Loss of habitat area and structural heterogeneity through anthropogenic fragmentation poses a threat to the survival of wildlife, which may be exacerbated by urban pressures. Understanding the underlying ecological processes that influence species’ persistence in fragmented landscapes is vital for conservation. We described the effects of forest fragmentation via measures of patch size and isolation on the taxonomic richness and functional richness of forest bird communities in five Protected Areas within the urban-forest mosaic of the Durban Metropolitan Area, South Africa. We conducted 137 fixed-radius point-count surveys across 41 distinct forest patches during the austral breeding season. We quantified the avian taxonomic, guild and functional richness and measured at each survey patch. We measured the influence of patch size, Euclidean isolation distance, patch shape and habitat configuration (i.e. habitat amount) on each diversity measure. We then conducted a series of General Linear Models to determine how fragmentation and patch configuration influenced the diversity of forest birds. The explanatory variables in the top models had a significant effect on all avian diversity measures but habitat amount did not. The amount of habitat surrounding a patch was not significant for measures of bird diversity but based on the Akaike’s weight it was important for specialist species. Isolation distance did not have a significant effect on the measures of bird diversity. An increase in patch shape index increased species richness. These results show the importance of large forest fragments/patches for the conservation of forest birds and for maintaining ecosystem functioning and services of forests in increasingly urbanising landscapes, to the benefit of the environment and its human population.

中文翻译：

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南非德班城市森林马赛克中生境斑块大小和斑块隔离对森林鸟类多样性的影响

由于人为分裂造成的栖息地面积损失和结构异质性对野生动植物的生存构成了威胁，而城市压力可能会加剧这种威胁。了解影响物种在零散景观中生存的潜在生态过程对于保护至关重要。我们通过斑块大小和隔离度的措施描述了森林破碎对南非德班都市区城市森林马赛克内五个保护区森林鸟类群落的分类学丰富度和功能丰富度的影响。在南方繁殖季节，我们对41个不同的森林斑块进行了137个固定半径的点计数调查。我们量化了禽类的分类学，行会和功能的丰富程度，并在每个调查补丁中进行了测量。我们测量了补丁大小的影响，每种多样性测度的欧氏隔离距离，斑块形状和栖息地配置（即栖息地数量）。然后，我们进行了一系列通用线性模型，以确定碎片和斑块配置如何影响森林鸟类的多样性。顶级模型中的解释变量对所有禽类多样性措施均具有显着影响，但栖息地数量却没有。斑块周围的栖息地数量对于衡量鸟类的多样性并不重要，但基于赤池的体重，这对专业物种很重要。隔离距离对鸟类多样性的测量没有显着影响。斑块形状指数的增加增加了物种的丰富度。