Quantitative Classification and Ordination of Wetland Vegetations in Danjiangkou Reservoir Region

Danjiangkou Reservoir is the water supplying area of the Middle-Route of South-to-North Water Transfers Project.To serve that purpose,the existing Danjiangkou Dam will be elevated to the level of 176.6 m(above sea level) from 162 m,and the normal pool level will be 170 m instead of the present 157 m.Thus,analysis for the composition and distribution of existing vegetation in Danjiangkou Reservoir Region will provide data for wetland management and water environment maintenance of the future.The present paper detected the distribution patterns and species composition of the wetland vegetations using TWINSPAN and DCA in the Danjiangkou Reservoir Region.TWINSPAN classification divided the vegetation into 14 associations,and their community characteristics were described.DCA ordination of samples revealed that soil type and humidity were the main factors influencing the structure and distribution of wetland community.The current floodplain vegetation in Danjiangkou Reservoir was dominated by Cy-nodon dactylon,Rumex maritimus,Mazus gracili and Echinochloa crusgalli.