关键词: RWEQ模型, 风蚀力, 土壤风蚀, 锡林郭勒盟, 植被盖度

Abstract: Soil wind erosion is a major ecological environment problem in northern China. Xilingol League is located in the arid and semiarid areas. As one of the areas suffering from most serious wind erosion in northern China, its ecological environment is very fragile. Because of this environmental fragility, the area was included in the Beijing-Tianjin Dust Storms Sources Control Project that was officially approved by The State Council and implemented in 2002. In order to better understand the status of soil erosion and guide the regional desertification prevention, it is necessary to assess the variation of soil erosion and reveal the influences of weather and vegetation on soil erosion in Xilingol. In this study, based on wind speed, temperature, precipitation and other meteorology data, the normalized difference vegetation index, snow coverage and other remote sensing data, the Revised Wind Erosion Equation (RWEQ), which takes Newton's first law of motion as the foundation, was applied to evaluate annual soil losses caused by wind erosion. The results show that: The average soil erosion in Xilingol League between 1990 and 2010 was 0.34 billion tons. The intensity of soil wind erosion is low in most parts of Xilingol—these areas were mainly concentrated in the eastern, central and southern areas, where vegetation coverage is higher, wind erosion forces is lower, and rainfall is abundant. The areas with medium and higher intensity of erosion were mainly distributed in the Hunshandac desert of Suninteyou Banner, Zhengxiangbai Banner and Zhenglan Banner, where the soil is highly prone to wind erosion. Since the 1990s, soil erosion in Xilingol showed a deceasing trend. The reduction of wind erosion intensity is related to the weakened wind energy and improved vegetation cover. Wind erosion forces is the main driving factor of wind erosion—soil erosion was significantly correlated with the wind erosion forces (r=0.95, p<0.05). Wind erosion in Xilingol occurred frequently in windy springs. At this time, the effect of soil erosion associated with low vegetation coverage is most significant. Soil erosion was significantly correlated with the spring vegetation coverage in regions of higher wind erosion forces (r>0.7, p<0.01). Increased vegetation coverage effectively reduced soil wind erosion of the region in the recent 20 years. Low vegetation coverage makes the prevention of soil erosion more difficult and improving the grassland condition, especially in the spring season, is the key to controlling wind erosion of the soil. The RWEQ model was mainly used in the farmlands of the United States and cannot be directly applied in the grassland areas of China. In order to better apply the model in grasslands, the soil particle content was converted into the US system, surface roughness was measured by the roller chain method and withered vegetation coverage (obtained by photos) was introduced to replace flat residues on the surface of the soil. Even so, more research is needed to solve problems such as the influence of relief on soil wind erosion, the determination of noneroding boundaries, among others.

Key words: RWEQ model, soil wind erosion, vegetation cover, wind erosion forces, Xilingol League