The research region is located in the west of the Taihu Lake. With the population increasing and economical development, the land of lakeside of west Taihu Lake was reclaimed to develop agriculture, farmland and factories. In this study, the ecological roles between restored Phragmites communis communities and disturbed ones were compared based on restored sectional disturbed wetland structures.
The survey results show that the ecological indices of restored wetlands are higher than that of disturbed ones, including biomass of plants, the concentrations of nitrogen and phosphorus nutrients in water and sediments, the numbers of three nitrogen cycle bacteria in sediments and the concentrations of heavy metals in sediments, etc. The species and numbers of plants in terrestrial area have a great number of changes, the biomass of plants in disturbed wetlands decreased 37%～60%. The concentrations of dissolved inorganic nitrogen in the water of terrestrial area, transition area of water and terrene and water area in the restored wetland are higher 25.36％, 89.39% and 2562.30% than those in the water of disturbed wetland. After analyzing the vertical sediments samples, the concentrations of TP in the sediments of terrestrial area of restored wetland are 3.19,2.62,2.25 and 1.74 times as much as those in disturbed one; The concentrations of TN are 1.84,6.08,2.09 and 2.46 times as much as those in disturbed ones. The concentrations of organic in the sediments of terrestrial area and transition area of water and terrene area are higher than those of water areas, especially, the concentrations of organic in the sediments in restored wetland reach to 42.17%～56.5%.On the contrary, the concentrations of organic in the sediments of water area are lower. In the restored wetland, the number of denitrifying bacteria in the terrestrial area and transition area of water and terrene area are 10.69 and 8.24 times as much as those of nitrobacteria in water area. The results demonstrate that denitrification play a significant role in nitrogen removal. Based on the quantitative analysis of four(Mn,Cu,Zn,Pb)heavy metal elements in the surficial sediments, the enrichment of Mn appears higher and that of the other heavy metals appear lower. The assessment result of the heavy metals’ ecological risk revealed except Mn, which belongs to middle potential risk, most heavy metals belong to the light potential ecological risk segment.