Abstract:

Pudong Dongtan, a vital stopover site for migratory waterbirds and wintering site for waterfowls, has experienced two largescale reclamations during last two decades, resulting in degradation of natural wetland and loss of biodiversity. Degradation wetlands were restored to compensate for the loss of natural wetlands. We carried out waterbird surveys in the ecological restored wetland and natural degraded wetland as a reference site in 2010 and 2012 to assess the effects of wetland restoration on waterbird communities. In our survey, a total number of 9,657 waterbirds corresponding to 49 species, 6 orders and 12 families were counted in the ecological restored wetland in 2010 and 2012. The dominant species are the Spotbilled Duck (Anas poecilorhyncha), Falcated Duck (Anas falcata) and Wigeon (Anas penelope). In the natural degraded wetland, 917 waterbirds were observed, which corresponded to 28 species, 6 orders and 9 families. The dominant species are the little grebe (Tachybaptus ruficollis), Common Moorhen (Gallinula chloropus) and Blackwinged Stilt (Himantopus himantopus). The waterbird diversity, the numbers of species and individuals in the ecological restored wetland are significantly higher than those in the natural degraded wetland, however, the significant difference was not observed in evenness. These results may be caused by the following reasons. Under the human management, diverse habitats were constructed to attract various waterbirds in the ecological restored wetland, whereas the less water surface area, mudflat area and the higher vegetation coverage were observed in the natural degraded wetland. The waterbird species number in the ecological restored wetland in 2012 was significantly lower than that in 2010, however, no significant difference in the waterbird diversity, evenness and the numbers of individuals were noted in 2010 and 2012. In the natural degraded wetland, the waterbird diversity, the numbers of species and individuals in 2012 were significantly lower than those in 2010, whereas no significant difference was noted in the evenness in 2010 and 2012. It is because that there are no obvious change in environment factors including water level, percentage of water area, the percentage of mudflat, vegetation coverage and human disturbance in the ecological restored wetland between 2010 and 2012 through vegetation management and water level control, whereas there are large changes appearing in the natural degraded wetland at the same time. In the addition, for without human management, the water level change in the natural degraded wetland was only decided by the amount of rainfall and the natural degraded wetland had been experiencing a rapid drought process, which was unable to meet the various needs of migratory waterbirds seasonally. In conclusion, the ecological restored wetland, as an alternative habitat to compensate for natural wetland loss, plays an active role in waterbird diversity conservation. We expected that our findings help protect the waterbird diversity effectively and provide waterbirds with important stop foraging and wintering sites in the coastal area of the Yangtze River