The changing relationship between spatial pattern of soil erosion risk and its influencing factors in Yimeng mountainous area, China 1986-2005

The relationship between soil erosion distribution and its influencing factors is critical for soil erosion modeling and soil conservation planning. Based on subbasins, this study quantitatively analyzed the variation of relationships between spatial pattern of soil erosion risk and its main influencing factors such as slope, rainfall, vegetation cover, and land use in Yimeng mountainous area from 1986 to 2005. The results showed that, on the hilly and mountainous region, the increase of vegetation cover and optimized land use structure resulted in an evident decline of erosion risk over the period of approximately 20 years, especially in the second half of the period. The number of subbasins with soil erosion risk index value over 2 decreased from 49 in 1995 to 29 in 2005 due to the Grain for Green Program implemented in this area. As the increase of spatial heterogeneity of rainfall erosivity in 2005, rainfall with a low contribution rate (about 5.4%) became one of the significant factors affecting the spatial pattern of erosion risk. With the impact of human activities on the erosion, the contribution rate (CR) of slope on the erosion pattern fell from 92.8 to 79.7%. The CR of vegetation cover diminished from 7.2% in 1986, while that of land use structure gradually enhanced to 14.9% in 2005. This study indicated that with the restoration of vegetation cover; the impact of land use pattern on soil erosion distribution had become increasingly important, suggesting that more attention should be paid to the role of adjustment and optimization of land use structure in soil erosion control in this area.