摘要
The knowledge of carbon(C) stock and its dynamics is crucial for understanding the role of grassland ecosystems in China's terrestrial C cycle.To date,a comprehensive assessment on C balance in China's grasslands is still lacking.By reviewing published literature,this study aims to evaluate ecosystem C stocks(both vegetation biomass and soil organic C) and their changes in China's grasslands.Our results are summarized as follows:(1) biomass C density(C stock per area) of China's grasslands differed greatly among previous studies,ranging from 215.8 to 348.1 g C m-2 with an average of 300.2 g C m-2.Likewise,soil C density also varied greatly between 8.5 and 15.1 kg C m-2.In total,ecosystem C stock in China's grasslands was estimated at 29.1 Pg C.(2) Both the magnitude and direction of ecosystem C changes in China's grasslands differed greatly among previous studies.According to recent reports,neither biomass nor soil C stock in China's grasslands showed a significant change during the past 20 years,indicating that grassland ecosystems are C neutral.(3) Spatial patterns and temporal dynamics of grassland biomass were closely correlated with precipitation,while changes in soil C stocks exhibited close associations with soil moisture and soil texture.Human activities,such as livestock grazing and fencing could also affect ecosystem C dynamics in China's grasslands.
The knowledge of carbon(C) stock and its dynamics is crucial for understanding the role of grassland ecosystems in China’s terrestrial C cycle.To date,a comprehensive assessment on C balance in China’s grasslands is still lacking.By reviewing published literature,this study aims to evaluate ecosystem C stocks(both vegetation biomass and soil organic C) and their changes in China’s grasslands.Our results are summarized as follows:(1) biomass C density(C stock per area) of China’s grasslands differed greatly among previous studies,ranging from 215.8 to 348.1 g C m-2 with an average of 300.2 g C m-2.Likewise,soil C density also varied greatly between 8.5 and 15.1 kg C m-2.In total,ecosystem C stock in China’s grasslands was estimated at 29.1 Pg C.(2) Both the magnitude and direction of ecosystem C changes in China’s grasslands differed greatly among previous studies.According to recent reports,neither biomass nor soil C stock in China’s grasslands showed a significant change during the past 20 years,indicating that grassland ecosystems are C neutral.(3) Spatial patterns and temporal dynamics of grassland biomass were closely correlated with precipitation,while changes in soil C stocks exhibited close associations with soil moisture and soil texture.Human activities,such as livestock grazing and fencing could also affect ecosystem C dynamics in China’s grasslands.
