137Cs-Based Variation of Soil Erosion in Vertical Zones of a Small Catchment in Southwestern China

Abstract

The study of the variability of soil erosion in mountainous areas provides the basis for soil and water conservation work and forest ecological construction in a targeted way. In this study, Liangshan Town catchment, a typical catchment in the Hengduan Mountains region, southwest China, was selected to investigate the variation of soil erosion in different vertical zones using the 137Cs tracing technique. The mean 137Cs reference inventories varied between 573.51 and 705.54 Bq/m2, with the elevation increasing from 1600 to 2600 m. The rates of soil erosion exhibited a significant variation. Under the same land cover condition, the average annual soil erosion modulus of high-elevation forest (elevation > 2200 m) was 400.3 t/(km2·a). However, the average annual soil erosion modulus of a low-elevation sparse forest (elevation < 1600 m) was as high as 1756 t/(km2·a). The average annual soil erosion modulus of the sloping farmland, mainly distributed at elevations of 1600–2200 m, was estimated to be 2771 t/(km2·a). These results indicate that effective soil management measures need to be implemented on the cultivated sloping land in the future.