China’s forest biomass carbon sink based on seven inventories from 1973 to 2008

Inconsistent estimates of forest biomass carbon stocks (BCS) in China have been reported in recent decades using inventory data. This study was to update China’s forest biomass carbon sink based on seven forest inventories from 1973 to 2008 and to identify the relative contributions to such sink from changes in forest area and biomass carbon density (BCD) as a result of growth, plantation and harvests in different regions. Our results indicated that total BCS of all forest types, including forest stands and other forest types (economic forests, woodlands, shrub forests, bamboo forests and trees on non-forest lands), increased by 65 % from 1973 to 2008 and recently reached 8.12 Pg C. Total BCS and BCD of forest stands (canopy coverage >20 %) increased from 4.11 Pg C and 35.10 Mg C ha−1 to 6.24 Pg C and 40.12 Mg C ha−1 during the study period, respectively. Forest stands acted as a biomass carbon sink of 0.17 Pg C year−1, which accounts for 84.4 % of the total sink of all forest types from 1999 to 2008 and have great potential to absorb more biomass carbon in the future due to large fractions of young and middle aged forests, which are increasing BCD. BCS of forest stands increased in all regions but the northeast region. Their biomass carbon sink was mainly driven by the BCD increase in the densely populated south and east regions and by the expansion of forest areas in the north, northwest, and southwest regions with abundant land resources.