Carbon storage in grasslands of China

Abstract

Carbon storage in grasslands of China was estimated by the carbon density method and based on a nationwide grassland resource survey finished by 1991. The grasslands in China were classified into 18 types, which are distributed mostly in the temperate region and on the Tibetan Plateau, and scattered in the warm-temperate and tropical regions. Based on the median estimate, vegetation, soil and total carbon storage of grasslands in China were 3·06, 41·03 and 44·09 Pg C, respectively. Vegetation had low carbon storage and most carbon was stored in soils. Of the four types of regions that have grasslands, alpine region (54·5%) and temperate region (31·6%) hold more than 85% of the total grassland carbon (in both vegetation and soils) in China. Considering specific types within these two regions, three grassland types, alpine meadow (25·6%), alpine steppe (14·5%) and temperate steppe (11%) constituted more than half of all carbon stored in China's grasslands. In general and regardless of regional vegetation types, steppes (38·6%) and meadows (38·2%) made up more than 2/3 of total grassland carbon. The carbon storage in alpine grasslands may have a significant and long-lived effect on global C cycles. This study estimated more carbon storage in vegetation and less in soils than previous studies. The differences of grassland carbon between this study and two previous studies were due probably to four reasons, i.e. different estimation methods, different classification systems of grasslands, different areas of grasslands, and different carbon densities. China's grasslands cover only 6–8% of total world grassland area and have 9–16% of total carbon in the world grasslands. They make a big contribution to the world carbon storage and may have significant effects on carbon cycles, both in global and in arid lands.