East China Normal University,Shanghai Science& Technology Museum,East China Normal University,East China Normal University
城市中的园林绿地呈现斑块状分布,其栖息地特征与岛屿栖息地相似。2008年11月至2009年10月,对上海市闵行区内的7块城市绿地进行调查,记录雀形目鸟类的分布情况,并运用Nestedness temperature calculator软件,检验其群落结构是否符合嵌套结构。运用Arc GIS软件分析该地区的卫星图片,收集7块样地的面积、绿地盖度、水源距离和人为干扰程度等数据,结合实地调查所得到的数据,分析这一嵌套结构的形成原因和影响因素。调查结果显示:上海市闵行区城市绿地中的雀形目鸟类分布是显著的嵌套结构,矩阵系统温度是21.78 ℃,填充度41.3%。7块样地中出现的物种数从14种到38种不等。其中,白鹡鸰(Motacilla alba)等11种鸟在7块样地中都有分布,黑卷尾(Dicrurusmacrocerus)等9种鸟类只在一个样地中出现过。园林面积、绿地面积和水源情况都对其嵌套结构有显著影响。但与真正岛屿上存在的群落分布嵌套结构不同,人为干扰程度对这一结构也有非常明显的影响。上述结果表明,影响上海闵行区园林鸟类群落嵌套结构的主要原因是栖息地结构和人为干扰程度。因此,建议在规划和建设城市公园和绿地时,应该偏重于面积较大,植被盖度和丰富度高,结构合理的园林,并尽量减少人为干扰对鸟类栖息地的影响。
Urban woodlots are isolated patches with habitat features similar to ‘habitat islands’. Spatial patterns between and within animal communities change with respect to habitat fragmentation, and this is especially the case for avian communities. The purpose of this paper was to test for nestedness within passeriformbird assemblages across urban woodlots of Shanghai, China and to inform conservation planning across this heavily populated city. From November 2008 to October 2009, we used line transect and point count methods to survey distribution patterns and species richness of passeriform birds across seven urban areas in the Minhang district of Shanghai. Areas surveyed included a neighborhood park, tourist park, sports park and water conservation forest, representing the main types of urban woodlots found in the area. Through surveys and satellite images we recorded park area, vegetation coverage, the distance from the center of the park to nearest water, and the extent of anthropogenic disturbance (distance from the center of habitat to arterial road). We used the Nestedness Temperature Calculator to examine whether bird communities in this area show signs of nestedness and what factors may be responsible for such a pattern. Results showed that the passeriform bird community followed a significant nested pattern influenced by habitat area, vegetation cover and water condition. However, nestedness was different from a real ‘island’ condition. Anthropogenic disturbance was also found to influence nestedness. Investigating the matrix system in which the urban woodlot bird communities are comprised showed that the temperature is 21.78 ℃, compactedness is 41.3%, and the number of species is between 14 to 38. Eleven kinds of bird exist across the seven focal urban areas, such as Motacilla alba and Parus major. However, some species as Dicrurusmacrocerus, Orioluschinensis are only found in a particular focal area. Habitat fragmentation contributes to the spread of birds. However, different urban woodlots have distinct habitat characters due to heterogeneity and human activities also interfere with the spread of birds and habitat choice. Vegetation also appears to influence the distribution of birds across urban woodlots. Birds tend to choose particular kinds of urban woodlots that include diverse species, have complex structure or are at a stage of senior evolution. These regions could provide stable food sources and concealed breeding grounds and habitats. Our findings suggest that more attention should be directed towards large habitats, those with a high level of vegetation cover and plant richness, and a reasonable structure of urban woodlot. From the point of nestedness stability, urban environments show instability following city development. Frequent change in urban woodlots influences the migration and spread of birds, and this is a fundamental difference from how ‘habitat islands’ function. Based on the application of 3S technologies to urban planning and ecological monitoring we can now utilize advanced technology such as remote sensing and GIS to monitor variation in urban woodlots and prevent the further habitat fragmentation. The extent of anthropogenic disturbance should be minimized when planning and constructing urban woodlots in major cities.