Abstract: The Yili River valley is an important production base of agriculture and animal husbandry in Xinjiang. Recently, soil loss is a significant ecological environment problem in this region. Based on the universal soil loss equation (USLE) and spatial analysis functions in ArcGIS, this study evaluated the temporal and spatial characteristics of soil erosion sensitivity according to selected factors (i.e. precipitation, vegetation cover, soil, slope, slope length) in the valley, with the factors of precipitation and vegetation being discriminated in different seasons. The results showed that in the study area, the soil erosion was most sensitive in spring, followed by autumn, while it was only slightly sensitive in summer and in the whole year. The total area of soil erosion with high sensitivity had a significant seasonal difference. It was largest in spring (32.2% of the total area), while only 6.1% in summer, and slightly less in autumn than in summer. Spatially, soil erosion area of low sensitivity was mainly distributed in plain area of the valley, while the area of medium and high sensitivity was mainly in the steep field, and in mountain area with elevation above 1500 m and slope about 20°. Furthermore, the influence of vegetation factor on soil erosion was greater than that of precipitation factor.

Key words: specific root respiration, fine root, precipitation exclusion, nonstructural carbohydrate