The impact of land degradation on the C pools in alpine grasslands of the Qinghai-Tibet Plateau.

摘要

Aims: To determine the effect of grassland degradation on the soil carbon pool in alpine grassland. Methods: In this study, we calculated the carbon pool in the above-and below-ground biomass, the soil microbial biomass carbon pool, the total organic carbon pool and the soil total carbon. Results: Grassland degradation has resulted in decreases in biomass and carbon content and has changed the ratio of roots to shoots. However, there was less influence of degradation on dead root biomass. There was most likely a lag effect of changes in dead root biomass following grassland degradation. In the alpine grassland ecosystem, the carbon pool in soil accounts for more than 92% of the total carbon both in vegetation and soil. The carbon in alpine grassland is stored primarily in the form of total organic carbon below-ground. As organic carbon decreases, the ratio of the microbial biomass carbon pool to the total organic carbon pool increases and then declines with increasing degradation level. Along the grassland degradation gradient, the total vegetation biomass (above-and below-ground) and the soil carbon pool (microbial biomass C, total organic C and total C) all decreased.