Woody vegetation and canopy fragmentation along a forest-to-urban gradient
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- 作者：Eric E. Porter ; Brian R. Forschner and Robert B. Blair
- 关键词：urbanization ; urban gradient ; woody plants ; landscape fragmentation ; diversity
- 刊名：Urban Ecosystems
- 出版时间：2001
- 出版年：2001
- 期刊代码：37_10838155
- 类别：ph
- 卷：5
- 期：2
- 页码：131-151
- 数据来源：sp
摘要
To identify patterns that can be used to predict vegetation and landscape characteristics in urban environments, we surveyed the species composition and size of woody plants, as well as the landscape structure of forest canopies, along a forest-to-urban gradient near Oxford, Ohio, USA. The gradient included six sites of increasingly urban land-use: a preserve, a recreational area, a golf course, a residential subdivision, apartment complexes, and a business district. We recorded species identity and stem diameter for all woody plants greater than 3 cm diameter at breast height (DBH) to examine the distribution of individual species as well as overall community composition. We used digitized aerial photographs to compare the spatial characteristics of the forest canopy at each site. We found predictable patterns in species diversity (Shannon index), spatial heterogeneity in species composition (mean percent dissimilarity), and all measures of patch fragmentation (canopy cover and patch number and size). There were clear differences in tree density and total basal area between forested sites and developed sites, but there was little resolution among developed sites. Species richness and average DBH showed no clear pattern, suggesting that landscaping preference largely determined these values. We present a modified version of an intermediate heterogeneity model that can be used to predict diversity patterns in urban areas. We discuss probable mechanisms that led to these patterns and the potential implications for animal communities in urban environments.