Abstract:

Allometric equations for different biomass components were developed using stem diameters at different tree heights (DBH; crown base, D_C; 30 cm height, D₃₀ and tree base, D_B). The effects of tree competition on biomass partitioning was also analyzed. The results showed that DBH was a simple and reliable predictor for estimating above- and belowground biomass components. The allometric equations estimated with stem diameters at different tree heights all slightly overestimated biomeass components in the smaller stem diameter trees (diameter≤10 cm). The prediction errors increased with tree diameters. The aboveground to belowground biomass ratio (T/R) did not correlate with tree age, individual plant biomass, mean annual growth rate of individual plant biomass and mean annual growth rate of tree height (P>0.05). With increasing competition intensity, the relative proportion of stem biomass decreased, whereas, that of canopy biomass (i.e., living branch and needle biomass) increased. The coarse root biomass maintained virtually constant proportion. As expected, the mean annual growth rate of DBH, mean annual growth rate of tree height and mean annual growth rate of individual plant biomass were negatively affected by competition intensity while T/R almost kept constant and was free of the intensity.

Key words: biomass equation, T/R, biomass proportion, tree competition, Abies nephrolepis