Dynamic forest biomass carbon pools in China and their significance

An improved biomass estimation method that converts timber volume to total forest biomass was used to estimate forest biomass carbon storage and its changes over to the past 50 years in China, by using inventory data of seven periods from 1949 to 1998 and forest biomass data obtained from direct field measurements. By the mid-1970s, forest carbon decreased by 0.62 Pg C (Pg=10 15 g), with a decreasing rate of 0.024 Pg C per year. Since then the biomass carbon showed a significant increase, from 4.38 Pg C by the end of 1970s to 4.75 Pg C by 1998, with an increasing rate of 0.022 Pg C per year, due mainly to the increased reforestation and afforestation. During the last two decades, planted forests have sequestered 0.45 Pg of carbon, with an annual rate of 0.021 Pg C. The average carbon density of plantations showed a significant increase from 15.3 Mg/hm 2 in the mid-1970 to 31.1 Mg/hm 2 in 1998, suggesting that the rising global temperature and CO 2 fertilization may enhance this increasing uptake as well as expansion of planted forests.