Trees for the Future Presentation to FEG Symposium 31 st October 2008 Elspeth Macdonald Barry...

Trees for the Future

Presentation to FEG Symposium31st October 2008

Elspeth MacdonaldBarry Gardiner, Shaun Mochan, John Fonweban and John Moore*

Timber Properties Research Programme

* Napier University CTE

FEG Symposium 31st October 2008

Outline

1. Objectives of timber properties research

programme and collaboration

2. Trees for the future – timescales

3. The next 10 years – assessment and sorting

4. 10 – 40 years – silviculture to improve quality

5. 40 years plus – establishing forests to maximise

quality

6. Conclusions



1. Investigating and modelling the effects of silvicultural practice and site factors upon conifer timber quality

2. Developing methods of defining, assessing and forecasting timber quality to provide improved information about future timber supplies to forest managers and wood using industries

Timber properties research - objectives



• Work reported includes projects undertaken by Forest Research and Napier University Centre for Timber Engineering (Napier CTE)

• We collaborate widely: Building Research Establishment Universities in the UK Industry –sawmilling and forest management companies European partners – universities and research organisations

• Funding: Forestry Commission Scottish Funding Council Scottish Forestry Trust Scottish Enterprise Highlands and Islands Enterprise European Union

Collaboration and acknowledgements



1. The next 10 years: • Silvicultural input to improve timber quality is minimal• Focus on assessing timber quality & allocating material to

the most appropriate end use to maximise value in the woodchain

2. 10 – 40 years:• Majority of timber production in this period will be from

forests already established• Main intervention will be thinning & choice of rotation length• Possibility of pruning

3. 40 years plus:• Majority of timber production from stands still to be

established• Greatest scope for silvicultural intervention – least certainty

about market demands

Trees for the future - timescales

Trees for the Future: the next 10 years


A number of ongoing projects relate to assessment of timber quality and informing allocation of material to different end uses:

• Stem form – straightness and branching• Acoustic measurement – standing trees and

logs• Airborne laser scanning (LIDAR)• Terrestrial laser scanning

The next 10 years – assessment and sorting



• System developed for use in Sitka spruce• Can be used to predict out-turn of “green” logs

Stem straightness scoring



Branching indices

• Height of lowest dead branch commonly used as branching index in Scandinavia

• Has been tested for use with Scots pine – improved predictions of log grade out-turn

Lowest dead branch



Acoustic tools• Provide information about mechanical properties

from trees and logs• Aim to assess quality early in the wood chain

SawmillRoad sideStand



• Project ongoing to integrate quality assessment with standard harvesting operations

• Trial in several FC Scotland forest districts • Stem straightness assessed before felling • Acoustic measurements on roadside logs• GIS mapping of results • Comparison of products actually cut with timber quality

data collected • Data will be used to validate models developed to predict

timber quality

Using these methods in practice



WAFD 18422

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WAFD 18447

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Moray - Culbin THIN

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Lorne 13531

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Galloway 1088

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• Lidar technology can be used to estimate stand and tree parameters (tree heights, crown width, stocking density, stem diameter)

Airborne Laser Scanning (LIDAR)

• These data can then be used as inputs to timber quality models → predictions of log grade and timber properties

• Work ongoing to evaluate the potential for timber quality assessment at this scale



• Terrestrial Laser Scanning provides detailed stem profile data

• Stem quality assessment (using straightness scoring) can be derived

Terrestrial Laser Scanning

• Forest Research working with Treemetrics to improve stem profile assessment above the range of the laser (taper functions)

• Potential for improved pre-harvest assessment of quantity AND quality



• Interventions that will influence the quality of timber from forests already established: Thinning Choice of rotation length Pruning

• Forest Research is working with Napier University and the Building Research Establishment to integrate growth, timber quality and timber performance models

• Such models allow the impact of different management alternatives on timber produced to be evaluated

10 – 40 years: silviculture for improved timber quality

Trees for the Future: 10 – 40 years

Thinning• Thinning is a key silvicultural tool used to:

improve stand by:• removing poor stems of poor form• concentrating increment on superior trees

provide an early economic return (?)manipulate

• stocking density and stand structure• canopies of seed bearing trees• light environment for regenerating crop


General effects of thinning• Compared to no-thin regimes, thinning will result

in: improvement in stem form and branching through

selection lower proportion of juvenile wood more uniform growth

• Timing is key: early thinning or respacing prior to canopy closure can result in: retention of deep living crown → large knots in logs increased taperpossible reduction in stem straightness


Juvenile wood area – modelling the effects of thinning

Juvenile wood area (15 growth rings)

Nominal sawn timber section

No thin Intermediate thin

31% juvenile wood 21% juvenile wood

Cross-section at 4.8m


• Current average rotation length for conifers: 40 – 50 years

• Transformation to CCF, retain trees for:seed sourceshelter for regenerating

crop landscape biodiversity

Longer rotationsTrees for the Future: 10 – 40 years

Consequences of longer rotations

• Lower proportion of juvenile wood

• Potential for significant amount of knot free timber

• Napier CTE evaluated timber properties of 83 year old Sitka spruce from Birkley Wood



Birkley Wood - Grade Distribution within a Log

Pos1 Pos2 Pos3 Pos4

Strength

(N/mm2)

17.5 22.7 23.6 27.5

Density

(kg/m3)

386 395 405 420

MOE

(kN/mm2)

7.8 9.2 9.9 10.4

Strength class

C16 C20 C20 C24



Birkley Wood: Distortion – Spring and Twist

1 4

0

2

4

6

8

10

12

14

Radial Position

Spri

ng

(m

m)

1 4

0

5

10

15

20

Radial Position

Tw

ist (

mm

)


Pruning• Pruning will always benefit

timber quality if performed well reduce knot area and

produce clear timber reduce the juvenile core reduce taper

• Economic return from pruning hard to predict

• Evidence of pruning essential

• Grants for pruning available under SRDP


40 years plus: establishing forests to maximise quality (or revenue?)• In this timescale, opportunity to influence

timber quality is greatest:Species choicePlanting stock – provenance, improved progenyPlanting or natural regenerationSpacing

• Markets in 40 years time uncertainShould we always grow for best possible quality?Should we grow to meet the needs of the renewable

energy market?

Trees for the Future: 40 years plus

Choice of species

• If species is not well suited to site:patchy establishmentpoor growthpossible stem form

problems

• Also need to considerpests & diseasesclimate change impact potential future markets


Choice of provenance

• Differences in growth and timber properties between provenances

• E.g. lodgepole pineproblem with brittle failure in

service (posts, pallets)South Coastal LP

• more compression wood• lower impact strength• an increase in brash fracture

compared to Alaskan and inland provenances

Fibrous fracture

Brash fracture


Choice of progeny

• Selective tree breeding can deliver improvements in: growth rate stem straightness branching wood density

fibre properties


Conifer breeding in Britain• Sitka spruce – main focus of breeding programme

significant gains made in growth rate and quality• Scots pine

seed orchard material: increased growth rate (8 – 12%) and improved stem straightness (0 – 3%)

• Douglas firUK selected seed standsFrench/USA seed from breeding programmes

• Hybrid larchSmall gains from untested seed orchardsProspects for vegetative propagation of superior

families, to give gains of 15–20% for diameter and 20–25% for stem straightness


Recent results: study of improved Sitka Spruce

• Progeny trial at Kershope in N. England, planted 1968 – half sib

• Unimproved QCI and 3 improved families:Family 2: The straightest treatment. Family 3: The most vigorous treatment. Family 4: The treatment with the highest wood

density.

• 36 trees from each family felled for testing


Predicted green log volume/ha (m3)

0

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QCI (Unimproved) Family 2 (Straightest) Family 3 (Mostvigorous)

Family 4 (HighestDensity)


Batten Stiffness (MOE)

C G O Y

4

6

8

10

12

Progeny

Glo

ba

l MO

E (

kN/m

m²)

Highest density

Most vigorous

Straightest Unimproved QCI



Summary of Results from Kershope

• Trees selected for improved straightness and vigour yielded a greater volume of green logs

• Wood mechanical properties of progeny of selected progeny did not differ from those of QCI trees

• Major sources of variation in mechanical properties were between battens within a log and between trees within progeny – gains could be made by assessment and sorting…


Planting or natural regeneration?

• Planting - advantagesOpportunity to select speciesVolume and quality gains from improved progenyControl over stockingMinimal variation in age class structure

• Planting - disadvantagesPossible stem form problems associated with

nursery practice and early instability (toppling)High establishment costsPossible patchy stocking – future timber quality

problems


Planting or natural regeneration?

• Natural regeneration - advantages Improved stability – possibly better stem formPotentially high stocking and large number of

trees for selection in thinningPotentially low costFits well with Continuous Cover Forestry

• Natural regeneration - disadvantagesNo opportunity for improvement in growth or TQ

through use of selected provenance/progenyDifficult to control species mix – may have a lot of

low value species (e.g. hemlock, grand fir)Costs of respacing/pre-commercial thinning


Spacing – a recent concern?

• Michie (1926) advocated a maximum spacing of 7’ (~2.1m) as adequately close to prevent the formation of “very large knots”

• Brazier (1993) “it is recommended that 2m is the maximum planting spacing used for spruce if commercially acceptable yields of timber grading to SC3 (C16) are to be obtained”


Wider spacing

• Larger, longer lived branches • Larger juvenile core• Reduction in straightness• Higher grain angle• Higher taper• Fewer trees for selection amongst when thinning• May not fully utilise biological capacity of site• BUT lower establishment costs, improved stability

and trees achieve merchantable volume earlier

Poorer mechanical properties and dimensional stability


Quantifying impact of spacing - Baronscourt study

12’ x 12’ (3.05m x 3.05m)

12’ x 18’ (3.05m x 5.5m)18’ x 18’ (5.5m x5.5m)

6’ x 6’ (1.8m x 1.8m)



Baronscourt - summary of properties

Property Spacing (feet)

18x18 18x12 12x12 12x6 6x6

MOR

(N/mm²)

13.08 11.22 15.16 18.90 21.01

MOE

(kN/mm²)

7.20 7.14 7.76 8.17 8.98

Density

(kg/m³)

361 360 376 378 375

Grade - - C14 C16 C16



• A range of technological advances allow timber quality assessments to be made in the forest: Strategic level – regional forecasts in conjunction with inventory, to

inform processing investments Forest level as part of pre-harvest assessment – allocation of

timber to different end uses

• At an individual stand level, a key priority is to maximise use of information gathered : Harvester data relating to logs cut Sorting in the forest according to quality classes Potential for log tracking

• At each stage the cost of gathering data must be weighed against the increase in value recovery achieved: Forest Research working with European partners to develop a

standardised method of valuing timber supply chains: www.woodwisdom.net

Trees for the Future – Conclusions (1)

• Silvicultural intervention can play a key role in determining the quality of timber produced from conifer forests in the future

• The outcome will not depend on any one action – impacts on timber quality depend on every aspect of management

• A key priority must be commitment to the production of quality timber at each stage:

“from plant to plank”!

Trees for the Future – Conclusions (2)


More information: www.forestresearch.gov.uk

Trees for the Future Presentation to FEG Symposium 31 st October 2008 Elspeth Macdonald Barry...

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