Abstract:

With natural wetlands loss and degradation as a consequence of human activities around the world,artificial wetland as alternative habitats for waterbirds receives more and more attention.Chongming Dongtan,located at the Yangtze River Mouth,is one of most important wintering and stopover sites for thousands of migratory waterbirds.During last decade,this area was reclaimed for multipurposes,and part of area was converted into four patterns of the artificial wetlands:(1)wetland park,(2)aquacultural ponds,(3)abandoned fishpond,and (4)artificial wetland restoration demonstration area.In order to understand the environmental impacts of different land use on the waterbirds after the coastal reclamation and sort out the key habitat factors impacting the waterbird distribution,we undertook a wetland survey and waterbird study in Chongming Dontan,Shanghai coastland during November 2011 to May 2012.The study focused on the four types of artificial wetlands(Dongtan wetland park,fishpond in Beibayao,abandoned fishpond,Spartina alterniflora controlled demonstration sampling area).During the survey,a total number of 20 050 waterbirds were counted in winter,covering 34 species of 5 orders and 9 families.The dominant species were the spotbilled duck(Anas poecilorhyncha),mallard (Anas platyrhynchos),northern pintail(Anas acuta),among which,3 oriental white storks(Ciconia boyciana) ranked as IUCN/ICWP Endangered Species were recorded regularly in the December.In spring,5 080 waterbirds were counted,belonging to 47 bird species of 6 orders and 7 families.The dominant species were the spotbilled duck(Anas poecilorhyncha),mallard(Anas platyrhynchos),northern pintail(Anas acuta).The further study indicted that there were significant difference in the waterbirds species,density and diversity ShannonWiener(H′) among the four artificial wetland in winter and spring with OneWay ANOVA analysis.Correlation analysis were undertaken between the waterbird characteristics(species number，H′ and evenness)and the habitat factors (water area,mean water lever,human disturbance,mudflat and vegetation areas).The number of species,H′ were positively correlated with water area,the number of species were negatively correlated with vegetation area in winter,and the number of species,density and H′ were positively correlated with area of mudflat in spring.The study results indicates the artificial wetland of Chongming Dongtan plays an important role in the biodiversity conservation for wintering waterbirds,in terms of alternative habitats.According to our results,some recommendations were raised for artificial wetland management:(1)to maintain the large water area and proper water lever for building up a suitable habitat for wild goose and ducks in winter;(2)to maintain large mudflat area and control the vegetation expansion for the shorebird in spring;(3)to reduced human disturbance,particularly,in terms of controlling the number of the visitors in the Dongtan wetland park