Trees for the Future

1. Trees for the Future Presentation to FEG Symposium 31st October 2008 Elspeth Macdonald Barry Gardiner, Shaun Mochan, John Fonweban and John Moore* Timber Properties Research Programme * Napier University CTE

2. Trees for the Future Outline • Objectives of timber properties research programme and collaboration • Trees for the future – timescales • The next 10 years – assessment and sorting • 10 – 40 years – silviculture to improve quality • 40 years plus – establishing forests to maximise quality • Conclusions

3. Trees for the Future Timber properties research - objectives • Investigating and modelling the effects of silvicultural practice and site factors upon conifer timber quality • Developing methods of defining, assessing and forecasting timber quality to provide improved information about future timber supplies to forest managers and wood using industries

4. Trees for the Future Collaboration and acknowledgements • 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

5. Trees for the Future: the next 10 years Trees for the future - timescales • 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 • 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 • 40 years plus: • Majority of timber production from stands still to be established • Greatest scope for silvicultural intervention – least certainty about market demands

6. Trees for the Future: the next 10 years

7. Trees for the Future: the next 10 years

8. Trees for the Future: the next 10 years

9. Trees for the Future: the next 10 years

10. Trees for the Future: the next 10 years The next 10 years – assessment and sorting 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

11. Trees for the Future: the next 10 years Stem straightness scoring • System developed for use in Sitka spruce • Can be used to predict out-turn of “green” logs

12. Trees for the Future: the next 10 years 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

13. Stand Road side Sawmill Trees for the Future: the next 10 years Acoustic tools • Provide information about mechanical properties from trees and logs • Aim to assess quality early in the wood chain

14. Trees for the Future: the next 10 years Using these methods in practice • 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

15. Trees for the Future: the next 10 years

16. Trees for the Future: the next 10 years

17. Trees for the Future: the next 10 years Airborne Laser Scanning (LIDAR) • Lidar technology can be used to estimate stand and tree parameters (tree heights, crown width, stocking density, stem diameter) • 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

18. Trees for the Future: the next 10 years Terrestrial Laser Scanning • Terrestrial Laser Scanning provides detailed stem profile data • Stem quality assessment (using straightness scoring) can be derived • 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

19. Trees for the Future: 10 – 40 years 10 – 40 years: silviculture for improved timber 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

20. 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

21. Trees for the Future: 10 – 40 years 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 taper • possible reduction in stem straightness

22. Trees for the Future: 10 – 40 years Juvenile wood area – modelling the effects of thinning No thin Intermediate thin 31% juvenile wood 21% juvenile wood Juvenile wood area (15 growth rings) Nominal sawn timber section Cross-section at 4.8m

23. Trees for the Future: 10 – 40 years Longer rotations • Current average rotation length for conifers: 40 – 50 years • Transformation to CCF, retain trees for: • seed source • shelter for regenerating crop • landscape • biodiversity

24. Trees 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

25. Trees for the Future: 10 – 40 years Birkley Wood - Grade Distribution within a Log

26. Trees for the Future: 10 – 40 years Birkley Wood: Distortion – Spring and Twist

27. Trees for the Future: 10 – 40 years 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

28. Trees for the Future: 40 years plus 40 years plus: establishing forests to maximise quality (or revenue?) • In this timescale, opportunity to influence timber quality is greatest: • Species choice • Planting stock – provenance, improved progeny • Planting or natural regeneration • Spacing • Markets in 40 years time uncertain • Should we always grow for best possible quality? • Should we grow to meet the needs of the renewable energy market?

29. Trees for the Future: 40 years plus Choice of species • If species is not well suited to site: • patchy establishment • poor growth • possible stem form problems • Also need to consider • pests & diseases • climate change impact • potential future markets

30. Fibrous fracture Brash fracture Trees for the Future: 40 years plus Choice of provenance • Differences in growth and timber properties between provenances • E.g. lodgepole pine • problem 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

31. Trees for the Future: 40 years plus Choice of progeny • Selective tree breeding can deliver improvements in: • growth rate • stem straightness • branching • wood density • fibre properties

32. Trees for the Future: 40 years plus 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 fir • UK selected seed stands • French/USA seed from breeding programmes • Hybrid larch • Small gains from untested seed orchards • Prospects for vegetative propagation of superior families, to give gains of 15–20% for diameter and 20–25% for stem straightness

33. Trees for the Future: 40 years plus 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

34. Trees for the Future: 40 years plus

35. Batten Stiffness (MOE) Highest density Most vigorous Unimproved QCI Straightest Trees for the Future: 40 years plus

36. Trees for the Future: 40 years plus 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…

37. Trees for the Future: 40 years plus Planting or natural regeneration? • Planting - advantages • Opportunity to select species • Volume and quality gains from improved progeny • Control over stocking • Minimal variation in age class structure • Planting - disadvantages • Possible stem form problems associated with nursery practice and early instability (toppling) • High establishment costs • Possible patchy stocking – future timber quality problems

38. Trees for the Future: 40 years plus Planting or natural regeneration? • Natural regeneration - advantages • Improved stability – possibly better stem form • Potentially high stocking and large number of trees for selection in thinning • Potentially low cost • Fits well with Continuous Cover Forestry • Natural regeneration - disadvantages • No opportunity for improvement in growth or TQ through use of selected provenance/progeny • Difficult to control species mix – may have a lot of low value species (e.g. hemlock, grand fir) • Costs of respacing/pre-commercial thinning

39. Trees for the Future: 40 years plus 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”

40. Trees for the Future: 40 years plus 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

41. 18’ x 18’ (5.5m x5.5m) 12’ x 18’ (3.05m x 5.5m) 12’ x 12’ (3.05m x 3.05m) 6’ x 6’ (1.8m x 1.8m) Trees for the Future: 40 years plus Quantifying impact of spacing - Baronscourt study

42. Trees for the Future: 40 years plus Baronscourt - summary of properties

43. Trees for the Future – Conclusions (1) • 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

44. Trees for the Future – Conclusions (2) • 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”!

45. More information: www.forestresearch.gov.uk