The Carbon Cycles of Chinese Terrestrial Ecosystems

The changes of Chinese terrestrial carbon storage depend not only on biogeochemical and climatological processes, but also on human activities and their interaction with carbon cycle. China,covering about 133.7 million hectares of forested land, has climate regimes ranging from tropical, to subtropical, temperate and cold temperate zones, and from southeast to northwest humid, semi arid and arid zones. A long history of agricultural exploitation, forest management practice, rapid change in land use, forestry policies, and economic growth suggest that Chinese terrestrial ecosystems play an important role in the global carbon cycles. Our recent results suggest that total carbon storage in Chinese terrestrial ecosystems is about 144 Pg C, including 7.3 Pg C in vegetation and 136.7 Pg C in soil. Chinese forests released about 0.68 Pg C between 1949 and 1980. Forest carbon storage has increased significantly after the late 1970s from 4.38 to 4.75 Pg C by 1998, mainly due to forest expansion and regrowth. Total organic carbon storage in soils in China is estimated to be about 70.31 Pg, representing 4.7%\ of the world storage. The results also indicated that a soil organic carbon loss of 7.1 Pg was primarily due to human activity, in which the loss in organic horizons has contributed to 77%\. This total loss of soil organic carbon in China induced by land use represents 9.5%\ of the world's soil organic carbon decrease.