Environmental range per unit space determines a unimodal pattern of species richness along a heterogeneity gradient

Although many studies have focused on the effects of the environment and area on local patterns of species richness, few studies have demonstrated how to reconcile the availability of more niches with smaller habitat areas in heterogeneous localities. Here, the environmental range that a species prefers was defined as a niche; a space was defined as an available space if the environmental range of the space matches a niche; and the metric “environmental range per unit space (ERUS)” was presented to describe the heterogeneity of localities. Because the spaces with stressful environmental ranges, outside the niche, increased with increasing heterogeneity, available spaces did not continue to indefinitely increase, but the proportion of available spaces in spaces was low at high heterogeneous localities. Consequently, the probability of species occurring in their respective available spaces was unimodal. Due to the presence of large spaces in homogenous localities and more spaces in hetero...

尽管已有诸多研究探讨了环境与面积对物种丰富度局域分布格局的影响，但鲜有研究阐明如何在异质局域生境中，协调更多生态位(niche)可获得性与更小栖息地面积之间的矛盾。本研究将物种偏好的环境范围定义为生态位；若某空间的环境范围与某一生态位匹配，则将该空间视为可利用空间；同时提出“单位空间环境范围（environmental range per unit space，缩写ERUS）”这一指标，用以表征局域生境的异质性。由于生态位之外的胁迫性环境范围对应的空间会随异质性升高而增加，因此可利用空间不会持续无限增长；且在异质性极高的局域生境中，可利用空间的占比偏低。由此，物种在其对应可利用空间中出现的概率呈单峰分布。鉴于均质生境中存在大面积空间，而异质生境中则拥有更多空间……