中文摘要：

摘要：内蒙古温带草原和海北高寒草甸的土壤侵蚀以风力侵蚀为主。利用改良的风力侵蚀模型，比较分析了这两类草地生态系统土壤保持价值日流量过程和累积过程。结果表明，风力侵蚀条件下，草地生态系统的土壤保持服务是离散的，不连续的，与风速和植被盖度直接相关。土壤保持价值构成以保持土壤养分为主。内蒙古温带草原的年潜在侵蚀量和年现实侵蚀量都高于海北高寒草甸。但是，内蒙古温带草原的土壤保持年价值高于海北高寒草甸，是海北高寒草甸年价值的7倍。春季和秋季是内蒙古温带草原潜在侵蚀量、现实侵蚀量和土壤保持量最高的两大季节。海北高寒草甸的潜在侵蚀量和现实侵蚀量主要分布在12月份到翌年4月份，土壤保持量主要分布在春季和夏季。

英文摘要：

Abstract： Grassland is the largest land resources by area in China. It plays an important role in food production, carbon fixation and sequestration, 02 release, soil and water conservation, water supply, nutrient recycling, entertainment, and biodiversity sustaining, among which, soil conservation is one of the most essential services delivered by grassland ecosystem. There have been few studies specially focusing on soil conservation value of grassland ecosystem till now, although soil conservation has historically been emphasized in the practice of grassland management, resulting in limited understanding about the mechanism of soil conservation of grassland especially at spot scale. Therefore, the dynamic flow processes of soil conservation value of grassland at spot scale are urgent to be researched. In the c zntext, the study targeted at the dynamic processes of soil conservation of two kinds of typical grasslands： Neimenggu Temperate Grassland and Haibei Alpine Meadow. Due to that soil erosion of both the selected grassland ecosystems was mainly cau~,~ed by wind, on the basis of simplicity and scientificity, we chose the Pasak wind erosion model and improved it through the input of factors to assess wind induced soil erosion. The accuracy of the model was tested by the existing research results of other scientists. Related data were from Chinese Ecosystem Research Net （CERN）. The soil conserved by grassland was the subtraction of soil eroded under vegetation coverage -- the actual soil erosion, from the soil eroded without vegetation -- the potential soil erosion. The soil conservation value was calculated using the method of shadow price and opportunity cost. The results showed that the soil conservation service supplied by grassland ecosystems was discrete, which was highly related to the wind velocity and vegetation coverage. The annual soil conservation value of Neimenggu Temperate Grassland was at 1.06×l04 ￥/hm2 ,while that of Haibei Alpine Meadow was at 1520 ~/hm2. The soil nutrient conserv