中文摘要：

草地生态系统是陆地表面最大的生态系统类型，其土壤保持功能对于维持敏感而脆弱的草地生态系统服务具有重要意义。在遥感和GIS技术支持下，采用改进的通用土壤流失方程（RUSLE）对内蒙古锡林河流域的土壤保持功能及其空间分布特征进行了研究。结果表明，全流域年土壤保持总量为1.65×10^8t／a，单位面积土壤保持量为168．18t／hm^2；流域土壤保持功能从上游至下游呈递减趋势；草甸草原的土壤保持功能最高，农田和典型草原其次，沙地植被和草甸最差；草地生态系统的土壤保持功能随植被覆盖度的增加呈非线性增长。可见，提高草地植被覆盖度，保持典型草原生态系统的结构与功能的完整性，有助于维持锡林河流域草地生态系统服务和区域生态安全。

英文摘要：

Grasslands represent the most extensive ecosystems on earth. Soil conservation is vital for maintai- ning grassland ecosystem services. Using RS and GIS technologies, the soil conservation function and its spa- tial distribution characteristics in grassland ecosystems of the Xilin River Basin, Inner Mongolia, China, are as- sessed using the RUSLE model. The results show that the quantity of soil conserved was 168. 18 t/ha, and 1.65X l0^8 t/a across the whole basin. The spatial variation of soil conservation capability reveals a declining trend from upper to lower catchment areas. The meadow steppe had the highest soil conservation capability, followed by farmland and typical steppe; sandy soils had the poorest capability. The soil conservation capability of grassland ecosystems increased non-linearly with increasing vegetation coverage. Sustaining grassland eco- system services in the Xilin River Basin can be achieved by increasing vegetation coverage, while maintaining the structure and function of the typical steppe.