Abstract:

Grasslands are an important component of terrestrial ecosystems and play a crucial role in the carbon cycle of terrestrial ecosystems. Studying the distribution of soil organic carbon and its influencing factors in grassland ecosystems is significant for enhancing regional carbon sinks and ecological restoration. This study focuses on the desert steppe， temperate grassland， and meadow steppe in the central Hexi Corridor. Through field surveys， sampling， and laboratory analysis， the spatial distribution characteristics of surface soil organic carbon content and soil organic carbon density were investigated. The relationships between surface soil organic carbon distribution and environmental factors such as soil bulk density， soil moisture content， vegetation coverage， and altitude were explored. The results show that： （1） Soil organic carbon content and density in different grassland types follow the pattern of meadow steppe > temperate grassland > desert steppe， with the overall spatial distribution showing more in the east and less in the west. High-value areas are concentrated in central Sunan County， southern Shandan County， and Huangcheng Town in Sunan County. （2） Soil organic carbon content and density are significantly positively correlated with altitude， soil moisture content， and vegetation coverage， and negatively correlated with soil bulk density， vegetation height， and gravel content. Altitude has the highest explanatory power for soil organic carbon content and density， and there is a significant synergistic effect between altitude and vegetation factors. （3） Herbaceous coverage and altitude are the key variables affecting the distribution of soil organic carbon in grasslands in the central Hexi Corridor.

Key words: soil organic carbon, soil organic carbon density, spatial distribution, environmental factors, middle section of Hexi Corridor