中文摘要：

探讨三江源区高寒草地生态系统土壤侵蚀问题在保障青藏高原乃至全球生态和生产功能方面具有重要意义。以~（137）Cs示踪法为基础,结合RUSLE（Revised Universal Soil Loss Equation）模型,以GIS反演为手段,综合分析三江源区2001-2012年土壤侵蚀影响因子的特征和土壤侵蚀空间分布规律。结果表明,1）土壤侵蚀影响因子呈现空间异质性特征,降雨侵蚀力因子年际浮动变化较大,但总体呈上升态势;土壤可蚀性因子呈斑块化分布特征,较高可蚀性类占到总面积的95.66%;坡度坡长因子的空间分布规律受海拔显著影响;植被覆盖与管理因子在研究区自西北向东南呈现空间异质性特点,过度放牧是引起下垫面侵蚀现象严重的主要原因。2）对RUSLE模型的验证显示相关系数和平均均方根偏差分别为0.49和75.29%,RUSLE模型估算存在一定的高估,在没有形成三江源区高寒草地土壤侵蚀机理模型前,应用RUSLE模型仍然是较好的现实选择之一。3）利用RUSLE模型估算的三江源2001-2012年平均侵蚀量为3.1×109 t/年,侵蚀强度分级重心转移分析表明中度侵蚀、强度和极强度侵蚀重心相对集中,侵蚀程度最高的3个地区为格尔木市唐古拉乡、治多县和兴海县。4）由土壤流失量结合市场价值法,估算出研究区2001-2012年平均有机质经济损失价值为114354元/km2,总年均经济损失达399亿元,整个研究区受土壤侵蚀现象所产生的经济损失数额巨大。因此,创新发展三江源区高寒草地＂分类、分级、分段、分区＂的土壤侵蚀防治措施已迫在眉睫。

英文摘要：

Investigating soil erosion in the Three-Rivers Headwaters area is of great significance for the protection of the ecology,production,and function of the alpine meadow ecosystem on the Qinghai-Tibetan Plateau.In this study,we conducted a comprehensive analysis of soil erosion,its spatial characteristics,and the factors affecting it in the Three-Rivers Headwaters area.For these analyses,we used a ~（137）Cs tracing technique,GIS（Geographic Information System）,and the RUSLE（Revised Universal Soil Loss Equation）model.The results showed that：1）soil erosion factors showed spatial heterogeneity.Rainfall-related erosion showed drastic interannual changes,but generally increased from 2001 to 2012.Soil erodibility varied spatially,and soils with a high erodibility index accounted for 95.66% of the total area.The spatial distribution of slope and slope length were significantly influenced by the altitude.The vegetation cover and management factors showed spatial heterogeneity from the northwest to the southeast of the study area,and overgrazing was the main cause of serious underlying surface erosion.2）In the validated RUSLE model,the correlation coefficient was 0.49 and the average root mean square error（ARMSE）was 75.29%.Although the RUSLE model tended to overestimate soil erosion,it was still one of the best choices to simulate alpine meadow soil erosion in the Three-Rivers Headwaters area.3）The total average erosion volume estimated by the RUSLE model（2001-2012）was 3.1×109 t/yr.Analyses of the erosion intensity classifications revealed the areas of moderate,strong,and extremely strong erosion.The three areas with the highest degrees of erosion were Tanggula township,and Zhiduo and Xinghai counties.4）Taking into account the amounts of soil loss and market values,the estimated average economic loss of organic matter was 114354RMB/km2 in the study area from 2001 to 2012,the total annual economic loss was 39.9billion,and economic losses caused by soil erosion were substantial across the whole stu