摘要：Determining precisely the soil organic carbon (SOC), below-ground biomass carbon (BGC), and their spatial distribution and influence factors is a prerequisite for accurately estimating the function of ecosystem carbon sequestration in alpine grasslands. Normalized differential vegetation index (NDVI), meteorological data and field investigation data from 2013 were used to determine the SOC, biomass carbon allocation and spatial distribution of alpine grassland in the upper reaches of the Shule River Basin, northeastern margin of the Qinghai-Tibet Plateau. Results indicate that a linear relationship between NDVI and biomass carbon can be used to accurately determine regional biomass carbon, particularly for below-ground biomass carbon (BGC) (BGC=16.11 NDVI-2.65, R~2 =0.59, P <0.001). The BGC is a significant resource of soil carbon, accounting for approximately 93.72% of the total carbon biomass. BGC can be used to explain most variations in SOC density at different soil depths (55% for 0-10 cm, 44% for 0-30 cm and 62% for 0-50 cm). The distribution of BGC and SOC had spatial heterogeneity across the study region, being greater in the south and east, and less in the north and west. A liner relationship between BGC and NDVI was found, which could be used in future prediction models and carbon budget assessments of the study area and vicinity.
