Determining stem biomass of Pinus massoniana L. through variations in basic density

Basic density is a key variable with which to express wood properties, but little attention has been paid to basic density traits in determining stem biomass. A total of 108 Pinus massoniana L. trees were selected from six sites in Hunan Province, China. Cross-sectional discs were cut for analysis using the stem analysis method. Results showed that the highest average basic density per stem for the six sites was 509.1 kg m−3 and the lowest 448.9 kg m−3. Basic density was significantly different (P < 0.05) among the sites. A significant effect of tree age on wood density was confirmed. Furthermore, the linear-mixed model was used to predict stem biomass. The allometric equation incorporating basic density at 10% of tree height (Model 4) was compared with the equation using only diameter at breast height and tree height as independent variables. The mean stem biomass predicted by Model 4 (16.5 kg tree−1) was not significantly different from the observed value (15.8 kg tree−1). The results indicated that incorporating basic density as part of the independent variables could improve model fitness.