol. Soc. Occ. Pub. No.2 15

A REVIEW OF CHARACTERISTICS OF MOUSE-EAR HAWKWEED(HIERACIUM PILOSELLA)

T. A. JenkinsDavid Scott, NZ Pastoral Agriculture Research Institute Ltd.

P.O. Box 60, CHRISTCHURCH

IntroductionMouse-ear hawkweed (Hieracium pilosella L.) isa weed of increasing abundance throughout theNew Zealand high country, sometimes forming acontinuous mat. This species is a problem weedin several countries, particularly in cool climates(Bingham, 1965; Hay and Ouellette, 1959; Healy,1976; Stevens and Hughes, 1973). The specieshas ecological and physiological adaptations thatallow it success over other species present, andthis review outlines the literature on some of theseadaptations.

TaxonomyHieracium is a large and complex genus. Thegenus comprises two subgenera, Hieracium (sensustricto) containing several thousand species andPilosella Hill containing 136 species originallyconfined to Europe. The Hieracium sectionprepared by Sell and West in the Flora Europaea(Tutin et al. 1976), lists 111 of the 136 species ofsubgenus Pilosella as originating frominterspecific hybrids, 67 of these are widespreadand 44 are limited in distribution. 33 of thehybrid origin species are noted as having H .pilosella as a possible ancestral parent. A revisionwas carried out suggesting that Pilosella be madea separate genus (see Makepeace, 1985a). SomeNew Zealand authors followed this suggestion fora period but a revision of NZ material preparedby Garnock-Jones (Webb et al., 1988) keptPilosella as a subgenus of Hieracium. The twosubgenera are morphologically distinct. Species ofthe Pilosella subgenus produce stolons from abasal rosette, whereas species of the subgenusHieracium are not stoloniferous.

There are five species of the subgenus Pilosellapresent in New Zealand including H.aurantiacum, H. caespitosum, H. pilosella, H.praealtum, and H. X stoloniflorum. There arefive members of the Hieracium subgenus present,H. argillaceum, H. lepidulum, H. murorum, H.pollichiae and H. sabaudum.

Mouse-ear hawkweed is distinguished from theother species by having a single stemmed, leaflessflower stalk bearing solitary capitula with yellowligules. The leaves have stellate hairs on theunderside forming a dense tomentum.

Mouse-ear hawkweed is likely to have beenintroduced into New Zealand as a contaminant ofpasture seed or grain from the United Kingdom.Only three of the eight morphological subspeciesdescribed by Tutin et al. (1976) have beenreported in New Zealand; ssp. micradenium (themost common), ssp. pilosella and ssp. Trichosoma(Webb et al., 1988). Although Tutin etal.(1976) list only eight subspecies, Turesson(1972) identifies those eight plus seventy twoother subspecies in Sweden alone. Thisdemonstrates the difficulty encountered with thetaxonomy of subspecies in such a partly apomicticspecies with a large variety of stablemorphological forms. Garnock-Jones states thatoccasional New Zealand specimens approachother subspecies (Webb et al., 1988). Thesubspecies are differentiated on the basis of theindumentum of the involucral bracts, whichprobably have no ecological significance. Thesubspecies are all found in a wide range of NewZealand high country regions.

Cytology and Chromosome NumbersThe diploid number of chromosomes for mouse-ear hawkweed is 18. The species bas beenrecorded with a wide range of ploidy levelsincluding diploid (2x; 20= 18), 4x (20=36), 5x(2n=45), 6x (2n=54) and 7x (20=63) noted bySell and West (1976). Gadella (1987) alsorecords the presence of 8x (2n=72), 9x (2n=81)and decaploids (l0x ; 20=90). In a study of 31New Zealand mouse-ear hawkweed populations,Makepeace (1981) found evidence only ofpentaploid (2n=45) chromosome numbers.Makepeace found variation in forms of mouse-earhawkweed populations that remained distinct in atransplant experiment. This is characteristic ofthe pentaploid chromosomal race (Turesson &

Record of a workshop of the New Zealand Ecological Society on çVegetation change in tussock grasslands, withemphasis on hawkweedsé, Cass Field Station, Canterbury, 1991.

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Turesson, 1960). No relationship however wasfound between ecological distribution and themorphological form. It is interesting to note thatH. pilosella subsp. pilosella is not recorded bySell and West (1976) as having a pentaploid formin Europe; they only describe the tetraploid form.

In Europe mouse-ear hawkweed is a well studiedspecies (Turesson and Turesson, 1960, Turesson,1972; Gadella, 1972, 1987). There is littlerelationship between cytology and morphologicalsubspecies. Four of the eight subspeciesdescribed by Sell and West (1976) have two ormore possible chromosome numbers recorded e.gsubsp. trichosoma can be 2n=36,45,54 or 63.The three subspecies occurring in New Zealandhave wide geographical distributions in Europeaccording to Sell and West (1976). H. pilosellasubsp. micradenium is noted for presence inpastures and sandy ground through most ofEurope, the subsp. pilosella is noted as mainlylowland throughout most of Europe, and thesubsp. trichosoma is noted as mainly present inNorth and East Europe. However Gadella (1972,1987) describes distribution according to sexual orapomictic biotypes and ploidy levels generally.Gadella (loc cit) states the pentaploids occur inWestern, Eastern and Northern Europe andparticularly in areas which were glaciated duringthe Pleistocene era. The pentaploids also occur inthe montane and subalpine zone. Makepeace(1981) believed that this could explain why theNew Zealand mouse-ear hawkweed grows so wellin the high country rather than the lowlands.Grime et al. (1988) make the point thatcytological and historical components areimportant for perspective of the autecology of aspecies.

Breeding SystemsGarnock-Jones (Webb et al. 1988) describes thesubgenus Pilosella as being sexual or partlyapomictic whereas the subgenus Hieracium isdescribed as being mostly obligately apomictic.However the polyploidal race of mouse-earhawkweed, such as is present in New Zealand, isreported to be usually facultatively apomictic(Turesson & Turesson, 1960; Gadella, 1972).Gadella (1987) states that pentaploid mouse-earhawkweed plants most ly reproduceagamospermously (by apomixis). In fact Gadella

N.Z. Ecol. Soc. Occ. Pub. No.2

stated that it was .highly probable that allseedlings of 5x plants are formed apomictically.(Gadella, 1987 p. 234). This was based on thefindings that all seedlings had the samechromosome number as the mother plant evenwhen potentially cross pollinated (no additionhybrids were found), and that approximately equalnumbers of viable achenes were produced afterboth isolation and cross pollination (43.6% and43.7% respectively). Some populations of NewZealand material of mouse-ear hawkweed andtussock hawkweed (H. lepidulum) have beenconfirmed as being apomictic. (R. Bicknell -perscomm).

If mouse-ear hawkweed is reproducingapomictically, then floral reproduction is simplyanother form of clonal reproduction, and thevariability within a population is potentially verysmall. If apomixis is the sole or dominant form ofseed production, then it does raise difficulties inexplaining the present variability in subspeciesand forms within New Zealand, and thesuggestion that there may have been evolutionaryadaption of the species to more suit the NewZealand environment. Either there have beenmultiple entry of different types into NewZealand, or there has been more sexual crossbreeding occurring than would be indicated by theploidy level and apomixis.

H. X stoloniflorum, a hybrid between H. pilosellaand H. aurantiacum, is present in New Zealand.It is not known when the hybridisation occurred,whether in the Northern Hemisphere or locally.In New Zealand populations of H. X stoloniflorumare isolated from populations of H. aurantiacumindicating that the crossing is unlikely to haveoccurred in those areas.

MorphologyMouse-ear hawkweed is a prostrate perennial herbwith a rosette of small, setose, entire leaves anda single terminal shoot apex. Leaves arelanceolate, often less than 1000 mm2 in area,lacking petioles and are usually appressed to theground. Stomata are present on the top as well ason the underside of the leaves. Field observationsin the Mackenzie country indicate that on averagea new leaf is produced every two weeks in mid tolate summer. The scape is erect and bears



glandular hairs. Each leaf base has a singleaxillary bud which is initially dormant. Axillarybuds can remain dormant for four years orlonger. The axillary buds give rise to eitherflowers or stolons. Only after an inflorescencehas been initiated, can stolons be produced fromother axillary buds, even if the floral partssubsequently abort (Grime et al., 1 9 8 8 ;Makepeace, 1985a).

Stolons generally remain appressed to the groundand can be observed within surroundingvegetation. Stolons generally have the potential toproduce a new daughter from the terminal bud.However stolons can branch in some cases froma bud at each leaf axis, with daughters potentiallybeing formed at the end. of each branch. Thestolons produce adventitious roots from rootinitials, located mostly at the nodes. Daughterrosettes are then formed, take root and canbecome functionally distinct with the breakdownof the stolon or the senescence of the mother plant(Grime et al., 1988). The stolons root in aboutFebruary after rainy periods and stolon elongationhas stopped (Makepeace, 1985a). It is not knownwhether there is a direct metabolic link betweendaughter rosettes and parents which are stillattached i.e. when the stolon is intact.Makepeace (1985a) said the transport ofphotosynthates, water and minerals wouldprobably be negligible based on findings for otherspecies. However I have observed in aglasshouse culture, that stolons may form rosetteswhich can proceed all the way to seed set withouttaking root. This indicates a some degree oftranslocation for distances of greater than 30cm.

Rosettes are monocarpic (semelparous), andtherefore after the completion of flowering arosette will die. If a new daughter rosettesurvives the winter Makepeace (1980) suggests itbe defined as a new individual plant.Overwintering leaves are characteristicallyreddened. In the Mackenzie country (Scott, 1984)new leaves start appearing in August. Fieldobservations indicate that over four leaves perrosette remain viable over winter. Initiation ofinflorescences and stolons begins aroundNovember and scape development and floweringis evident 1 to 3 weeks later. The development ofthe inflorescence is more or less completed near

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ground level, and the scape development andactual flowering can occur within one day(Makepeace, 1985a). Seeds are fully ripened onthe capitula around December to January and arewind dispersed usually within a few days.

Each flower produces approximately 20-40 seeds.Estimates from five contrasting sites give totalseed production in the range of 30-1340 millionper hectare (Makepeace 1985).

Mouse-ear hawkweed characteristically formsmats. In the centre of dense patches it is foundthat flowering, stolon formation and the generalproduction of new daughters are reduced(Makepeace, 1980, 1985a; Bishop & Davy,1985). This could be partly due to auto-inhibitionthrough allelopathy which is discussed in a latersection. However it is probably related to a lackof resources in the densely populated zone,Makepeace (1980) mentions the lack ofphosphorous in particular. There is an observablegradient of flowering and stolon production fromthe centre of a patch to the edge, where activity isgreatest.

In Table 1 a comparison of population dynamicsbetween several different sites is given.Makepeace (1980, 1985a) found that five newrosettes resulted from stolon growth in one seasonin a dense mature mouse-ear hawkweed stand(Sawdon). This was only sufficient to offset thedeath of rosettes that senesced after flowering,and therefore there was no net increment for theyear. This compares to a net increment of 64%in the Wolds site where mouse-ear hawkweed wasrapidly colonising.

Mouse-ear hawkweed has been described in NZas having a deep root system. However Grime etal. (1988) and Anderson (1927) in theirdescription of the species in the UK, state that theroot system is shallow. The UK authors suggestthat the shallow root system is the reason whymouse-ear hawkweed patches can be seen tosuffer from drought. Drought stress is apparentin New Zealand also (personal observation).Mouse-ear hawkweed is reported by Grime (pers.comm.) to have roots to the depth of 50cm. Thusthe species has the potential to have deep roots ifsoil conditions permit. There are high numbers

Record of a workshop of the New Zealand Ecological Society on .Vegetation change in tussock grasslands, withemphasis on hawkweeds., Cass Field Station, Canterbury, 1991.


Table 1: Population dynamics of H. pilosella in five unfertilised high country sites of increasing rainfall in 1978/79(Makepeace 1980, 1985a).

Site Ben Ohau Ruataniwha Wolds Sawdon Glentanner

Rainfall (mm) 475 600 675 800 1300Soil s+v s+v m m mH. pilosella density m m c d mPlant flowering( %) 46 49 79 5 34Abort (%) 3 2 27 3 1Seedling estab.(%) 0.9 1.0New daughters(%) 68 102 173 5 53Autumn mort. (%) 9 25 30 0 1% survival 87 75 83 100 98Net increment(%) 13 28 64 0 18Half-life (years) 1.1 1.0 0.4 13.5 1.7

Soil: s= shallow; v= variable, m= moderate.Density of H. pilosella: m= moderate; c= newly colonising; d= dense.Plant flowering: individual plants which flower and subsequently die.Abort: inflorescences which aborted before seed production.New daughters: plants produced in mid summer.Autumn mort.: mortality of new daughter plants in the autumn.% survival: % of daughters surviving into autumn.Net increment: nett change from late winter to autumn.Half-life: = ln 2 / (10 n2 - 10 n1) [where n1 = 100 and n2 = l00-reproductive].

of wiry primary roots with relatively sparselateral roots, which are apparently long lived.The roots generally have a very heavy vesicular-arbuscular mycorrhizal colonisation, which canincrease seedling growth by 9 times (Grime et al. ,1988).

Although the form of mouse-ear hawkweed isgenerally appressed, the leaves can be held moreupright by surrounding vegetation, according toGrime et al. (1988). However in experimentsinvolving the shading of mouse-ear hawkweedwith shade cloth in pots, there was very littleeffect on form, though leaf size wasapproximately doubled with 10% shade conditionscompared to open light (Makepeace 1980).

Mouse-ear hawkweed may be relatively unusualin having a relatively fixed relationship betweenleaf position (numbered from apex) and dryweight of the leaf, over five sites (Makepeace1980, 1985a). This contrasts with theconsiderable variability between these sites in theking devil hawkweed (H. praealtum) leaf dryweight relationship to leaf position.

Population DynamicsBecause rosettes are monocarpic, thus dying aftersetting seed, there can be a high turnover ofrosettes within mouse-ear hawkweed populations.Table 1 (from Makepeace, 1985a) shows how thisturnover is less in the dense established standsthan the newly colonising patches. The Wolds site(newly colonising) showed 79 % flowering, andtherefore death of rosettes, whereas the Sawdonsite showed only 5 % flowering. The differentsites also showed differences in new daughterproduction from stolons, with 5 new rosettes per100 existing ones at Sawdon, and 173 newrosettes per 100 existing at Wolds. Overall therewas a large difference in turnover between thefive sites in Table 1, and there was a wide rangeof net increases of stolons from 0 at Sawdon, to64 per 100 existing rosettes at Wolds.

Makepeace (1985a) (see Table 1) found that thehalf life of individual mouse-ear hawkweed plantsvaried from 0.4 years at Wolds to 13.5 years atSawdon. Bishop and Davy (1984) found that theturnover of rosettes was less in the presence ofrabbit grazing, mainly due to the removal of



flower heads resulting in the longer life ofrosettes. An older age structure was also noted inthe rabbit grazed swards.

EstablishmentOriginally the spread of mouse-ear hawkweed intothe New Zealand high country would have beenby seed. However more recently the spreadappears to be mainly by vegetative means i.e.stolon production. Makepeace (1985a) found thatrosettes originating from seed accounted for only1 % of total new rosettes in plots in the MackenzieCountry. Scott (1984) concluded that emphasisfor control should be placed on the vegetativespread rather than floral reproduction. In the UK,mouse-ear hawkweed plants arising from seed areuncommon compared to plants arising fromvegetative spread (Grime et al. 1988).

No persistent seed bank is evident for mouse-earhawkweed either in the UK (Roberts 1986) or inNew Zealand (Makepeace 1980), but Roberts(1986) stated that there can be a delay betweendispersal and germination. Fungal contaminationresulting in seedling death is common inlaboratory studies.

Seedling establishment in the UK was found byWatt (1962) to occur mostly during a wet springand more where grazing was limited. Makepeace(1985b) found that in the Mackenzie countryseedling establishment was mostly in warm wetsummers immediately following seed shed, theseed needing no post dispersa1 ripening.Seedlings that establish successfully, quickly reachadult size in 8 to 10 weeks (Makepeace, 1985b).

Table 2 shows the effect of temperature andosmotic stress levels on germination of mouse-earhawkweed, as measured by Makepeace (1985b).At 2!C no germination was evident. Optimumgermination was at 22!C, with regard both to thetotal number of germinated seeds, and to thenumber of days taken till 50% had germinated.At 32!C, there was reduced germination. Thelevel of osmotic stress had a profound effect ongermination, with 85 % of seeds germinated in themoist conditions of 1 bar.

The removal of inflorescences prior to seed-set isreported to increase stolon activity and therefore

19

Table 2: The effect of temperature and osmotic stresson the germination of mouse-ear hawkweed(Makepeace, 1985b).

Treatment % germination

(a) Temperature (!C)2

17222732

062665011

(b) Osmotic Stress (bars)137

1115

85622000

vegetative spread (Makepeace, 1985b). This canoccur through grazing. However Mason (1987),in glasshouse pot experiments, found that althoughthere was some increased stolon productionfollowing an initial removal of inflorescences,there was no obvious response followingsubsequent removals of inflorescences.

AllelopathyMouse-ear hawkweed has been demonstrated tocontain allelopathic chemicals. Most literature isfocused on the presence of allelochemicals in theleaves. The phenol compounds identified includeumbelliferon which is the major allelochemicalaccording to Makepeace et al. (1985), as well ascaffeic acid and chlorogenic acid (Adams, 1987;Makepeace et al., 1985; Duquenois, 1956).These chemicals are retained in living tissue andonly released into the soil upon senescence andsubsequent leaching. Henn et al. (1988) foundthe allelochemicals umbelliferon and apigenin-glucoside also in the roots of mouse-earhawkweed. These chemicals are secondarymetabolites not directly involved in metabolicpathways. It is not known whether they serve adistinct role such as anti-herbivory or allelopathy.

Water extracts from the leaves of mouse-earhawkweed were shown to slow the rate ofgermination in some pasture species (Makepeaceet al. 1985). Abnormalities in root growth ofpasture species were noted in glasshouse grown


20

plants which had soil amended by the waterleachates of mouse-ear hawkweed. Symptomsincluded the absence of root hairs, damage to roottissue and the browning of apical meristems.Species affected included mouse-ear hawkweeditself, king devil hawkwed, perennial ryegrass,white clover, sheeps sorrel and two annualgrasses. Alsike clover was not affected. Scott(1984) pointed out that any negative effect onplant roots would exacerbate difficulties inobtaining moisture and mineral nutrients. Thiswould particularly affect the establishment ofpasture species.

Henn et al. (1988) concluded that allelopathy wasnot significant for mouse-ear hawkweed inNorthern France in maintaining a stage ofsucces s ion . Makepeace et al. (1985)demonstrated allelopathic effects of mouse-earhawkweed in both the laboratory and theglasshouse. Leaf extracts inhibited rootproduction and activity. However in the fieldMakepeace et al. (1985) could not findmeasurable levels of umbelliferon in the soil.They suggested that the effect would be transitoryin the field with levels only being significant atcertain times eg after summer drought killing ofleaves followed by autumn rain leaching ofchemicals into the soil. Adams (1987) found thatthe levels of allelochemicals produced by mouse-ear hawkweed were greater in the harsh fieldconditions than in a glasshouse regime.

Auto-inhibition by allelopathy was purported byMakepeace et al. (1985) to be responsible for themouse-ear hawkweed patches often having barespaces in the centre. Observational evidence ofinterspecific allelopathy could be confounded bythe effect of competition particularly forphosphorous (Makepeace et al., 1985).

Herbivory and Animal SelectionBecause of the generally slow and appressedgrowth of mouse-ear hawkweed and its possibleexclusion of other species the total stock feedavailable is limited in much run country.However the species is not unpalatable to stock.In fact Hughes (1975) found that mouse-earhawkweed was one of the herb species that wasactively selected for on undeveloped run countrynear Lake Ohau. Through cuticle analysis of the


sheep faeces mouse-ear hawkweed was identifiedby Hughes (1975) as the seventeenth to twentiethmost selected species in developed andundeveloped land. However in later work on theHarper-Avoca area with dense mouse-earhawkweed, the proportion of the species in thediet was less than in the vegetation composition(Harris and O'Connor 1980). The mineralcontent of mouse-ear hawkweed is good (Scott &Maunsell, 1974; Grace and Scott, 1974). Fieldobservation indicates that sheep will preferentiallyselect flowering heads when available.

Grazing by rabbits is thought to promote mouse-ear hawkweed infestation through the grazing ofsurrounding vegetation. Rabbits evidently have apreference for resting on mouse-ear hawkweedpatches - probably due to the low, dry vegetation- as indicated by a high frequency of rabbit faeceson the patches possibly leading to a mineralnutrition advantage for mouse-ear hawkweedpatches over the surrounding vegetation.

Changes in pasture vegetation can infer lowacceptability of species which become dominant(Hughes, 1975; Scott & Maunsell, 1974).However this is generally the result of greaterpreference for other species.

Diseases and PestsIn New Zealand mouse-ear hawkweed appears tobe relatively free of pests and diseases. There areno confirmed reports of plant diseases and onlypolyphagous insect herbivores such as porina anda common seed eater have been noted on thespecies. No host specific insects have beenrecorded in New Zealand. Scott (1984)summarised the presence of pests and diseases inEurope and the UK.

Plant StrategiesThere appears to be a difference of opinion overwhether mouse-ear hawkweed takes advantage ofbare ground in the inter-tussock zone, or whetherit can grow and displace existing vegetation. Anexamination of actual processes involved isneeded. Makepeace (1985a, 1985b) published acomprehensive study of establishmentcharacteristics of mouse-ear and king devilhawkweed which are relevant to the "bare groundquestion".



Darkness reduced the germination of mouse-earhawkweed, from 64 % in the light to 49 %. Thiswas a minor change compared to king devilhawkweed seed germination which dropped from55 % to 12 %. Mouse-ear places more reserves inits seed than king devil hawkweed. Mouse-earhawkweed has a resource allocation resulting in ahigher root to shoot ratio. High allocation toroots and also to seed are characteristic of speciesadapted to survival in competition with otherspecies e.g. in a stable pasture (Makepeace,1985b).

Makepeace (1980) showed that mouse-earhawkweed leaves remained essentially horizontaleven under shading. Scott (1984) noted that thischaracteristic was one of the few which indicatedless adaptation for growing in a sward than kingdevil.

DiscussionIt is too early to attempt a synthesis of what thegenetic and physiological characters of mouse-earhawkweed are which have allowed it to soeffectively exploit the New Zealand high countryenvironment. What the review has given is theknown facts which will have to be included in thatsynthesis along with other investigations still to bedone.

It is probably easier to highlight the major areaswhich have not been investigated in any detail.These areas require study before any synthesisand decision on whether the current landdegradation is better interpreted as being theresult of hawkweed invasion or whetherhawkweed is just a symptom of other degradationprocesses. The major aspects needinginvestigation are the mineral nutrition and waterrelationships of mouse-ear hawkweed, particularlyas they relate to its drought susceptibility in thelow rainfall areas. There is also the whole fieldof pest and disease interactions which are notapparent in New Zealand, but which the literatureindicate are present in its home territory andcould be the basis of a biological controlprogramme. The perspective of such features willbe obtained by comparing the characteristics ofmouse-ear hawkweed with resident native species,other adventive species, and also those specieswhich have similar ecology to mouse-earhawkweed in its home territory but do not appear

21

to have become important in New Zealand.However even within the aspects covered in thisreview, some require further work.

Present' indications are that only a smallproportion of morphological and cytologicaldiversity of the species has entered New Zealand,and yet it has dominated the high country to alevel rare in its home territory. The confirmedapomictic status of the material in New Zealandinfluences the consideration of; whether there hasbeen evolutionary adaptation to New Zealandconditions, its likely further diversification, andthe possible impact of control options.

Further work is needed on the role of seed in thelife history of mouse-ear hawkweed. Themagnitude of the seed production is at variancewith the very low observed frequency ofseedlings. This may be explained by the veryrapid reported growth of seedlings - but this needsto be checked. There is also debate on the typeof micro-site in which mouse-ear hawkweed cansuccessfully establish. The physiologicalcharacters of king devil hawkweed would seem toindicate bare soil and open sites, while those ofmouse-ear hawkweed would indicate adaptation tolow vegetation.

AcknowledgementThe financial support of the Miss E.L. HellabyIndigenous Grassland Trust is appreciated.

ReferencesAdams, J.A. 1987. Studies on Pilosella

officinarum Hill. (mouse ear hawkweed):changes in nitrogen balance and phenolicchemical levels under varying soil fertilityconditions. Unpublished BSc(Hons) Thesis,Lincoln College, Canterbury.

Anderson, V.L. 1927. Studies of the vegetationof the English chalk 5. The water economy ofthe chalk flora. Journal of Ecology 15: 72-129.

Bingham, S.W. 1965. Hawkweed control withturf herbicides. Northeastern Weed ControlConference 19: 486-489.


22

Bishop, G.F.; Davy, A.J. 1984. Significance ofrabbits for the population regulation ofHieracium pilosella in Breckland. Journal ofEcology 72: 273-284.

Bishop, G.F.; Davy, A.J. 1985. Density and thecommitment of apical meristems to clonalgrowth and reproduction in Hieraciumpilosella. Oecologia (Berlin) 66: 417-422.

Gadella, T.W.J. 1972. Biosystematic studies inHieracium pilosella L. and some relatedspecies of the subgenus Pilosella. BotaniskaNotiser 125: 361-369.

Gadella, T.W.J., 1987. Sexual tetraploid andapomictic pentaploid populations of Hieraciumpilosella (Compositae). Plant Systematics andEvolution 157: 219-245.

Grace, N.D.; Scott, D. 1974. Diet and mineralnutrition of sheep on undeveloped anddeveloped tussock grasslands. I. The macro-and micro-element composition of bloodplasma and herbage. New Zealand Journal ofAgricultural Research 17: 165-175.

Grime, J.P.; Hodgson, J.G.; Hunt, R. 1988.Comparitive Plant Ecology. A functionalapproach to common British species. UnwinHyman, London. 742 pp.

Harris, P.S.; O'Connor, K.F. 1980. The grazingbehaviour of sheep (Ovis aries) on a highcountry summer range in Canterbury. N e wZealand Journal of Ecology 3:85-96

Hay, J.R.; Ouellettee, G.J. 1959. The role offertilizer and 2,4-D in control of pastureweeds. Canadian Journal of Plant Science 39:278-283.

Healy, A.J. 1976. Identification of Weeds andClovers. Editorial Services, Wellington. 271pp.

Henn, H.; Petit, D.; Vernet, P. 1988.Interference between Hieracium pilosella andArrhenatherum elatius in colliery soils ofNorth of France: allelopathy or competition.Oecologia (Berl) 76(2): 268-272.


Hughes, J.G. 1975. A study of the grazingpreferences of sheep on developed andundeveloped grassland at a high-country site.M.Agr.Sc. Thesis, Lincoln College,Canterbury .

Makepeace, W. 1980. Ecological studies ofHieracium pilosella and H. praealtum. Ph.D.Thesis , Universi ty of Canterbury,Christchurch, New Zealand.

Makepeace, W. 1981. Polymorphism and thechromosomal number of Hieracium pilosellaL. in New Zealand. New Zealand Journal ofBotany 19: 255-257.

Makepeace, W. 1985a. Growth, reproduction,and production biology of mouse-ear and kingdevil hawkweed in eastern South Island, NewZealand. New Zealand Journal of Botany 23:65-78.

Makepeace, W. 1985b. Some establishmentcharacteristics of mouse-ear and king devilhawkweeds. New Zealand Journal of Botany23: 91-100.

Makepeace, W.; Dobson, A.T.; Scott, D. 1985.Interference phenomena due to mouse-ear andking devil hawkweed. New Zealand Journal ofBotany 23: 79-90.

Mason, C.R. 1987 (unpublished). Rhizomatouslegumes for hawkweed dominated grasslandr.M.Applied.Sc. Thesis, Lincoln College,Canterbury .

Roberts, H.A. 1986. Seed persistence in the soiland seasonal emergence of some plant speciesfrom different habitats. Journal of AppliedEcology 23: 639-656.

Scott, D. 1984. Hawkweeds in run country.Tussock Grasslands and Mountain LandsInstitute Review 42: 33-48.

Scott, D.; Maunsell, L.A. 1974. Diet and mineralnutrition of sheep on undeveloped anddeveloped tussock grassland. II. Vegetationcomposition and availability. New ZealandJournal of Agriculture 17: 117-189.

Record of a workshop of the New Zealand Ecological Society on “Vegetation change in tussock grasslands, withemphasis on hawkweeds", Cass Field Station, Canterbury, 1991.

N.Z. EcoL Soc. Occ. Pub. No.2

Scott, D.; Keoghan, J.; Cossens, G.C.; Maunsell,L.A.; Floate, M.J.S.; Wills, B.J.; Douglas,G. 1985. Limitations to pasture production andchoice of species. In: Burgess, R.E; BrockJ.L. (Editors) Using Herbage Cultivars.Grasslands Research and Practice SeriesNo.3. New Zealand Grassland Association,Palmerston North.

Scott, D.; Sutherland, B.L. 1992 (in submission).Competition between some pasture species andmouse-ear and king devil hawkweed. NewZealand Journal of Ecology.

Sell, P.D.; West, C. 1976. Hieracium. In: Tutin,T.G.; Heywood, V.H.; Burgees, N.A.;Moore, D.A.; Valentine, D.H.; Walters,S.M.; Webb, D.A. (Editors), Flora EuropaeaVol 4. Cambridge University Press.Cambridge University Press. pp. 358-410.

Stevens, E.J.; Hughes, J. 1973. Distribution ofsweet briar, broom and ragwort onMolesworth Station. Tussock Grasslands andMountain Lands Institute Special PublicationNo.9.

Turesson, B. 1972. Experimental studies inHieracium pilosella L. II. Taxonomy and

23

differentiation. Botaniska Notiser 125: 223-240.

Turesson, G.; Turesson, B. 1960. Experimentalstudies in Hieracium pilosella L. I.Reproduction, chromosome number anddistribution. Hereditas 46: 717-736.

Tutin, T.G.; Heywood, V.H.; Burgees, N.A.;Moore, D.A.; Valentine, D.H.; Walters,S.M.; Webb, D.A. 1976: Flora Europaea Vol4. Cambridge University Press

Voss, E.G.; Bohlke M.W. 1978. Tbe status ofcertain Hawkweeds (Hieracium subgenusPilosella) in Michigan. The Michigan Botanist17: 35-47.

Watt, A.S. 1962. Tbe effect of excluding rabbitsfrom grassland "A" (xerobrometum) inBreckland. Journal of Ecology 50: 181-198

Webb, C.J.; Sykes, W.R.; Garnock-Jones, P.J.1988. Flora of New Zealand. Vol IV,Naturalised pteridophytes" gymnosperms,dicotyledons. DSIR Botany Division,Cbristchurch. 1365 pp.

Record of a workshop of the New Zealand Ecological Society on "Vegetation change in tussock grasslands,with emphasis on hawkweeds", Cass Freld Station, Canterbury, 1991.


SESSION ONE DISCUSSION:PLANT SOCIOLOGICAL ISSUES

It was observed that scientists are havingdifficulty getting the message across to thecommunity that hawkweed dominance could besymptomatic of degraded grassland ecosystems aswell as of invasion by weeds.

A need was identified to explicity define conceptsof degradation as different researchers, resourcemanagement officers and the community mayassume different meanings. A particular issue waswhether or not concepts of vegetationdegradation also included elements of soildegradation, in physical, chemical or biologicalterms.

M. Treskonova clarified her use of the termdegradation, which is based most strongly onnative plant species records, with loss of speciesor decline in species abundance being indicatorsof degradation. However, soil physical properties,(e.g., thickness of the A horizon) were alsoimplicated.

It was noted that degradation in a vegetation sensewas open to interpretation. Alternative measuresof vegetation degradation, including replacementof nutritionally rich species by poor species anddeclining species diversity, may lead to differentinterpretations.

A. Rose reiterated that in the Harper-Avocacatchment, loss of beech forest had led to theinduction of a range of unstable plantcommunities. Changes back from short tussock totall tussock grassland, to scrub and to beech forestcould be checked, at least in the short term, byintervention such as by grazing management,pasture improvement and by the invasion of well-adapted species (e.g., hawkweeds). Instability ofplant communities, induced since deforestation,was an underlying feature.

The farming community also has had difficultywith concepts of degradation. In particularfarmers who are involved with application offertiliser to improve land had difficulty acceptingconcepts of soil degradation/depletion.

It was asked if we could recognise the reverse ofvegetation degradation, in the field, wheredegraded plant communities are entering a stageof recovery beyond hawkweed. M. Treskonovahad recognised such plant communities in herpublished models for vegetation change in Waitakibasin. Sites in the Awatere Valley, where nativespecies had become established in hawkweedvegetation have also been interpreted in this way.In the Harper-Avoca, snow tussock seedlingshave established in tussock hawkweed-dominantvegetation. A light infestation of mouse-earhawkweed in tall tussock grassland in BlackRock Scientific Reserve has been virtuallyeliminated since grazing exclusion in 1972.However, no clear trends of widespread changefrom hawkweed dominance to other vegetationhad been identified.

Questioned about the influence of climate onvegetation change, A. Rose clarified that he hadfound no significant climatic effect in the Harper-Avoca. Climate had fluctuated over time, buthawkweeds had increased linearly with time.Specific weather factors may trigger change, butprobably won't alter the direction of vegetationchange.

The ability of hawkweeds to lock up nutrients wasquestioned. It was considered that the 'halo effect'of hawkweed mats, having vigorous, floweringrosettes surrounding a dead centre, may relate tothe uptake of P and N by the younger, outerrosettes.

Clarification was sought on the low contributionof seed establishment in hawkweed populations(especially mouse-ear hawkweed). Theunderstanding was that although wind-dispersedseed has made the main contribution to thegeographic dispersal of hawkweeds, vegetativespread has been the main mechanism forsubsequent increases in local abundance and hastherefore accounted for most plants. As seed isviable only for a short time, the rate, pattern andtiming of widespread establishment may havebeen influenced by climatic triggers, including



wind patterns and soil moisture levels in summerfollowing seed release.

Field observations suggest a range of mechanismsof spread, and differences between species.Observations interpreted as supporting theimportance of wind dispersed seed in the earlyphases of invasion included:

The Nevis Valley, where the down-valley edgeof significant mouse-ear hawkweed ingrassland was abrupt, and not obviouslyrelated to management and site factors.Beyond the 'edge', scattered plants ingrassland were initiating new sites for spread.

25

The Central Otago farm survey, whichidentified extensive areas of grasslandcontaining small, localised mats of mouse-earhawkweed.

Humid western Otago where individualtussock hawkweed plants have establishedthroughout vigorous valley floor grassland.Tussock hawkweed may be non-stoloniferousand seed may be the predominant mechanismfor establishment of new plants.

The need to re-evaluate allelopathy was stressed.Although no allelopathic effects have beenconfirmed in the field, recent work has shownthat a range of plant communities produce largeamounts of phenols. Umbelliferone production byhawkweeds could be very significant.


SESSION TWO

CASE STUDIES FROMVEGETATION MONITORING PROGRAMMES

N.Z. Ecol. Soc. Occ. Pub. No. 2 29

TRENDS OF MOUSE-EAR HAWKWEED (HIERACIUM PILOSELLA) IN THE SOUTH OPUHA CATCHMENT

J. CuffCanlerbury Regional Council, P. O. Box 550, TIMARU

The South Canterbury Catchment Boardestablished four line transects in the South Opuhacatchment in April 1963. The transects have beenre-surveyed annually in the autumn (with theexception of occasional years) to provide anindication of annual variation in condition. Therecord for mouse-ear hawkweed (Hieraciumpilosella) bas been extracted from these data andis presented in this paper.

The four sites are located in the headwaters of theSouth Opuha catchment about 20 km north-westof Fairlie in South Canterbury. The sites are onsteep west-facing slopes at 1070-1460 m altitudeand are estimated to receive about 1250 mm meanannual rainfall.

At each site eight 30 m lines were established ina radiating pattern. Each line was sampled at 0.6m intervals using a weighted 6.3 mm diameterring.

The occurrence of mouse-ear hawkweed variedbetween sites and over time (Fig 1). Mouse-earwas abundant at site A in the early 1960's,plentiful at site B and erratic to absent at sites Cand D. There has been an increase in mouse-earat all sites to the extent that it now has anoccurrence of approximately 30 % at site A.Mouse-ear hawkweed occurrence was correlatedwith time (Table 1).

Gradient values from the regression equations

show that the rate of increase in mouse-earreduces with increasing altitude. Regressing thesegradient values against altitude gives an equationof:

Gradient value = 11.5 - 0.0075 Altitude (m)(r=0.89 p<0.05)

The relative abundance of mouse-ear hawkweedfor any given year is inversely proportional toaltitude (Fig 2).

The variation in mouse-ear occurrence may bedue in part to three measured variables of time,altitude and rainfall. There was a relativelyconsistent increase in mouse-ear at sites A and Bfrom 1963 up to the 1980's (Fig 1). This trendbas stabilised or possibly slightly reversed duringthe 1980's. At these two sites, it is possible thatthe most suitable and available areas forcolonisation have been taken up. Mouse-earestablishes best on decaying plant litter. Futureexpansion may occur as present vegetation dies.Mouse-ear began establishing and increasing atthe higher elevation sites C and D about 1980.This increase bas continued to the present.Variation in altitude or rainfall does not explainthe overall trend of mouse-ear hawkweedincrease, although between year variability maybe influenced by rainfall. It appears that theincrease in mouse-ear over time is a measure ofnatural expansion on sites of this condition in this

Table 1: Regression between mouse-ear hawkweed occurrence and time, at four sites in South Opuha catchment.

Site Altitude Regression Correlation Years

(metres) * r2

A 1070 H = 3.1Y - 149 0.74 (p<0.01) 1963-88

B 1250 H = 2.7Y - 159 0.8 (p<0.01) 1963-88

C 1460 H = 0.3Y - 22 0.3 (ns) 1982-91

D 1370 H = l.02Y - 81 0.75 (p < .01) 1981-91

* H - mouse-ear hawkweedY - years



environment once mouse-ear hawkweed hascolonised and become established. Past land usemay have influenced this initial site condition.The virtual lack of grazing during the studyperiod indicates that current grazing is not a causeof the subsequent increase in mouse-ear at thesesites.

There is little evidence that growing seasonrainfall, based on records of adjacent rainfallstations, is a useful predictor of either short-termor long-term trends in mouse-ear hawkweedabundance.

Figure 1:Occurrence of mouse-ear hawkweed at 4 sites in the South Opuha Catchment, Canterbury, 1963-1991.

Figure 2:Effect of altitude and time on occurrence of mouse-ear hawkweed in the South Opuha Catchment, Canterbury.



EFFECTS OF BURNING ON OTAGO TUSSOCK GRASSLANDS - GLENSHEESTATION

K. B. DugganOtago Regional Council, Private Bag, DUNEDIN

The Otago Regional Council is concerned with theimpacts of burning and grazing and theintroduction of exotic plant species in the tussockgrasslands. It has established and maintainednetworks of sites for the collection of data aboutchanges in ground cover in response toenvironmental and management factors. Resultsare used to assist with the identification andpromotion of sustainable grasslands management.

In 1957, eight line transects were established inTimber Creek catchment on Glenshee Station,located on the Ida Range north of the ManiototoPlain, to monitor vegetation responses to burningsnow tussock grassland. The sites were burned in1959 and have subsequently carried at least twomore fires. The transects have been resurveyednine times, most recently in 1986. Ground coverat points along the transect were recorded as'living vegetation' (subdivided into 'tussock', 'matplants', 'shrubs', 'herbs', 'exotics' (clover andsward grasses)), 'dead plant material' and threecategories of 'bare ground'. The transects are onsteep slopes in the elevation range 820 to 1050m.Soils are mapped as Tengawai Hill and Kaikourasteeplands. Annual rainfall ranges from 700 to1200mm, generally increasing with altitude.

Immediately after burning, total 'livingvegetation' declined from between 28 % and 85 %of the pre-bum levels. Initial recovery was rapid,with the cover returning to pre-burn levels withinone and a half to three years following fire. Itcontinued to increase until peaking about fiveyears after fire, at levels exceeding pre-bumvalues. Changes in 'bare ground' and 'deadvegetation' were the inverse of living vegetation,although the levels of 'dead vegetation' wereaffected by the intensity of the burns.

Although resurvey intervals in recent years havebeen insufficient to monitor long-term trends inrelation to the full fire history, results indicatethat 'living vegetation' has increased at most sitesfrom 1957 to 1986. There has been a

corresponding decrease in 'dead vegetation', and'bare ground' has remained at relatively stablelevels.

The pre-bum 'living vegetation' cover wasdominated by 'tussocks'. 'Herbs' was animportant subdominant category at many siteswhereas 'shrub' and 'exotic' categories combinedusually accounted for <10% of the cover.Following the fire, the 'tussock' categoryresponded quickly and increased for up to fiveyears to peak at pre-bum levels. At some sites'tussock' cover then declined. The responses of'herb' cover was more pronounced and thesespecies peaked three to five years after a fire, atlevels which exceeded pre-bum values by up to300%. Values for herbs then declined in relationto other cover categories. Although the levels oftussock cover have not changed overall, thiscategory is now subdominant to either 'herbs' or'exotic' cover categories according to site.

Within the 'herb' category, hawkweeds had notbeen recorded prior to 1980. In that yearhawkweeds were recorded at low levels in fourtransects and in 1986 were recorded on fivetransects and contributed from 8 to 11 % of thetotal cover on four of them. Hawkweeds wererecorded on a wide range of altitudes, slopes andaspects.

Following the implementation of a soil and waterconservation plan in the early 1980's, there hasbeen a major development programme onGlenshee, involving subdivision fencing, erosioncontrol fencing and aerial oversowing and topdressing. The 590ha blocks containing thetransects are now set stocked with 2000 ewesprior to lambing until weaning (6 months) andwith 2000 wethers (2 months) and 1000 hoggets(1 month) over late autumn and winter. There isconcern that hawkweeds have spread over a rangeof sites contained within this developmentprogramme.


/oc


HAWKWEEDS IN OTAGO - DISTRIBUTION, ECOLOGY, MANAGEMENT

N. S. Harris and A. F. MarkBotany Department, University of Otago, P. O. Box 56, DUNEDIN

Serious infestations of hawkweeds (Hieraciumspp.) in the tussock grasslands of Otago appear tobe anomalous in their distribution, particularly inrelation to climatic regimes and patternselsewhere in the South Island high country (GHunter, 1991).

Two hawkweed species predominate: mouse-ear(Hieracium pilosella) and tussock hawkweed (H.lepidulum). Tussock hawkweed is limited indistribution to Wanaka, Lindis, Pisa and DunstanEcological Districts (E.D.).

It dominates several sites - Pisa Station andLuggate Creek on the Pisa Range, Thompson'sCreek on the Dunstan Mountains and the upperRob Roy Valley, Wanaka - and appears to beactively invading westward into Mt. AspiringNational Park. Mouse-ear is more widespread,with a major infestation throughout much of theManorburn E.D., and smaller areas on lowerslopes in the Nevis Valley (Remarkables and OldMan E.Ds.) and on the western slopes of theRock and Pillar Range (Rock and Pillar E.D.).

Figure 1:Height/frequency values for four sites in Black Rock Scientific Reserve (c.700m), Waipori E.D. for 1972(adapted from Bulloch 1973) and 1988. Vie more important vascular species (biomass index >4 for at least one site)are arranged alphabetically. * indicates species with biomass index values significantly higher than in comparativesamples. The first four letters of binomials have been used.



The Lindis Valley and Dansey E. D. apparentlyhave serious infestations but were not covered inour survey.

Most other areas in Otago appear to be largelydevoid of serious hawkweed infestations, notablythe eastern slopes of the Old Man Range adjacentto the severely infested Knobby Range(Manorburn E.D.) to the east of the CluthaValley. King devil (H. praealtum) is locallycommon, usually with one or both of the othertwo species, particularly in the Manorburn E.D.

A series of long-term monitoring sites, using theheight frequency method of sampling, have beenestablished in Otago-northern Southland to followfuture trends in vegetation, including hawkweedinfestation.

Monitoring of snow tussock grassland at BlackRock Scientific Reserve (Waipori E. D.; 700m),hom its inception in 1972, has revealed thevirtual elimination of a relatively light infestationof mouse-ear over the ensuing 16 years as thesnow tussock has recovered in both height andcover (Fig. 1). Similar monitoring, initiated in1988, on conservation tussockland and associatedmountainlands in Otago and northern Southland /southern Old Man Range (Old Man-UmbrellaE.Ds.); Maungatua Scientific Reserve (WaiporiE.D); Nardoo Scientific Reserve (Waipori E.D);Lammermoor Range (Waipori E.D); EyreMountains stewardship land (Eyre E.D)(Dickinson et al 1992) revealed negligibleamounts of hawkweed, with king devil at two

33

sites on Old Man Range and mouse-ear at Nardooand Lammermoor Range.

Over the 1990-91 summer, similar monitoringwas established at S2 sites throughout much of theOtago high country (Waipori, Rock and Pillar,Manorburn, Old Man, Dunstan, Pisa,Remarkables E.D.s), specifically to assess andmonitor hawkweed infestation. Topsoil (0-10cm)was collected at each site for bioassay usingbrowntop (Agrostis capillaris) (Harris, 1991).

General distribution, together with an apparentpreference for disturbed sites, indicates thattussock hawkweed (and king devil) has higherrequirements for moisture and fertility thanmouse-ear. Even though its rosettes are erect anddiffuse, tussock hawkweed is still able to formextensive areas of virtually pure stands (Fig. 2).

Tussock hawkweed and king devil do not appearto represent a serious threat to pastoral activitiesin Otago by virtue of their erect habit and presentdistribution. However, the presence of tussockhawkweed in the upper Rob Roy Valley on theeastern edge of Mount Aspiring National Park, onsites with no recent history of ungulate grazing,represents a major threat to conservation values inthese areas. King devil occupies equivalent sitesin western parts of south and mid-Canterbury,e.g., North Temple Stream and Hopkins Valley.

Anomalies with the distribution of mouse-ear inOtago are more difficult to explain. It does notappear to be related to climate patterns but its

Figure 2: Height/frequency values for the more important species (biomass index >4) arranged in order of importancefor a sue on Pisa Station (885m), Pisa E.D., with severe infestation of tussock hawkweed (H. lepidulum), 23.1.91.


34 N.Z. Ecol. Soc. Dec. Pub. No.2

association with present or relict red tussockgrassland and relatively stable mature soils with ahigh loessial content in the Manorburn district

Figure 3: Changes in mouse-ear hawkweed (H.pilosella) biomass index in relation to short tussockspecies cover.

may be relevant. General nutrient deficiency, butparticularly of nitrogen, phosphorus and/or boronin soils of this district may also be significant (GCossens, pers. comm.). Analysis of sample sites(Fig. 3) showed a negative relationship betweentussock cover and mouse-ear dominance, despitethe very wide environmental gradients present,and implicates pastoral management in mouse-eardominance.

Results of the bioassay did not indicate anyallelopathie effects of mouse-ear dominated soils(Harris 1991).

ConclusionsContinued monitoring and additional research isneeded before conclusions and recommendationscan be offered on future management. Retentionof a healthy tussock cover through lenient grazingand reduction in the frequency of burning, withadequate post-fire spelling (at least one year) areimplied from the evidence for tall tussockgrasslands in Otago. Maintenance of canopy coveralso appears important in short tussock grasslandsand continued oversowing and topdressing issupported as a preventive measure in areas leastaffected by mouse-ear (Fig. 4). Few options forareas already heavily infested with mouse-ear areavailable and successful replacement with morefavoured species appears unlikely

References

Dickinson, K.J.M.; Mark, A.F.; Lee, W.G.1992. Long-term monitoring ofnon-forest communities for biologicalconservation purposes. New ZealandJournal of Botany 30: 163-179.

Hunter, G.G. 1991. Distribution of hawkweeds(Hieracium spp.) in the South Island,indicating problem status. Review. Journalof the N.Z. Mountain Lands Institute 48: 21-31.

Harris, N.S. 1991 (unpublished) Aspects of theecology and distribution of hawkweeds(Hieracium spp.) in Central Otago, NewZealand. B.Sc.Hons. thesis, Univ. of Otago.

Fig. 4: Height/frequency values for the more important species (biomass index >4) arranged in order of importancefor a site in the Remarkables (950m), Remarkables E.D. with a potential problem involving two species, mouse-earhawkweed (H. pilosella) and tussock hawkweed (H. lepidulum). 15.1.91

Record of a workshop of the New Zealand Ecological Society on çVegetation change in tussock grasslands, withemphasis on hawkweeds", Cass Field Station, Canterbury, 1991.


HAWKWEEDS AND VEGETATION MONITORINGIN THE RABBIT AND LAND MANAGEMENT PROGRAMME

K. Colhoun, B.D. Foran and W.D. RossLandcare Research New Zealand Ltd - Manaaki Whenua

P. O. Box 276, ALEXANDRA

AbstractData from 240 vegetation monitoring sites in thecore Rabbit and Land Management problem areagive a snapshot of the hawkweed problem fromthe 1990/91 sampling period. Hawkweeds(Hieracium spp.) cover 16% and 4% of thesampling sites in Canterbury and Otagorespectively. Species frequency (% presence inmetre square quadrats) data confirm thewidespread nature of mouse-ear (H. pilosella)(Cant. >60%; Otago >20%) king devil (H .praealtum) (Cant. >30%; Otago> 10%) andtussock hawkweed (H. lepidulum) (Otago 20%).No site characteristic analysed so far showed amajor causative effect on hawkweed dominance.The difference between Canterbury and Otago isprobably as much a time one as a site one. Ourmonitoring efforts will not solve the hawkweedproblem, but might give early warning of the nextmajor landscape change. We discuss whethermonitoring activities might have broken theinactivity cycle that seems to have characterisedthis major landscape change. If landscapemonitoring does have a part to play we suggestthat all institutions accept a minimum data set ofspecies frequency on high country landscapes.This will enable the landscape records fromdifferent institutions and generations to be tiedtogether more effectively, and stimulategovernment to develop vision in its landmanagement policies.

IntroductionThis paper reports on the baseline data collectedin the 1990/91 summer in the core rabbit pronelandscapes of Canterbury and Otago. While thereal aim of monitoring is to measure vegetationchange away from the baseline as rabbit controltakes effect, the relevance of the data for thisworkshop on hawkweeds, is the recent samplingwithin the core hawkweed area defined by Hunter(1991). This paper reports mainly on a regionalview of the hawkweed problem within the Rabbitand Land Management Programme area, with

some analysis of site factors which might enablea more detailed risk of hawkweed dominance tobe assessed.

MethodsSites of 4-6 ha in area were selected at regularintervals of 3-6 km along rabbit countingtransects. Ground cover was measured with thewheel point apparatus and 500 points per site.Species frequency was measured by the presenceof species in 50 placements of a metre squarequadrats. Scrub cover was measured by Bitterlichgauge at 25 points. A wide range of site data wascollected including soil type, aspect, altitude,proneness to erosion etc. A total of 241 sites weresurveyed with 129 in Canterbury and 112 inOtago.

Results

Hawkweeds and Ground CoverComparisons of the average regional cover valuesshow that the two regions, Canterbury and Otagohave equivalent readings for most of thecomponents of ground cover e.g. bare ground,grasses, tussocks etc. However the sites sampledin Canterbury have a higher coverage ofhawkweeds (16%) than those in Otago (4%). Thiscan probably be explained by a mixture of thehistory of the problem, difference in soil type andsoil fertility, and rainfall. However it could alsobe judged that the trends in both regions are thesame, Canterbury having the advantage of years,and a more advanced problem.

The hawkweed cover situation becomes clearerwhen we look at data from districts within theregions. Sites from the Tekapo and Pukakiregions had an average of 30% and 20% coverrespectively. The other districts are close to 10%or lower. No district average for sites in theOtago region was greater than about 5 %hawkweed cover, although there were individualsites with values greater than 30 % .


36

The average bare ground was about 37 % for bothregions. Site averages for the Mackenzie andManiototo districts were both considerably greaterthan the regional average, and this is probably acombination of rainfall, rabbits, stock grazing andlong term site potential. It does howeveremphasise that the opportunity for theencroachment of bare ground colonisers such asmouse-ear hawkweed, are frequently present insome areas. Tussock cover was mostly below 5 %in the districts, while other grasses were mostly inexcess of 20% except in the Tekapo andAlexandra districts.

Hawkweeds and Species FrequencyMouse-ear had a higher frequency in Canterbury(>60%) compared to Otago (>20%), while kingdevil (30% in Canterbury, 10% in Otago) wasalso sufficiently present to become a focus forspread in the future. Tussock hawkweed (20 %frequency) mainly featured in the Otago sites, andwas never sufficiently frequent to rate in theCanterbury sites. .

Tekapo, Pukaki and Mackenzie districts are themajor problem areas for mouse-ear hawkweedwith a greater than 60 % frequency. The higherrainfall Ahuriri district by comparison had lessthan 20 % frequency. Sites from the Alexandradistrict had the highest mouse-ear frequency(>40%) in Otago, with Hawkdun andLindis/Hawea being next with greater then 20%frequency.

King devil hawkweed had a frequency of greaterthan 40 % in the Pukaki district, and greater than20% in the Ahuriri, Omarama and Tekapodistricts in Canterbury. In Otago it appeared to bemainly a problem in sites in the Lindis/Haweadistrict. Tussock hawkweed was most obvious onsites in the Alexandra (40% frequency) and UpperClutha (32%) districts.

Hard tussock (Festuca novae-zealandiae) had afrequency of greater than 30 % across the regionsand was greater than 50 % in the Tekapo regionwhere mouse-ear hawkweed had its highestfrequency. Many of these hard tussock plantswere small and not readily apparent at a generallandscape view, but their continued presenceoffers some opportunity for tussock recovery.


Silver tussock (Poa cita) and blue tussock (Poacolensoi) did not show much difference on aregional basis, but there were large differencesbetween districts. Both species have much lowerfrequencies where mouse-ear hawkweed isdominant. Snow tussock (Chionochloa rigida) isgenerally absent from our sites in Otagocompared to Canterbury where it has a frequencyof greater than 40 %. This may reflect arainfall/altitude interaction with different numbersof sites located in the montane zone (> 600 m) inthe two regions (Canterbury 48; Otago 34). Itmay also suggest that the impact of burning andpastoral use have been greater or longer in Otago,within the rabbit problem areas where oursampling sites are located.

Site Factors Correlated to HawkweedDominance

i) Altitude and AspectSite selection was biased towards the drier end ofthe high country environment, where rabbitscontinue to be a problem. The sites in bothregions range in altitude from 200 to 1100 m.Within these limits some trends have emerged.While all three species appear to be able todominate at any altitude, frequencies of > 50%can be found at altitudes greater than 400m inCanterbury and 600m in Otago. In Canterburyaspect did not appear to have an effect on thefrequency of any of the hawkweed species. InOtago mouse-ear hawkweed was similarlyfrequent on northerly, easterly and southerlyaspects, but tussock hawkweed may have beenconfined to more easterly and southerly aspects.

ii) Soil TypeSoil type was a little more obvious in its effect. InOtago the sites with the higher mouse-earhawkweed frequencies (>50%) were almostentirely Yellow Grey Earths (Fig. 1). InCanterbury Upland Yellow Brown Earths weremore important (Fig. 2). In functional terms, theYGE and UYBE of Otago and Canterbury arefairly similar especially in measures of soilresilience (Allan Hewitt, pers. comm.). In bothregions the lower resilience soils seem to tripeasier into hawkweed dominance.When these broad soil types were subdivided intosoil sets, and selected on the basis of those soil



Figure 1: Frequency. classes of mouse-earhawkweed (0-25%, 26-50%, 51-75%, 76-100%)in relation to soil types in Otago.

Figure 2: Frequency classes of mouse-earhawkweed (0-25%, 26-50%, 51-75%, 76-100%)in relation to soil types in Canterbury.

sets where a particular hawkweed species wasgreater than 50 % frequency, further detailemerged. From the 17 soil sets represented by ourOtago sites, the Arrow and Linnburn favouredboth mouse-ear and tussock hawkweeds. TheNaseby and Linnburn favoured mouse-ear alone,while the Alexandra favoured tussock hawkweedalone. From the 14 soil sets represented by ourCanterbury sites, Acheron, Tekapo, Omarama,Pukaki and Benmore favoured both mouse-ear andking devil hawkweed. The others (Mackenzie,

37

Grampians, Waitaki, Meyer, Otematata,Benmore) favoured mouse-ear predominately.From this frequency data, it is obvious thathawkweeds find many soil sets to their liking. Onour Canterbury sites, soil set would almost seemto be the least important factor influencinghawkweed distribution. In Otago there stillappears to be some soil characteristic (or a timefactor 1) preventing the levels of mouse-earhawkweed problem found in Canterbury.

iii) RabbitsThe simple correlation and regression analysestesting the relationships over all the sites betweenrabbit spotlight counts and hawkweed cover orspecies frequency gave no indication of anyrelationship. When these data were bulked up intodistrict averages, some significant correlationswere obtained. Using independent variables ofpre- and post-kill rabbit numbers, total plantcover (R2 0.86), grass cover (R2 0.68), herbcover (R2 0.66), tussock cover (R2 0.48),hawkweed cover (R2 0.72) and bare ground(R2 0.79) all had a reasonable proportion of theirvariation explained. These results probablyintegrate the difference between districts, ratherthan the short and long term effect of rabbitsper ser. For example, the rabbit/total plant coverrelationship is mainly due to the Tekapo district,where reductions of high rabbit populations (80down to 5 per spotlight km), and reasonablesummer rains saw the total plant cover rise toaround 80 %.

iv) Other FactorsMany other site factors (> 50) and species(> 130) are held within this data set awaitinganalysis. Seasonal rainfall is an obvious onewhich will be the major driving factor indetermining the response of the whole plantcommunity, both its composition as well as itsproductivity.

Discussion

Monitoring and HawkweedsFrom some of New Zealand's more media richpastoral lands, we have presented data from ourvegetation monitoring program. We have not beenable to add clarity to either the cause, or thesolution of the hawkweed problem. Rather we


38

have presented some baseline data for cover andfrequency of the main hawkweed species.Changes for the better or worse can be measuredagainst these baselines.

A cursory examination of the literature over thelast few decades shows that some causes andsome solutions have been around for a long time(Scott, 1984). Intensive agronomic work(Makepeace, 1985; Lambrechtsen and Sheppard,1979; Trought and Morgan, undated; Cossens andBrash, 1980) has been well underway for 15 yearsor more. These same 15 years have seen profoundchanges in scientific institutions, generous farmsubsidies in the core problem area (rabbit killing,land development and destruction, 'skinny sheep'schemes), some years of excellent fine woolprices, a drought or two, and many otherinfluences. As well as immersing ourselves in thebiological detail, should we also be askingourselves why we haven't progressed in the last15 years. Is it a lack of scientists talking out, anincorrect research emphasis, or is it a lack of anaudience listening in ?

Would Monitoring Have Helped ?Casual conversations over morning tea at anymeeting seem to liberate filing cabinets full ofdata that are relevant to the high country. Theexpectation is always that "someone" should writeit up. It is good to see some of the importantlonger term data liberated at this workshop. Thedifficult decision as a scientific manager iswhether to "put good money after bad" (old datasets are always messy and time consuming),whether to start monitoring now for the future(the next wave of problems), and whether toprove the cause, or develop the solution.

Would we have had this workshop in 1985 if wecould have had a constant stream of data rollingin which said that the hawkweed problem (definedat the Lincoln College workshop, 30/6/1975, citedin Lambrechtsen and Sheppard, 1979) was then50 % worse. It is difficult to say, because we as ascientific group have not confronted thehawkweed problem with a sense of mission orurgency (Mountain Lands Institute, a notableexception to this). We continue to tack the wordHieraciwn onto all our research bids, in the hopeit might liberate the extra $100k that we needed topursue our major career interest. The major

N.Z. Eco1. Soc. Occ. Pub. No. 2

themes of this workshop (the cause; restricting thespread; fixing it up) probably coincide with themajor institutions that will do the work during thenext decade. Little projects won't solve theproblem. A couple more integrated projects thatare 100% committed might do a little better.

And If Monitoring Might Have Helped !

The Minimwn Data SetMost monitoring on rangelands throughout theworld (USA, South Africa, parts of Australia)have come back to species frequency in metresquare quadrats (or nested sizes if you needthem) as being a robust standard that can tieinstitutions and generations together. Frequencymethodology is good for showing change inspecies composition and can also be presented inthe broader biodiversity context. Institutions canthen add their own requirements to this minimumdata set. The R&LM team also measure herbagelayer plant cover, scrub cover and describe sitecharacteristics.

Who Does It and For Whom?A small team of players is obvious. Farmers,Landcorp, Regional Councils, Lincoln and OtagoUniversities, Department of Conservation,National Institute of Land Environments (DSIR,FRI, MAF) and the Forest and Bird Society.Before we all rush out to collect the data, therehas to be a team who is competent to analyse andreport on the data probably on a yearly basis. Ourfiling cabinets jammed packed with data sheetsand photos are a stunning comment on this lack ofmanagement direction in the past. The Rabbit andLand Management team has the following yearlylabour commitment to maintaining 300 sites: 12scientist, 9 student, and 6 technician months peryear. Cooperation with other like mindedlandscape measurers is the only way that wemight expand our high country vision into a morenational view, which farmers land managers andgovernment might listen to.

ReferencesHunter, G.G. 1991. The distribution ofhawkweeds (Hieracium spp.) in the SouthIsland, indicating problem status. Review.Journal of the New Zealand Mountain LandsInstitute 48: 21-31.



MONITORING CHANGES IN NON-FOREST ECOSYSTEMS: CASE STUDIES FROMMOLESWORTH STATION AND THE MACKENZIE (WAITAKI) BASIN

K.J.M. DickinsonSchool of Biological Sciences. Victoria University, P. O. Box 600, WELLINGTON

IntroductionExisting protected natural areas, and areasrecommended for protection (RAPs) as part of theProtected Natural Areas (PNA) Programme, havebeen targeted for long term monitoring of changesin non-forest ecosystems. Against thisbackground, a network of 50-metre permanenttransects using a modified height-frequency (h-f)method (cf. Scott 1965; Dickinson et al 1992;Harris and Mark, Allen et al this workshop) hasbeen established: North Island Central Plateau (9),Nelson Red Hills (6), Molesworth Station (19),Mackenzie (Waitaki) Basin (18) and CentralOtago / Southland (Harris and Mark thisworkshop).

Case study one: Molesworth StationThirty six RAPs were identified in a PNA surveyon Molesworth Station in 1987/1988.Negotiation in 1988/89, resulted in some RAPsbeing recognised for their conservation value byintended exclusion of cattle by fencing.Consequently, monitoring has been initiated inboth fenced and unfenced areas to follow changesas a result of cessation of grazing (Table 1).Hawkweeds were recorded in all transects (exceptfive transects in wetland communities). Mouse-earhawkweed (H. pilosella) was present in tentransects and king devil (H. praealtum) in five.Both species were particularly abundant in theshort - tussockland communities in Sedgemere(Figs 1 & 2). The majority of highly modifiedFestuca short-tussock land communities have been

excluded from the fenced off areas because ofperceived grazing value. With high abundance ofpasture species these communities harbourhawkweeds but at relatively low frequencies.

Areas with high natural value have been includedin the reserved areas. Thus, in many cases, anadjacent equivalent area outside of the fence wasnot present. Consequently, change will befollowed in these communities without anunfenced control.

Hawkweeds appear widespread, are mostabundant in, but not exclusive to short -tussockland communities. The impact of cattleremoval will need to be monitored closely,following fencing.

Case study two: Mackenzie (Waitaki) BasinResults of the PNA survey of the MackenzieEcological Region are described by Espie et al(1984). To date, five RAPs in the region havebeen legally protected, out of a total of 103 whichwere identified during the survey. Noticeabledeterioration in the natural values of several RAPsthrough rabbit and introduced plant invasionprompted calls for monitoring in late 1989. TenRAPs, covering a range of tussockland andshrubland communities representative of theclimatic range occurring in the Basin, werechosen for study (refer also Espie and Meurk thisworkshop). Of these ten, six are being monitoredusing the modified height-frequency (h-f) method(underlined Table 2).

Location

Table 1: Vegetation types on transects in the Molesworth Station RAPs chosen for study.

Vegetation typesNo. oftransects

Sedgemere RAP 10

Altitude(metres)

940 - 1030

Tennyson /Island Pass RAPsOyster RAP

1020 - 11203

5 1220 - 1460

Chionochloa rubra tall-tussockland, Festuca short-tussockland, modified Festuca short-tussockland,sedgeland. Halocarpus bidwillii - Phyllocladus alpinusshrubland/short tussockland.modified short-tussockland, sedgeland.

Festuca - Chionochloa pallens tussockland, Festuca -Rvtidosperma tussockland, modified Festuca tussockland.



Figure 1: Diagrammatic representation of the dominant species recorded using the height-frequency (h-j) method(Dickinson et al 1992) along 50 metre transects at five sites on Molesworth Station.Mole 5 short Festuca tussockland, 1030 m. 8.11.89.Mole 6 short Festuca tussockland, 1000 m. 9.11.89.Mole 7 short Festuca tussockland, 1000 m. 9.11.89.Mole 8 short Festuca tussockland, 1000 m. 9.11.89.Mole 10 short Festuca tussockland / pasture, 1120 m 10.11.89.Species frequency is given in 5 cm height classes and labelled alphabetically by the first four letters of their binomials.Bryophytes and lichens are offset to the right.

Figure 2: Diagrammatic representation of the dominant species recorded using the h-f method along 50 m transects atthree sites, Oyster RAP, Molesworth Station.Saxt 1 short Festuca tussockland, 1245 m. With cattle grazing. 2.2.90.Saxt 2 short Festuca tussockland, 1245 m. Excluding cattle. 2.2.90.Saxt 3 short Festuca tussockland, 1460 m. Excluding cattle. 2.2.90.Species frequency is given in 5 cm height classes and labelled alphabetically by the first four letters of their binomials.

Record of a workshop of the New Zealand Ecological Society on "Vegetation change in tussock grasslands, withemphasis on hawkweeds", Cass Field Station, Canterbury, 1991 .


Table 2: Vegetation types on transects in the Mackenzie Ecological District RAPs chosen for study.

Vegetation type

Festuca tussockland (moist)

Festuca tussockland / low shrubland (moist)

Festuca tussockland (wet)

Festuca tussockland (very depleted, moist)

Festuca tussockland (dry)

Poa cita tussockland (dry)

Chionochloa rubra / Festuca tussockland (moist)

Chionochloa rubra / Festuca tussockland (dry)

Chionochloa rigida tussockland

Chionochloa rigida tussockland / shrubland (moist)

Location RAP no.

Ben Ohau Pukaki 8

Maryburn Pukaki 14

Richmond Tekapo 30

Sawdon Pukaki 16

Simons Hill Pukaki 9

Rostrievor Benmore 9

Balmoral Tekapo 11

Pukaki Downs Pukaki 3

Lindis Lindis Pass S.R.

Omahau Pukaki 7

The study aims to differentiate the effects ofrabbits and sheep through the monitoring of twoc. 60 x 60 metre exclosures (one rabbit-proofedusing wire netting, the other fenced with postsand wire only to exclude sheep) and a similarunfenced control at each site. First recording wasundertaken in early 1990 prior to fence erection inAugust 1990. Various methods have beenemployed at each site which will fulfil the furtheraim of comparing the aptitudes of each approachin the monitoring of non-forest ecosystems (referalso Espie and Meurk this workshop).

Unfortunately, the rabbit-proof fencing is onlynow (October 1991) being brought up to anacceptable standard. Consequently, nointerpretation of results for the first 18 months, inrelation to sheep: rabbit impact is possible. Thequality of the data in relation to the treatments,the timing and standard of fencing, together withthe rabbit poisoning activities at each site, has tobe very carefully assessed. Furthermore, damageby those doing the monitoring must dictate thefrequency of recording. Annual monitoring,proposed for, at least, the first three years of thetrial may be excessive.

One h-f transect was established in each treatmentat each of the six sites in January / March 1990.Each was revisited in January 1991,rephotographed and three sites rescored. Onlyone, Omahau, showed an appreciable change invegetation structure and composition, directlyattributable to successful rabbit poisoning

activities in the area. Thus, a similar reduction inrabbit browsing occurred across all treatmentshere. Generally, the woody species manuka(Leptospermum scoparium) and matagouri(Discaria toumatou) increased in frequency values(biomass index). Likewise, the grasses narrow-leaved snow tussock (Chionochloa rigida), hardtussock (Festuca novae-zelandiae), Deyeuxiaavenoides, and brown top (Agrostis capillaris)also increased their biomass index. Hawkweedspecies showed no change in the unfenced control,but a decline in the exclosures. Because of thefencing problems no definite conclusions can bedrawn (Fig. 3).

Mouse-ear hawkweed has high biomass indices onfour of the six sites (Balmoral; Omahau;Richmond; Sawdon). King devil hawkweed ispresent but its frequencies vary between sites,being absent from Sawdon. Hawkweeds arepresent on both Ben Ohau and Rostrievor but atlow frequencies in comparison to the other sites.The Ben Ohau community is species-rich withswales dominated by Festuca and ridges occupiedby a close sward of herb species. Althoughhawkweeds are less prominent than on other sites,another introduced species, sheeps sorrel (Rumexacetosella) is abundant (Figs 4 and 5).

Rostrievor was complicated by the vagaries ofresponse to rainfall by ephemeral species in thesedryland areas. Recording even in early January istoo late for ready identification of some of theherbs.



Figure 3: Diagrammatic representation of the dominant species recorded using the h-f method along 50 m transects ineach of the three treatments on Omahau Station (Omah).Omah 1 +R +S = control, ie unfenced plot.Omah 2 -R-S = rabbit-proofed exclosure.Omah 3 +R -S = sheep exclosure.Species frequency is given in 5 cm height intervals and labelled alphabetically by the first four letters of their binomials.

Figure 4: Diagrammatic representation of the dominant species recorded using the h-f method along 5Om transects ineach of the three treatments on Ben Ohau Station (Ben).Ben 1 -R-S = rabbit-proofed exclosure.Ben 2 +R-S = sheep exclosure.Ben 3 +R +S = control, ie unfenced plot.Species frequency is given in 5 cm height intervals and labelled alphabetically by the first four letters of their binomials.



Figure 5: Diagrammatic representation of the dominant species recorded using the h-f method along 5Om transects ineach of the three treatments on Sawdon Station (Sawd).Sawd 1 +R-S = sheep exclosure.Sawd 2 -R-S = rabbit-proofed exclosure.Sawd 3 +R +S = control, ie unfenced plot.Species frequency is given in 5 cm height intervals and labelled alphabetically by the first four letters of their binomials.

Since presentation of this paper all sites have beenresurveyed in December 1991.

AcknowledgementsThis research has been supported by the MissE.L. Hellaby Indigenous Grasslands ResearchTrust. The monitoring programme forms a part ofa larger network established in association withAlan Mark (Otago University) and Bill Lee (DSIRLand Resources). I wish to thank ShannelCourtney, Susan Scobie and Mark Davis for theirhelp during the Molesworth and Mackenzie fieldwork. The Mackenzie Grazing Trial is a co-operative venture with Peter Espie (FRI) andColin Meurk (DSIR Land Resources). TheDepartment of Conservation provided logistical,and some financial, support. Susan Scobie andPhillippa Spackman helped with the drafting.

ReferencesDickinson, K.J.M.; Mark, A.F.; Lee, W.G.

1992. Long-term monitoring of non-forestcommunities for biological conservationpurposes. New Zealand Journal of Botany30: 163-179.

Espie, P.R.; Hunt, J.E.; Butts, C.A.; Cooper,P.J.; Harrington, W.M.A. 1984. MackenzieEcological Region. New Zealand ProtectedNatural Areas Programme. Department ofLands and Survey, Wellington.

Scott, D. 1965. A height frequency method forsampling tussock and shrub vegetation, NewZealand Journal of Botany 3: 253-260.



REGENERATION AFTER FIRE ON THE LEIDIG RANGE, MOUNT COOKNATIONAL PARK; THE ROLE OF HAWKWEEDS (HIERACIUM SPP.)

DURING THE FIRST 20 YEARS.

Hugh Wilson160 Salisbury St, CHRISTCHURCH

A major accidental fire on 28-30 March 1970burned about 1200ha of forest, scrub, shrublandand snow tussockland between about 850 m and,the upper limit of alpine grassland, about 1900m,on the Leibig Range, Mount Cook National Park.About 200 ha of this land had been burned some50 years previously; these carried fire-inducedshrublands which recovered more quickly thatremaining areas which had probably not beenburnt for centuries.

Ten 6m x 6m quadrats, charted in 1971, 1973,1975, 1980, 1985 and 1990, recorded theregeneration of vegetation across the burn andmonitored species and individual plants involvedin this process.

Mean annual rainfall in the study area is estimatedbetween 2000 and 3000 mm. The ten plots rangefrom 900 to 1800 m, on well-drained subalpineand alpine yellow-brown earth soils. Haresexerted moderate browsing pressure throughoutthe 20 year study, while the larger mammals(thar, chamois and red deer) were at low levelsexcept at the beginning of the study period andagain in recent years.

Recovery of vegetation was faster on the area thathad been previously burnt because of the greatlyincreased proportion of fire-resilient species ableto resprout after burning.

King devil hawkweed (Hieracium praealtum)occurred in only two of the plots in 1971, but by1990 was present throughout.

King devil cover varied from 1 %, in mid altitude,vigorous, regenerated shrubland, to 8 % in highaltitude degraded snow tussockland, to 97% (anearly pure king devil sward) on land that hadbeen under subalpine tall scrub with largemountain celery pine (Phyllocladus alpinus),mountain ribbonwood (Hoheria lyalii) and Hall'stotara (Podocarpus hallii) before the fire. Theincrease of king devil hawkweed in this latter plotwas spectacular. It first appeared in 1975 when itrepresented less than 1 % cover. At the same timeYorkshire fog (Holcus lanatus) represented 26 %,catsear (Hypochoeris radicata) 20%, hawksbeard(Crepis capillaris) 16 % and sheep's sorrel (Rumexacetosella) 8 % with only 4 % bare ground.Yorkshire fog and catsear continued to increaseuntil 1980 when king devil hawkweed had alsoincreased to 10%. By 1985, however, king devilhad increased to 97 %, Yorkshire fog, catsear andhawksbeard were all absent and sheep's sorrelformed < 1 % of the cover. Throughout the studynative woody species formed < 1 % cover.

In this climate and on these soils, king devilhawkweed shows a high degree of competitivenessand invasiveness on disturbed sites, but appears tobe kept at a much lower level where shrubland,scrub and tall tussock recovered quickly after thebum. Mouse-ear hawkweed (Hieracium pilosella),on the other hand, has so far proved to be only aminor element in the post fire vegetationchanges. It had appeared only in onelower-altitude plot by 1975, and although by 1990it occurred throughout the whole altitude range, itwas present only in three plots, and in none ofthem formed> 1 % of the cover.



A PRELIMINARY ASSESSMENT OF THE EFFECTS OF MANAGEMENTON MOUSE-EAR HAWKWEED (HIERACIUM PILOSELLA) ESTABLISHMENT INNARROW-LEAVED SNOW TUSSOCK (CHIONOCHLOA RlGIDA) GRASSLAND,

LAMMERMOOR RANGE, EAST OTAGO.

R.B. Allen1, W.G. Lee1 and A.F. Mark2

1Landcare Research New Zealand Ltd - Manaaki Whenua, Private Bag 1930, DUNEDIN2Botany Dept., University of Otago, Private Bag, DUNEDIN

SummaryThe frequency of mouse-ear hawkweed(Hieracium pilosella) was measured annually onpaired 50 m transects in narrow-leaved snowtussock (Chionochloa rigida) grassland subject tothree management regimes: unburnt for > 30years, burnt in 1988 but not grazed, and burnt in1988 and subsequently grazed by cattle. Mouse-ear hawkweed is present at low densities on tracksand firebreaks in the area. No establishment ofmouse-ear hawkweed was recorded on theunburnt transects. Mouse-ear hawkweed wasrecorded at 2-3 % frequency on oneburnt/ungrazed transect from 1989-1991, and at2% on one burnt/grazed transect in 1990. Thesetransects had the lowest litter frequenciesrecorded. Mouse-ear hawkweed probablyestablished at low frequency from chancegermination of wind-borne seed on suitable sitescreated as a 'window of opportunity' by burningand grazing the previously dense tussockgrassland. Monitoring will continue to assess thepersistence of mouse-ear hawkweed.

IntroductionAs part of a study of the recovery of narrow-leaved snow tussock grassland from fire, with andwithout grazing, three topographically similarsites unburnt for at least 30 years were selected innarrow-leaved tussock grassland at c. 1070 m onthe Lammermoor Range, east Otago. One siteremained unburnt, the second was burnt inSeptember 1988 but not subsequently grazed, andthe third was similarly burnt but subsequentlyheavily grazed by cattle.

Mouse-ear hawkweed was present within ahundred metres of each site as scattered plants onbulldozed firebreaks and vehicle access tracks.Data obtained from the sites present anopportunity to make a preliminary assessment ofthe effects of management on mouse-ear

hawkweed distribution and establishment.

MethodsTwo 50 m permanent transects were establishedon opposing aspects (NE and SW) at each sitefollowing burning (Table 1), and height/frequencydata (presence in vertically contiguous 100cm3

samples) at 0.5 m intervals were collectedannually on each.

Table 1: Site Descriptions, Transects T1-T6.

Aspect unburnt burnt burnt/grazed

NE T1 T3 T5

SW T2 T4 T6

ResultsThree years' data for narrow-leaved snow tussock(including intact tussock bases), mouse-earhawkweed, litter (excluding intact tussock basesbut not recorded on T1 and T2 at any time, on T3in May 1991, and on T4 in November 1988 andMay 1991), and bare ground, are presented inFig. 1.

Narrow-leaved snow tussock height/frequencyvalues (biomass indices) changed little on theunburnt transects (T1 and T2), where no bareground or hawkweeds were recorded.

On the burnt/ungrazed transects (T3 and T4),narrow-leaved snow tussock biomass indicesincreased rapidly in the first growing season(November 1988-April 1989), but changed littlethereafter. No bare ground was recorded exceptin April 1990 on T4 (4%). Litter values remainedmore or less constant on T3 at 76-85 %, but were



considerably lower (50-63%) on T4. Mouse-earhawkweed was recorded at 2 % frequency on T4at the end of the first growing season afterburning, again a year later, and at 3 % frequencyat the end of the third season.

On the burnt/grazed transects (T5 and T6),narrow-leaved snow tussock biomass indicesincreased slightly over the three growing seasonsbut remained markedly lower than that on theburnt only transects. Bare ground was present onT5 (10%) and T6 (12%) at the end of the firstgrowing season following burning, declined to 1 %in May 1991 on T5, but increased on T6 to 19%in May 1991. Litter values were consistentlyhigher on T5 (65-74%) than T6 (54-56%).Mouse-ear hawkweed appeared on T6 in April1990 (2%), but was not recorded there in May1991.

Discussion and ConclusionsThe transects on the Lammermoor Range are atleast 500m higher than the nearest majorinfestation of mouse-ear hawkweed in the adjacentManorburn Ecological District (Report onHawkweeds Workshop, Lincoln University,March 1990), 40-50 km to the north-west. Annualrainfall on the Lammermoor Range is 1050mm(DSIR Water Resources Survey, Dunedin;unpublished), compared with about 500 mm at750 m elevation in the Manorburn area.Vegetation differs markedly, with more or lessintact narrow-leaved snow tussock grassland onthe Lammermoor Range, and highly modifiedgrassland with generally sparse silver tussock(Poa cita), red tussock (Chionochloa rubra) andnarrow-leaved snow tussock in the Manorburndistrict.

Figure 1: Height / frequency diagrams for Chionochloa rigida and frequency values (%) for Hieracium pilosella, bareground and litter, Lammermoor Range. Dashes indicate where litter frequency was not measured.



The Lammermoor Range thus provides a differentenvironment from that of the Manorburn district,and, except for altitude, from that considered tobe optimal for mouse-ear hawkweed, namelyintermontane basins, valley floors and adjacentfootslopes, annual rainfall 650-800mm, altitude upto 1200m, and low vegetation such as hardtussock (Festuca novae-zelandiae) grassland(Report on Hawkweeds Workshop, LincolnUniversity, March 1990; McKendry & O'Connor1990).

Nevertheless, mouse-ear hawkweed is establishedon disturbed ground on the Lammermoor Range,as elsewhere in tall tussock grasslands (Report onHawkweed Workshop, Lincoln University, March1990). The results to date of this study suggestthat it can spread from these sites to enter andpersist for at least three years ill tall tussockgrassland where narrow-leaved snow tussock andassociated litter biomass indices have beensubstantially reduced by fire.

The low frequency of mouse-ear hawkweedrecorded in this study may reflect its intrinsic lowrate of establishment from seed (McKendry &O'Connor 1990) and little vegetative spread in thetime since establishment.

47

Although there was a tendency for mouse-earhawkweed to establish on transects with thelowest litter frequencies, differences in mouse-earhawkweed frequency between transects areprobably a chance effect of establishment ratherthan the result of differences in habitat suitability.

The burning of narrow-leaved snow tussockgrassland, with or without subsequent grazing,has evidently provided a 'window of opportunity'for mouse-ear hawkweed establishment at thestudy site. Further monitoring is required todetermine the invasive ability and ultimate placeof mouse-ear hawkweed on narrow-leaved snowtussock grassland on the Lammermoor Range inrelation to the level of modification caused byfire, with and without subsequent grazing.

ReferencesMcKendry, P.J.; O'Connor, K.F. 1990. T h e

ecology of tussock grasslands for productionand protection. Unpublished report for theDepartment of Conservation, Centre forResource Management, Lincoln University.


48 N.Z. Ecol. Soc. Occ. Pub. No. 2

TIME SEGMENT ANALYSIS OF PERMANENT QUADRAT DATA: CHANGES INHAWKWEEDS (HIERACIUM SPP.) IN THEWAIMAKARIRI IN 24 YEARS

D. ScottNZ Pastoral Agriculture Research Institute Ltd.

P.O. Box 60, Lincoln, CANTERBURY

SummaryThe data in Scott et al (1988) is re-examined withrespect to hawkweeds. A new technique isdescribed for determining time trends frompermanent quadrats using a scattergram of meansand rates of change from individual quadrats.While the mean cover of hawkweeds were lowduring the period, the analysis indicates that thereis an exponential increase once they appear in aquadrat. .

IntroductionOne of the longest and most accurate records ofground cover is from central Waimakariri for1947-63, 1980 and 1981. Species cover were alsorecorded for 1956, 1959, 1962 and 1980.Permanent quadrats give precise changes at onepoint, but often differ greatly in mean level andrate of change from those at other points. Thesedifferences merge ecological variability withexperimental variability and are not strictlyindependent for statistical analysis.

Time segment analysisTo overcome the non-independence of successivemeasurements the data for each species (eghawkweed cover) in each quadrat is combined todetermine the mean and rate of change from thatquadrat. Long term vegetation trends appear asdistinctive scattergram patterns of these ml".aDSand rates of change. Long term trends can beextrapolated from fitted parameters.

MethodsA full description of the sites and the fieldsampling methods is given in Scott et al (1988).In summary, permanent transects were establishedin 1947 at seven locations in the PorterRiver/Broken River area of the centralWaimakariri Basin on steep slopes, in the 780-1300m altitudinal range and on various aspects.Each transect extended 200 or 300m up slope.Approximately 400 point samples at 50mmintervals were taken per 20m. Ground cover at

each point was recorded as either livingvegetation, dead material or bare ground.Measurements were taken annually in January orFebruary from 1947 to 1963 and also in 1980 and1981. In 1956, 1959, 1962 and 1980 the speciestouched by a third of the needles was alsorecorded.

The basic unit used for the present analysis was a5m interval along a transect for a particular year,comprising approximately 100 ground cover and30 composition records and converted topercentages. The same 5m intervals were used forsamples in different years. There were 38-60 suchsamples per transect.

ResultsHawkweeds were only common on two transects(Cloudy Knoll South and Middle). Scattergramfor Cloudy Knoll Middle showed a linearrelationship between rate of change of hawkweedsand mean level for the 58 quadrats. Whenintegrated this implied an exponential increase inhawkweed cover. The fitted relationship gave:-

% hawkweed cover = 0.0076*exp(0.0945*year)

This extrapolation estimated that there would beat least 50 % cover of hawkweeds in the presentera. Extrapolation estimates were similar forCloudy Knoll South.

Association analysis between species made adistinction between "mutual occurrence of speciesusing all data, and interaction when hawkweedswere present in the quadrat. Hawkweeds wereassociated with good ground cover and were mostclosely associated with brown top (Agrostiscapillaris) and patotara (Leucopogon fraseri).There was an initial association with goldenspaniard (Aciphylla aurea).



DiscussionThe exponential increase in hawkweeds observedin these transects is more consistent with the viewof an invasive weed into a new environment withfew environmental restraints, than that of aspecies exploiting a patchy degradingenvironment. Comparison is made with similarassociation analysis of Mackenzie Country data(Treskonova 1991).

49

ReferencesScott, D.; Dick, R.D.; Hunter G.G. 1988.

Changes in the tussock grasslands in thecentral Waimakariri River basin, Canterbury,New Zealand, 1947-1981. New ZealandJournal of Botany 26: 197-222.

Treskonova, M. 1991. Changes in the structureof tall-tussock grasslands and infestation byspecies of Hieracium in the MackenzieCountry, New Zealand. New ZealandJournal of Ecology 15 (1): 65-78.



KING DEVIL HAWKWEED (HIERACIUM PRAEALTUM) IN WET, ALPINE, TALLTUSSOCK GRASSLAND, HOPKINS VALLEY, SOUTH CANTERBURY.

G.G. HunterLandcare Research New Zealand Ltd - Manaaki Whenua


IntroductionIn 1991 the main species present in midribbedsnow tussock (Chionochloa pallens) grasslandsand associated short tussock grasslands in theupper Hopkins Valley were assessed at a numberof sites using a height frequency sampler. Thedistribution of hawkweed species at three sites,which differed in sheep grazing histories, isoutlined. The sites were in a lower alpine (1380-1580 m), superhumid (annual rainfall 4000mm/year) environment. They were located onmoderately steep slopes having northerly to north-easterly aspects. Soils at sites 1 and 2 wereyellow-brown earths and site 3 was on a recentsoil on landslide debris.

All sites have carried moderate to high numbersof red deer, Himalayan thar and chamois,although populations have been relatively lowover the last decade. Sheep have been grazed inthe area since 1965. Grazing levels were nil (site1), extensive, light summer grazing (site 2), andconcentrated summer grazing within an extensivegrazing regime (site 3 ) (Table 1). There havebeen no recent fires in the area.

Results and DiscussionKing devil (Hieracium praealtum) and mouse-earhawkweed (H. pilosella) were recorded at lowfrequencies in the study area. King devilhawkweed had become established within whatare now relatively intact tall tussock grasslands(and associated subalpine scrub), in which livingvegetation and litter provide a nearly completeground cover (Table 1). It typically occurred asan inter-tussock species having a frequency of< 1 %, but it reached 16% at site 1 and waslocally dominant nearby on areas disturbed bylandslide.

Results do not indicate any positive relationshipbetween impacts of past or present grazing bysheep and the distribution of hawkweeds. Kingdevil reached highest frequencies at and near the

site which had no history of grazing by sheep.This species is preferentially grazed inunimproved rangelands (Hughes 1975) andgrazing may have suppressed its frequency.However, the ungrazed area had the highestrainfall and was surrounded by the most brokenand bluffy terrain. Consequently it may have beenprone to natural disturbances (e.g. snowavalanche, landslide) which may also favour theestablishment of hawkweeds. This naturaldisturbance effect is corroborated by thedominance of king devil hawkweed on colluvialfootslopes below high rock bluffs and onfloodways in the nearby Temple Stream. (A.F.Mark pers. comm.) and on a landslide near site 1.Past grazing by wild animals, especiallyconcentrated feeding by thar, may have depletedthe cover and predisposed some areas to invasionby hawkweed.

Conversion of the most heavily grazed site (site 3)from tall tussock to short tussock grassland wouldhave pre-dated the arrival of a local hawkweedparent source. Hawkweeds have not subsequentlyextended in cover, even in local bare areas withinthe overall dense grass sward. This lack ofsuccess may be related to a combination of plantcompetition and grazing effects.

Although king devil hawkweed was occupyingsites which would otherwise have been occupiedby other species, it is unknown whether or not ithas directly displaced other species or colonisedbare ground. It is also unclear if it will bedisplaced, over time, by other species, butphotographs show that king devil has beendominant in naturally disturbed areas in TempleStream for at least 10 years. Its dominance inthese areas may be preserved by periodicdisturbance.

ConclusionsKing devil hawkweed is a significant species intussock grasslands in superhumid, alpine and


N.Z. Ecol. Soc. Dec. Pub. No.2

subalpine environments immediately east of themain divide. It is generally an intertussock speciesbut is locally dominant. It is unlikely that areduction in grazing intensity in these grasslandswould induce extensive hawkweed dominance,because of the well developed plant canopy andground cover, but its frequency as an intertussockspecies may increase.

Although mouse-ear hawkweed is locally presentat very low frequencies in the grasslands, therewas no evidence, in the study area, of itsincreasing.

AcknowledgementsThe Department of Conservation supported thisinvestigation.

51

ReferencesHughes, J.G. 1975. What sheep eat on developed

and undeveloped high country. TussockGrasslands and Mountain Lands InstituteReview 31 : 20-30.

Rose, A.B. 1983. Succession in fescue (Festucanovae-zelandiae) grasslands of the Harper -Avoca catchment, Canterbury, New Zealand.FRI Bulletin No. 16. New Zealand ForestService. .


Grassland midribbed snowtussock

Midribbed snowtussock/false spaniard

blue tussock/sweet vernal/Matthew'stussock

Sheep grazing nil light, extensive summergrazing (<0.1su/ha/yr)

heavy, concentrated grazing withinExtensive grazing system(1.2 su/h/yr)

Ground cover %

living vegetation 44 44 84

dead 53 52 10

bare around 3 4 6

Hawkweedfrequency moderate (1) low (2) low (2)


Site 1 Site 2 Site 3

(1) King devil 16% frequency, and higher in some adjacent areas. Locally dominant on landslide scars and intertussockareas. Mouse-ear hawkweed a minor species, with frequency < 1 % and absent in many areas.

(2) King devil and mouse-ear hawkweed were minor and localised species, with frequency < 1 %. Species absent frommuch of the area.

Table 1: Site description for three grassland transects in Hopkins Valley.


SESSION TWO DISCUSSION:VEGETATION MONITORING CASE STUDIES

Time-sequential photographs of vegetation changeon the South Opuha plots demonstrated thatmouse-ear hawkweed plants often established anddisappeared on a year-by-year basis, unrelated tolonger-term trends. Such variations are importantfor interpretation of field records that are taken atinfrequent intervals of time.

Relationships between hawkweed distribution,environment, disturbance factors, and time werediscussed for specific sites:

On the Knobby Range, patchiness in thedistribution of mouse-ear hawkweedvegetation appears unrelated to environmentalconditions. Some observers interpreted itsdistribution as being related to historicdegradation of the vegetative cover, amanagement effect. An alternative hypothesiswas that the distribution is related to chanceestablishment from seed, and subsequentthickening up by vegetative spread. D. Scottconsidered this phenomenon to be consistentwith his observations of hawkweeds at thedry end of their habitat range.

Tussock hawkweed and king devil are locallydominant species in rank, humid, valley'grasslands' which have not been grazed byfarm stock. Many invaded sites are subject toperiodic natural disturbance (i.e., land slidescars, colluvial cones). It was hypothesizedthat other invasions may be related toconcentrated grazing by feral animals, but noconclusive evidence was presented.

It was suggested that we have failed to make mosteffective use of the available information fromexisting long-term monitoring programmes,including ecological studies and agricultural trials.A limitation at the land management level hasbeen the lack of reporting of derived managementimplications and advice, from monitoringprogrammes back to the community.

Key findings could be identified from a series ofmajor, long term monitoring programmes and be

integrated. Initial management implications couldbe derived and disseminated. However it isunlikely that we are yet at the stage where we canconfidently relate hawkweed species performanceto environments and management factors, or todefine the limits of hawkweed species potentials.

Some elements of a successful monitoringprogramme were identified:

they should be initiated with a clear conceptof what is required, especially in terms ofecological issues and management needs,they need to be of sufficient dimension toaccommodate new ecological andmanagement questions as new issues arise.(As hawkweeds are just one element oftussock grasslands management, it would beinappropriate to focus new programmes toonarrowly.),sites should be representative of ecosystems,landscapes and management so that resultscan be widely applied,they require a long term commitment ofresources,results must be carried through tomanagement implications and advice which isavailable to the community,farmers should be involved at an early stage.

Consideration was given to the respective roles ofthe Crown and the farming community ingrassland monitoring and research. Whereas theCrown has supported, and should continue tosupport, investigations, the community was in thestrongest position to make many of the necessarymanagement responses. Investigations shouldtherefore address management needs, andresearch implications and management advicemust be in community hands. This requires earlyconsultation between researchers and farmers.Benefits from having the community activelyinvolved with monitoring programmes, within astandardised framework, were suggested.

Ecological implications of evidence from themonitoring programmes were reviewed.



Experience to date has shown that it is difficult togeneralise as the 'hawkweed story' variesaccording to species and to vegetation andenvironments. Short tussock grasslands are moststrongly affected and most at risk. Short tussockgrasslands have been relatively recently inducedfrom deforestation or destruction of tall tussockgrassland. They tend to be unstable communitieswhich are transforming to forest and scrub(comprising exotic and indigenous species), talltussock grassland, weedy communities (especiallyhawkweeds), improved agricultural pastures or todegraded, open grasslands. The nature and timingof changes at any site depend on factors such asmanagement (historic and present), climate andlocal vegetation types. Whereas strongly degradedtussock grasslands are at greatest risk of invasion,pictorial evidence suggested that mouse-earhawkweed established more successfully in plantlitter and in association with other vegetation thaninto bare ground.

53

A semi-open canopy with patchy litter and bareground, characteristic of most dry, short tussockgrasslands, puts many communities at risk. Futuremanagement options for short tussock grasslandsneed to recognise the inherent instability of theinduced short tussock grasslands.

Tall tussock grasslands appear to be lesssusceptible to hawkweeds overall, particularly inthe alpine zone. However, it is clear thatsubhumid to humid, subalpine tall tussockgrasslands, most closely associated with themontane short tussock grasslands, have also beenstrongly degraded and invaded. There may bemore opportunities for management to preservetall tussock grasslands than for short tussockgrasslands.


SESSION THREE

CASE STUDIES FROM PLANT INTRODUCTION,AGRONOMIC AND GRAZING TRIALS


HAWKWEED CONTROL AND RESIDUAL EFFECTS OF OVERSOWING,OVERDRILLING AND HERBICIDE IN OTAGO

G. G. CossensMAF, Invermay Agricultural Centre

Present address: 38 Adamson Drive, Arrowtown

Effects of oversowing, overdrilling andherbicideIn a series of 12 field trials, between MacraesFlat and Alexandra, from which grazing wasgenerally excluded, mouse-ear hawkweed coverwas reduced from 60 to 3 % ground cover withinthree years by topdressing with superphosphateand oversowing or overdrilling with legumes andgrasses, and to 22 % by herbicide control with2,4-D ester. There was a. corresponding increasein clover cover from 3 % to 60% with overdrillingor oversowing but none on the untopdressedherbicide treatments. The grass component overall trials increased from 17 to 39 % cover ontreated plots.

In the fourth year following treatment applicationthe treatments were again opened to stock andafter nine years under light grazing with little orno further fertiliser, the residual effect of theinitial treatments was still apparent. Mouse-earhawkweed had increased on treated plots from 8to 29% or 2.3% per year, but had declined on niltreatments from 62 to 38% or 2.7% per year.Cloven on the treated plots declined from 45 to6% but increased slightly from 3 to 10% groundcover on controls. The grass component increasedfrom 17 to 31 % and 43 % cover on nil and treatedplots respectively. Bare ground (15 %) and otherweeds (6-8%) showed no changes over the 12 to15 year life of the trials.

When mouse-ear hawkweed populationsdominated pasture cover to at least 60% theysubsequently collapsed either naturally but slowlyover 9 years, or rapidly under the influence ofchemical, fertiliser or plant competition.

Herbage yieldTotal herbage dry matter yield on oversown oroverdrilled treatments in the presence ofsuperphosphate at 250kg/ha/yr for three years wasincreased by 700% over nil fertiliser and by1,210% with superphosphate plus nitrogen at 300

kgN/ha annually. Yield of nil fertiliser treatmentswas approximately 500 kgDM/ha and hawkweedgenerally made up 15 % of the herbagecomponents irrespective of fertiliser treatment.The herbage yield response occurred within sixmonths of the initial fertiliser application.

Trigger valuesAll mouse-ear hawkweed trial sites had 60 % ormore of mouse-ear ground cover, the mouse-earhaving already been at this level for aconsiderable number of years. One area betweenMiddlemarch and Macraes Flat was known tohave had a marked infestation for at least 25 yearsand indicated a modal area for mouse-earinvasion. This indicated that certain siteparameters or trigger values might be used tohighlight probable nucleus areas from whichmouse-ear hawkweed might spread. The derivedthreshold trigger values were:

• A November to April warm season meantemperature of 11.8°C.

• A September to April growing seasonwith a total rainfall of 350mm.

• A September to April growing seasonwith 100 drought days.

Other functions which interact with these triggervalues would be:

• The amount of bare ground: i.e., soiltemperature rises with increase of bareground.

• Aspect: e.g., northerly aspects have amean warm season temperature gain of5-20%, southerly a loss of 5-12%.

• Soil depth: critically affects the numberof drought days.

Mouse-ear hawkweed invasion will occur outsidethese limits but more slowly.



Table 1: MAF "Quick Test" 0-8cm soil nutrient analyses for hawkweed trial sites

Soil nutrient statusTypically, nucleus sites show mouse-earhawkweed to have a predilection for soils with apH of 5.2, medium phosphate and highmagnesium levels, but sulphur appearsnon-limiting. The mean and range of values onhawkweed trial sites for the MAF "Quick Test"analyses are given in Table 1.

Browntop decline - hawkweed invasionThe invasion of browntop (Agrostis capillaris)into the tussock grasslands between 1900 and1950 has many similarities with the movement ofmouse-ear hawkweed into the same areas between1950 and 1990, with the modal site betweenMacraes Flat and Middlemarch being typical.Mouse-ear hawkweed thus becomes a successor tobrowntop which has been subject to any form ofstress from insects and drought or fromovergrazing by domestic or feral animals.

Record of a workshop of the New Zealand Ecological Society on "Vegetarian change in tussock grasslands, withemphasis on hawkweeds", Cass Field Station, Canterbury, 1991.

Ph P Mg Ca K S

Mean 5.2 21.5 38.3 5.7 8.1 1.5

Range 4.8-5.9 9-38 19-81 4-17 6.7 1.7


PLANT INTRODUCTION TRIALS IN HAWKWEED COMMUNITIESON GALLOWAY STATION, UPPER MANORBURN

B.J. Wills, W.T. McDougall and J.S.C. BeggLandcare Research New Zealand Ltd - Manaaki Whenua

P.O. Box 276, ALEXANDRA

IntroductionIn the early 1980's, the Plant Materials Centre ofWater and Soil Division (now DSIR ConservationPlants Section) was involved in setting up plantintroduction trials on a site moderately affected byhawkweed at Galloway, near the UpperManorburn Dam, Central Otago. Nearly 10 years-later, following dis-establishment of the trials in1988, it is interesting to look at the situation nowexisting at Galloway and relate those observationsto the current "explosion" of hawkweed (mainlymouse-ear hawkweed, Hieracium pilosella) in thetussock grasslands.

In this paper we discuss vegetation changes thathave occurred in the oversown fertilised trials,large and small scale, in comparison with plantspecies survival in the non-fertilised "drilled"trials.

MethodsA Large Scale Oversowing trialsTrials were established in two seasons (Autumnand Spring) in each of two years (1982 and1983). Control (non-oversown) areas wereincluded for each year of sowing. Species usedincluded Lotus tenuis (corniculatus not then beingavailable in quantity), yellow sweet clover(Melilotus officinalis), lucerne (Medicago sativa),Alsike clover (Trifolium hybridum), cocksfoot(Dactylis glomerata), wheat grass (Agropyrontrichophorum) and sheeps burnet (Sanguisorbaminor). Pertiliser (250 kg/ha sulphur super +Mo), was applied at time of sowing.

B Alternative Plant/Time of Sowing trialsThese trials were established adjacent to the abovetrial in two seasons (Autumn and Spring) in eachof three years (1983, 1984 and 1985). "Drill"lines were established in dense hawkweed with asmall rotary hoe converted to cut slots (similar tothe Hunter slot seeder) and a wide selection ofplant species were seeded into these as 2 x 1 mlines, replicated (where seed quantity allowed)

both within season of planting and over the threeyears of planting. No fertiliser was applied.

Table 1: Site Details

SoilsAltitudeMean annualrainfall

Matarae YGE'sapproximately 750 m a.s.l.497 mm (1913-1977, ManorburnDam) December (52 mm) andJanuary (58 mm) receiving mostrainfall.

TemperatureRangeMean annualGround frosts

18.6 C to 34.6.6 C (daily range 11 C)155 days/year.

Results and DiscussionThe dominant features of the oversowingprogramme were the successful establishment ofAlsike clover and a peak of haresfoot trefoil(Trifolium arvense) growth following fertiliserapplication. This was followed by a rapidregression of Alsike clover and subsequently areturn to even higher ground-cover levels ofhawkweed. The point analysis data indicates thathawkweed never really decreased in groundcover,but was simply overgrown for a couple of seasonsby the Alsike and/or other species responding tothe fertiliser.

Looking at both this trial and that set up by theMAF to investigate species/fertility levelinteractions (the latter having had total exclusionof animals for its duration), there are two notablefeatures:

1) The rapid vegetation response which canbe gained once fertility regimes areraised and productive plant species areintroduced to these soils.

2) The equally rapid reversal in productivityand survival of such plant species oncesoil nutrients are depleted, in this casewith a consequent increase in groundcover of hawkweed.


oo

o

60

In the main we believe this increase was due tothe interim suppression of endemic, perennialplants by the competing biomass associated withthe introduced Alsike clover and some annualspecies, something which the hawkweed couldtolerate for a longer period and recover morequickly from. While taller statured tussocksshould also be able to survive the additionalbiomass presence for some time, the rapidchanges in soil fertility and hawkweed vigour mayhave sealed their fate.

On fertile soils where inputs can be maintainedthere is unlikely to be any problem withhawkweeds - these will remain productive as longas agronomic methods are feasible and fertiliserapplication remains economic. On areas lesslikely to be fertilised, however, we should bemaking much more effort to introduce "low"fertility species and allow these time, plus respitefrom rabbits, burning and stock, to gain afoothold in hawkweed affected country.

As regards the "low" fertility plant introductions,the situation in 1991 remains largely unchangedfrom the presented results, collected in 1988.Lotus corniculatus remains the dominant speciesover each of the three years x two seasons"drilling" with many of the original plots stillvery visible and vigorous. The other notablespecies is Festuca ovina which, while not ahighly productive grass, does seem to be able toco-exist quite happily with hawkweed - it is alsoa very valuable soil conservation plant.

Tall oat grass ( Arrhenatherum elatius) i sestablishing slowly but effectively and wasactively growing when seen recently. Theseplants were superior selections made frommaterial introduced from the USDA by the SoilConservation Centre. Some red clover(Trifolium pratense) and Dorycnium hirsutumplants are still apparent and growing in the trial,but birdsfoot trefoil considerably out-producesthem at this altitude.

It is interesting to note the survival of some nativeand other plant species in hawkweed swards ofincreasing density. Several of these plantsappear more resistant to hawkweed competitionand can, to a degree, provide an indicator of the


state of pasture "degradation". For the drier,mid-altitude Otago tussock grasslands these plantsare as follows: (Note that the list does not includeimproved pasture type plants which may only bepresent by virtue of OSTD programmes in thefirst place)

High susceptibility (to degrading soils/hawkweed)Small intertussock dicots, ego Celmisia gracilenta,Wahlenbergia albomarginata, Dichondra repens,Ranunculus lappaceus and other plants like Carexspp., Luzula rufa, Poa colensoi, P. lindsayii , P.maniototo,Agrostis muscosa, Agropyron (Elymus)scabrum along with small annuals like Airacaryophyllea, Bromus tectorum, Vulpiabromoides, Cerastium glomeratum, Geraniumsessiliflorum, haresfoot trefoil etc.

Moderate susceptibilityA broad grouping of many other tussockgrassland plants, the mainstays among thembeing: Festuca novae-zelandiae, F. matthewsii,Bromus spp., Dichelachne crinita, Rytidospennaspp., Acaena spp., Crepis capillaris, Hypericumgramineum, Hypochoeris radicata, Stellariagracilenta, Taraxacum officinale, Vittadiniaaustralis etc.

Low susceptibilityBasically this group includes the taller tussocks(Chionochloa spp) and shrubby species -H y m e n a n t h e r a , O l e a r i a , C o p r o s m a ,Muehlenbeckia, Pimelea, Rosa etc. Other hardyplants which do persist include Erythrantherapumila, Aciphylla spp. and the scabweeds(Raoulia spp.). Also included in this group are the"low" fertility, introduced species mentionedabove such as Chewing's fescue (Festuca rubra)tall oat grass and Lotus corniculatus which arevery effective in growing with hawkweed,provided they are given time. Plants such asbrown top (Agrostis capillaris), sweet vernal(Anthoxanthum odoratum), vipers bugloss (Echiumvulgare), flannel weed (Verbascum thapsus) andsheeps sorrel (Rumex acetosella) probably shouldbe included here, although they tend to overlapwith the previous group.

Thus, although it is difficult to tie particularindicator plants into definitive stages of



degradation or hawkweed invasion - the above listis by no means exhaustive and the plants listed bygroup will vary depending on whichsoil/altitude/climate combination affects them -trends are apparent.

ConclusionWhat do we need for the future? We must makeseed of appropriate plants, plus information ontheir management in hawkweed country, readilyavailable to farmers at moderate cost. There aresome who will opt for forestry/agro-forestryoptions, but we believe most hill and high countryfarmers would prefer to keep their pastoralsystems alive. We may need some form ofincentive to assist with the introduction of alteredstock management systems and plant types for thisto be successful. We believe there is enoughinformation available to get change underwayquickly. The problems lie with measures to ensurethat time is available for biological remedies totake effect - we cannot afford to establish theseplants only to return to grazing them within 1 - 2years, or have rabbits eat them out in the interim.

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Grazing management systems must adjustaccordingly - lower stocking rates, re-seedingperiods, more cattle etc.

On the research side we see a need for more inputinto biological control methods and theiroptimisation, as well as into selection andbreeding of improved and more diverse plantspecies adapted to conditions under whichhawkweed currently thrives. We know muchabout plant introduction in tussock grasslands, butvery little about the same in hawkweed deserts -this area needs attention, particularly with regardto low cost options suitable for the vastly differinglanduse types and climatic regimes with which weare faced in New Zealand. A major problemfacing plant introduction into hawkweed swards,with or without fertiliser, is increasedsusceptibility to drought-stress induced by mouse-ear hawkweed. Reduced litter content, fasterwater infiltration and more exposed soil surfacescombine to create a stressful environment forplant establishment even in moderately highrainfall regions.



LONG TERM CLIMATE RECORDS - CAN THEY ASSIST REAL-TIMEMANAGEMENT DECISIONS IN OUR TUSSOCK GRASSLANDS?

B.J. Wills, W.T. McDougall and J.S.C. BeggLandcare Research New Zealand Ltd - Manaaki Whenua

P. O. Box 276, ALEXANDRA

IntroductionLong term meteorological records along with datafrom corresponding. growing seasons can be usedto identify rainfall periods critical to subsequentpasture growth in semi arid areas. Comparison ofpresent rainfall figures, within the identifiedperiods, with long term means allows somepredictions of the upcoming growing season.Given sufficient warning this then allowsimplementation of appropriate grazingmanagement.

Climate records for several sites in the Alexandra"region" have been accumulated with the aim ofdeveloping a reactive management system to aidfarmers in managing grazing on drought proneland. The system described below aims to enablefarmers to take precautionary measures to protecttussock grasslands in low or variable rainfallyears when pasture growth may be detrimentallyaffected.

MethodsMonthly rainfall totals have been compiled from:

Alexandra from 1922Earnscleugh from 1947Clyde Dam / DSIR from 1980.

Long term rainfall means, up until 1990, havebeen calculated for all sites. These were comparedand combined to produce an overall long term(LT) mean monthly rainfall picture for the local"region" (Fig 1).

Monthly rainfall figures (including totals anddeviations from the mean) for each of the past 11years (1980-1990) inclusive were compared withthis "regional" LT mean and with the success orfailure of the corresponding growing seasons.

Results and DiscussionTwo rainfall periods have been identified thataffect availability of feed in late winter throughspring, a critical time for feed availability.

i) Mid February to mid April. Long termmonthly records indicate relatively highrainfall but also high variation from themean during this period. Good rainfall atthis period (above LT mean) may benefitearly spring growth by increasing soilmoisture levels prior to winter, providedgood rainfall also occurs in late winter /early spring. Lack of rainfall during theautumn period is likely to result in poorvegetation responses during autumn andtherefore affects utilisation in July /August.

ii) July to September. Long term monthlyrecords indicate relatively low rainfallduring this period and low variation fromthe mean. This indicates a reliance onsteady but low moisture input during latewinter / early spring to "kick off" latespring / early summer growth.

In 1991, February to April had a lower than meanrainfall. The above predictive model wouldsuggest decreasing the grazing on low to midaltitude class 7 (and other critical land types) inspring in order to sustain vegetative cover. Thetwo to three month warning period allows themanager to make alternative grazingarrangements.

Altitudinal and geographical differences of eachsite must be accounted for. The long term meansare based on valley bottom records. These tend tobe the driest sites in the area and should thereforeprovide conservative recommendations. What mayappear to be a dry season at 100 m asl may be areasonable growing season at 300 - 600 m asl.

By following rainfall closely during these criticalperiods, we hope to be able to build a picture ofthe likely situation for the autumn and springgrowing periods, and have this informationavailable in a form that can be clearly understood


N.Z. EcoL Soc. Dec. Pub. No.2 63

of climate records from the many regionalstations.

and acted on by runholders, with appropriateadvice from Otago Regional Council officers.

In future, long term records of screen and groundtemperatures may also be used to identify keytrends. The model is being developed to make use

"Real time" comparison of key identified factorswith long term means will allow for moreaccurate management decisions on land prone todrought and to depletion by inappropriate grazing.

Figure 1: Rainfall occurrence (%) and deviation (mm) 1980-1990 from long term mean for Alexandra / Clyde /Earnscleugh.



A PADDOCK BASED SURVEY OF MANAGEMENT FACTORSRELATING TO MOUSE-EAR HAWKWEED (HIERACIUM PILOSELLA) DOMINANCE

IN CENTRAL OTAGO

B. D. Foran1, J. Bates2, P. Murray3, G. Heward3 and D. Pickens3

1Landcare Research New Zealand Ltd - Manaaki Whenua, P.O. Box 276, ALEXANDRA.2 MAF Farm Consultancy, P.O. Box 276, ALEXANDRA

3 Landcorp, P.O.Box 27, ALEXANDRA

AbstractA paddock survey was conducted in thesummer/autumn period of 1991 throughout themajor pastoral districts of Central Otago to helpin defining the extent and location of thehawkweed problem, and to generate possiblehypotheses for its cause. A total of 107 paddockswere surveyed, many of them at a landscape sizeof 1000 ha or more. Data were collected (mostlyestimates) on the cover dominance of the majorhawkweed species (Hieracium spp.), and farmmanagement factors that might have contributed tothe problem. Multivariate analysis of the datashowed that there were four main influences inthe data that explained, in part, the mouse-earhawkweed (Hieracium pilosella) problem. Thefirst influence was related to the strength orresilience of the ecosystem, with weaker systemstending to trip over into mouse-ear hawkweeddominance easier than stronger systems. Thesecond influence was related to grazing, and inparticular spring grazing. The third influence wasrelated mainly to climate, particularly theoccurrence of droughts. The fourth influence wasrelated to a number of management effects, theclearest of which was development by oversowingand topdressing during the "Land Devlopment andEncouragement Loans" period and then a failureto keep up maintenance fertiliser applications. Themultivariate techniques used do not providescientific proof of cause and effect, but rathergive an overall framework within which newhypotheses can be developed and tested. Fromthis wide ranging survey, we propose a number ofmanagement guidelines which might help holdmouse-ear hawkweed in check.

IntroductionPossible causes for the widespread dominance ofhigh country landscapes by hawkweeds(particularly mouse-ear (Hieracium pilosella) and

tussock hawkweed (H. lepidulum) in this study)have been hotly debated. Hypotheses include'grazing/disturbance', 'invasive weed' and'climate change' all have a place to play in theresolution of the hawkweed problem. Thesehypotheses need to be set in a framework withdata to give initial leads to land managers, focusfor research onto halting the hawkweed spread,and to find economic ways to rehabilitate thoseareas now dominated by hawkweeds.

In this paddock survey emphasis was placed onspatial scale of landscapes, and coverage of arange of locations along environmental gradients.To gain coverage with limited field time, datawere mostly estimates along traverses withinpaddocks rather than measurements. Samplepaddocks were selected on where hawkweed"was" and "wasn't", rather than random orregular sampling. The number of paddocks (107)and land units within paddocks (340) gave awidely drawn population, within which samplingwas based on land unit, rainfall, altitude andmanagement history.

MethodsA data collection sheet was developed with sitecharacteristics (land unit makeup, soil, aspect,rainfall, altitude etc.), dominance of hawkweedspecies on a cover basis (mouse-ear, tussock, kingdevil hawkweed (H. praealtum) cover, and spatialpatterning of cover and spread) and landscapemanagement details (season and intensity ofstocking, years since last burning, rabbits, porinainfestation, development history and maintenance,experience of management etc.). Survey time wasallocated to cover rainfall and managementgradients within the different farming areas of theregion. Eight primary landscape units weredefined for data collection as follows, sunnyfaces, dark faces, dry flats, campsites, wet flats,



neutral hills, dry eroded ridges and gullies.

Data analysis went through three main phases.Correlation and multiple regression attempted todelineate simple relationships of site andmanagement characteristics to hawkweeddominance. A suite of classification andordination methods in the PATN multivariateanalysis package (Belbin 1989) were used tolocate major influences in the data. This produceda somewhat synthetic species composition array of8 land units by 2 species giving the equivalent ofa 16 species array. Vector values produced fromthe ordination were then regressed back toenvironmental descriptors to indicate “strength” ofinfluence. Finally the data for individual landunits were graphed in three dimensions withmeasures or ratings of site descriptors as the xand y values, and the cover of mouse-earhawkeed as z values. When these data wereincorporated into a smoothed surface, the peaksor valleys so displayed sometimes helped tosuggest important influences that would not beshown with numeric analytical methods.

Results

Land Units and Mean ValuesMost of the land units in the survey were sunnyfaces and dark faces, and most time in analysiswas spent on them. Dry flats and sunny faces,and wet flats and dark faces were combined insome analyses on the basis that they providedsimilar opportunities for plant growth. Mouse-earwas the most important hawkweed on a groundcover basis, and most analysis concentrated on it.Tussock hawkweed was quite dominant on severalsites, but replication was considered inadequate toexplore in depth the possible causes of itsdominance.

Maximum ground cover values of 65-75 % werefound for mouse-ear hawkweed on sunny anddark faces, dry flats and dry eroded ridges. Meanground cover values varied from 0% incampsites, to a range of 12-28 % in the major landunits sampled. The survey sample of paddockshad many sites with zero or very little hawkweedcover. Tussock hawkweed reached a maximumvalue of 20% ground cover on a wet flat, and wasimportant in cover terms in only 21 of the 340

65

land units surveyed.

Correlation AnalysisAll correlation and regression analyses ofhawkweed species ground cover against site andmanagement descriptors gave disappointingresults, with little variation accounted for. Thiswas expected because of the many factors thatappear to be operating in the hawkweed complex.Any attempt to define a relationship betweenmouse-ear hawkweed ground cover and anenvironmental descriptor was always confoundedby a large number of zero hawkweed values.

Ordination and Pattern AnalysisThe first four vectors of the ordination analysisaccounted for 57 % of the variation in thehawkweed species by Land Unit matrix (Vector 1:20%; Vector 2: 15%; Vector 3: 12%: Vector 4:10%). Correlation of the vector values with thesite and management values gave some indicationof the possible contributing factors for eachvector.

• The First InfluenceThe first influence (Vector 1) was correlated tothe 'strength of the site' or 'site resilience'.Unfortunately this was not rated or measureddirectly in the site survey, but showed up in a'site aridity/soil depth/water holding capacity'rating, and another one on 'tussock vigour'.There was also a negative correlation to the timeback to last burn which might indicate a lowsystem productivity, and a lack of need to burn.This strength/resilience vector as the dominantinfluence agrees well with the site notes andattitudes offered by the individual paddocksurveyors. In lower rainfall areas, mouse-earhawkweed did not dominate locations with veryshallow soils or stone and rubble dominated areas.Dominance therefore seemed to be a feature oflandscapes with intermediate to low landscaperesilience, and it then petered out on locationswhich provide very poor opportunities for plantgrowth. Work proceeding in Central Otago (AllanHewitt, per. comm., DSIR Dunedin) aims toprovide good estimates of landscape resilience andsoil depth, based on a soil prediction model usingslope, slope shape and aspect as the main inputs.The zones of intermediate resilience where we



expect mouse-ear hawkweed to be mostadvantaged, are in the yellow grey or pallic soilsat intermediate altitudes, the main developmentzone for oversowing and topdressing. Validatingand testing these concepts of landscape resilienceto other zones in the high country should be thefirst recommendation from this workshop.

The Second InfluenceSpring grazing and maximum yearly temperature,seem to be linked influences in this second vector.For both the sunny and dark faces these combineto apparently describe the spring grazing country(Fig. 1).

Figure 1: The relationship between mouse-earhawkweed ground cover (z), spring grazing days (x)and maximum yearly temperature (y).

Parallel to this finding is the opinion gleaned fromRabbit and Land Management Program propertyplans in Canterbury, that mouse-ear hawkweedtends to be associated with spring grazing andewe-lambing country. There are a number ofcontributing factors to this opinion. The allocationof flocks to the lambing blocks usually has verylittle flexibility, and has probably gone on sincethe start of extensive pastoralism. The samenumber of ewes go onto the same blocks whetherthere is drought or plenty. Sunny lower blockssuch as these are often good habitat for rabbits aswell. The feed requirements of the ewe flockincrease by up to 300% after lambing. This

increase, combined with a lack of availability ofother country and a highly variable opening to theseason, provide a scenario of how extremegrazing pressure could be exerted, year after yearon the same block, even in well managedenterprises with land managers who aresympathetic to land conservation values. The keypoint to be addressed, is the lack of flexibility inthe farming system, given that shearing andlambing are the key economic hinge on which thepastoral enterprise operates. They are essentiallynon moveable events in the mountain landsenvironment. The correlation of spring grazingdays and mouse-ear hawkweed abundance doesnot prove the çgrazing/disturbanceé hypothesis,but rather it provides a tighter definition for thegrazing hypothesis, which can be then proven orotherwise.

The Third InfluenceClimate was the main factor correlated with thisvector, and in particular climate cycles (Fig. 2).

Figure 2: A surface showing the relationship of theyearly rainfall in 1980 (x) and 1985 (y) on groundcover of mouse-ear hawkweed (z).

From a somewhat sketchy rainfall database of thelast 10 years, for 15 stations chosen to be as closeas possible to our survey areas, the years 1980and 1985 seemed to separate out some mouse-earhawkweed dominant dark faces. 1980 was a yearwith rainfall 100 mm greater than average across



the district, while 1985 was a drier year with 100mm less than average. The blowouts of mouse-earseems to have occurred in areas that bad drierthan average years in both 1980 and 1985 i.e.twice the drought frequency.

To suggest cause and effect of droughts inthemselves is a little risky, but drought incombination with several other factors such ashigh stock numbers etc. is a possible scenario.Opinions from farmers noted by the fieldsurveyors point to drought being identified as atrigger in mouse-ear hawkweed increase, probablydue to bare ground providing an opportunity forcolonisation. There was also some correlation ofthis vector with a rating on Porina/grass grubinfestation. This is some. support to a view thatgrass grub and/or porina are key agents inweakening tussock systems thereby allowinghawkweeds to gain a competitive advantage. Thelong term botanical studies presented at thisworkshop, should add more rigour to the viewthat rainfall cycles (wetter or drier) are importantinfluences in the complex of factors which helphawkweeds assume dominance.

The Fourth InfluenceA mixed bag of management factors were relatedto the fourth vector or fourth influence. One wasthe influence of development (Fig. 3). There wasa peak of mouse-ear hawkweed cover that relatedto a development phase about 10 years ago, whichbad not received any subsequent maintenancefertiliser. This seems to correspond to the days ofçLand Development and Encouragement Loanséwhere easy money encouraged capital expenditureon oversowing and topdressing, without a farmercommitment to proper maintenance andmanagement of this technology. We can alsoassume that droughts and rabbits were playing apart in this complex of management factors.

A number of social ratings of farmer attitude andability also correlated with this influence. Fieldofficers were asked to rate the farmers managerialcompetence (1 =poor, 5 = good) and recordkeeping ability (1-5). A low rating on managerialability and a medium rating on record keepingcoincided with the major peak of mouse-earhawkweed ground cover. It is difficult to knowwhether this says more about the attitude of thedata collectors or the ability of farmers. The

çWhite Fence Syndromeé whereby farm visitorsassume a good relationship between neatness ofhomestead and land management ability is onethat could be easily disproven. In addition therecould have been an auto-correlation of 'highhawkweeds means poor management'. It doesemphasise however, that practical descriptions ofthe people side of land management, are asimportant as the biological ones, in finding a wayto trade our way out of the hawkweed problem.

Figure 3: A surface relating mouse-ear hawkweedground cover (z) to time since pasture development (x)and time since last fertiliser (y).

Areas Most Prone To Mouse-Ear HawkweedDominanceThis survey data for Central Otago shows thatsunny faces can trip over into mouse-earhawkweed dominance across the whole altitudeand rainfall range. On the dark faces the riskareas seem to lie in a rainfall range from 300-500mm and an altitude from 2500-4000 feet. Thesesomewhat rough data tend to agree with theconcept of landscape resilience, and suggest theneed for a more rigorous data collection, as aprecursor to the development of a çresilienceéfield methodology. Ratings on tussock cover andtussock vigour, also show a threshold of around


68

20-30% tussock cover, below which mouse-earhawkweed finds it easy to become dominant,especially where tussock vigour is low. Thisthreshold is general across the other land unittypes. These general landscape data, and themanagement effects highlighted in influences 1-4(vectors 1-4 of the multivariate analysis), lead usto proposing a number of very shiftygeneralisations to help focus future managementadvice.

Management rules to avoid mouse-earhawkweed dominance

Rule 1: Ecological strength or resilience of alandscape is a predisposing factor for proneness tomouse-ear hawkweed dominance. Therefore theecological resilience of all paddocks on a farmshould be assessed as part of the long termstrategic management plan.

Rule 2: There appears to be a threshold of around20-30% tussock cover below which mouse-earhawkweed has a competitive advantage, especiallywhere tussock vigour is low. Don't graze, bum orbugger up a paddock or site which is hoveringaround the cover/vigour threshold.


Rule 3: There seems to be an effect of springgrazing, ewe/lambing blocks and warm country.Buy or develop alternative spring grazing country ,that allows flexibility of the grazing enterprise,particularly in drought years and dry springs.

Rule 4: Pasture development without the fullcommitment of regular fertiliser maintenance willprobably tip over into mouse-ear hawkweeddominance with a little help from grazing pressureand drought years. Once you are on thedevelopment treadmill, you are committed to stayon it.

Rule 5: Climate cycles playa part in triggeringmouse-ear hawkweed dominance, and they couldplaya part in getting rid of it. In times of droughtand plenty, you must be prepared to destock andde-rabbit completely to either minimise systemstress, or allow possible recovery.

ReferencesBelbin, L. 1989 (unpublished). PATH: Pattern

analysis package. CSIRO Division of Wildlifeand Ecology. Canberra, Australia.


N.Z. EcoL Soc. Occ. Pub. No.2 69

MANAGEMENT EFFECTS ON HAWKWEEDS - THE STONY CREEK EXPERIENCE

Caroline MasonLandcorpManagement Services Ltd., P. O. Box 142, CHRISTCHURCH

IntroductionIn 1982, the former Department of Lands andSurvey established a demonstration trial on theStony Creek pastoral lease (eastern Mackenziebasin). The aim of this trial was to investigatesome management options for pastures containinghawkweeds (Hieracium spp.) on a scale relevantto management of pastoral leases.

The trial site is 248 ha of hawkweed dominatedhill country within the semi-arid rainfall zone.The altitudinal range is 640m to 850m and theaspect is predominantly north-east, south-westwith a balance of half summer and half wintercountry. Soils are mapped as Omarama SteeplandYellow Grey Earths.

Three management strategies for control ofhawkweeds were allocated to three farmlets ofapproximately equal size and balance of country;

(a) Attempt 'low-cost' control using lowmoisture and fertility demanding species,subdivision and stock management:Farmlet A.Attempt 'conventional' control usingrelatively high cost inputs of seed andfertiliser along with subdivision andintensive stock management: FarmletB.Do nothing i.e. extensive management:Farmlet C.

(b)

(c)

The farmlets have been run as self-containedunits, stocked with merino wethers and managedusing the same constraints as would normallyoperate on this type of country. Vegetationcomposition has been monitored on permanentline transects, with ground cover estimates,biomass ranks and photos. Stock numbers andweight, wool weight and climate have also beenmonitored for the nine years the trial has beenrunning.

Preliminary results from the trial are brieflysummarised, concentrating on information

collected on hawkweeds in relation to the threemanagement options.

SummaryCover of mouse-ear hawkweed (Hieraciumpilosella) has tended to remain stable on bothaspects of Farmlet B (at about 8% sunny and 30%shady) and on shady faces of Farmlet A (30%cover). A slight increase in cover has been notedon sunny faces of A (from 2 to 7 %approximately), while cover has increased on bothaspects of C (from 15 to 30% on sunny, and 32to 40% on shady).

This suggests that the application of fertiliser mayhave limited any increase in cover of mouse-earon Farmlet B and shady faces of Farmlet A. Incontrast, ferti1iser appears to have little impact onthe sunny faces of Farmlet A. Introduction ofmore productive species on Farmlet B (where thishas been successful) seems to have resulted in adecrease in cover of hawkweeds. However, it isdifficult to generalise, due to the variability inresponse to oversowing and top dressing (OSTD)experienced throughout the trial.

King devil hawkweed (H. praealtum) was lessabundant than mouse-ear hawkweed (initial coverranged from 0 to 35 % compared with 0 to 80 %),but showed a similar distribution in relation toaspect. To date the cover of king devil hasremained stable or declined along most transects.

Aspect (or more probably soil moisture) obviouslyhas a major influence on distribution of bothspecies of hawkweed, as well as on likely successof OSTD. The most successful OSTD was thatundertaken in 1982 which was followed by a wetspring. In this climate of variable rainfall andhigh potential evaporation, spring rainfall appearsto be a critical factor in determining success ofOSTD. The variable seasons experienced over}the term of the trial probably explains much ofthe patchy success of oversowing to date. Thedisappointing results obtained from oversowingwith 'non-traditional' species highlight the


70

problems associated with establishment of thesespecies in country where aerial application is theonly practical option.

While detailed analysis of grazing records inrelation to changes in vegetation cover(particularly cover of hawkweeds) have not beenundertaken to date, preliminary assessments showlittle obvious relationship. Stocking rates weresubstantially increased on Farmlet B, and this hassome localised impact on vegetation cover.Estimates for bare ground and litter werenoticeably higher in December 1985 for severalpaddocks grazed just prior to monitoring. At thisstage, there is little evidence that this has had anyimpact on hawkweed cover, but this aspect needsfurther investigation.


AcknowledgementsPeter Innes (runholder, Black Forest Station) hasbeen responsible for stock management and day today running of the trial, and Ray Ward-Smith(Landcorp, Timaru) co-ordinated the oversowingand development programmes. Waitaki CatchmentCommission (Canterbury Regional Council)established and maintained the climate stationuntil 1990, when DSIR Water Resources, Tekapotook over. Numerous field workers have helpedwith the monitoring. Di Robertson helped with thepreparation of this paper.


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RESPONSE OF MOUSE-EAR HAWKWEED (HIERACIUM PILOSELLA) IN THREELONG TERMMANIPULATIVE AGRICULTURAL TRIALS


D. ScottNZ Pastoral Agriculture Research Institute Ltd


SummaryThe three trials related to fertiliser, seeding andgrazing treatments on hawkweed dominated fescuetussock grassland communities. These weremonitored for 6-9 years in terms of inputsrequired and sheep stocking rates and vegetationcomposition/cover achieved. Mouse-earhawkweed decreased or disappeared under highfertiliser and sowing inputs but remained anincreasingly important- component undersuccessively lower fertiliser inputs. The approachof agricultural trials is contrasted with that ofecological surveys in determining managementoptions for mouse-ear hawkweed control.

MethodsThe first trial had 3 developments (undeveloped,fertiliser+simple general mix, fertiliser+speciesstrips) x 4 times of set stocking (spring, summer,autumn, nil or mob stocking) x 2 sites ( moderatesoil + high mouse-ear hawkweed, shallow soil +low initial mouse-ear), (1975-82).

The second and third trials were a complexspecies mixture sown at the Mt John trial sitewith high initial mouse-ear hawkeed (1981 -present). The second trial had 27 combinations ofP and S annual fertiliser rates. The third trial had5 fertiliser rates (0, 50, 100, 250, 500 + irrigationsuperphosphate/yr) x 3 stocking rates (lax,moderate, hard) x 2 stocking methods (mob,sustained) x 2 replications. Vegetationcomposition was from spring rank scoring andconverted to species composition by geometricseries relationship of four classes:- mouse-earhawkweed, tussock, legume sown grass andothers. Anima1 grazing days per plot wererecorded.

ResultsThe main response in vegetation composition andcarrying capacity was to fertiliser. Stocking rateand method had relatively little effect on theproportions of the main vegetation classes. The

carrying capacity increased 3-5 fold withdevelopment.

In the first trial, mouse-ear hawkweed remaineddominant or increased on unfertilised treatments.Mouse-ear was suppressed on the moderate sitewith fertiliser and sowing but increased during thelong legume establishment phase on shallow soil.In the second and third trials mouse-ear remaineddominant at nil or low fertiliser inputs. Russellupin (Lupinus polyphyllus) at low fertiliserinputs, and alsike (Trifolium hybridum) and whiteclover (T. repens) at high fertiliser input weredominant for six or more years. Sown grass onlybecame dominant at high fertiliser input followingthe legume phase.

DiscussionMouse-ear hawkweed control will depend onidentifying those environmental factors that can bemodified, and to which the hawkweeds aresusceptible. The approach of the survey ecologistand experimental agriculturalist differ in theemphasis given to the two aspects. The ecologisttries to identify the environmental factors towhich hawkweed is responding in the hope thatsome are manageable, while the experimentalisttries altering the environment in the hope that oneof them will control hawkweeds. Both approacheswill need to go through an experimental validationand costing phase.



INTERACTION BETWEEN SOME PASTURE SPECIES AND TWO HAWKWEED(HIERACIUM) SPECIES

D. Scott and B.L. SutherlandNZ Pastoral Agriculture Research Institute Ltd., P. O. Box 60, Lincoln, CANTERBURY

SummaryThe input/output regression of harvest frombinary mixtures was used to determine thecompetitive interaction between 13 pasturespecies, mouse-ear hawkweed (Hieraciumpilosella) and king devil (H. praealtum) in a lowfertility soil. Treatments included a factorial ofpresence or absence of compartments separatingroot and shoots of species. Species differed intheir mean growth rate relative to hawkweedspecies, but the rate was not related to theproportion of hawkweeds in the combinationindicating a general lack of specific competitiveeffects. Mean growth rates (relative to mouse-earhawkweed) were; white clover (Trifolium repens)(best), smooth brome (Bromus inermis), sheep'sburnet ( Sanguisorba minor), fescue tussock(Festuca novae-zelandiae), chewings fescue(Festuca rubra), tall oat grass (Arrhenatherumelatius), sweet vernal Anthoxanlhum odora/um),birdsfoot trefoil (Lotus corniculalus), catsear(Hypochoeris radicata), alsike clover (Trifoliumhybridum), and milk vetch (Astralagus cicer).Shoot partitions decreased interaction of whiteclover while root partitions increased interactionwith smooth brome.

IntroductionThe search for species which out-competehawkweeds bas two components; identification ofspecies which have greater growth rates thanhawkweeds, and those that may have particularcompetitive abilities against hawkweeds. Mostcompetition experiments should be called'interaction' or 'interference' experiments becausethey do not differentiate between resource captureand other interactions.

MethodsThe species were compared in binarycombinations in two ratios; 4 plants of species Ato 1 plant of species B (or vice versa). Speciesmixtures were grown in containers that were200x200x200 mm in size, in high country yellow-brown mixed topsoil/subsoil of the Craigieburn

set. Within containers, an additional treatment ofan above ground or below ground partition aroundthe central plant was imposed. Most speciescomparisions were made on unamended soil but afertility treatment comparison (weekly addition ofa nutrient solution) with unamended soil wasadded to 6 of the 19 species combinations tested.Each species pair, root/shoot partition and fertilitytreatments were replicated 3-6 times. Containerswere grown in a field situation at DSIR Lincoln.

Shoots of each species pair were harvested 3-6times per year depending on growth rates. Data(dry weights from shoot harvests) were analysedusing a modified input/output ratio method. Ratioswere rotationally transformed so that regressionintercepts became direct tests of differences inmean growth rates, and gradients direct tests ofcompetitive or interaction effects.

ResultsGrowth rates were generally low. There weresignificant difference between species in growthrates relative to the hawkweed component. Nospecies showed significant gradients, indicating ageneral lack of specific competitive effects. Thedifference between species did not alter witbfertility.

DiscussionCompetition is a simple concept, but difficult todefine accurately. Mason (1987) similarly foundno indication of specific competition effects.Continued search for species with specificcompetitive effect is probably not a usefulallocation of research effort.

ReferencesMason, C.R. 1987 (unpublished). Rhizomatous

legumes for hawkweed dominated grasslands:M.Applied Sc. thesis, Lincoln College,University of Canterbury.



LONG TERM EFFECTS OF PASTORAL MANAGEMENT ON IMPROVED TUSSOCKGRASSLAND VEGETATION

B.E. Allanl and R.J. Doney2

1MAF Technology, P.O. Box 24, LINCOLN2Previously MAF Tara Hills, Private Bag, OMARAMA.

SummaryThe ecology of much of the South Island tussockgrassland is under threat, particularly fromhawkweed (Hieracium spp.), and present pastoralpractices are perceived to be aggravating thisthreat. Eleven years of research evidence from along term grazing trial at Tara Hill High CountryResearch Station near Omarama identifies effectspastoral management has on the botanicalcomposition of improved tussock grasslands.Effects on native tussocks include:

• Fescue tussock (Festuca novae-zelandiae)cover can be maintained under carefulgrazing management (optimal from an animalproduction point of view) but will be lost athigher stocking rates.

• Blue tussock (Poa colensoi) cover can beenhanced by grazing, even at relatively highstocking rates. Blue tussock will respond tograzing by producing high quality stock feed.Its value as a pastoral and conservationspecies is under-rated.

• Tussock cover is generally stable and notinfluenced greatly by year to year climatevariability .

• Changes in tussock cover are induced bystocking rate rather than grazing practice (iecontinuous stocking versus rotational grazing)

• considered the greatest threat on the high(1200m asl) improved sunny YBE soilswhere it increased while clover and tussockcover decreased.

• King devil hawkweed (H. praealtum) was ofhighest occurrence on the high (1100 masl)improved shady YBE soils but appeared tobe in balance with other pasture species.

• King devil hawkweed occurrence increasedsubstantially on the high (1500 masl)unimproved YBE soils, reducing the amountof bare ground.

In 1985 the management from the grazing trialthat gave optimal, yet sustainable pastureutilisation was applied to the commercial hill farmat Tara Hills. Whole farm vegetative monitoringwas started in 1986 to record the impact ofmanagement change. Transects were recorded in1990 and results with particular reference to theoccurrence of hawkweeds are presented.

• There was no occurrence of hawkweed onthe low sunny BGE/YGE soils that areimproved, carefully grazed and wellmaintained.

• Mouse-ear hawkweed (H. pilosella) was

Responsible high country farming should berecognised as a manipulative tool that canenhance rather than deplete ecological values ofthe tussock grasslands, but for this to happengenerally, there must be change in managementand attitude amongst high country land managers.

Record of a workshop of the New Zealand Ecological Society on “.Vegetation change in tussock grasslands, withemphasis on hawkweeds”, Cass Field Station, Canterbury 1991.


RABBIT AND SHEEP GRAZING IN MACKENZIE TUSSOCK GRASSLANDS:VEGETATION CHANGE 1991

P.R. Espie1 and C. Meurk2

1Forest Research Institute. Present address: 29 Woodford Tce, CHRISTCHURCH 52Land Resources, D.S.I.R., Private Bag, LINCOLN

Grazing and hawkweeds (Hieracium spp.) are twocritical factors affecting management of montanetussock grasslands, for both pastoralism andnature conservation. The effect of rabbit andsheep grazing on the major short and tall tussockgrassland communities in the MackenzieEcological Region is being assessed yearly in along-term monitoring programme.

Ten study sites were chosen from the MackenzieProtected Natural Areas Programme survey(Espie et al 1984) with representative red(Chionochloa rubra) , fescue (Festuca novae-zelandiae), silver (Poa cita), and snow tussock(Chionochloa spp.) grassland communities. Thesites range from the top of Lake Tekapo toBenmore, and from Burke's Pass to Lindis Pass,spanning the major climatic gradients in the basin.At each site three grazing treatments (60 x 60 mor 75 x 75 m) were established:a) Ungrazed (post and 2 cm mesh netting

exclosure)b) Grazed by rabbits (post and wire exclosure)c) Grazed by rabbits and stock (unfenced)

Within each treatment a 20 x 20-m plot wasrandomly located and eight randomly selectedstereo-pair photo-points were recorded (Allen etal 1983). A 50 x 50 cm quadrat at the centre ofevery photo-point was used to identify andvisually estimate percentage cover of all speciespresent, including bryophytes and lichens. Basalcover at ground level was also recorded for tallspecies. Two additional quadrats were randomlylocated outside the plot. Tussock density and sizewere measured on a variable area plot (Batcheler1986), randomly located within the 20 x 20 mplot. The plots were measured in January 1990and again in 1991. The exclosures were fencedbetween July and September 1990.

Preliminary results are that vegetation coverincreased by 4 %, and litter cover declined 2 %between 1990 and 1991, attributable to overall

reduction in grazing pressure and a favourablespring in 1990. Severely depleted grasslandsrecovered rapidly after release from grazing;vegetation cover increased by 23 % at one site.Shrub and grass recovery was conspicuous on thedeeper moister soils.

Overall, the removal of grazing has not yet had astatistically detectable effect on extent of bareground, total vegetation, tussock, grass, orhawkweed cover. Exclosures were fenced only 3-5 months before remeasurement, and rabbitexclusion was inadequate in some sites. Thetrend, however, is as expected: total grass coverincreased 0.4% (on average) in the exclosurescompared with only 0.2% in the grazedgrasslands.

Hawkweeds are continuing to spread in theMackenzie Basin. Cover increased an average of1.5% across the Basin, varying from a 2.0%decline on an eroding site to a 6.2 % increase inmesic grassland. Mouse-ear hawkweed ( H .pilosella) appears to be increasing faster than kingdevil (H. praealtum) although this variedaccording to site.. It is too early to see anydifferences that might be due to grazing.

ReferencesAllen, R.B.; Rose, A.B.; Evans, G.R. 1983.

Grassland survey manual: a permanent plotmethod. NZ Forest Service, FRI Bull. 43.

Batcheler, C.L. 1986. Rapid inventory andmonitoring of vegetation and animals byvariable area and pellet sampling. I n :Stewart, G.H. and Orwin, I.(Eds.)Indigenous Vegetation Surveys: Methods andInterpretation, pp. 18-24. Forestry ResearchCentre, FRI, Christchurch.

Espie, P.R.; Hunt, J.E.; Butts, C.A.; Cooper,P.J.; Harrington, W.M.A. 1984. MackenzieEcological Region, New Zealand ProtectedNatural Areas Programme. Department ofLands & Survey, Wellington. 140pp.



STUDIES OF HAWKWEEDS IN THE DIET OF SHEEPIN NEW ZEALAND TUSSOCK GRASSLANDS

K.F. O'Connor and N. CovacevichCentre for Resource Management. P.O. Box 56. Lincoln University, CANTERBURY

IntroductionComments are frequently made that hawkweedssuch as mouse-ear (Hieracium pilosella) are noteaten by sheep because of their appressed growthhabit. Such evasion of grazing is offered as areason for their increase in the tussock grasslandcommunities. Other comments have suggested thattheir acceptability to sheep is affected by grazingpressure or by topdressing. I have recently beenreviewing a series of studies of sheep diets intussock grasslands, mostly as part of a post-graduate programme of persons under mydirection or supervision. The following summarynotes are abstracted from this incomplete review,to supply referential information on the place ofhawkweed species in sheep diets.

MethodologyAll of the six studies examined have involvedestimation of species rank abundance in herbagemass. Most of them have involved estimation ofspecies rank abundance in the diet of sheep bydetermination of species composition of cuticlefragments in faecal samples. Some of them haveinvolved estimation of species rank abundance inherbage mass before and after a grazing period.Large advance in rank from field to diet wouldindicate selection by animals; large declines inrank would indicate rejection. Only species invery high rank in diet (1-5) are likely tocontribute appreciably to animal intake. Likewise,in many herbaceous communities only species ofhigh abundance (ranks 1-10 or even ranks 1-5),contribute measurably to herbage mass.

Summary of resultsMouse-ear hawkweed has been at low fieldabundance (rank >30th) at Ribbonwood (J.G.Hughes 1975), Tara Hills (A.B. Edge 1979) andvery low at Brooksdale (E.J. Stevens 1977). Itwas frequently evident in diet at Ribbonwood, butprincipally as stem material. It was rarely evident,even as flower stem material, at Tara Hills orBrooksdale. It was at high field abundance at

Glenthorne (P.S. Harris 1978) and at Mt. John(N. Covacevich 1991). In both these locations itwas selected against, even when no longerappressed (Covacevich 1991). Before partial areatopdressing at Glenthorne, its rank declined frommean 5th in field abundance to mean 25th in diet(Harris 1978). After partial area topdressing itmay have been consumed with clover in theoversown and topdressed sward (Abrahamsonet al 1982)

King devil hawkweed (H. praeallum) was atmoderate field abundance at Ribbonwood (ca. 7thrank in undeveloped, ca. 14th in developed area)and at Tara Hills (from 11th to 20th). It was atlow field abundance at Glenthorne, but not foundat Brooksdale. At all topdressed sites where it waspresent, it was selected positively in diet. It wasclearly rejected or selected against wheretopdressing had not been done.

Summmary conclusionsThese two species are different in theiracceptability to sheep. This difference may not bedependent on growth habit. Acceptability may beaffected by pasture topdressing, especially forking devil and possible for tussock hawkweed (H.lepidulum) which has been include with it atGlenthome.

ReferencesAbrahamson, M.; O'Connor, K.F; Harris, P.S.

1982. Sheep distribution and herbageutilisation after oversowing and topdressingpart of a high country summer range.Proceedings N.Z. Society Animal Production42: 77-78.

Theses referred to are available for consultation atLincoln University Library. The publication of thecomplete review of these diet studies is expectedbefore 1994.



NUTRIENT MASS BALANCES IN PASTORAL HIGH COUNTRY

K.F. O'Connor and P.S. HarrisCentre for Resource Management, P.O. Box 56, Lincoln University, CANTERBURY

Mass balances of N,P,S and K have beencalculated for different sectors of the high countryas part of a larger study of historic and currentpastoral uses. Models have been developed whichare primarily driven by livestock numbers fordefined areas. For three groups of runs in theMackenzie Basin represented in Figure 1,livestock numbers are derived from sheep returnsfrom earliest times to 1952, integrated withresults of periodic surveys by TGMLI from 1965to 1982. Rabbit numbers have been partitionedfrom the 'best estimates' of regional populationsfrom 1870 to 1960. In Figure 1, consumption ofherbage phosphorus is the nutrient depletivefunction of animal numbers. Returns from animalsto the grazing areas, and, more recently, fertilisertopdressing are the nutrient repletive components.

A fuller account, illustrating sulphur balances, ispresented by O'Connor and Harris in Proceedingsof the Napier November 1991 Conference onSustainable Land Management.

Important features of these mass balances are thesignificance of variation in time (and locality) inlivestock numbers, the early role of fire affectingN and S loss, the importance of rabbits and theoverall significance of nutrient non-return becauseof transfer by livestock away from grazing areas.Whether decline in vegetation condition orincrease in hawkweeds can be related to suchindicated trends as a matter for speculation. Thesemodels are also being applied to blocks of knownstocking history.

Figure 1: Depletive and repletive components for phosphorus, within Dry, Moist and Wet Run Groups (1850 - 1982).



SESSION THREE DISCUSSION: PLANT INTRODUCTION,AGRONOMIC AND GRAZING TRIAL CASE STUDIES

The impact of pasture development (egoversowing and topdressing) on hawkweeds wasdiscussed in the light of results from a number ofagronomic trials. It was clear from these trialsthat a reduction in cover of hawkweed speciescould be achieved, but questions remain as towhether these reductions could be maintained inthe long term, without continued fertiliser input.

The difficulties of getting establishment of moreagronomically productive species in areas ofhawkweed dominance was highlighted particularlyin relation to the so-called 'alternative species'.Climate, in particular. variability of springrainfall, was identified as a major constraint tosuccessful agronomic improvement in low-rainfallareas.

An observation was made (based on plantintroduction trials in the Manorburn area) that anincrease in cover of mouse-ear hawkweedappeared to coincide with an opening up of redtussock stands. There was some debate about theexplanation of this phenomenon.

The role of grazing management was discussed.Results from a long-term grazing trial at TaraHills suggest that maintenance of inputs andcareful grazing management may 'exclude'hawkweed species from short tussock grasslands.However, concern was expressed about the lowresilience of unimproved grasslands. Theimportant role that stock play in distribution ofnutrients within grazing systems was highlightedin discussion following Kevin O'Connor's paperon nutrient budgets.

The problem of hawkweed dominance in shorttussock grasslands was discussed from theperspective of nature conservation. One view wasthat short tussock grasslands were especiallyvulnerable to hawkweed 'invasion'. The issue ofthe types of communities that were leastvulnerable to hawkweed 'invasion' was debatedwith some opinions being expressed thatwood/shrubland communities were relativelyresilient.

It was generally accepted that maintaining natureconservation values in essentially seralcommunities (e.g short tussock grasslands) wouldrequire intensive manipulation and management.The lack of options for managing communitieswith a large hawkweed component for natureconservation was discussed. Agronomic options(e.g. altering fertility, adding new species, etc.)were not considered to be desirable because of theneed to maintain 'naturalness'. Options weretherefore limited to those that directly attackhawkweeds. Some of the options discussedincluded biological control, handweeding,herbicides and looking at the genetic structure ofhawkweeds. It was recognised that some of theseoptions were extremely labour intensive orexpensive and therefore could only be applied inselected areas. The potential impact of biologicalcontrol options (e.g rusts and mildews) wasdiscussed. The point was made that the aim ofbiological control would not be to kill the plant,but rather to slow down growth rates.

The role of forestry as an alternative land use forhawkweed dominated areas was briefly discussed,D. Scott commented that the issues was not'whether to have forestry or not' but rather whatcould be achieved for an investment of $100/ha or$200/ha or $500/ha. He suggested that sustainableagriculture could be achieved within 5 years foran investment of $200/ha.

The view was expressed that the fact that largeareas of the high country are now becoming'hawkweed environments' means that there is aneed to look at the competence of natural systemsto recover and at options for recovery. Thesuggestion of 'reconstruction' of communities(particularly tall tussock grasslands) was made.The need to identify where the variousmanipulative options were applicable washighlighted.

The comment was made that the manipulativeapproach was only likely to be successful to thedegree to which the land would allow on apermanent basis. The role of economicrestrictions was recognised.


SESSION FOUR

DEVELOPMENT OF SIMPLE MODELSRELATING HAWKWEED PERFORMANCE TO

ENVIRONMENTAL AND MANAGEMENT CONDITIONS

To set the scene for the working group sessions, contributors were invited to present (at shortnotice) their models of vegetation change, with particular emphases on hawkweeds, based on theirown data and their own data and other material presented or discussed in earlier sessions at theworkshop. Models are presented here for two regions:

• The Harper - Avoca catchment, North Canterbury.• Otago, east of the Lakes District.

Models of vegetation change for a third region, the Mackenzie country, have been published as:

Treskonova, M. 1991. Changes in the structure of tall-tussock grasslands and infestation by speciesof Hieracium in the Mackenzie country, New Zealand. New Zealand Journal of Ecology 15(1): 65-78.


A GENERAL MODEL OF PAST AND LIKELY FUTURE VEGETATION CHANGES INGRAZED AND RETIRED TUSSOCK GRASSLANDS OF THE HARPER-AVOCACATCHMENT, 700-1400 M ALTITUDE, 1200-1500 MM ANNUAL RAINFALL

A.B. RoseLandcare Research New Zealand Ltd -Manaaki Whenua

Marlborough Research Centre, Private Bag 1007, BLENHEIM.

Notes on the model

1. The model lists the dominant vegetation components and changes.

2. The main short tussock involved is fescue tussock (Festuca novae-zelandiae), with blue tussock(Poa colensoi) prominent at high elevations. The main tall tussocks are slim-leaved snow tussock(Chionochloa macra (south aspect) and broad-leaved snow tussock (C. flavescens) (north aspect).

3 . The trend towards woody vegetation will probably be faster on retired sites and assumes acontinued lack of burning.



TEMPORAL CHANGES IN THE INDIGENOUS VEGETATION PATTERN OFOTAGO, EASfW ARDS FROM THE LAKES DISTRICT

A. F. MarkBotany Department, University of Otago

P. O. Box 56, DUNEDIN

A request to produce, at short notice, a twodimensional model of indigenous vegetation ofOtago eastward from the Lakes District (Fig. 1), isfraught with hazard. Nevertheless such a modelwill provide a basis for discussion and debate thathopefully will lead to further refinement.

The model uses major environmental factors(climate, edaphic) as one co-ordinate and time asthe other co-ordinate. The time scale begins withthe probable pattern immediately prior to humanoccupation.

The major influence of fire during the period ofPolynesian occupation has been broadlydocumented on the basis of a range of evidence(charcoal, surface logs, forest dimples, soil, pollen;see Molloy et al. 1963; McGlone 1989; Mark et al.in prep.) for widespread forest over all but thedriest parts of the intermontane valleys (asindicated by the brown-grey earth soils and a meanannual rainfall of < c. 400 mm), and above atreeline (associated with mean summer isotherm of10 C at c. 800-1200 m according to distance fromthe coast or increased continentality.

Figure 1: Temporal trends in the indigenous vegetation pattern of Otago, eastwards from the Lakes District. Majorclimatic and edaphic factors are shown (mean annual precipitation, mean annual air temperature, and soil classification:brown-grey earths (BGE), yellow-grey earths (YGE), yellow-brown earths (YBE), upland yellow-brown earths (U YBE)and alpine yellow-brown earths (A YBE)) as they relate to the pre-I840 vegetation pattern. The generally acceptedbaseline for the Protected Natural Areas programme (PNAP) is also shown.


o


Descriptions of the vegetation during the earlyperiod of European settlement (Buchanan 1868)contain limited relevant information while that fromthe first half of the present century is invaluable(Petrie 1912; Poppelwell 1914; Cockayne 1919,1921, 1922, 1928; Bathgate 1922; Zotov 1938;Gibbs and Raeside 1945). Information from thesecond half of this century, relevant to the presentpattern of vegetation, while more abundant,(Wardle and Mark 1956; Mark 1955, 1965;McCraw 1962; Mark and Bliss 1970; Wells 1972;McIntosh et al. 1983; Brumley et al. 1986; Wardet al. 1987; Dickinson 1988, Molloy 1988; Fagan1989; Comrie in prep.) is still deficient in detail formany areas and/or vegetation types.

ReferencesBathgate, A. 1922. Some changes in the fauna and

flora of Otago in the last sixty years. NewZealand Journal of Science and Technology 4:273-283.

Brumley, C.F.; Stirling, M.W.; Manning, M.S.1986. Old Man Ecological District SurveyReport for the Protected Natural AreasProgramme. Department of Lands and Survey,Wellington.

Buchanan, J. 1868. Sketch of the botany of Otago.Transactions of the New Zealand Institute 1(part III): 22-53.

Cockayne, L. 1919. An economic investigation ofthe montane tussock-grassland of NewZealand. No. XI. Notes on depletion of thegrassland. New Zealand Journal of Agriculture19: 129-138.

Cockayne, L. 1921. An economic investigation ofthe montane tussock-grassland of NewZealand. No. XI. The grassland of theHumboldt Mountains established since theburning of their covering. New ZealandJournal of Agriculture 23: 137-147.

Cockayne, L. 1922. An economic investigation ofthe montane tussock grassland of New ZealandNo. XU. The regrassing experiments inCentral Otago, Part 1. An account of thedepleted area in relation to the experiments.New Zealand Journal of Agriculture 24: 321-

83

324.

Cockayne, L. 1928. the Vegetation of NewZealand. (2nd ed.) Leipzig, Enge1mann. (DeVegetation der Erde XIV)

Comrie, J. (in prep). Dansey Ecological District:survey report for the New Zealand ProtectedNatural Areas Programme.

Dickinson, K.J.M. 1988. Umbrella EcologicalDistrict. Survey report for the New ZealandProtected Natural Areas Programme.Department of Conservation, Wellington.

Fagan, B. 1989. Protected Natural Areas Survey ofthe Manorburn Ecological District. Unpub.MSc. Thesis, University of Otago.

Gibbs, H.S.; Raeside, J.D. 1945. Soil erosion inthe high country of the South Island.Department of Scientific and IndustrialResearch Bulletin No. 82.

McCraw, J.D. 1962. Sequences in the mountainsoil pattern of Central and western Otago.New Zealand Society of Soil ScienceProceedings 5: 16-18.

McGlone, M.S. 1989. The Polynesian settlement ofNew Zealand in relation to environmental andbiotic changes. New Zealand Journal ofEcology 12 (Supp.): 115-129.

McIntosh; P.D.; Lee, W.G.; Berks, T. 1983. Soildevelopment and vegetation trends along arainfall gradient on the east Otago uplands.New Zealand Journal of Science 26: 379-401.

Mark, A.F. 1955. Shrubland and grassland onMaungatua, Otago. New Zealand Journal ofScience and Technology .A37: 349-366.

Mark, A.F. 1965. Vegetation and mountainclimate. In: R. G. Lister and R. P.Hargreaves (eds.) Central Otago: New ZealandGeographical Society Special Publication.Miscellaneous Series 5: 69-91.


84

Mark, A.F.; Bliss, L.C. 1970. The high-alpinevegetation of Central Otago, New Zealand.New Zealand Journal of Botany 8: 381-451.

Mark, A.F.; Johnson, P.N.; McGlone, M.S.;Dickinson, K.J.M. (in prep). Alpine patternedmires in southern New Zealand.

Molloy, B.P.J.; Burrows, C.J.; Cox, J.E.;Johnson, J.A.; Wardle, P. 1963. Distributionof subfossil forest remains, eastern SouthIsland, New Zealand. New Zealand Journal ofBotany 1: 68-77.

Molloy, L.F. 1988. The Living Mantle: Soils in theLiving Landscape. Mallinson Rendel,Wellington. 239 pp. .

Petrie, D. 1912. Report on the grass-denuded landsof Central Otago. New Zealand Department ofAgriculture, Industries and Commerce Bulletin23 (i.e., 28). Wellington, Government Printer.

Poppelwell, D.L 1914. Notes on the plantcovering of the Garvie Mountains with a listof species. Transactions of the New ZealandInstitute 47: 120-142.


Ward, C.M.; Bruce, D.L; Rance, B.D.; Roozen,D.A. 1987 (unpublished). Lindis, Pisa andDunstan Ecological Districts. Draft surveyreport for the Protected Natural AreasProgramme. Department of Lands and Survey,Wellington.

Wardle, P.; Mark, A.F. 1956. Vegetation andclimate of the Dunedin District. Transactionsof the Royal Society of New Zealand 84: 33-44.

Wells, J.A. 1972. Ecology of Podocarpus hallii i nCentral Otago. New Zealand. New ZealandJournal of Botany 10: 399-426.

Zotov, V.D. 1938. Survey of the tussock-grasslands of the South Island, New Zealand;preliminary report. New Zealand Journal ofScience and Technology A20: 212-244.

Record of a workshop of the New Zealand Ecological Society on "Vegetation change in tussock grasslands,with emphasis on hawkweeds", Cass Field Station, Canterbury, 1991.

N.Z. Ecol. Soc. Dec. Pub. No.2 85

WORKING GROUP REPORT: DEVELOPMENT OF SIMPLE MODELS OFHAWKWEED PERFORMANCE IN TUSSOCK GRASSLANDS.

Compiled by: G.G. HunterLandcare Research New Zealand Ltd - Manaaki Wheua


IntroductionWorking groups convenor Barney Foran introducedthe sessions by expressing concern aboutunresolved issues of hawkweeds in tussockgrasslands, despite recognition of, and researchinto, the phenomenon for at least 15 years. Therewas a need to evaluate the range of hypotheseswhich have been put forward to explain the successof hawkweeds and to present some generalisations,based on present understanding, which c8n be usedto guide management.

The working groups were presented with aframework, based on the relationships and patternsthat had emerged from the workshop, within whichto consider the hawkweeds phenomenon. Thequestion posed was: 'to what degree doenvironmental and management factors help toexplain the performance of hawkweeds in tussockgrasslands, based on our collective knowledge?'There was provision in the framework to considerregional effects, time sequences, and differentecosystems and climate zones.

Five working groups each included, as far aspossible, ecological, production and conservationinterests as well as a regional spread of knowledgebetween Otago, Canterbury and Marlborough.Working groups responded to the framework andreported back to the workshop.

Group leaders subsequently integrated the groupresponses and presented a single overall outcomewhich is presented in this report (Fig. 1).The session was a pragmatic attempt to indicate therelative importance of a number of environmentaland management factors on hawkweed success.Each factor was subjectively ranked as having anegligible (0), weak (I), moderate (2) or strong (3)effect. The quality of the outcome from theworking group is limited by such factors as: thedifficulty for a large and diverse group, withlimited time, to systematically evaluate theinformation; the requirement to derive a ranking ona best-estimate basis, irrespective of the amountand quality of the evidence; and the differentinterpretations that could be placed on information.A more thorough, systematic and critical evaluationof the evidence still needs to be undertaken.

The categories 'semi-arid', 'short tussock' and 'talltussock' used in Fig. 1 are generalised groupingscovering contrasting combinations of vegetation andenvironment. They were used by the workinggroups to simplify the number of vegetation andenvironmental situations that needed to beaccommodated (Table 1). Ony three species ofhawkweeds were considered; mouse-ear (Hieraciumpilosella), tussock (H. lepidulum) and king devil(H. praealtum).

Table 1: Vegetation environments used in the consideration of hawkweed performance

Vegetation Typical vegetation Typical climate Typical soil groupsenvironment

èsemi-aridê (1) dry herbfield semi-arid (<400mm) & BGEannual grasses subhumid (400-600mm) dry subhygrous YGE

èshort tussockê short tussock subhumid to humid YGEbrowntop, sweet vernal (600-1200mm) montane dry-hygrous U&HCoversown pasture (<950m) YBE

ètall tussockê tall tussock humid (>1200mm) hygrous U&HC YBEsubalpine & alpine(>950m)

1. category covers two contrasting rainfall ranges: hawkweeds are poorly adapted) to the driest areas ( <400mm) but welladapted towards the 600mm end of the range. Unless specified, comments in this report relate to interactions at the weten of the range.


86

Hawkweed-environment-managementrelationships

Environmental effects1) Climatic trigger i.e., have short term

weather or climate conditions or long termclimate trends triggered hawkweed success?

• A moderate to strong climatic trigger effect onmouse-ear hawkweed and a slight to moderateeffect for king devil in montane semi-arid andshort tussock grassland environments washypothesized.

• As seed viability is short lived, a wet summermay enhance establishment by seed.

• Droughts have stressed pre-existing plantcommunities and pre-disposed them to invasion.

• No trigger effect was registered in tall tussockgrasslands, which were thought to be less proneto climatic fluctuations.

• Climatic triggers may affect the rate of changerather than the direction of change.

• Effects of longer term climate change were notconsidered and require further evaluation.

2) Soil state i.e. does the success ofhawkweeds relate to soil properties, includingfertility, depth and texture, but excluding soilmoisture?

• Overall, soil conditions were considered to be ofslight to moderate importance. However,relationships are poorly understood.

• Hawkweeds were regarded as moderate fertilityspecies which are particularly competitive whenplant communities are stressed.

• Evidence that the present distribution ofhawkweeds is related to the spatial or temporaldistribution of soils of low fertility isinconclusive. However, enhancement of soilfertility by the application of fertiliser hasenhanced the success of improved pasturespecies.

• Possible relationships between hawkweedsuccess and soil degradation, including declinein nutrient status and soil organic matter, requireinvestigation.

3) Site conditions i .e., are there otherconditions associated with particular siteswhich influence hawkweed success, e.g., soilmoisture, vegetation structure/depletion,topoclimate?

• Conditions of low soil moisture in semi-aridand


short tussock environments, especially at siteswith shallow, stony soils, have enhanced thesuccess of mouse-ear hawkweed and king devil.

• Aspect differences modify these relationship inthe driest, (< 400 mm) semi arid areas: onnortherly aspects, soil water levels tend to betoo low for hawkweeds. At the wet end of therange, the reverse may occur, with moist aspectssupporting a vegetative cover able to resisthawkweeds.

• Hawkweeds extend over wide temperatureranges, from the lowland into the alpine zonesup to at least 1500 m. Low temperatures maylimit vigour in the alpine zone.

• Mouse-ear hawkweed and king devil have beenmore successful in depleted, degraded plantcommunities, often related to managementhistory and drought stress.

• Although site effects were generally weaker fortall tussock grasslands, degraded tall tussockgrasslands in subhumid to humid areas,especially those gradational to short tussockgrasslands were highly prone to hawkweeds.

4) Natural disturbance i .e. , have naturaldisturbance regimes, including snow avalanche,landslides and overland flows/jloods influencedhawkweed success?

• Natural disturbance was a weak influence insemi-arid and short tussock environments.Greater effects in tall tussock grasslandsreflected a higher rate of disturbance in theseenvironments. Generally, effects were local.

• The distribution of king devil and tussockhawkweed in western, wet tall tussockgrasslands appeared to be strongly associatedwith naturally-disturbed sites.

5) Dispersal i.e., is the present distribution ofhawkweeds related to the process and timing ofdispersal and spread by seed and stolons?

• Plant dispersal mechanisms and timing mayhave been a moderate to strong factor inexplaining the present rather confusingdistribution of all species across allenvironments. Although vegetative spread bystolons was considered. To be the major modeof spread for mouse-ear and king devilhawkweeds, initial colonisation over extensiveareas was by dispersal of seed. As seed viabilityis short lived, critical combinations of seedproduction and favourable weather



conditions may have influenced initial dispersalof new plants. This may help to explain theapparently different stages of spread in Waitakibasin (the earliest) and in Otago andMarlborough (the more recent).

• Spread of tussock hawkweed has probably beenonly by seed, as it is non-stoloniferous.

• There is an implication that it may still be 'earlydays' and that the geographic range of allspecies will increase.

Management & vegetation effects

1) Grazing and rare history• Previous grazing and fire history has strongly

predisposed all vegetation environments tomouse-ear and king devil hawkweedestablishment. This has been in terms ofreducing the biomass, structure and productivityof the vegetation in the general progressionfrom forest and scrub to tall tussock to shorttussock and degraded, semi arid grasslands.Depleted short tussock grasslands and semi-aridlands, and open tall tussock grasslands arecompetitively disadvantaged and hence prone tohawkweeds. .

• The situation for tussock hawkweed is lessclear. Some circumstances indicate a strongmanagement response whereas it has also beensuccessful in other areas with no significantgrazing by domestic stock or fire history.

2) Current grazing• Evidence along fencelines and at sheep camps

indicated an ongoing moderate grazing effect,which may have differed between species. Ingeneral, present grazing may have continued thepatterns set historically, but at reduced levelsdue to improved stock control and pastureimprovement. The relative roles of historic andcurrent grazing impacts need investigation.

• Evidence of recent hawkweed invasion into'marginal' grasslands, once improved but nolonger being maintained, have provided awarning for future land development strategies.

• King devil may increase in response to areduction in grazing pressure, especially wherethere is bare ground. This response was notregarded as a further stage in the degradation ofthe plant communities as there is evidence thatother species also become established.

87

3) Current fire• As fire is seldom used as a management tool in

semi arid and short tussock grasslandenvironments, it has had only a local, low tomoderate effect. Burning of short tussockgrassland for scrub control was of ongoingconcern however. Oversowing and top dressingafter fire has helped to reduce the competitiveadvantage of hawkweeds in burned areas, butsuch management inputs must be maintained.

• Fire has had a moderate to locally stronginfluence for all species in tall tussockenvironments, where burning is still practiced tocontrol the rank tussock canopy, especially inOtago. Hawkweeds have colonised andestablished parent plant sources on burned areasand along access tracks.

4) Competition i.e., has the ability of othergrassland species to withstand hawkweedinvasion influenced distribution?

• Opportunity and life form interactions betweenhawkweeds and other grassland species havehad a moderate to strong effect, increasingfrom semi arid to short tussock to tall tussockenvironments. Intact tall tussock grassland wasrelatively resistant to invasion by hawkweeds,whereas hawkweeds have had an advantage indepleted short tussock grasslands. Degradedtall tussock grasslands with inter-tussock bareground have also been invaded by hawkweeds.

• Reduced hawkweed success has also beenobserved in improved pastures and in rankvegetation such as that on shady aspects, freeof disturbance.

• Exceptions to this competition effect haveincluded the local success of king devil andtussock hawkweed in apparently intact talltussock and scrub communities in wetenvironments.

• The competitive ability or 'resilience' of sometall tussock grasslands may explain the lowerabundance of hawkweeds observed in thesecommunities. However, hawkweeds havebecome widely established and are likely toincrease in abundance if conditions becomefavourable to them.

5) Invasion• All species have demonstrated strong invasion

in most vegetation environments. They have


88

established most effectively in depleted ordisturbed vegetation and bare ground, althoughindividual plants have also established inrelatively intact plant communities. Mouse-earhawkweed has been particularly invasive in theshort tussock grasslands. King devil and tussockhawkweed have been invasive in short and talltussock grasslands, especially those which havebeen depleted or disturbed.

Regional distribution of hawkweedsHawkweeds affect both production and conservationin tussock grassland environments in Marlborough,Canterbury, Otago, and Southland. Mouse-earhawkweed occurs extensively in all regions. It ispresent in all vegetation environments, with majorconcentrations in dry montane areas. King devilhas a wide distribution in Marlborough andCanterbury, where it is most common in short andtall tussock grasslands. It has been observed onlylocally in Otago. Tussock hawkweed is mostabundant in the western lakes area of Otago andoccurs sporadically throughout all regions,especially in humid environments but possibly alsoin subhumid ones. It is often associated with themargins between short or tall tussock grasslandand forest or scrubland. It has seldom beenobserved in semi arid landscapes. A fourth species,field hawkweed (H. caespitosum), is only commonin Marlborough and locally in other regions.Individual plants are present in many areas. It hasoften been mis-identified as king devil.

All species appear to have been extending theirgeographic range, and extensive areas of apparentlysuitable vegetation-environments are available forthis process to continue. The least affectedenvironments at present appear to be the semi-arid(rainfall < 400 mm) brown grey earth soils, andhumid alpine tall tussock grasslands. The Waitakibasin has supported the oldest extensive areas ofhawkweeds and the distribution in Otago andMarlborough appears to have represented earlierstages of invasion. Reasons for these regionaldifferences are unclear, but they may be related tohistoric patterns of plant dispersal as well asregional differences in environmental andmanagement conditions.

Summary of environmental and managementeffects


• Hawkweeds are highly invasive species,particularly in depleted or disturbed tussockgrasslands. Invasion appears to be initiated byestablishment of wind dispersed seed intodepleted grassland. Depending on the species,this may be into open plant cover or bare soil.The second phase of invasion involves anincrease in ground cover by vegetative spread.

• The competitive advantage of hawkweeds tendsto increase from tall tussock to short tussock tonon-tussock semi arid grasslands. However, thedegree of hawkweed invasion varies accordingto local environmental and management factorsand for each hawkweed species.

• Past management has predisposed manygrasslands to hawkweed invasion. Heavygrazing by stock and rabbits, and burning, aremajor factors in this process. Lower biomassand productivity, reduction in canopy cover andincrease in bare ground resulting from thesemanagement impacts have reduced thecompetitive advantage of the grasslands andpredisposed them to invasion.

• The present distribution and abundance ofhawkweeds is strongly related to seed dispersaland vegetative spread, and possibly toassociated climatic triggers. Establishment fromseed may be enhanced by a wet summer. Thesubsequent increase in hawkweed cover byvegetative spread may be favoured by areduction in the competitive advantage of thevegetation either by environmental (e.g.,drought stress) or management (e.g., heavygrazing) factors.

• There is insufficient evidence to confirm ordiscard the hypothesis that the recent increase inhawkweed success is associated with a longterm decline in soil fertility or levels of soilorganic matter. The temporal and spatialdistribution of soil properties, especiallynutrient status, organic matter and water holdingcapacity, in relation to hawkweed distribution,require further investigation.

• Natural disturbance regimes including snowavalanche, floods, landslides and drift regimesappear to locally predispose grasslands tohawkweeds. Effects are most noticeable inmoist, tall tussock environments.



MANAGEMENT IMPLICATIONS

Although it was not a main aim of the workshop,the opportunity was taken to identify some keymanagement implications of hawkweeds in tussockgrasslands.

• All degraded or disturbed tussock grasslandcommunities are likely to be invaded byhawkweeds, to the extent that they affectproduction and/or conservation values. Theshort tussock grasslands in the semi-arid tohumid montane environments (rainfall 500 to1200 mm) are at greatest risk. Low abundanceof hawkweeds in some areas may be related todelays in establishment rather than to aresistance to invasion.

• The cumulative effects of past management inpredisposing tussock grassland ecosystems tohawkweeds underlines the need for thedevelopment and implementation of sustainablemanagement practices to minimise furtherdegradation.

• Maintenance of a vigorous, competitive,vegetative cover and associated resilient soils isthe best-available general measure to minimisehawkweed establishment and spread. Attributesof a competitive vegetative cover include tallstature, high levels of biomass and productivity,and low levels of bare ground.

• A vigorous, competitive vegetative cover canbe promoted by reduction or elimination ofgrazing, burning and other disturbances (forconservation and extensive grazing systems)and by programmes of pasture improvementand management (for agricultural areas). Theincidence and extent of the use of fire should beminimised and emphasis placed on post-bumtreatments including oversowing andtopdressing. Baring of ground along fencelinesand tracks, by over-grazing, high rabbitnumbers and drought stress must be minimised.

• Particular attention must be paid to the ongoingmanagement of pasture improvementprogrammes, which reduce the vigour ofspecies present in the 'unimproved' grasslands.Where competition from improved pasturespecies or other disturbance has displacedtussocks and

89

other relatively enduring species, pasturemanagement programmes must be maintainedto prevent subsequent 'reversion' to hawkweedcommunities.

• However, application of sound managementpractices now will not guarantee a decline inhawkweeds. Even when stock and rabbits havebeen excluded, or where maintenancetopdressing has been consistently applied,hawkweeds may continue to be abundant.

• Climatic cycles may playa part in triggeringhawkweed dominance, and they may playa partin hawkweed control. In times of stress and alsoin times of plenty, managers should be preparedto minimise impacts (e.g., stock reduction andrabbit control) for stress-reduction and topromote possible recovery.

• Hawkweeds will continue to be present inindigenous grasslands managed for natureconservation. Management efforts in montane-subalpine grasslands may need to be directedtoward minimising the risk of hawkweeddominance which could arise throughmanagement-related disturbance, rather than topreventing initial establishment or to reducingexisting distributions. Hawkweeds are lesswidely distributed and less abundant in alpinegrasslands and they may be further containedby promotion of a vigorous grassland canopy.

• Notwithstanding these generalities, theresilience of grassland ecosystems, and hencetheir susceptibility to hawkweeds, variesaccording to interact ions betweenenvironmental and management factors. Long-term management plans must take into accountthis variability on a block-by-block, site-by-sitebasis.



Figure 1: An assessment of the influence of environmental and management factors on the performance of threehawkweed species in the tussock grasslands in the eastern South Island hill and high country. The line length representsthe relative strength of interactions, based on the mean responses from individual working groups. For each species,management/vegetation effects are listed on the left and environmental effects on the right.



REQUIREMENTS FOR URGENT RESEARCH INTO HAWKWEED (HIERACIUM SPP.)

Compiled by: A.F. MarkUniversity of Otago, Private Bag, DUNEDIN

In considering relationships between vegetation change and environmental and management factors,major gaps in knowledge were identified that are seriously inhibiting the management andcontainment of hawkweed impact in tussock grasslands. Four major areas of research that are inneed of urgent action and funding were identified. Working groups were asked to allocate researchfunding on the basis that it was to be made available purely for hawkweed research. The collatedvalues are given as percentages, of total research effort dedicated to this topic, for each of the fourmain research areas identified. Funds allocated within these research areas should be additional toresources allocated to the wider issues of tussock grasslands management, even though proposedand existing research programme should be integrated.

Recommendedallocation (%)

I IDENTIFICATION OF SUSTAINABLE LAND MANAGEMENT OPTIONS 35%

Research should embrace the following components:

(a) Land use planning studies at a regional level, to propose, test and identify the most suitableland use options, given the present state of the land and its ecological potential (i.e. pastoralismand conservation/recreation/tourism alternatives).

(b) Within "land uses" and "land use zones" so delineated, develop and test adaptivemanagement strategies (i.e. ones that attempt to use more ecologically sensitive ways of doingthings, and react to what is going on) to achieve stabilisation and/or rehabilitation of land.

(c) To work within present management structures with the aim of enabling new land uses andadaptive management strategies to be implemented by pastoral, conservation, recreation andother types of managers. A free exchange of information between researchers and managers,including the land managers/occupiers, is essential.

II GENERAL ECOLOGY OF HAWKWEEDS IN TUSSOCKGRASSLAND ECOSYSTEMS - defining the cause(s) 30%

(a) Plant competition - comparative studies of the three hawkweeds with associatedindigenous/exotic species.

(b) Plant demography - recruitment, extension, survival and turnover of individual plants andclones in a population.

(c) Burning - the role of fire (timing, frequency, intensity, post-fire spelling) in hawkweedinvasion and extension.



(d) Grazing - its role in hawkweed invasion and extension, in relation to the type (animal),intensity (stocking rate), method (mob vs set stocking at particular densities) and time (season).

(e) Entomology - the role of invertebrates in invasion and extension (through weakening of nativegrassland species) as well as control of hawkweeds within their ranges.

(f) Climatic factors - role of trigger factor(s) facilitating invasion/extension of hawkweeds, andin defining the limits of each hawkweed species to determine potential geographic ranges.

(g) Soil factors - the role of soil physical, chemical and microbiological factors in facilitatinginvasion/extension and limitation of hawkweeds. This includes determining the role of long-term soil degradation.

(h) Systems analysis and modelling - development of mathematical models (environmental,demographic, etc.) to simulate invasive conditions for particular species of hawkweed and topredict future changes for a range of scenarios.

III GRASSLAND REHABILITATION TECHNOLOGIES 20%

Long term, low input technologies/strategies - their development and assessment in relation tohawkweed invasion/control for sustainable production and conservation purposes.

IV BIOLOGICAL CONTROL 15%

(a) Fungal - assessment of exotic fungal pathogens for control/inhibition purposes.

(b) Entomological - assessment of invertebrates for control/inhibition purposes.

V MONITORING --

Generally applicable to I-IV above and financed within them.

(a) Basic monitoring

(b Research by management

The New Zealand Ecological Society stresses the need for adequate funding of urgently requiredresearch and for research funding agencies, scientists and land managers/occupiers alike, to adopta collaborative attitude and a fully integrative approach to researching the serious and complexissues associated with hawkweeds in tussock grasslands.



ANNOTATED BIBLIOGRAPHY ON HAWKWEEDS (HIERACIUM SPP.)

Compiled by: D. Scott1, T.A. Jenkinsl and P.R. Espie2

1 NZ Pastoral Agriculture Research Ltd., P. O. Box 60, Lincoln, CANTERBURY2 Forest Research Institute. Present address: 29 Woodford Tce, CHRISTCHURCH 5

Adams, J.A. 1987. Studies on P i l o s e l l aofficinarum Hill. (mouse ear hawkweed):changes in nitrogen balance and phenolicchemical levels under varying soil fertilityconditions. Unpublished B.Sc(Hons) thesis,Lincoln College, Canterbury.

Allan, B.E. 1985. Grazing effects on pasture andanimal production from oversown tussockgrassland. Proceedings of the New ZealandGrassland Association 46: 119-125.

• hawkweeds not mentioned on developed dryhill site

Allan, H.H. 1920. A note on weeds. T h eMagazine of the Agricultural and PastoralAssociation 1: 39-40.

• noting the invasion of king devil and mouseear into the South Canterbury foothills

Allan, H.H. 1940. A handbook of the naturalisedflora of New Zealand. DSIR ResearchBulletin 82.

Anderson, V.L. 1927. Studies of the vegetationof the English chalk 5. The water economyof the chalk flora. Journal of Ecology 15:72-129.

Anonymous 1976. Hieracium - good or bad?Tussock Grasslands and Mountain LandsInstitute Review 32: 38-54.

• Popular article, good overview

Anonymous 1983. Hawkweeds. Annual report ofCommittee of Management 1982/83.Tussock Grasslands and Mountain LandsInstitute.

Anonymous 1990. Action on hawkweeds.Journal of the New Zealand Mountain LandsInstitute Review 47: 1-13.

• report on meeting at Lake Tekapo

Archer, A.C.; Cutler, 'E.l.B. 1983. Pedogenesisand vegetation trends in the alpine andsubalpine zones of the northeast Ben QhauRange, New Zealand. New Zealand journalof science 26: 127-150.

• hawkweeds uncommon

Ashdown, M. Lucas, D. 1987. Tussockgrasslands: landscape value and wlnerability.New Zealand Environmental Council,Wellington. 122 pp.

• hawkweeds threat noted

Barabashova, V.N. 1979. Karyotypes of stemeelworms of wild plants. Parazitologiya13(3): 257-261.

• .stem eel worm in hawkweeds

Barker, A.P. 1953. An ecological study oftussock grasslands, Hunter Hills, SouthCanterbury. Department of Scientific andIndustrial Research Bulletin 107: 58.

• only occasional occurrence of hawkweeds

Bascand, L.D. 1979. Hawkweed occurrence andimportance in South Island agriculture andpastoral land. Unpublished report.

• based on postal survey

Bate-Smith, E.C.; Sell. P.D.; West. C. 1968.Chemistry and taxonomy of Hieracium L.and Pilosella Hill. Phytochemistry 7: 1165-1169.

• biochemical case for separation ofstoloniferous hawkweeds into separate genes

Bill, F. 1976. Study of the distribution of thegenus Hieracium in the Department Pur deDome, France. Revue des SciencesNaturelles d'Auvergne 42 (1-4): 23-38.

Bingham, S.W. 1965. Hawkweed control withturf herbicides. Northeastern Weed ControlConference 19 486-489.

Record of a workshop of the New Zealand Ecological Society on "Vegetation change in tussock grasslands, withemphasis on hawkweeds", Cass Field Station, Canterbury. 1991.

94

Bishop, G.F.; Davy, A.J. 1984. Significance ofrabbits for the population regulation ofHieracium pilosella in Breckland. Journal ofEcology 72: 273-284.age structure and population turnover ofhawkweeds greater in presence of rabbits

Bishop, G.F.; Davy, A.J. 1985. Density and thecommitment of apical meristems to clonalgrowth and reproduction in Hieraciumpilosella. Oecologia 66: 417-422.UK study on resource allocation withinspecies, density affects resource partitioning

Bishop G.F.; Davey, A.J.; Jefferies, R.L. 1978.Demography of Hieracium pilosella in aBreckland grassland. Journal of Ecology 66:615-29.increase of hawkweeds principally vegetative,susceptibility to drought.

Blumer, S . 1967. Echte mehltaupilze(Erysiphaceae) ein bestimmungsbuch fur diein Europa vorkommenden arten veb. GustavFischer berlag. Jena.powdery mildew on hawkweeds

Bobbink, R.; Willems, J.H. 1987. Increasingdominance of Brachypodium pinnatum (L.)Beauv. in chalk grasslands: a threat to aspecies-rich ecosystem. B i o l o g i c a lConservation 40: 4, 301-314.hawkweeds decreasing under brachypodiuminvasion

Boesewinkel, H.J. 1979. Erysiphaceae of NewZealand. Sydowia, Annales Mycologicia SerII 52: 13-56.powdery mildews in NZ - no record onhawkweeds

Brandenburger, W. 1985. Parasitische pilze angesfasspflanzen Europa. Gustav Fischerverlag. Jena.fungi species recorded on hawkweeds

Burrows, C.J. 1962. Flora of Waimakariri Basin.Transactions of Royal Society of NewZealand 15: 196-215.

Burrows, C.J. (Ed.) 1977. Cass History and


Science of the Cass district Canterbury, NewZealand (List of fungi prepared by W.H.Lintott), Botany Dept, University o fCanterbury .General account of vegetation in area.Hawkweeds not prominent, rust recorded onhawkweeds but no voucher specimen

Carson, W.P.; Picket, S.T.A. 1990. Role ofresources and disturbance in the organisationof an old field plant community. Ecology17: 226-238.Hieracium pratense responded more tomoisture than nutrient enhancement

Chevassut, G. 1987. Parasitic microfungirecorded on spontaneously growing plants inthe Nantes region. Bulletin Trimestriel de laSociete Mycologique de France 103: 309-313.fungi species recorded on hawkweeds

Clark, R. 1984. Man vs hieracium: how's thescore? New Zealand Journal of Agriculture148(4): 52-53.popular article

Cockayne, L.; Foweraker, C.E. 1915. Notesfrom the Canterbury College MountainBiological Station No.4. The principal plantassociations in the immediate vicinity of thestation. Transaction of the New ZealandInstitute 48: 166-186.no hawkweeds

Cockayne, L. 1928. The vegetation of NewZealand. 2nd Edition, Engelmann, Leipzig,Germany. 456 pp.no mention of hawkweeds

Connor, H.E. 1964. Tussock grasslandcommunities in the Mackenzie Country,South Island, New Zealand. New ZealandJournal of Botany 2: 325-351.hawkweeds only rarely recorded in previousdecade .

Connor, H.E. 1965. Tussock grasslands in themiddle Rakaia Valley, Canterbury, NewZealand. NZ Journal of Botany 3: 261-276.hawkweeds rare



Connor, H.E. 1990. The distribution andabundance of Hieracium species inCanterbury in the 19608.

• unpublished report presented at Tekapomeeting

Connor, H.W.; MaCrae, A.H. 1969. Montaneand Subalpine Tussock Grasslands inCanterbury. In: G.A. Knox (Editor), 7heNatural History of Canterbury. Wellington:Reed pp. 157-204.

• mouse-ear generally absent or sparse infescue and snow tussock though one sitequarter cover, some king devil and snowgrass on limestone.

Connors, I.L. 1967. An annotated index of plantdiseases in Canada. Canada Departmelll ofAgriculture Publication. 1251.

• diseases on native hawkweeds - none onintroduced stoloniferous hawkweeds

Cossens, G.G.; Brash, D.W. 1980. Agronomiccontrol of mouse-eared hawkweed(Hieracium pilosella). New Zealand MeAnnual Report 1978/9. p266-267.

• report on fertiliser and oversowing trials inOtago

Cossens, G.G.; Mitchell, R.B.; Crossan, G.S.1989. Matagouri, hawkweed and purplefuzzweed control with sheep, goats andlegumes in the New Zealand tussockgrassland. Brighton crop protectionconference, pp. 879-884. British CropProtection Council, London, UK.

• control of hawkweeds by fertiliser andoversowing

Crane, E., Walker, P., Bay, R. 1984. Directoryof important world honey sources.International Bee Research Association,London.

• hawkweeds listed as a secondary bee fodderspecies

Cuff, J.R.I. 1974. Erosion in the upper OpihiCatchment. South Canterbury CatchmentBoard publication no. 6: 152 p.

95

Darlington, A. 1968. A pocket encyclopedia ofplalll galls in colour. Blanford Press,London. 191 pp.

• leaf galls on hawkweeds

Daly, G.T.; Mason, C.R. 1988. Rhizomatouslegumes for hawkweed dominated grasslands.Proceedings of the New Zealand GrasslandAssociation 49: 218.

Davy, A.J.; Bishop G.F. 1984. Response ofHieracium pilosella in Breckland Grassland-heath to inorganic nutrients. Journal ofEcology 72: 319-330.

• over 4 years hawkweeds decreased underfertiliser but decrease offset in presence ofrabbits

Dawes, D.S.; Maravolo, N.C. 1973. Isolationand characteristics of a possible allelopathicfactors supporting the dominant role ofHieracium aurantiacum in the bracken-grasslands of northern Wisconsin. WisconsinAcademy of Sciences, Arts and Letters, 61,235-61.

de Lacy. H. 1986. Weedy strangler stalks highcountry grasses. New Zealand Farmer107(8): 12-15.

• popular article

de Retz, B. 1976. Contributions of the knowledgeof Hieraciological Flora of France 4. GenusHieracium in Corsica. Bulletin de la SocieteBotan/que de France 123(9): 571-580.

• species and distribution

Delcourt, E. 1972. Contribution of l'etudecytotaxonomique de Hieracium pilosella L.Bulletin Societie Botanique France 119: 287-302.

Dethier, V.G. 1980. Food aversion learning in 2polyphagous caterpillars Diacrisa vlrginicaand Estigmene congrua. PhysiologicalElllomology 5: 321-328.

• Hawkweeds not among avoided species

Dick, R.D. 1952. The changing tussockgrasslands. Proceedings of the New ZealandGrassland Association 14: 114-122.


96

Dick, R.D. 1978. Towards greater understandingof the Waimakariri mountain tussockgrasslands. Proceedings of the conference onerosion assessment and control in NewZealand, Christchurch, Aug. 1978. pp 43-61.

• hawkweeds hardly mentioned

Dunbar, G.A. 1977. Another Hieracium.Tussock Grasslands and Mountain LandsInstitute Review 35: 68.

• comment on increasing importance of'lachenali' (H. lepidulum).

Duquenois, P.E.; Greib, E.; Haag, M. 1956.Development et de activite 1 Hieraciumpilosella L. au cours de sa vegetation.Bulletin Societie Botanique France 103, 426-9.

Ellenberg, H. 1974. Zeigerwerte de GefaBpflanzen Miteleuropus. Scripta Geobotanica9: 1-97.

• fungi on hawkweeds in Europe

Ellenberg, H. 1986. Vegetation Ecology ofCentral Europe, 4th ed., CambridgeUniversity Press. 731 pp.

• discusses hawkweeds spp. in context ofgeneral vegetation ecology

Espie, P.R. 1987. Edaphic ecology of Festucanovae-zelandiae, Lotus pedunculatus andTrifolium repens on Craigieburn high-countryyellow-brown earth and related soils.Unpublished Ph.D. thesis, Lincoln College,University of Canterbury. 313 p.

• hawkweeds uncommon or rare inWaimakariri grasslands near lower BrokenRiver

Evans, G.R. 1980. Phytomass, litter and nutrientsin montane and alpine grasslands,Graigieburn Range, New Zealand. NewZealand Forest Service, Forest ResearchInstitute Technical Paper No. 70: 956-109.

• H. pilosella contributed 34 % above groundbiomass: 10% below ground biomass: highin N, P, K,, Mg, Ca content

Gadella, T.W.J. 1972. Biosystematic studies inHieracium pilosella L and some related


species of subgenus Pilosella. BotaniskaNotiser 125: 361-369.

Gadella, T.W.J. 1987a. Life history in an apo-amphimictic species complex. XIVthIn terna t iona l Botanc ia l Congress .International Botanical Congress Abstracts17(0): 440 pp.

• a series of paper on cytology and genetics ofhawkweeds - in particular that NZ pentaploidrace is probably apomictic

Gadella, T.W.J., 1987b. Biosystematic studies inHieracium pilosella L. and some relatedspecies of the subgenus Pilosella. BotaniskaNotiser 125: 361-360.

Gadella, T.W.J. 1987c. Sexual tetraploid andapomictic pentaploid populations ofHieracium pilosella (Compositae). PlantSystematics and Evolution 157: 218-245.

Gadella, T.W.J. 1988. Some notes on the originof polyploidy in Hieracium pilosella aggr.Acto Bot Neerl 37: 515-522.

• Hawkweeds capable of producing manydifferent hybrids

Gaumann, E . 1959. Die Rostp i lzeMitterleuropus" Mit te l , BuchdruckereiBuchler & Co. Bern.

• rusts on hawkweeds

Godwin, H. 1956. The History of the BritishFlora. Cambridge University Press, 384 pp.Paleobotany of hawkweed speciesrecorded in the UK from the late-glacialperiod onwards

Grace, N.D.; Scott, D. 1974. Diet and mineralnutrition of sheep on undeveloped anddeveloped tussock grasslands. I. the macro-and micro-element composition of bloodplasma and herbage. N.Z. Journal ofAgricultural Research, 17. 165-75.

• hawkweeds good mineral composition

Greib, E.; Duquenois, P. 1954. Acadamienationale de Medecia Bulletin 138: 63-65.


N.z. Ecol. Soc. Occ. Pub. No.2

Grieve, M. 1984. A modern herbal. PenguinBooks. 912 pp.

• herbal properties of hawkweeds

Grime, J.P. 1979. Plant strategies and vegetationon processes. John Wiley & Son. 222 pp.

• concepts of competitors, stress toleration andrudera1s in species including hawkweeds

Grime, J.P.; Hodgson, J.G.; Hunt, R. 1989.Comparative Plant Ecology. A functionalapproach to common British species. UnwinHyman, London. 742 pp.

• ecological and adaptive characteristics given

Grime, J.P.; Lloyd, P.S. 1973. An EcologicalAtlas of Grassland .Plants. Edward Arnold,London.

• UK distribution of hawkweeds given andrelationship to ecological factors

Grundy, T.P. 1989. An economic evolution ofbiological control of hieracium. Agribusinessand Economics Research Unit, LincolnUniversity Research 202: 41 p.

• estimate of cost of hawkweeds to agricultureand affordable investment in investigationinto biological control options

Gutherie-Smith, H. 1953. Tutira: the story of aNew Zealand sheep station. WilliamBlackwood & Son 444p

• hawkweeds not among many adventivespecies before 1940

Guyot, A.L.; Becker Y.; Massenot, M.;Montigut, J. 1951. Les excretions racinaerestoxiques chez lez vegetaus. BulletinTechnique d'Information des ServicesAgricoles, 59: 346-59.

• allelopathy

Harris, P.S. 1978 (unpublished). A study of thegrazing behaviour of sheep on a high countrysummer range. M.Agr.Sc. thesis, LincolnCollege, Canterbury, New Zealand.

• hawkweeds common

Harris, P.S.; O'Connor, K.F. 1980. Grazingbehaviour of sheep on a high countrysummer range in Canterbury, New Zealand.

97

New Zealand Journal of Ecology 3: 85-96.• distribution of hawkweeds in one area and

contribution to sheep diet

Hay, J.R.; Ouellettee, G.J. 1959. The role offertilizer and 2,4-D in control of pasturesweeds. Canadian Journal of Plant Science39: 278-283.

• effect of herbicides

Healy, A.J. 1976. Identification of Weeds andClovers. Editorial Services, Wellington. 271pp.

• standard reference for identification andnaming until superseded by Webb et al. 1988

Healy, A.J. 1984. Standard common names forweeds in New Zealand. N.z. Weed and PestControl Society.

Heijne, B.; Heil, G.W.; Van Dam, D. Relationsbetween acid rain and vesicular arbuscularmycorrhiza. 2nd European Symposim onMycorrhizae. 2

Henn, H.; Petit , D.;Vemet, P. 1988.Interference between Hieracium pilosella andArrhenatherum elatius in colliery soils ofNorth of France: allelopathy or competition.Oecologia 76: 268-272.

• allelopathy probably not the reason forsuccess of hawkweeds over tall oat grass

Hopkins, B. 1978. The effects of the 1976drought on chalk grassland in SussexEngland. Biological Conservation 14: 1-12.

• susceptibility of hawkweeds to severedrought

Howard, W.E. 1958. The rabbit problems inNew Zealand. DSIR Information Series 16.

Howes, F.N. 1979. Plants and beekeeping.Faber & Faber, London & Boston. 236 pp.

• hawkweeds listed as a secondary bee foragespecies


98

Hughes, J.G. 1975a (unpublished). A study of thegrazing preference of sheep on developed andundeveloped grass at a high-country site.M.Agr.Sci. thesis, Lincoln College,University of Canterbury. 278 p.

Hughes, J.G. 1975b. What sheep eat ondeveloped and undeveloped high country.Tussock Grassland and Mountain LandInstitute Review 31: 20-30.

• popular account of above

Hunter, G.G. 1991. The distribution ofhawkweeds (Hieracium) in the South Island,indicating problem status:

• Unpublished report (now published in Review48: Journal of the New Zealand MountainLands Institute 21-31)

Ja1as, J.; Pellinen, K. 1985. Chromosome countsof Erigeron, Hieracium Pilosella a n dSonchus (Compositae), mainly from Finland.Annales Botanici Fennici 22. 1, 45-47.

• range in ploidy levels

Johnson, M.F. 1977. The genus Hierac iumcichorieae Asteraceae in Virginia USA.VIrginia Journal of Science 28: 151-156.

Johnson, C.D.; Thomas, A.G. 1978.Recruitment and survival of seedling of aperennial Hieracium species in a patchyenvironment. Canadian Journal of Botany56: 572-80.

• low seed establishment of hawkweeds,greater in bare soil than in moss

Johnston, P.R. 1990. Potential of fungi for thebiological control of New Zealand Weeds.New Zealand Journal of AgriculturalResearch 25: 503-510.

• potential for hawkweeds not regarded asgood

Kerr, I.G.C. 1983. Production, performance andprospects in the high country. In Proceedingsof the 1983 Hill and High Country Seminar.Centre for Resource Management, SpecialPublication No. 26.


King, T.J. 1977. The plant ecology of ant hillsin calcareous grasslands Part 1 Patterns ofspecies in relation to ant hills in southernEngland. Journal of Ecology 65: 235-278.

• hawkweeds tends to be excluded from closeproximity of ant hills because of soildeposition

Lambrechtsen, N.C.; Sheppard, J.S. 1979.Hieracium in New Zealand. Water and SoilDivision, Aokautere Science Centre InternalReport PN 79/4.

• popular account

Lightwood 1986. Hierac;um: The IncredibleSpreading Weed. AgriSearch 17:

• popular account

Lord, J.M. 1990. The maintenance of Poa citagrassland by grazing. New Zealand Journalof Ecology 13: 43-49.

Lucas, R.J.; White, J.G.H.; Daly, G.T.; Jarvis,P.; Meijer, G. 1981. Lotus, white clover andCaucasian clover oversowing, MesopotamiaStation, South Canterbury. Proceedings ofthe New Zealand Grassland Association 42:142-150.

• hawkweeds present in plots

Macfarlane, M.J. 1980 (unpublished).Allelopathic effects of white clover (Trifoliumrepens L.) on pasture species in the highcountry environments. M.Agr.Sc. Thesis,Lincoln College, Canterbury, New Zealand.

• allelopathy of hawkweeds less than that ofwhite clover

Macfarlane, M.J.; Scott, D.; Jarvis, P. 1983.Allelopathic effects of white clover, N.Z.Journal of Agricultural Research 25: 503-518.

McKendry, P.J.; O'Connor K.R. 1990. Theecology of tussock grasslands for protectionand production. Centre for ResourceManagement Occasional Report, June 1999.161 pp.

• noted increasing importance and concern ofhawkweeds


N.Z. Ecol Soc. Occ. Pub. No.2

MacKenzie, E.H.C. 1981. New Zealand rustfungi, additions and corrections. N.Z.Journal of Botany 19: 227-232.

• no rust on hawkweeds but closely alliedspecies adventive on introduced and nativespecies

McLennan, M.J. 1974. The alpine grassland inthe upper Waimakariri Catchment from 1961to 1972. New Zealand Protection Forestryreport no. 130: 20 p.

• Hawkweeds not mentioned

Makepeace, W. 1976. Allelopathy of moUSCHmHawkweed. Proceedings of the 29th NewZealand Weed and Pest Control Conference.106-109.

Makepeace, W. 1980 (unpublished). Ecologicalstudies of Hieracium pilosella and H.praealtum. Ph.D Thesis, University ofCanterbury, Christchurch, New Zealand.

• detailed field, glasshouse and laboratorystudy of some aspect of hawkweeds in theMackenzie and Cass. Most results reportedin papers below

Makepeace, W. 1981. Polymorphism andchromosomal number of Hieracium pilosellaL. in New Zealand. New Zealand Journal ofBotany 19: 255-257.

• only pentaploid race in NZ

Makepeace, W. 1985a. Growth reproduction andproduction biology of mouse-ear and kingdevil hawkweed. New Zealand Journal ofBotany 23: 65-78

Makespeace, W. 1985b. Some establishmentcharacters of mouse-ear and king devilhawkweed. New Zealand Journal of Botany23: 91-100.

Makepeace, W.; Dobson, A.T.; Scott, D. 1985.Interference phenomena due to mouse-earand king devil hawkweed. New ZealandJournal of Botany 23: 79-90.

• allelopathy and plant competition studies

Malcolm, N.A. 1925 (unpublished). Montanetussock grassland with special reference to

99

the effect of spelling. M.Sc. Thesis,Department of Botany, University ofCanterbury. 127 pp.

Mark, A.F. 1955. Grassland and shrubland onMaungatua, Otago. New Zealand Journal ofScience &: Technology A37: 349-366.

• hawkweeds not present

Mark, A.F.; Bliss, L.C. 1970. The high-alpinevegetation of Central Otago, New Zealand.New Zealand Journal of Botany 8: 381-415.

• no mention of hawkweeds

Mason, C.R. 1987 (unpublished). Rhizomatouslegumes for hawkweed dominated grasslands.M.Applied.Sc. Thesis, Lincoln College,Canterbury .

• effect of zig-zag clover, caucasian clover,and crown vetch on hawkweeds

Matthews, L.J. 1975. Weed control by chemicalmeans. Government Printer, Wellington.

• herbicide for hawkweeds

Maylaender, M.; Reuther, M.; Duquenois, P.1968. La pilosella cultivee: variationsmorphologiques et chemiques sousl'influencedes ingrais. Plantes Medicinales etPhytotherapie, 3: 13-25.

• chemical composition

Meeklah, F.A. 1980. Chemical Weed Control.New Zealand MAF Annual Report 1978/9.

• herbicide trials

Meeklah, F.A.; Mitchell, R.B.; McMillan, H.1981. Chemical control of mouse-earhawkweed. Proceedings of the 34th Weedand Pest Control Conference: 132-136.

Moar, N.T. 1985. Pollen analysis of NewZealand honey. New Zealand Journal ofAgricultural Research 28: 39-70.

• hawkweeds pollen listed as present in honeyfrom some areas

Moffat, R.W. 1957 (unpublished). Ecologicalstudies on montane tussock grassland.M.Agr.Sci. Thesis, Lincoln College. 111 pp.


100

Moore, L.B. 1976. The changing vegetation ofMolesworth Station New Zealand 1944 to1971. New Zealand Department of Scientificand Industrial Research bulletin 217: 118 p.

• original rarity but great increase inhawkweeds

Murphy, M. 1878. New Zealand Country Town2: 253.

• early report of hawkweeds from SouthCanterbury

New Zealand Office of the ParliamentaryCommissioner for the Environment 1991.Sustainable land use for the dry tussockgrasslands in the South Island. Office of theParliamentary Commissioner for theEnvironment, Wellington.

• hawkweeds listed as of major concern in highcountry along with rabbits

Nieves Aldrey J.L. 1984. 1st data on therepresentatives of the family Ormyridae inSpain with the description of a new speciesHymenoptera chalcidoidae. Graellsia 40:119-128.

• insect gall attacking hawkweeds

Nikolaeva, V.G. 1977. Plants used by ethnicgroups of the USSR for treating diseases ofthe liver and bile secretory system. Rastitelnye Resursy 13(2): 396-403.

• herbal effects of hawkweeds

Noel, W.O.; Belles, W.S.; Wattenburger, D.W.;Lee, G.A. 1979. Chemical control of orangehawkweed on rangeland. ProceedingsWestern Society of Weed Science 32: 77.

• herbicide

O'Connor, K.F. 1961. Nitrogen and grasslandproduction in the mid-altitude zone ofCanterbury, New Zealand III. The effects ofnitrogenous and other fertiliser material onuncultivated pastures. New Zealand Journalof Agricultural Research 4: 709-721.

• king devil minor component increasing withfertiliser, mouse-ear not mentioned

Parmelee, I.A.; Saville, D.B.O. 1981.Autoecious species of Puccinia on Cichorieae


in North America. Canadian Journal ofBotany 59: 1078-1101.

• probable report of European hawkweeds rustadventive on adventive stoloniferoushawkweeds

Panebianco, R.; Willemsen, R.W. 1976. Seedgermination of Hieracium pratense, asuccessional perennial. Botanical Gazette137: 255-61.

• seed viability low but up to 2 years

Perring, F.H.; Walters, S.M. 1962. Atlas of theBritish Flora. Thomas Nelson 432 pp.

• distribution of H. pilosella mapped;widespread

Papp, M. 1987. A six year study of a secondarysuccession after deforestation in NorthHungary . Fol ia Geobotanica e tPhytotaxonomica 22: 405-413.

• hawkweeds present in forest and persistedfollowing clearing

Pennycock, S.R. 1989. Plant diseases recorded inNew Zealand. Plant Diseases Division,DSIR, Auckland. 3.

• nothing on hawkweeds

Peterson, R.L. 1979. Root buds in Hieraciumflorentinum: effects of nitrogen andobservations on bud growth. B o t a n i c a lGazette, 140: 407-13.

• growth enhanced by N fertiliser

Pollock, K.M. 1989. Grass establishment andperformance on a high country soil fertilisedwith nitrogen. New Zealand Journal ofAgricultural Research 32: 7-15.

• hawkweeds of decreasing importance underhigh inputs

Pollock, K.M.; Scott, D. 1992. Production ofpersistence of five introduced grass species indry hill country III High country, Tekapo.New Zealand Journal of AgriculturalResearch (in press).

• hawkweeds persistent under nil or low P butdecrease under P & N

Record of a workshop of the New Zealand Ecological Society on "Vegetation change in tussock grasslands, withemphasis on hawkweeds", Cass Field Station, Canterbury. 1991.


Pratt, R.M.; Putman, R.J.; Ekins, J.R.;Edwards, P.J. 1986. Use of habitat by free-ranging cattle and ponies in the New Forest,southern England. Journal of AppliedEcology 23: 539-557.

• hawkweeds abundant under long term ponygrazing

Probst, R. 1909. Die specialisation der Pucciniahieracii, Centralblattfur BakJeriologie Ser 22: 676-720.

• classical work on physiological races in rustsbased on hawkweeds rusts

Quarante, M. 1970. Test of treatment of humanbrucel losis by Hieracium pilosella:Observation of clinical case contracted by aveternarian. Review of PathologicalComparative Medical Experiment 70: 85-88.

• medicinal effects of hawkweeds

Raven, J. & Walters, M. 1956. M o u n t a i nFlowers. Colios 240 pp.

• popular discusses history of Hawkweedstaxonomy in the UK

Ravensdown Fertiliser 1991. Hieracium andfertiliser

• unpublished report on a Mackenzie countryfield day

Reader, R.J. 1978. Structural changes in aHieracium f loribundum (Compositae)population associated with the process ofpatch formation. Canadian Journal of Bot any56: 1-9.

• soloniferous species adventive to Canada;resource allocation to rhizomes andvegetative growth increase as cover increase

Reader, R.J. 1985. Temporal variation inrecruitment and mortality for the pastureweed Hieracium floribundum: implicationsfor a model of population dynamics. Journalof Applied Ecology 22: 175-183.

• annual recruitment very variable; mainlyrelated to predation and soil moisture

Reader, R.J. 1 9 9 0 . Competition constrained bylow nutrient supply: an example involvingHieracium floridundum Wimm & Grub.

101

(Compositae). Functional Ecology 4 : 573-577.

• low fertility constrained competition andfavoured hawkweeds

Reader, J.J.; Thomas, A.G. 1977. Stochasticsimulation of patch formation by Hieraciumfloribundum (Composite) in abandonedpasture lands. Canadian Journal of Botany55: 3075-3079.

• growth related to patch density; c. 25 yearsto reach steady state

Reader, R.J.; Watt, W.H. 1981. Response ofhawkweed (Hieracium floribundum) patchesto NPK fertiliser in an abandoned pasture.Canpdian Journal of Botany 59: 1944-1949.

• improved fertility increased grass competitionand limited hawkweeds growth

Roberts, H.A. 1986. Seed persistence in the soiland seasonal emergence of some plantspecies from different habitats. Journal ofApplied Ecology 23: 639-656.

• hawkweeds limited seed life

Rose, A.B. 1983. Succession in fescue (Festucanovae-zelandiae) grasslands of the Harper-Avoca catchment, Canterbury New Zealand.FRI bulletin no. 16: New Zealand ForestService.

• increasing importance of hawkweeds

Rynal, R.J. 1979. Population ecology ofHieracium florentinum (Compositae) in acentral New York limestone quarry. Journalof Applied Ecology 16: 287-298.

Scott, D. 1975. Allelopathic interaction ofresident tussock grasslands species ongermination of oversown seed. New ZealandJournal of Experimental Agriculture 3: 135-41.

• hawkweeds in middle of range is comparisonof species


• review of knowledge at that time


102

Scott, D. 1989. Hieracium (hawkweeds).Proceedings of Institute of Noxious PlantsOfficers Conference: 97-103.

• summary of previous

Scott D. 1990. Management for Hieracium.unpublished leaflet for soil conservators andDOC

Scott, D.; Bennell, A.P. 1992. Host/pathogenrelationships of the hawkweed rust Pucciniahieracii var. piloselloidarum. Annals ofBotany (in press)

• background investigation for possiblebiological control

Scott, D.; Dick, R.D;; Hunter, G.G. 1988.Changes in tussock grasslands in the centralWaimakariri River basin, Canterbury NewZealand, 1947-1981. New Zealand Journal ofBotany 26: 197-222.

Scott, D.; Maunsell, L.A. 1974. Diet and mineralnutrition of sheep on undeveloped anddeveloped tussock grassland II. Vegetationcomposition and availability. New ZealandJournal of Agriculture 17: 177-189.

• vegetation data, including hawkweeds usedby Hughes 1975

Scott, D.; Covacevich, N. 1987. Effects offertilizer and grazing on a pasture speciesmixture in high country. Proceedings of theNew Zealand Grassland Association 48: 93-98.

• hawkweeds dominant at low fertiliser inputbut suppressed at high

Scott, D.; Robertson, J.S.; Burgess, R. 1989.Species and fertiliser efficiency - a highcountry example. Proceedings of the NewZealand Grasslands Association 50: 157-162.

Scott, D.; Robertson, J.S.; Archie, W.J. 1990.Plant dynamics of New Zealand tussockgrassland infested with Hieracium pilosella.I. Effects of seasonal grazing, fertiliser andoverdrilling: II Transition matrices ofvegetation changes. Journal of AppliedEcology 27: 224-241.

• hawkweeds trends in 6-7 years in a 2 site x


2 development comparison

Scott, D.; Sutherland, B.L. 1981. Grazingbehaviour of merinos on an undevelopedsemi-arid tussock grassland block. N e wZealand of Experimental Agriculture 91: 1-9.

• king devil an abundant species in study area

Scott, D.; Wallace, A.R. 1978. Effect of groundcover and tussock proximity on legumeestablishment. New Zealand Journal ofAgricultural Research 21: 93-105.

• king devil a common ground cover on driestsite

Scott, D.; Keoghan, J.; Cossens, G.C.;Maunsell, L.A; Floate, M.J.S.; Wills, B.J.;Douglas, G. 1985. Limitation to pastureproduction and choice of species. In Burgess,R.E., Brock, J.L. (Editors), Using herbagecultivars. Grasslands Research and PracticeSeries No.3. New Zealand GrasslandsAssociation Palmerston North.

• concepts of species niche, includinghawkweeds, in relation to gradients ofmoisture, temperature, soil fertility andmanagement

Sell P.D. 1974. Material of a flora of TurkeyXXX - Hieracium. Notes for the RoyalBotanical Gardens, Edinburgh 33: 241-244.

Sell, P.D. 1987. An Introduction to the study ofBri t ish Hieracia 1. History andClassification. Watsonia 16 (4): 365-371.

• case for separation of stoloniferoushawkweeds into separate genus Pilosella

Sell, P.D.; West, C. 1967. Notes on BritishFlora. Watsonia 6 (5): 313-314.

Sell, P.D.; West, C. 1975. Pilosella Hill. In:Stace, C.A. (Editor), Hybridisation of theflora of the British Isles. Academic Press,London, New York, San Francisco pp 433-438.

• lists hybridism in Hieracium and Pilosella



Sell, P.D. 1976. Hieracium. In: Tutin, T.G.;Heywood, V.H.; Burges, N.A.; Moore,D.A.; Valentine, D.H.; Walters, S.M.;Webb, D.A. (Editors), Flora Europaea Vol.4. Cambridge University Press. 358-410.

• current European standard flora with manyspecies, all retained with Hieracium but withstoloniferous species in subgenus Pilosella

Sewell, T.G. 1952. Tussock grasslandinvestigations. Proceedings of the NewZealand Grasslands Association 14: 123-132.


Smale, M.C. 1990. Ecology and Dracophyllumsubulatum - dominant heathland frost flats atRangitaiki and north Pureora, central NorthIsland, New Zealand. New Zealand Journalof Botany 28(3): 225-248.

• presence and spread of hawkweeds in centralNorth Island

Stergios, B.G. 1976. Achene productiondispersal, seed germination and seedlingestablishment of Hieracium aurantiacum inan abandoned field community. CanadianJournal of Botany, 54: 1189-97.

Stevens, E.J., Hughes, J.G. 1973. Distribution ofsweet briar, broom, and ragwort onMolesworth Station. Tussock Grasslands &Mountain Lands Institute Special PublicationNo.9.

• some reference to hawkweeds

Suzuki, S.; Narayama, T. 1977. Orangehawkweed (Hieracium aurantiacum L.) as analien pasture weed in Hokkaido. HokkilidoNational Agricultural Experimental StationResearch Bulletin No. 117: 45-55.

• as an adventive problem weed in parts ofJapan

Taylor, R.A.; MacBryde, B. 1972. Vascularplants of British Columbia. University ofBritish Colombia Press, 754 pp.

• lists occurrence and abundance of hawkweedspecies in B.C.

Thomas, A. G. 1972. Autecological studies ofHieracium in Wellington County Ontario.

103

Ph.D. Thesis, University of Guelph.

Thomas A.G. 1975. The role of seedreproduction in the dynamics of establishedpopulations of Hieracium floribundum and acomparison with that of vegetativereproduction. Canadian Journal of Botany53: 3022-31.

Thomas, A.G.; Dale, H.M. 1974. Zonation andregulation of old pasture populations ofHieraciumfloribundum. Canadian Journal ofBotany 52: 1451-58.

• stolons only produced from floweringrosettes; significant within patch demographydifferences

Thomas, A.G.; Dale, H.M. 1975. The role ofseed reproduction in the dynamics ofestablished populations of H i e r a c i u mfloribundum and a comparison with that ofvegetable reproduction. Canadian Journal ofBotany 53: 3022-3031.

• seedling establishment very low, only 1 % ofpopulation

Thomas, A.G. 1976. Cohabitation of threeHieracium species in relation to the spatialheterogeneity in an old pasture. CanadianJournal of Botany 54: 2517-20.

Travers, W.T.L. 1884. New Zealand CountryTown 8: 408-412.

• early report of hawkweeds from SouthCanterbury

Treskonova, M. 1991. Changes in the structure oftall-tussock grasslands and infestation byspecies of Hieracium in the MackenzieCountry. New Zealand. New ZealandJournal of Ecology 15:

• place of hawkweeds in vegetation degradationsequence inferred from resampling of relevesafter 26-28 years

Turesson, B. 1972. Experimental studies' inHieracium pilosella L. II. Taxonomy anddifferentiation. Botaniska Notiser 125: 223-240.


104

Turesson, G.; Turesson, B. 1960. Experimentalstudies in Hieracium pilosella L. I.Reproduction, chromosome number anddistribution. Hereditas 46: 717-736.

Tussock Grassland Research Committee 1954.The high-altitude snow-tussock grassland inSouth Island, New Zealand. New ZealandJournal of Science and Technology 36: 335-364.

USDA 1960. Index of plant diseases in the UnitedState Agriculture Handbook No. 165. U.S.Government Printing Office.

• diseases on native hawkweeds - none onadventive stoloniferous species

Vanderkloet, S.P. 1978. Biogeography ofHieracium pilosella L. in North Americawith special reference to Nova Scotia.Proceedings Nova Scotia Institute of ScienceVolume 28: 127-134.

• abundant in Nova Scotia but not further south

Voss, E.G.; Bohlke, M.W. 1978. The status ofcertain hawkweeds (Hieracium subgenusPilosella) in Michigan. The MichiganBotanist 17: 35-47.

• adventive from Europe

Walsh, R.S. 1967. Nectar and pollen sources.National Beekeepers Association of NewZealand.

Wardle, P. 1991. Vegetation of New Zealand.Cambridge University Press 672pp

• noted general increase in hawkweeds

Watt, A.S. 1962. The effect of excluding rabbitsfrom grassland. A (Xerobrometum) inBreckland, 1936-60. Journal of Ecology 50:181-98.

Watt, A.S. 1981a. A comparison of grazed andungrazed grassland. A. In East AnglianEngland UK Breckland. Journal of Ecology69: 499-508.

• 38 year study of vegetation and hawkweedschange with rabbit exclosure


Watt A.S. 1981b. Further observations on theeffects of excluding rabbits from grasslandA, in East Anglia England UK Breckland :the pattern of change and factors affecting it1936-1937. Journal of Ecology 69: 509-536.

Webb, C.J.; Sykes, W.R.; Garnock-Jones, P.J.1988. Flora of New Zealand. Vol IV.Naturalised pteridophytes, gymnosperms,dicotyledons. DSIR Botany Division,Christchurch. 1365 pp.

• present standard for identification andnaming of hawkweeds species in NewZealand

Whitby, M.C. 1979. Economics of pastoraldevelopment in the Upper Waitaki. N e wZealand Man and the Biosphere Report No.3 220 pp.

Widera, M. 1978. Competition betweenHieracium pilosella L. and Festuca rubra L.under natural conditions. Ekologia Polska 26:359-90.

• similar in habit and interaction dependent onsoil fertility and allelopathy

Wilson, M.; Henderson, D.M. 1966. British RustFungi. Cambridge University Press.

• rusts on hawkweeds

Wraight, M.J. 1963. The alpine and uppermontane grasslands of the Wairau RiverCatchment, Marlborough. New ZealandJournal of Botany 1: 351-376.


Wraight, M.J. 1966. The alpine and uppermontane grasslands of the Waimakariricatchment. New Zealand Forest ResearchInstitute Protection Forestry Report no. 29(unpublished).

Yeung, E.C.; Peterson, R.L. 1972. Studies onthe rosette plant Hieracium floribundum. L.Observations related to flowering andaxillary bud development. Canadian Journalof Botany 50: 73-8.

Record of a workshop of the New Zealand Ecological Society on "Vegetation change in tussock grasslands. withemphasis on hawkweeds". Cass Field Station, Canterbury. 1991.


Zarzycbi, K. 1983. The competitive performanceof grassland plants on acid soils as influencedby fertilization and with different plantcompetitors in semi-natural meadows in thePien iny Nat iona l Park , Po land .Verhandlungen der Gesellschaft fur Olwlogie11: 505-509.

• hawkweeds on acid soils and decreasedmarkedly with P fertiliser

Zotov, V.D. 1938. Survey of the tussockgrasslands of the South Island, New Zealand.New Zealand Journal of Science andTechnology 20A: 212-244.

• hawkweeds not mentioned


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