Abstract: The aim of this research is to explore the impact of land use changes on the erodibility of surface soils. The changes of physical and chemical properties of surface soil after land use change were examined with four typical land use patterns as case study. Such land use patterns include: natural forest, and three land use patterns converted from natural forest, namely, Chinese fir forest, orchard, and terracing farmland in Dawei Mountain of eastern Hunan Province and Xiaoxi National Nature Reserve of western Hunan Province. Moreover, the Torri.D model was employed to calculate the value of soil erodibility K, and hierachical clustering method was adopted to analyze the physical and chemical properties of the sample soil and the soils from the Red Soil Ecological Experimental Station of Chinese Academy of Science in Jiangxi Province. The measured data was used to correct the model calculation results. Results revealed that: 1) The sand content of Chinese fir forest, orchard, and terracing farmland converted from natural forest increased significantly, and the soil tended to become coarse. 2) The organic carbon content of surface soil in western Hunan was higher than that in eastern Hunan. After the conversion of land use pattern, the organic carbon content of soils in Chinese fir forest, orchard and terracing farmland were smaller than that of natural forest in the same area. 3) In east Hunan Province, the value of soil erodibility K of Chinese fir forest reclaimed for seven years was the largest among the four typical land use patterns, followed by that of natural forest, orchard (terraces) for seven years, and terracing farmland for seven years; in west Hunan Province, value of soil erodibility K of terracing farmland reclaimed for ten years was the largest, followed by that of orchard for ten years, Chinese fir forest for ten years, and natural forest. After the conversion of natural forest, soil erodibility varies according to the change of microtopography and the years of crop cultivation. Soil and water conservation measures are of help to improving the soil condition.

Key words: land use change, subtropical hilly region, red soil, soil erodibility, physicochemical properties of soil