The Influence Of Multiple-Scale Habitat Structure On Bird Community In Urban Parks

The acceleration of urbanization has led to a loss of biodiversity, which is a global ecological problem of great concern. The urban population as a proportion of the global population is expected to grow from 50% in 2009 to 70% in 2050 and most of urbanization growth would be concentrated in developing countries China has been experiencing rapid urbanization for 30 years. With a population of over 20 million and an area of about 5800 km2, Shanghai is the most crowded city in China, and 88% of its population lives in urban area. The rapid expansion of urban areas has already caused habitat loss, habitat fragmentation, and the reduction of biodiversity in urban ecosystems. Thus, the conservation of biodiversity is one of the main goals of the 12th five-year plan of the Shanghai Municipal Government. The conservation of biodiversity is essential in urban ecosystems because:(1) urban areas include the natural habitats of many native resident and migratory wild species; (2) biodiversity is an important part of any healthy ecosystem; (3) urban biodiversity is essential for the quality of life and recreation of residents. How best to quantify and enhance the function of urban green space as wildlife habitat has been frequently studied in recent years.There have been 438 bird species recorded in Shanghai since early 20th century, 85.2% of which are migratory birds. Thus, protecting birds in Shanghai not only benefits the local biodiversity, but also promotes bird conservation throughout the entire migratory region. Urban parks are one of the main types of urban green space and they are considered important habitats for wild birds. To facilitate biodiversity conservation and human recreation needs, the total area covered by urban parks in Shanghai city expanded from 1153 ha to 1687 ha from 2000 to 2009. However, the bird species richness and diversity of urban parks have not increased significantly. Improving the vegetation composition and structure was shown to be a feasible and efficient method for improving bird conservation in urban parks. However, the influence of multiple-scale habitat structure on bird community, especially fine scaled vegetation-bird community interaction, has never been studied carefully in Shanghai City. This type of study may explain how the bird community responds to different vegetation compositions and provide important insights into urban re-vegetation with respect to biodiversity conservation in a city experiencing rapid urbanization.In this research, we focused on five topics:(1) As the most crowded city in China, the conservation of biodiversity is essential to the health of the urban ecosystem of Shanghai. How best to quantify and enhance the function of urban green space as wild bird habitat has been given great concern. This type of study may explain how the wildlife community responds to different vegetation compositions and provide important insights into urban re-vegetation with respect to biodiversity conservation in a city experiencing rapid urbanization. Thus, we carried out a study on interactions between bird communities and microhabitat vegetation composition in Binjiang Forest Park. Areas within the 25 m of 40 sampling sites and> 5 km long line transect were surveyed for bird species, quantities of each species, and the individual behavior, while microhabitat of birds were evaluated in each 20x20 m2 sampling square centered in the 40 sampling sites. Among the 60 bird species observed from the three habitat types, significantly more species (i.e.,55 species) were observed in woodland with shrubs,36 species in woodland without shrubs, while only 29 species recorded in lawn. Multiple linear regression models confirmed that both vegetation complexity and structure had significant positive effects on the bird community composition. Regression tree analysis further demonstrated that the woody plant species richness and diversity were significant microhabitat variables to all of the three bird community indices (i.e., the bird species richness, abundance, and diversity). Moreover, we confirmed that the vegetation horizontal coverage, particularly the horizontal shrub coverage was essential to birds living in heavily human disturbed areas. In addition, our data suggested that well-designed water system should be beneficial to bird conservation in urban areas. This study highlighted the importance of microhabitat vegetation composition and structure to the bird conservation in heavily urbanized areas. However, we also suggested that studies about relationships between bird community and urban green vegetation in Shanghai City should be carried out in more urban parks with the consideration of the urban landscape context in the near future.(2) The acceleration of urbanization has led to a loss of biodiversity, which is a global ecological problem of great concern. Meanwhile, birds are useful indicators in monitoring environmental changes in urban ecosystem. Urban green areas have always been paid great attention because of their functions as natural habitats for many wildlife species. Bird guilds are groups of species that use environmental resources in similar ways. Therefore, we analyze the function of vegetation structure to bird community and bird guilds so that we make suggestions related to the design of urban green spaces in Shanghai. From October 2009 to October 2011, we set the line transect to survey the bird community in Shanghai Binjing Forest Park. According to the height of plant, we divided the habitat vegetation into three vertical levels including tree layer, shrub layer and ground layer. Chi-square test showed that there were significant differences among behaviors in three vegetation layers. The frequency of perching and moving in tree layer was more significant than that in other two layers and the frequency of feeding in ground layer was more significant than that in other two layers. According to the variables based on the location, feeding habits and foraging behavior pattern of birds, we classified 8 bird guilds including herbivorous collecting, herbivorous pecking, insectivorous collecting, insectivorous flying catching, insectivorous pecking, omnivorous collecting, omnivorous pecking and raptorial flying catching. There were differences and overlaps among the frequency of three behaviors of 8 bird guilds in three layers, so we considered there was niche overlap among 8 bird guilds. According to Morisita-Horn Index, the results indicated that insectivorous collecting guild, omnivorous collecting guild, flying catching guild and herbivorous collecting guild had high niche overlap of perching, and moving and feeding so these guilds reached niche separation by their diets. Insectivorous pecking guild and insectivorous flying catching guild had the most perching niche overlap with each other, and they reached niche separation by their foraging behavior patterns. Based on the results above, we concluded that trees were one of the most important vegetation components that enhance the bird species richness and diversity in urban green spaces because they provide roosting, nesting, hiding, and foraging sites. The shield function of shrub cover was confirmed to be an important habitat component and the ground layer provided food resources to bird community. The suggestion and recommendation in construction of urban parks was presented based on this study. The density and coverage of shrub layer should improve and large area of artificial lawn should be divided into several small pieces. We also discuss the conflicts between habitat for biodiversity maintenance and recreational function in urban parks.(3) The bird communities and vegetation communities in Shanghai Century Park and Bingjiang Forest Park were respectively surveyed from December 2011 to November 2012. In accordance with the result of principal components analysis of 12 vegetation variables, the vegetation in the two parks was grouped into 8 types including T type (habitat with developed tree layer), S type (habitat with developed shrub layer), G type (habitat with developed ground cover layer), T+S type (habitat with developed tree layer and shrub layer), T+G type (habitat with developed tree layer and ground cover layer), S+G type (habitat with developed shrub layer and ground cover layer), T+S+G type (habitat with complex vegetation structure), D type (disturbed habitat). Chi-square test suggested that the S type and T+S type habitat in Binjiang Forest Park was significantly more abundant than those in Century Park while G type and T+G type habitat in Century Park was significantly more abundant than those in Binjiang Forest Park. Developed tree layer habitat was abundant both in the two parks and More than 70%of the bird richness and bird abundance were recorded in these habitat. Bird richness was significantly different in habitat types in Century Park, but the richness difference was not significant in Binjiang Forest Park. There were 24 common bird species in the two parks, which were indicated to have performed higher utility rate in Binjiang Park than those in Century Park in accordance with paired sample t test result. Analysis of the bird richness in common habitat types of the two parks showed that the richness of Muscicapidae in Binjiang Park was significantly higher than that of their counterparts in Century Park. Due to the forgoing, we concluded that (1) trees were one of the most important vegetation components that enhanced the bird species richness and diversity in urban green spaces; (2) shrubs were usually treated as being as important as trees for birds living in urban areas, where they provided some forest birds with nesting sites; (3) ground cover layer provided the ground foraging groups with feeding resources. Our research emphasized that habitat types significantly influenced the structure of bird communities in the urban parks in Shanghai. Therefore, we suggest that hierarchical vegetation types should be adopted while planning and constructing large-scale urban parks so that the bird diversity will be improved. Furthermore, in order to perform higher utility rate of urban birds, diversified shrubs and different kinds of herbaceous plant should be planted under the tree layer.(4) The bird community was surveyed in Binjiang Forest Park, Gongqing Forest Park, Haiwan Forest Park, Shanghai Botanical Garden and Century Park during May 2012 to April 2013 by line transect method. We used ArcGIS 10.0 to classify the patches within the urban parks. Five kinds of the patches was classified including Building, Grassland, Plant, Road and Water. Based on the classification,34 patch variables including patch number, patch density, patch area and patch total edge was set to analyze the relationship between bird communities and patch variables. Chi-square test suggested that there was significant difference among bird richness, bird abundance, the number of patches in 5 urban parks. The largest number of patches occured in Haiwan Forest Park and the smallest number occured in Gongqing Forest Park. The richest bird species and the most individuals existed in Haiwan Forest Park. There were 4 common classes (Podicipediformes, Ciconiiformes, Columbiformes and Passeriformes) and 12 families belong to Passeriformes (Pycnonotidae, Laniidae, Regulidae, Turdidae, Timaliidae, Motacillidae, Sturnidae, Passeridae, Paridae, Fringillidae, Sylviidae and Paradoxornithidae) in the five parks. Moreover, Muscicapidae, Emberizidae, Corvidae and Hirundinidae were recorded in four parks. Multiple linear regression models confirmed that there was significant positive correlation between bird richness and the number of Water patch (WNP) and Grassland patch shape index (GSI). There was significant negative correlation between bird richness and the largest patch index (LPI).(5) The bird community was surveyed in Binjiang Forest Park, Gongqing Forest Park, Haiwan Forest Park, Shanghai Botanical Garden and Century Park during May 2012 to April 2013 by line transect method. We used ArcGIS 10.0 to classify the patches around the urban parks with 5km× 5km area. Six kinds of the patches was classified including Building, Grassland, Plant, Road, Water and Beach. Urbanization level index was defined by the area of Building and Road patch. Chi-square test was used to analyze the variance of patches and urbanization level index about five urban parks. The result highlighted that there was significant difference among the urbanization level indexes of five urban parks. Urbanization level index was positive correlative with Corvidae and the dominance of dominant bird species. However, Urbanization level index was negetive correlative with Pycnonotidae, Laniidae, Emberizidae, Aegithalidae and winter resident. The urbanization level index of Shanghai Botanical Garden is highest and the index of Haiwan Forest Park is lowest. Homogenization appeared along the urban gradient. The dominance of dominant bird species became more dominant along the urban gradient.