Silviculture – what raw materials will NZ’s forests deliver?

1. Silviculture – what raw materials will NZ’s forests deliver? John Moore and Wayne Miller† 4 April 2019

2. Wayne Miller 16 March 2019

3. Development of Pruned Radiata Pine Forests • 1913 – NZ Royal Commission on Forestry: • “The natural forests belong……to a class which cannot regenerate sufficiently quickly to allow them to be kept as permanent forests yielding a succession of crops” • Recommended the State plant extensive exotic forests, with radiata pine being one of the main species • 1922 – NZ Forest Service formed: • Initially disagreed with Royal Commission findings, but changed to favour exotics • ‘First Planting Boom’ in 1920s, continuing in 1930s and ‘40s. Virtually no silviculture used. • 1950s/60s – Initial utilisation of radiata pine from early plantings • Supported by Forest Research Institute (now Scion) • Fast-grown radiata pine potential confirmed • Building codes specifying radiata for most uses • 1960s/1970s – NZFS/FRI examined economics of radiata pine silvicultural regimes • Development of ‘direct sawlog regime’: heavy early thinning to waste, pruning, short rotations • 10.8% return, higher than farming

4. Development of Pruned Radiata Pine Forests (contd.) • 1972-75 Wink Sutton, PhD – ‘Long-term Export Prospects for NZ Radiata Pine’: Considered three opportunities: • Wood for Fibre • Returns not sufficient to justify purpose-grown plantations • Dominated by production from residues • Other higher yielding species available • Structural Lumber • Radiata branches are too large, even with close spacings, etc. • Radiata not a stiff wood. • Other species/regions more suitable for producing structural lumber • Prices never very high • Clearwood • Need a large diameter log. Typically from old trees, but radiata can produce this at a young age • Radiata clearwood has good properties: machining, gluing, staining, etc “The opportunity for New Zealand that offers the most promise and poses the least risk is radiata pine intensively managed for clearwood production”. Wink Sutton, 1998

5. Our silviculture was radical in the 1960s Clearwood regime developed by Fenton and Sutton The world was going to run out of high quality clearwood Their economic analysis showed that maximum profit would come from growing large pruned logs on short rotations We deliberately understocked sites to grow large-diameter pruned logs quickly

6. Perfecting the pruned log regime How many trees to grow per ha? When to prune? How to prune? Optimum time to remove followers Development of techno-economic models to support decision making

7. NZ has a large pruned log resource

8. But……pruned stands are being replaced with unpruned stands Source: NEFD 2014

9. Forecast pruned log supply in the central North Island Pruned log supply (m3 x 100,000) Source: J TomblesonNZ J Forestry 2018 Year

10. Spatial economic analysis of silvicultural regimes Watt et al (2017) Forest Ecology and Management, 406: 361-369

11. Clearwood Markets Exterior market - Cladding, trim, decking, windows, doors Exterior market is much bigger than interior Indicative US Exterior Decking Prices (2008): Dreamdex (MF modified radiata US$2500/m3 Trex ‘Tropics’ US$2230/m3 Trex ‘Transcend’ US$1960/m3 Hardwood (1x6) US$1860/m3 Redwood Con Heart US$1000/m3 Treated SYP (2x6) US$400/m3 NZ Exterior products pricing (2008 wholesale): Clear Radiata NZ$1000/m3 Kwila NZ$3000/m3 Accoya NZ$3500/m3 Trex ‘Enhance’ NZ$4000/m3 Trex ‘Transcend’ NZ$5300/m3 Market is prepared to pay for performance/appearance/low maintenance

12. Durable, high performance, exterior wood products • Naturally durable timbers are becoming in short supply: • Dwindling supplies from old growth and tropical forests • Quality is reducing • Durability of younger wood not the same as old growth • Harder to get large sections and longer lengths • Treated wood is being viewed with increasing scrutiny • Permitted wood preservation actives are getting fewer in number (40+ in 1980, 10 now) • Consumers seeking a more environmentally acceptable option In addition, treatment does little to improve stability or appearance in service This is driving development of modification processes that can deliver alternative products with equivalent/ improved performance to traditional durable wood species

13. Wood Modification – Changing the Wood Considerable R&D effort (esp. in Europe): universities and companies, supported by government and EU Moving from R&D to Commercial practice: • Thermal Modification (Thermowood): Developed commercially in Finland. Over 300,000m3/yr production (2015) – mainly knotty wood. Plants in many countries (incl NZ) • Acetylation (Accoya): First investigated in 1940s, commercialised in Netherlands. • Furfurylation (Kebony): Originally investigated in USA in 1950s, with significant further development in Canada in 1980s. Commercialised in Norway. • DMDHEU (Belmadur): Various investigations from 1960s. BASF (Germany) developed the technology, with pilot plant capacity 2-5000m3/yr. • Melamine Resin (Fibre7): Developed in NZ (Scion), commercial production from late 1990s. Plant being built in Wales • Others: Hot Oil treatment. Heat/Resin treatment, silicanes, chitosan (crustacean shells) Modified wood is happening. Initially Europe, but extending to other markets

14. Radiata Pine and Modification Radiata pine is the preferred species for modification: • Accepts chemical impregnation (pressure process), and by-product removal better than other species • Mainly sapwood, little heartwood (in high grade) – able to achieve consistent modification • Uniform: little earlywood/latewood contrast – more uniform properties/ performance/ appearance • Available in wide, thick, long length clears – allows production of high value products • Lower density than potential competing species, e.g. SYP - Saving of 20% on chemical requirements (Huge benefit) • Renewable, sustainable resource, available FSC certified • Economic supply! Wood modification is a new growth market for high grade radiata pine

15. Acetylated Radiata Pine - Accoya Dublin University Entrance (up to 8m high) Moses Bridge-Netherlands Public Walkway-Auckland Black stained Cladding- Auckland Handrails – Ruapehu (3yrs old) Natural Cladding - UK Canal Lining - Netherlands Exterior joinery and trim - Netherlands

16. Accoya Motorway Bridges Project • Largest wooden bridges built in last 100 yrs • First wooden bridges rated for heaviest load class of 60 tonnes. • Bridges span 32 m, 16 m high • Tenon supplied 2x1200m3 of high grade structural radiata pine lumber in 2006-7. Modified wood (acetylated) had the lowest long term cost – initial and maintenance

17. Furfurylated Radiata Pine - Kebony Beach House Cladding - UK Knife Handles –Norway (Maple) Marina Decking - USA Hotel Decking - Germany Public Seating - Oslo 17

18. Thermally Modified Radiata Pine Radiata Cladding, Sauna Panelling- Finland Market Barrows – Rotorua, NZ Beehives – New Zealand Radiata Cladding, Taupo, NZ Sauna Showroom - Estonia

19. NZ Sawn Timber Exports to Europe Initially NZ lumber exports to Europe were largely to Spain Shipments of radiata pine for modification started in early-mid 2000s (trials and process development), with small regular shipments commencing around 2006 (Accsys). Shipments to others: Kebony and various Thermal Modification companies commenced around 2010-12

20. Projected Radiata Pine Volumes for Modification in Europe Significant growth in demand expected from all modified wood companies: Accsys (acetylation) Doubling production (to 80,000m3/yr) at existing plant from April 2018, additional 60,000m3 capacity planned in 2020 Kebony (furfurylation) Doubling capacity with extra plant in Belgium ramping up from April 2018. Further new plant planned (Germany). Thermal modification Companies developing additional uses/opportunities for radiata pine

21. The future radiata pine resource is changing Harvest coming from new sites Changing genetic base Changing silvicultural regimes

22. 1990s planting spike due to high prices Fertile pasture sites Toppling occurred in some stands Small woodlots biggest ownership group Often on steep sites with no road access Less well characterised compared with the large owner resource The Shifting Resource Base - Sites

23. Soil Fertility Forest site Farm site Beets and Kimberley (2007) NZJFS • Impacts of site fertility and interventions aimed to boost growth being assessed through a number of trials • LTSP1 trials – data collected at Woodhill, Tarawera and Berwick • Biosolids trial at Rabbit Island • Tikitere agroforestry experiment • Analysis has shown that wood density is related to soil C:N ratio • ~ 25 kg m-3 difference between typical farm and forest sites

24. Nursery salesCP vs OP vs Stand Select

25. Genetic improvement has changed radiata pine

26. Genetic correlations between growth and quality traits Wu et al (2008) NZJFS

27. Genetics can increase wood density and stiffness

28. Will faster growth lead to shorter rotations? Kimberley et al (2015) CJFR Each unit of GF Plus growth = 1.51% increase in volume 1.91% increase in stumpage value 4 month reduction in rotation length

29. The Corewood Conundrum in Conifers

30. DiscBot – a new technology for wood property assessment on disc samples

31. [Lig] [Gal] [Glu] DEN / [kg/m3] SGA / [deg] MFA / [deg]

32. Summary • We’ve seen a shift away from pruned regimes to unpruned regimes • Future demand for radiata pine clearwood may help raise pruned log prices and improve the economic returns from pruned regimes • Demand is being driven from the modified wood sector • Future resource is changing due to harvest coming from new sites, genetic improvement and higher stocked stands • Focus of much wood quality research in recent years has been on density and stiffness, which are key to structural applications • Need to remember other traits of importance to different wood processors