Avian Diversity Patterns Along An Urbanization Gradient In Shanghai Parks

Urbanisation is gathering pace in China since the beginning of 21 century, casuing a series of environmental problems such as natural habitat loss, habitat fragmentation and environment pollution, which are certainly threatening the maintenance of biodiversity. As a sensitive animal taxon to urbanization, bird is a hot spot of urbanization-biodiversity researchesbecause of its effective indicating for the degree of unbanization. For a long time, there is a controversial problem about bird diversity pattern along urban-rural gradient. Most of studies showed that urbanization depressed bird diversity, but othersshowed highest diversity at the middle degree of urbanization. Absence of partitioning the impacts of urbanization on habitat and on its surrounding environment is the main reason of controversy.Therefore, in this research, only parks with large area were chosen in Shanghai to minimize the variations of habitats of birds, based on which the impacts of urbanization on bird diversity were dicussed by analyzing the diversity pattern among those parks on urabn-rural gradient. Finally, ecological habits of birds that corresponding to biodiversity variation along urabn-rural gradient were discussed. To achieve those aims,30 parks in Shanghai were select for bird survey and habitat data was collected from December 2013 to May 2014.30 parks were divided into 5 gradients by cluster analysis with visitors flow rate, number of metro lines, number of bus lines, and artificial surface area percentage as urbanization indexes. Distributions along the five urbanization gradients were check by indicator species analysis for each species. The main conclusions are as follow.(1) Bird diversity declined with the increasing degree of urbanization. Visitor flow rate, number of metro lines, number of bus lines, and artificial surface area percentage had a significant negative correlation with bird diversity.(2) 88 species can be classified into five distribution types. With descending order of species richness, the five distribution type is urban sensitive, middle urban adapter, seasonal adapter, urban adapter, urban enthusiast. Thus, only few species can adapt or even rely on high degree of urbanization, while most species are sensitive to urbanization. Such distribution pattern resulted in the decline of bird diversity.(3) Ecological habits were tightly related with the bird distribution along the urbanization gradient. Residents, plant eaters, common plants enthusiasts, and high foragers are more adapt to urbanized region, most of which are urban enthusiasts, urban adapters, or seasonal adapters. On the contrary, migrants, ground gleaners and insectivores are sensitive to urbanized region and tend to be middle urban adapters and urban sensitives.In conclusion, bird diversity declined with the increasing degree of urbanization provided that the habitat is similar but with heterogeneous surrounding environment, which can be explained by different ecological habits of species.