Ecology. 2014 Apr;95(4):1010-21. doi: 10.1890/13-0705.1.
The installation of green roofs, defined here as rooftops with a shallow soil cover and extensive vegetation, has been proposed as a possible measure to mitigate the loss of green space caused by the steady growth of cities. However, the effectiveness of green roofs in supporting arthropod communities, and the extent to which they facilitate connectivity of these communities within the urban environment is currently largely unknown. We investigated the variation of species community composition (beta diversity) of four arthropod groups with contrasting mobility (Carabidae, Araneae, Curculionidae, and Apidae) on 40 green roofs and 40 extensively managed green sites on the ground in the city of Zurich, Switzerland. With redundancy analysis and variation partitioning, we (1) disentangled the relative importance of local environmental conditions, the surrounding land cover composition, and habitat connectivity on species community composition, (2) searched for specific spatial scales of habitat connectivity for the different arthropod groups, and (3) discussed the ecological and functional value of green roofs in cities. Our study revealed that on green roofs community composition of high-mobility arthropod groups (bees and weevils) were mainly shaped by habitat connectivity, while low-mobility arthropod groups (carabids and spiders) were more influenced by local environmental conditions. A similar but less pronounced pattern was found for ground communities. The high importance of habitat connectivity in shaping high-mobility species community composition indicates that these green roof communities are substantially connected by the frequent exchange of individuals among surrounding green roofs. On the other hand, low-mobility species communities on green roofs are more likely connected to ground sites than to other green roofs. The integration of green roofs in urban spatial planning strategies has great potential to enable higher connectivity among green spaces, so that eventually even communities of low-mobility species become connected. Furthermore, improving the design of green roofs (composition and configuration of vegetation and soil types) could enhance the ecological value, particularly for low-mobility species.
绿色屋顶的安装，这里定义为具有浅层土壤覆盖和广泛植被的屋顶，被提议作为缓解城市不断发展导致的绿地损失的一种可能措施。然而，绿色屋顶在支持节肢动物群落方面的有效性，以及它们在多大程度上促进城市环境中这些群落的连通性，目前在很大程度上还不得而知。我们调查了四个具有不同移动性的节肢动物类群（Carabidae、Araneae、Curculionidae 和 Apidae）的物种群落组成（β多样性）在瑞士苏黎世市的 40 个绿色屋顶和 40 个地面广泛管理的绿色场所中的变化。通过冗余分析和变异划分，我们（1）分离了局部环境条件、周围土地覆盖组成和生境连通性对物种群落组成的相对重要性，（2）寻找了不同节肢动物类群的特定空间尺度的生境连通性，（3）讨论了城市中绿色屋顶的生态和功能价值。我们的研究表明，在绿色屋顶上，高移动性节肢动物群（蜜蜂和象鼻虫）的群落组成主要由生境连通性决定，而低移动性节肢动物群（甲螨和蜘蛛）则更多地受到局部环境条件的影响。地面群落也出现了类似但不太明显的模式。生境连通性在塑造高移动性物种群落组成方面的重要性表明，这些绿色屋顶群落通过个体在周围绿色屋顶之间的频繁交换而在很大程度上相互连接。另一方面，绿色屋顶上低移动性物种的群落更有可能与地面站点而不是其他绿色屋顶相连。将绿色屋顶纳入城市空间规划策略具有很大的潜力，可以提高绿色空间之间的连通性，从而使最终即使是低移动性物种的群落也能相互连接。此外，改善绿色屋顶的设计（植被和土壤类型的组成和配置）可以提高生态价值，特别是对低移动性物种。
