Published Online - 1 Jan 2003.
Butt logs of 15 trees of Eucalyptus nitens (Dean et Maiden) Maiden, aged 15 years, diameter at breast height 55 cm, were cut into appearance-grade lumber and rotary-peeled and sliced veneer, and the second logs into rotary-peeled veneer. A 1-m billet was removed from between butt and second logs of each tree, as well as discs at successive heights. In addition, breast-height increment cores and breast-height measurements of longitudinal growth strain served to characterise the wood properties and processing, product, and clearwood mechanical properties of each tree. Fibre dimensions, density, and microfibril angle were measured by SilviScan on a sample from height 6 m. Boards were quarter-sawn from the 1-m billet and air- and dehumidifier-dried, and internal checking and shrinkage were measured on these boards and on discs from height 6 m. Sawability" variables of the butt log (viz log-end splits, flitch movement off the saw, timber crook, and timber conversion percentage) showed strong intercorrelations with one another and with longitudinal growth strain, measured at breast height on the standing tree. Amounts of internal checking and collapse in the air-and then kiln-dried butt-log boards were strongly correlated with checking measured on discs and on the billet boards. Shrinkage of the 1-m boards and of blocks from the 6-m-height disc was correlated moderately with collapse and checking in the butt-log boards. Clearwood modulus of elasticity, measured on eight test sticks cut from the billet from height 6-7 m, showed a strong increasing gradient from pith to bark as well as wide variation among trees. Density showed only a small pith to bark increase, while microfibril angle showed a rapid decrease from the pith over the first seven rings. Clearwood modulus of elasticity was moderately correlated with modulus of elasticity of veneer sheets, measured sonically. Tree-mean clearwood modulus of elasticity was strongly correlated with the density/microfibril angle ratio, as was modulus of elasticity of individual test sticks. Trees varied strongly in product characteristics and wood properties, and there were strong correlations (a) between breast-height growth strain and sawability characteristics, and (b) between checking and collapse in butt-log boards and tangential shrinkage and checking measured on discs. This indicated possibilities for genetic selection against growth-stress-related sawing problems and internal checking on drying, the two main deficiencies of E. nitens for appearance lumber. Good correlations of appearance-lumber and veneer properties with similar traits measured on the standing tree or from cores, discs, and a 1-m billet, indicated that effective evaluation of species, provenances, and individual trees is possible without recourse to full-scale sawing studies"