Environmental filtering and spatial processes have been associated with variation in ecological communities and biodiversity; however, their relative importance on multiple dimensions of beta diversity has not been fully explored in montane streams. Here, we examined the relative contribution of local, catchment and climate environmental variables and spatial factors to variation in three dimensions of macroinvertebrate beta diversity in the upper Han River Basin. Taxonomic, functional, and phylogenetic beta diversities and their respective turnover and nestedness components were calculated for macroinvertebrate assemblages sampled in a total of 130 stream sites across a large mountainous landscape. We investigated the correlations between beta diversity facets using MSR-Mantel procedure and then examined the relative influence of each set of ecological factors through redundancy analysis and variance partitioning. Our results revealed relatively low spatial congruence among beta diversity dimensions, indicating these diversity dimensions are independent measures which offer complementary information of community assembly. Beta diversity dimensions and components were best explained by spatial and local environmental factors, whereas the large-scale catchment and climate factors appeared less influential. Moreover, spatial and environmental factors generally exerted different controls on beta diversity depending on the dimensions under consideration. Taxonomic and phylogenetic beta diversities were more strongly determined by spatial factors via dispersal limitation, while functional beta diversity was mainly associated to local environments through habitat filtering. Our results challenge the perspective that using one diversity facet as a surrogate for others is enough, and highlight the need to integrate multiple diversity dimensions in metacommunity and biodiversity research.

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