Forest biomass estimation at regional and global levels, with special reference to China's forest biomass

Accurate estimation of forest biomass size and regional distribution is a prerequisite in answering a long-standing debate on the role of forest vegetation in the regional and global carbon cycle. Appropriate biomass estimation methods and available forest data sources are two key factors for this purpose. Among the estimation methods, the continuous Biomass Expansion Factor (BEF; defined as the ratio of all stand biomass to stem volume or biomass) method is considered to be the best. We applied the continuous BEF to forest inventory data of China and estimated a biomass carbon of 4.6 PgC and a biomass carbon density of 38.4 Mg ha(-1). A review of recent literature shows that forest carbon density in major temperate and boreal forest regions in the Northern Hemisphere has a narrow variance ranging from 29 Mg ha(-1) to 50 Mg ha(-1), with a global mean of 36.9 Mg ha(-1). This suggests that the forest biomass density in China is closely coincident with the global mean.