Prediction of wood tangential shrinkage from cellulose crystallite width and density in one 11-year-old tree of Eucalyptus globulus Labill

Abstract

Summary The relationship between variation in wood shrinkage and cellulose crystallite width determined by X-ray diffraction was assessed using SilviScan-2 (a system developed at CSIRO for rapid assessment of wood microstructure). Cellulose crystallite width, density and microfibril angle were determined for 600μm wide zones on small wood samples with known tangential shrinkage. The tangential shrinkage measurements included shrinkage to 12% moisture content after reconditioning (MC AR); and a shrinkage differential calculated from tangential shrinkage to 12% MC AR recorded for each zone; and the minimum shrinkage recorded in adjacent wood of similar cambial age. Spearman correlations and forward stepwise regressions showed that the cellulose crystallite width was a good predictor of the shrinkage measures and that density was a minor predictor. Together, cellulose crystallite width and density could explain 75% of the variation in tangential shrinkage for randomly selected locations throughout the tree, and 87% of the variation in tangential shrinkage in samples selected from the lower 5% of tree height. The results suggest that SilviScan-2 can be used to predict tangential shrinkage during drying in increment cores, and may therefore be useful in developing nondestructive sampling strategies in tree improvement programs for E. globulus.