Analysis of soil erosion change since “natural forest protection project” beginning in the Hengduan mountain area

The research area's land use data and vegetation cover data were extracted from the remote sensing imagery, which were acquired in 2001 and 2008. Then combined with topographic data, the soil erosion data of study area in 2001and 2008 were acquired. Final, the spatial and temporal patterns of soil erosion over the study area from 1985 to 2008 were examined and the major changing soil erosion types and their transfer between each other ware explored. Results show that: (1) The soil erosion of study area is slight. The results in 2001 and 2008 all show the middle, light and slight erosion are the primary soil erosion types, and their area account for 69.82% in 2001 and 67.23% in 2008. (2) From 2001 to 2008, the soil erosion structure has changed significantly. The area of slight erosion, pole intense erosion and severe erosion were all increased markedly. And the middle eroded area, light eroded area and intense eroded area decreased significantly. The results of field survey show that deforestation is the main reason which leads to the soil erosion in study area becoming more seriously.