Community assembly studies are very important for explaining the formation and maintenance of biodiversity, so they have continually been a hot topic in the field of ecology. Under niche-based processes, environmental filtering and the species interactions are considered as the most fundamental drivers of community assembly. In particular, environmental filtering is often determined as the driving force of community assemblages processes. It is well known that environmental filtering as a deterministic pattern of community assemblages, inevitably leads to a decreasing range of traits value and increasing niche overlap. From the perspective of phylogeny and traits, environmental filtering will lead to a tighter correlation of coexisting species or more similarity of specific traits. Hence, the dissimilarity of phylogenetic and functional pattern varying along the environmental gradient is an effective tool to explore the driver of community assembly processes.Are there any phylogenetic signals in functional trait data? Does environmental filtering drive the community assembly process along the environmental gradient? What environmental factor is the most crucial in community assembly process? Sixty plots were located along the downstream Yellow River. Seven functional traits and a phylogenetic tree were used to estimate beta diversity using the standardized effect size along environmental gradient. We tested the phylogenetic signals in trait data using the Blomberg’s K statistic. The key environmental factor was assessed via the variance partitioning method.
Results/Conclusions
The phylogenetic and functional beta diversity showed clustering patterns, with the exception of leaf nitrogen concentration and leaf phosphorus concentration. The standardized effect sizes based on multi-traits, maximum height, leaf dry matter content were significantly linearly related to environmental gradient, and all of the traits had weak significant phylogenetic signals (K < 1). The soil salinity in edaphic variables provided the best explanation of the phylogenetic and functional turnover. Our results demonstrate that environmental filtering is the driver of plant community assemblages in the riparian marsh of downstream Yellow River. However, we also find that some inconsistent patterns exist in our results when we estimate beta diversity based on univariate trait and phylogeny. Therefore, we do not ignore the potential influence of other ecological processes in community assembly. Moreover, the edaphic variables explain the most variance in phylogenetic and functional turnover between communities. Especially soil salinity, which has good explanatory power to whole traits and phylogeny, is the key environmental factor influencing plant community assembly in the riparian marsh of downstream Yellow River.