中文摘要：

三江源地区的草地生态系统对于维持区域生态平衡和保障社会经济可持续发展具有重要意义。本文基于千年生态系统评估（Millennium Ecosystem Assessment,MA）的生态系统服务分类体系,采用多种方法对三江源草地生态系统的9项服务价值逐项进行了评估,得出2000年三江源草地生态系统服务价值为562.60亿元,其中价值最高的两种服务类型依次为气候调节和食物生产,分别达259.09亿元和111.68亿元,贡献率分别为46.05%、19.85%。按照草地类型划分,高寒草甸和高寒草原服务价值分别为490.95亿元、64.68亿元,占总服务价值的87.42%和11.52%。虽然沼泽单位面积服务价值最高,为4230.77元/hm2,但在草地生态系统面积中所占比例较低,总价值相对很低。本文关于三江源草地生态系统的评估结果可以为制定区域生态保护和生态补偿政策提供科学支撑。

英文摘要：

Grassland ecosystem in the Sanjiangyuan Region （Three-River Headwater Region） plays an impor- tant role in maintaining ecological balance and guaranteeing sustainable development of social-economic sys-tem. By using multiple methods, we assessed the value of nine types of ecosystem services in the Sanjiangyuan region based on the ecosystem services classification system of MA. The results showed that the total value of grassland ecosystem in the Sanjiangyuan Region was 56.26 billion RMB yuan in 2000. The top two values of ecosystem services were climate regulation and food production, which were 11.17 billion RMB yuan and 2.59 billion RMB yuan, with the contribution rate of 46.05% and 19.85% respectively. With respect to different grass-land types, alpine meadow and alpine grassland have the values of 49.10 billion RMB yuan and 6.47 billion RMB yuan, contributing 87.42% and 11.52% to the whole value. Swamp has the highest value of 4230.77 RMB yuan per hm2, but its area is small, thus a relatively low value in total. The results of this study provide the scien-tific support for policy making in ecosystem protection and the practice of ecological compensation.