Gavish Yoni, Ziv Yaron
Spatial Ecology Lab, Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
PLoS One. 2016 Dec 29;11(12):e0168417. doi: 10.1371/journal.pone.0168417. eCollection 2016.
Understanding the main processes that affect community similarity have been the focus of much ecological research. However, the relative effects of environmental and spatial aspects in structuring ecological communities is still unresolved and is probably scale-dependent. Here, we examine the effect of habitat identity and spatial distance on fine-grained community similarity within a biogeographic transition zone. We compared four hypotheses: i) habitat identity alone, ii) spatial proximity alone, iii) non-interactive effects of both habitat identity and spatial proximity, and iv) interactive effect of habitat identity and spatial proximity. We explored these hypotheses for spiders in three fragmented landscapes located along the sharp climatic gradient of Southern Judea Lowlands (SJL), Israel. We sampled 14,854 spiders (from 199 species or morphospecies) in 644 samples, taken in 35 patches and stratified to nine different habitats. We calculated the Bray-Curtis similarity between all samples-pairs. We divided the pairwise values to four functional distance categories (same patch, different patches from the same landscape, adjacent landscapes and distant landscapes) and two habitat categories (same or different habitats) and compared them using non-parametric MANOVA. A significant interaction between habitat identity and spatial distance was found, such that the difference in mean similarity between same-habitat pairs and different-habitat pairs decreases with spatial distance. Additionally, community similarity decayed with spatial distance. Furthermore, at all distances, same-habitat pairs had higher similarity than different-habitats pairs. Our results support the fourth hypothesis of interactive effect of habitat identity and spatial proximity. We suggest that the environmental complexity of habitats or increased habitat specificity of species near the edge of their distribution range may explain this pattern. Thus, in transitions zones care should be taken when using habitats as surrogate of community composition in conservation planning since similar habitats in different locations are more likely to support different communities.
了解影响群落相似性的主要过程一直是许多生态学研究的重点。然而，环境和空间因素在构建生态群落中的相对作用仍未得到解决，并且可能依赖于尺度。在这里，我们研究了生境特征和空间距离对生物地理过渡区内细粒度群落相似性的影响。我们比较了四个假设：i）仅生境特征，ii）仅空间邻近性，iii）生境特征和空间邻近性的非交互作用，以及iv）生境特征和空间邻近性的交互作用。我们在以色列犹大南部低地（SJL）陡峭气候梯度沿线的三个破碎景观中，针对蜘蛛探究了这些假设。我们在35个斑块中采集了644个样本，对14854只蜘蛛（来自199个物种或形态物种）进行了采样，并将其分层到九个不同的生境中。我们计算了所有样本对之间的Bray-Curtis相似性。我们将成对值分为四个功能距离类别（同一斑块、同一景观中的不同斑块、相邻景观和遥远景观）和两个生境类别（相同或不同生境），并使用非参数多变量方差分析进行比较。我们发现生境特征和空间距离之间存在显著的交互作用，即同生境对和异生境对之间的平均相似性差异随着空间距离的增加而减小。此外，群落相似性随着空间距离的增加而衰减。此外，在所有距离上，同生境对的相似性都高于异生境对。我们的结果支持生境特征和空间邻近性交互作用的第四个假设。我们认为，生境的环境复杂性或物种在其分布范围边缘附近增加的生境特异性可能解释了这种模式。因此，在过渡区进行保护规划时，当使用生境作为群落组成的替代指标时应谨慎，因为不同位置的相似生境更有可能支持不同的群落。
