Centre for Research on Ecological Impacts of Coastal Cities, Marine Ecology Laboratories A11, School of Biological Sciences, The University of Sydney, Sydney, Australia.
PLoS One. 2013 Apr 8;8(4):e61349. doi: 10.1371/journal.pone.0061349. Print 2013.
Despite edges being common features of many natural habitats, there is little general understanding of the ways assemblages respond to them. Every edge between two contrasting habitats has characteristics governed by the composition of adjoining habitats and/or by the nature of any transitions between them. To develop better explanatory theory, we examined the extent to which edges act independently of the composition of the surrounding landscape and to which transitions between different types of habitats affect assemblages. Using experimental landscapes, we measured the responses of assemblages of marine molluscs colonising different experimental landscapes constructed with different compositions (i.e. different types of habitats within the landscape) and different types of transitions between habitats (i.e. sharp vs gradual). Edge effects (i.e. proximity to the edge of the landscape) were independent of the internal composition of experimental landscape; fewer species were found near the edges of landscapes. These reductions may be explained by differences in differential larval settlement between edges and interiors of experimental landscapes. We also found that the sharpness of transitions influenced the magnitude of interactions in the different types of habitats in experimental landscapes, most probably due to the increased number of species in areas of transition between two habitats. Our experiments allowed the effects of composition and transitions between habitats to be disentangled from those of proximity to edges of landscapes. Understanding and making predictions about the responses by species to edges depends on understanding not only the nature of transitions across boundaries, but also the landscape in which the edges are embedded.
尽管边缘是许多自然栖息地的共同特征，但人们对生物群落如何对边缘做出反应的了解甚少。每一个连接两个截然不同栖息地的边缘都具有由毗邻栖息地的组成以及它们之间任何过渡的性质所决定的特征。为了发展更好的解释性理论，我们研究了边缘在多大程度上独立于周围景观的组成，以及不同类型的栖息地之间的过渡在多大程度上影响生物群落。我们使用实验景观来测量不同实验景观中海洋软体动物群落对不同组成（即景观内不同类型的栖息地）和不同类型的栖息地过渡（即急剧与逐渐过渡）的反应。边缘效应（即靠近景观边缘）与实验景观的内部组成无关；在景观边缘附近发现的物种较少。这些减少可能是由于边缘和实验景观内部之间的幼虫定居差异造成的。我们还发现，过渡的尖锐程度影响了实验景观中不同类型栖息地之间相互作用的程度，这很可能是由于两个栖息地之间过渡区域的物种数量增加所致。我们的实验允许将栖息地的组成和过渡的影响与靠近景观边缘的影响区分开来。了解物种对边缘的反应取决于不仅要了解跨越边界的过渡的性质，还要了解边缘所嵌入的景观。
