干旱区生态环境知识资源中心

Soil texture plays an important role in controlling vegetation production and soil organic carbon (SOC) concentration in arid desert grassland ecosystems. However, little is known about the occurrence and extent of these textural effects in the arid desert grasslands of Northwest China. This study used 160 soil profiles taken from 32 desert grassland sites in similar topographical units (alluvial-diluvial fans) in the middle of Hexi Corridor region of Northwest China to investigate vegetation biomass, SOC storage, and soil texture of seven layers in the top 100cm of soil. The mean aboveground biomass, below-ground biomass, and total biomass in arid desert grassland were 155.3, 95.3, and 256.3gm(-2), respectively. More than 95% of the below-ground biomass was distributed in the top 30cm of soil. Spatially, vegetation biomass was positively related to soil clay content and silt+clay content. The mean SOC density in the top 100cm was 2.94kgm(-2) and similar to 46.8% of the storage was concentrated in the top 30cm. SOC concentrations and stocks were positively and significantly related to clay content and silt+clay content in the seven soil layers sampled from the top 100cm. The soil silt+clay content explained 42-79% of the variation in SOC stocks in the different soil depths. In conclusion, soil texture appears to be an important control on vegetation productivity and SOC capacity in arid Hexi Corridor desert grassland soils.