KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Content Wood quality: resource to end-use "You can't make a Silk Purse out of a Sow's Ear.“ Jonathan Swift (1667 - 1745) • Definition • The link between resource quality and end use • Growth manipulation and wood quality • Genetic improvement and wood quality • Measuring wood quality Art work, MONA 0.0 title ! www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics Wood quality: resource to end-use www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics Definition of wood quality • Wood quality is the combination of characteristics of the log and properties of its wood that affect: – the recovery of useful products and – their value and serviceability in intended applications (Hillis 2000) The link between resource quality and end use • The characteristics are not consistent For any log, they vary with: – the species of the source tree, – its growing conditions and age at harvest, – the section of the tree that the log comes from, and – the part of the log sampled • While generally applied to the log, the term can be applied at other stages during production and use Wood quality: resource to end-use Veneer at DEEDI, Qld www.csaw.utas.edu.au www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Resource to end-use market: sawn wood Limits on the function of timber products • Timber product functionality is limited by: – The form of the log • Its shape, length and diameter • Its primary wood properties – Size constraints on recovered pieces – The directionality of its key properties – Its structural consistency Patterns like this demonstrate that differences exist in the value and serviceability in the applications of sawn material drawn from different resources Wood quality: resource to end-use www.csaw.utas.edu.au Wood quality: resource to end-use www.csaw.utas.edu.au 1! KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Table of resultant primary wood elements Log resources obviously differ Decreasing length Decreasing width and/or thickness Long grain elements Poles Timber Scantling Short grain elements Chips or flakes Strands Splinters Fiberal Elements Fibre bundles Whole fibers Macerated Fibrils fibers Chemical elements Cellulose Lignin Polvols Veneer Veneer Veneer 2.4mm thick Strips Shavings Sawdust Wood flour Hydrocarbons Carbon Extractives Increasing formability, decreasing strength/weight ratio, reducing dependence on log quality, increasing homogeneity and isotropy From Marra, 1972, Wood products into the future Wood quality: resource to end-use www.csaw.utas.edu.au What are desirable log and wood characteristics? Wood quality: resource to end-use www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Desirable wood properties Visual Character • Different wood properties can be loosely grouped under four headings, namely: – Visual character; – Wood properties - Usage; – Wood properties - Processing; and – Log Characteristic - Form • The groupings are not exclusive and assessment of their importance varies at the production stage and point of sale Visual Character Rounds Appearance Structural Clear wood - present 2.3 4.1 2.4 Grain - even 2.0 4.2 2.3 Colour consistency present 2.0 3.9 2.3 Colour - pale - present 2.0 2.9 2.2 Gum Vein -kino -present 2.3 1.2 2.0 Insect feature- present 1.8 1.4 1.8 Knots - present 1.5 1.2 1.7 Source: Nolan et al 2005 Eucalypt Plantations for Solid Wood Products in Australia FWPRDC project PN04.3002 Wood quality: resource to end-use www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics Wood Properties-Processing Rounds Appearance Structural 3.5 4.7 4.3 Stability - high 4.0 4.3 3.8 Lyctus resistant sapwood 3.8 4.2 3.7 Workability Machining - high 3.5 4.3 3.8 Durability - high 4.8 2.8 3.7 Preservative retention -high 4.5 2.4 3.5 Stiffness - SD4 pref 3.5 2.9 3.9 Strength - SD4 pref 3.5 2.9 3.9 Fire Performance 3.3 2.8 3.2 Density - high 3.3 2.7 3.1 Hardness - high 2.5 3.3 3.2 Joint Group 3.0 2.8 3.0 Microfibril angle 2.5 2.4 2.8 Source: Nolan et al 2005 Eucalypt Plantations for Solid Wood Products in Australia FWPRDC project PN04.3002 Wood quality: resource to end-use www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics Wood Properties -Usage Wood Properties -Usage Gluability - high Wood quality: resource to end-use www.csaw.utas.edu.au Wood Properties-Processing Rounds Appearance Structural Tension wood - low 3.8 4.7 4.5 Growth strain - low 3.8 4.4 3.9 Internal checking - low 2.5 4.7 3.4 Surface checking - low 3.0 4.6 2.9 Collapse - low 2.3 4.4 3.6 Shrinkage - low 2.5 4.0 3.5 Shrinkage ratio -tangential/radial 2.5 3.1 2.4 Source: Nolan et al 2005 Eucalypt Plantations for Solid Wood Products in Australia FWPRDC project PN04.3002 Wood quality: resource to end-use www.csaw.utas.edu.au 2! KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Log characteristic - Form Log diameter and value recovery Rounds Appearance Structural Decay - low 4.8 4.8 4.3 branch frequency - low 4.0 4.7 3.9 End split - low 4.3 4.0 4.0 Knotty core diameter -small 3.0 4.9 4.2 Log form - taper - low 3.3 4.0 3.8 Heartwood content - high 3.0 3.6 3.3 Sapwood thickness - low 2.8 3.5 3.2 Heart / corewood diameter - low 3.0 3.1 2.9 60 Recovery of select grade (% of log volume) Log characteristic - Form 50 40 30 20 r = 0.68 10 15 20 25 30 35 40 45 50 55 60 65 Log small end diameter (cm) Plot of log diameter and recovery for pruned eucalypts processed with standard industry practice (Washusen and Clark, in prep) Source: Nolan et al 2005 Eucalypt Plantations for Solid Wood Products in Australia FWPRDC project PN04.3002 Wood quality: resource to end-use www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics Wood quality: resource to end-use www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics Log quality and value recovery Growth manipulation and wood quality Silviculture is day-to-day forestry techniques used to modify growth and wood quality Wood quality: resource to end-use www.csaw.utas.edu.au www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Forestry for wood quality Limits on manipulation • Forest management objectives limit silvicultural options and the potential for manipulation • Manipulation is constrained with native forestry: • Wood quality correlates strongly with: – The genetic characteristics of the resource and – Growth manipulation through silvicultural practice – wood production is only one objective in broad multi-use forestry • Manipulation is encouraged with plantation forestry: – wood production for a given target market is a primary objective Wood quality: resource to end-use www.csaw.utas.edu.au Wood quality: resource to end-use www.csaw.utas.edu.au 3! KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Variables for manipulation Different genetic background • Trees for harvest may differ through being: • For native forests, trees from a site generally provide the seeds used to regenerate a site – Different genetic background (between or within species), – Grown to different ages – Grown in different environments – Managed differently over their growing life – Genetic selection is generally not an option • For plantation forestry, trees with desirable characteristics are selected from growth trials, and propagated in seed orchards • Even with all these factors being constant, grown trees still differ from tree to tree Wood quality: resource to end-use www.csaw.utas.edu.au Wood quality: resource to end-use www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Selecting preferred genetic material Managed differently: silvicultural approaches For a given site and species, the major silvicultural options for plantations are: • Thinning – Reducing the stocking levels of trees to give each tree more space and resources – The result is bigger trees and larger logs • Pruning – Removing branches to encourage the growth of clear wood – The result is more consistent, high value wood in the logs Genetic assessment and selection Wood quality: resource to end-use www.csaw.utas.edu.au Wood quality: resource to end-use www.csaw.utas.edu.au KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Managed differently: unthinned, unpruned Managed differently: unthinned, unpruned Landscape view Close up view Wood quality: resource to end-use www.csaw.utas.edu.au Wood quality: resource to end-use www.csaw.utas.edu.au 4! KDA503/335 Timber, its origin and characteristics Managed differently: thinned Managed differently: thinned 25 62 12 24 37 49 74 98 0.700 0.680 0.660 0.640 0.620 0.600 0.580 0.560 0.540 0.520 0.500 68 50 43 05 29 65 14 82 basic density (t/m3) KDA503/335 Timber, its origin and characteristics final stocking (sph) Relation between crown width and dbh in E globulus grown in Galicia, Spain Source: Nutto and Touza (2004), Figure Wood quality: resource to end-use www.csaw.utas.edu.au heavier thinning = higher basic density Basic density versus final stocking in 33-year-old E grandis in South Africa (Malan and Hoon 1992) – All treatments established at 6,850 stems per Wood quality: resource to end-use www.csaw.utas.edu.au hectare, multiple thinning operations KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Managed differently: prune Managed differently: thin, prune, wait While the branches are still green (a) The stem cross-section highlighting the defect knotty core The knotty core is a product of the diameter over-pruned branch stubs (DOS); plus the additional growth before clear wood is produced to give the DOO, and (b) the tapering characteristic of the knotty core withinquality: the tree Source: Montagu et al (2003a), Figure Wood resource to end-use www.csaw.utas.edu.au 10 year old unthinned, unpruned E.nitens KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Wood quality: resource to end-use 28 year old thinned, pruned E nitens www.csaw.utas.edu.au Grading for forest products Measuring and sorting for wood quality www.csaw.utas.edu.au Harvested trees yield logs of different quality and characteristics up the stem These are graded (and separated) at the harvesting site, and checked in the log yard Wood quality: resource to end-use www.csaw.utas.edu.au 5! KDA503/335 Timber, its origin and characteristics KDA503/335 Timber, its origin and characteristics Log grade definitions Defective quarters GRADE 25-30 SED >30-35 SED >35-40 SED >40-45 SED >45-50 SED >50-55 SED >55-60 SED >60-65 SED >65-70 SED >70-75 SED >75-80 SED >80-85 SED >85-90 SED >90-95 SED >95-100 SED Sweep Grain tight kino 3mm width : length% of diameter loose kino/kino pockets/shakes : length % of diameter stain 0 2+ 3+ 4 4 4 4 4 4