Allometry and partitioning of individual tree biomass and carbon ofAbies nephrolepisMaxim in northeast China

Abies nephrolepis Maxim is an important commercial conifer species in northeastern China. In this study, we compared the partitioning and variations of biomass and carbon concentration for four tree components (i.e. stem, root, branch, and foliage). The results indicated that foliage had the largest carbon concentration, which was significantly different from other tree components. Above-ground biomass or carbon accounted for about 78% of the total tree biomass or carbon, whereas below-ground biomass or carbon corresponded to about 22%. The root-to-shoot ratio averaged .28 for biomass and .27 for carbon. We applied likelihood analysis to investigate the error structure of allometric relationship W = a·Db and found that the multiplicative error structure was favored. Thus, the additive systems of biomass and carbon equations in a log-transformed scale were constructed using nonlinear seemly unrelated regression. The model fitting results showed that all biomass and carbon equations fitted the data well. Further, five approaches for calculating carbon stock of individual trees were evaluated and compared. The carbon allometric equations and the estimated biomass multiplied by weighted mean carbon concentration were more advantageous, whereas using the generic carbon concentration constants produced significant biases in estimating the carbon stock of individual trees.