Relationships among the Stem, Aboveground and Total Biomass across Chinese Forests

Forest biomass plays a key role in the global carbon cycle. In the present study, a general allometric model was derived to predict the relationships among the stem biomass M_S, aboveground biomass M_A and total biomass M_T, based on previously developed scaling relationships for leaf, stem and root standing biomass. The model predicted complex scaling exponents for M_T and/or M_A with respect to M_S. Because annual biomass accumulation in the stem, root and branch far exceeded the annual increase in standing leaf biomass, we can predict that M_T∝M_A∝M_S as a simple result of the model. Although slight variations existed in different phyletic affiliations (i.e. conifers versus angiosperms), empirical results using Model Type II (reduced major axis) regression supported the model's predictions. The predictive formulas among stem, aboveground and total biomass were obtained using Model Type I (ordinary least squares) regression to estimate forest biomass. Given the low mean percentage prediction errors for aboveground (and total biomass) based on the stem biomass, the results provided a reasonable method to estimate the biomass of forests at the individual level, which was insensitive to the variation in local environmental conditions (e.g. precipitation, temperature, etc.).