Pillsbury Finn C, Miller James R
Department of Natural Resource Ecology and Management, 339 Science II, Iowa State University, Ames, Iowa 50011, USA.
Ecol Appl. 2008 Jul;18(5):1107-18. doi: 10.1890/07-1899.1.
Urbanization has been cited as an important factor in worldwide amphibian declines, and although recent work has illustrated the important influence of broad-scale ecological patterns and processes on amphibian populations, little is known about the factors structuring amphibian communities in urban landscapes. We therefore examined amphibian community responses to wetland habitat availability and landscape characteristics along an urban-rural gradient in central Iowa, USA, a region experiencing rapid suburban growth. We conducted call surveys at 61 wetlands to estimate anuran calling activity, and quantified wetland habitat structure and landscape context. We used canonical correspondence analysis (CCA) to examine patterns in anuran community structure and identify the most important variables associated with those patterns. Urban density at the landscape scale had a significant negative influence on overall anuran abundance and diversity. While every species exhibited a decrease in abundance with increasing urban density, this pattern was especially pronounced for species requiring post-breeding upland habitats. Anurans most affected by urbanization were those associated with short hydroperiods, early breeding activity, and substantial upland habitat use. We suggest that broad-scale landscape fragmentation is an important factor underlying anuran community structure in this region, possibly due to limitations on the accessibility of otherwise suitable habitat in fragmented urban landscapes. This study underscores the importance of a regional approach to amphibian conservation in urban and urbanizing areas; in fragmented landscapes, a network of interconnected wetland and upland habitats may be more likely to support a successful, diverse anuran community than will isolated sites.
城市化被认为是全球两栖动物数量减少的一个重要因素，尽管最近的研究表明大规模生态模式和过程对两栖动物种群有重要影响，但对于塑造城市景观中两栖动物群落的因素却知之甚少。因此，我们在美国爱荷华州中部一个郊区快速发展的地区，沿着城乡梯度研究了两栖动物群落对湿地栖息地可用性和景观特征的反应。我们在61个湿地进行了鸣声调查，以估计无尾目动物的鸣叫活动，并量化了湿地栖息地结构和景观背景。我们使用典范对应分析（CCA）来研究无尾目动物群落结构的模式，并确定与这些模式相关的最重要变量。景观尺度上的城市密度对无尾目动物的总体丰度和多样性有显著的负面影响。虽然每个物种的丰度都随着城市密度的增加而下降，但这种模式在需要繁殖后高地栖息地的物种中尤为明显。受城市化影响最大的无尾目动物是那些与短水期、早期繁殖活动和大量高地栖息地利用相关的物种。我们认为，大规模景观破碎化是该地区无尾目动物群落结构的一个重要潜在因素，这可能是由于破碎化城市景观中其他适宜栖息地的可达性受限所致。这项研究强调了在城市和城市化地区采用区域方法进行两栖动物保护的重要性；在破碎化景观中，相互连接的湿地和高地栖息地网络可能比孤立的地点更有可能支持一个成功、多样的无尾目动物群落。
