中文摘要：

草地生态系统是我国陆地上面积最大的生态系统，不仅生产大量的产品，而且提供巨大的生态服务功能。利用遥感技术估算草地生态系统服务价值，具有廉价、动态、快速、范围广等优点，并可解决传统方法所不能解决的空间异质性问题。论文考虑有机物质生产、维持CO2和O2平衡、营养物质循环、对环境污染的净化作用、土壤侵蚀控制和涵养水源等主要服务功能，提出了一个基于净初级生产力（NPP）和植被覆盖率的草地生态系统服务价值估算方法，并介绍了从MODIS数据反演NPP和植被覆盖率的方法。对2003年我国草地生态系统服务价值的估算结果表明，我国草地生态系统总服务价值达17050．25×10^8元，平均48．44×10^4元／km^2，是草地生产收益的19倍；不同类型的草地生态系统单位面积服务价值空间差异悬殊，从5．62×10^4元／km^2变化到99．0×10^4元／km^2以上。

英文摘要：

Grassland ecosystem is a very important terrestrial ecosystem in China.It provides not only a large number of economic products but also many ecological services for mankind. Estimation of the grassland ecosystem services values is urgently required for administration of the precious natural resource.This paper intends to propose a practical method to estimate grassland ecosystem services value using remote sensing data.First of all,the relationship between the value of organic matter production,O2 released and CO2 fixed,nutrient recycle,and environmental pollution cleaning and the net primary productivity （NPP）was established using various methods such as market value,substitution,shadow price,opportunity cost.Consequently, the relationship between the value of soil erosion control and the quantity of soil conservation,which can be calculated from vegetation coverage fraction,was also constructed.The value of water conservation function was calculated by vegetation coverage fraction.Then,a net primary productivity （NPP）model of grassland based on photosynthesis efficiency model was proposed,in which all the parameters were retrieved from EOS/MODIS data.The method of determination of vegetation coverage fraction was also introduced.Finally,the value of grassland ecosystem services of China in 2003 was computed using the proposed method.Our results indicated that spatial variation of the ecosystem services value per unit area was consistent with the distribution of grassland types.The service value per unit area varied greatly with different grassland types. Shrub-meadow with sparse trees had the highest services value of 990259yuan/km^2 （RMB）.The service value of upland meadow is also high up to 968586yuan/km^2（RMB）.Alpine desert steppe had the lowest services value of 56202yuan/km^2 （RMB）.Alpine desert also had a low services value of 89952yuan/km^2（RMB）.Total service values of Chinese grassland ecosystem in 2003 was 1.70503×10^12yuan （RMB）.Different grassland types had different tot