都市樹林地における鳥類群集と樹林地周辺の土地被覆との関係

概要

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To examine the influence of site scale (vegetation) and landscape scale factors (e.g., surrounding land cover) on avian communities in patchy urban woodlands, we censused birds at 52 stations located in 13 urban and suburban woodlands in and around Tokyo, Japan from 2006 to 2007 in both the wintering and breeding seasons. The recorded species were divided into three groups, urban avoiders, urban adapters, and urban exploiters, based on literature in which the response of bird species to an urbanization gradient was considered. Vegetation surveys were also carried out each season. Hierarchical linear models were constructed using avian species richness as the response variable, vegetation structure variables as site scale explanatory variables, and average vegetation structure variables in each woodland and surrounding land cover variables as landscape scale explanatory variables. The results indicated that the percentage of open lands including agricultural fields and grasslands had a positive effect on urban avoider species richness, perhaps because the percentage of open lands is a good indicator of non-urbanization and the distribution of urban avoider species was determined based on the landscape-scale potential of species inhabitation. Open lands may also contribute to the ease of movement in birds and/or play a role of a part of habitat.