Abstract: Wetland ecological system, forest and ocean are the world's three major ecosystems. Now, with the environmental changes and increasing human activities, the decrease of wetland resource is becoming more and more serious. It is the current hot topic in the research field of wetland ecosystem. The purpose of this paper is to analyze city wetland resources and ecosystem service value based on remote sensing. Using the Landsat remote sensing images in 1987, 2000 and 2007, combined with field investigation and geography datum of research area, the wetland resources in Shanghai from 1987 to 2007 were monitored by RS and GIS analysis method. The ecosystem service value theory was employed to estimate the ecosystem service value of the wetland resources' change in the study area. The results showed that: first, the wetland resources in Shanghai exhibited a gradual deterioration from 1987 to 2007, mainly in the decrease of wetland areas, especially after the year of 2000, when a significant reduction of paddy fields, rivers, ponds and shoaly lands were found. The wetland areas reduced 152 203.16 square hectometer, accounting for 18.84% of all wetland areas, among them rivers reduced 3 542.79 square hectometer, reduced by 8.17%; ponds reduced 1 489.13 square hectometer, reduced by 4.46%; paddy fields reduced 115 122.7 square hectometer, reduced by 38.87%, which is the highest of all reductions, mainly because of the transformation into industrial land, residential area and commercial crop planting areas. Only lake areas show a slight increase, and increased about 597.26 square hectometer, or increased by 9.64%. From 1987 to 2007, lakes decreased first and then increased, attributing to the construction of Dishui Lakes in 2007. Secondly, the reductions of the wetland areas have leaded to the corresponding change of ecosystem service value in Shanghai. The general wetland ecological value in Shanghai showed a downward trend, among which the ecosystem service value of rivers decreased 0.03 million, ponds decreased 0.44 million and paddy fields decreased 5.88 million, while the ecosystem services value of beaches increased 0.15 million and shoaly lands increased 1.66 million. According to the analysis, appropriate measures were proposed to deal with these problems, such as the rebalance between land use and wetland protection, preserving wetland while developing the economy, realizing the synchronous development of economy, ecological and social benefits; building wetland information database and enhancing the monitoring of wetland dynamics to provide a basis for wetland protection; propagandizing wetland culture to let people know the importance of wetland. The decreases of wetland resources and the value of ecosystem services in Shanghai are mainly a result of rapid urbanization, which may attach importance to the protection, development and use of wetland resources in urban development for the government to provide evidence.

Key words: remote sensing, wetlands, ecosystem service value, Shanghai