Rivers are heterogeneous and patchy-structured systems in which regional biodiversity of aquatic communities typically varies as a function of local habitat conditions and spatial gradients. Understanding which environmental and spatial constraints shape the diversity and composition of benthic communities is therefore a pivotal challenge for basic and applied research in river ecology. In this study, benthic invertebrates were collected from 27 sites across three hydro-ecoregions with the aim of investigating patterns in α- and β diversity. We first assessed the contribution to regional biodiversity of different and nested spatial scales, ranging from micro-habitat to hydro-ecoregion. Then, we tested differences in α diversity, taxonomic composition and ecological uniqueness among hydro-ecoregions. Variance partitioning analysis was used to evaluate the mechanistic effects of environmental and spatial variables on the composition of macroinvertebrate communities. Macroinvertebrate diversity was significantly affected by all the spatial scales, with a differential contribution according to the type of metric. Sampling site was the spatial scale that mostly contributed to the total richness, while the micro-habitat level explained the largest proportion of variance in Shannon–Wiener index. We found significant differences in the taxonomic composition, with 39 invertebrate families significantly associated with one or two hydro-ecoregions. However, effects of environmental and spatial controls were context dependent, indicating that the mechanisms that promote beta diversity probably differ among hydro-ecoregions. Evidence for species sorting, due to natural areas and stream order, was observed for macroinvertebrate communities in alpine streams, while spatial and land-use variables played a weak role in other geographical contexts.

河流是异质和斑驳结构的系统，其中水生社区的区域生物多样性通常根据当地生境条件和空间梯度而变化。因此，了解哪些环境和空间限制会影响底栖生物的多样性和组成是河流生态学基础研究和应用研究的关键挑战。在这项研究中，底栖无脊椎动物是从三个水生生态区的27个地点收集的，目的是调查α-和β多样性的模式。我们首先评估了从微型栖息地到水生态区域的不同和嵌套的空间尺度对区域生物多样性的贡献。然后，我们测试了α的差异生态区之间的多样性，分类学组成和生态独特性。方差分区分析用于评估环境和空间变量对大型无脊椎动物群落组成的机械作用。大型无脊椎动物的多样性受到所有空间尺度的显着影响，根据度量类型的不同会有不同的贡献。采样地点是主要影响总丰富度的空间尺度，而微观生境水平解释了香农-维纳指数中最大的方差比例。我们发现分类学组成上存在显着差异，有39个无脊椎动物家族与一个或两个水生态区显着相关。但是，环境和空间控制的影响取决于上下文，表明促进β多样性的机制在水生态区域之间可能有所不同。观察到由于自然面积和溪流顺序而对物种进行分类的证据，表明高山溪流中的无脊椎动物群落，而空间和土地利用变量在其他地理环境中的作用很弱。