The Landscape Pattern Analysis And Assessment Of Wetland Ecosystem Health For Nanhui Biantan, Shanghai

The coastal wetland as a typical transitional zone between land and ocean, is a multi-functional and complex ecosystem with huge function on water and element cycle, special ecological values and potential resources. With the development of human society and economy, it is more and more seriously disturbed by human activities. Nanhui Biantan wetland is a silting flat which locates on the southeastern Shanghai and where is the intersection area of Yangtze estuary and Hangzhou Bay. It is an important part of Yangtze estuarine wetlands. In the past two decades, two large-scale reclamations of tidal flats were executed in Nanhui Biantan, and the flats above elevation of Om had been reclaimed entirely. The wetland ecosystems are disturbed by human activities frequently.In this research, the Landsat TM images of 1990a,2003a and 2008a were interpreted firstly which based on the collection of historical data and field survey in order to study the landscape type dynamics and landscape pattern change of Nanhui Biantan wetlands. The Nanhui Biantan wetland ecosystem health assessment index system based on PSR model was then established to carry out Nanhui Biantan ecosystem health assessment. The major results were summarized as following.In the past 20 years, especially after two Nanhui Biantan Reclamation Projects were executed, the natural wetland landscape of middle and high intertidal flats in Nanhui Biantan had turned into human introduced landscape which made the total area of natural wetland landscape especially the area of wetland plants decrease, The dominant landscape type changed into human introduced landscape from saltmarsh vegetation landscape, and the differences in area between the various landscape components declined. The number of small patches in the wetland increased when there were less patches with high-connectivity found. The patch shape was more complex and irregular at the same time. The landscape pattern became to be more fragmented as a whole. Nanhui Biantan wetland ecosystem was in sub-healthy condition with the unhealthy and ill zones accounting for the total wetland area of 30.63%, while the healthy zone accounting for the total wetland area of only 19.18%. Nanhui Biantan wetland ecosystems were faced with higher pressure from significant human activity disturbance which had gradually exceeded the extent of that ecosystem self-regulation can maintain.Nanhui Biantan wetland is located on the mainland with developed agriculture and industry. Compared to the wetlands located on the island such as Chongming Dongtan wetland and Jiuduansha shoal wetland, Nanhui Biantan wetland is, more vulnerable to human activity disturbance. If its lack of effective management and protection in a long term, Nanhui Biantan wetland ecosystem health could deteriorate further since it hasn't been included in the list of conservation area up to the present.