Wetland is the transitional zone between land and waters on the earth. Its ecosystem features special structure and functions，listed as one of three major ecosystems together with forest and ocean in World Conservation Strategy （1980）；hence it gets another name as “Kidney of the Earth”. Sanjiang Plain Wetland is one of the largest fresh marsh wetlands in China，its ecosystem boasts a diversity of functions，not only providing tremendous social and economic benefits，but also high ecological benefits，playing an important role in maintaining the ecological balance，protecting the biological diversity and species of wild animals as well as haboring water resources，storing flood water against drough