Prediction of whole-tree basic density and pulp yield using wood core samples in Eucalyptus nitens

The potential for predicting whole-tree basic density and pulp yield from core samples of 12-year-old Eucalyptus nitens was evaluated using trees from three sites in Tasmania. A total of 55 trees were used to examine longitudinal patterns of variation for basic density and to determine the relationship between whole tree values and core samples. Twenty-five trees from one site were tested to determine the relationship between whole-tree pulp yield, and cellulose and extractive contents of core samples. A subset of these trees was used to determine longitudinal patterns of variation for cellulose and extractives content and to calculate relationships between cores and whole tree values. Equations were developed to predict whole tree values for both basic density and kraft pulp yield. Whole tree values for basic density, cellulose content and kraft pulp yield were all reliably predicted by core samples from 0.9 m above ground. For basic density, the core samples explained between 85 and 92% of variation in whole-tree density whilst for cellulose content 89% of variation was explained. Cellulose content of a core was also a very good predictor of kraft pulp yield of the whole tree, with potentially 86% of variation in pulp yield at Kappa 18 accounted for by the core sample. The relationship between extractives content and pulp yield was significant and negative but not sufficiently strong to be used as a predictive tool.