Effects of environmental filtering and dispersal limitation on the β-diversity of coastal wetland plant communities

The spatial distribution of plant communities is often explained by the joint effects of environmental filtering and dispersal limitation. However, the relative importance of these two processes in shaping plant β-diversity patterns (which characterize environmental gradients and ecological processes) in coastal wetlands remains insufficiently explored, and it is still unclear how anthropogenic disturbances influence such patterns. In this study, we examined the β-diversity patterns of plant communities along 10 parallel transects spanning a human-impacted zone (with constructed embankments) and a natural coastal wetland zone within the coastal wetlands of the Yellow River Delta. Differences in plant communities between the two zones were assessed by principal coordinates analysis. β-diversity was partitioned using a distance matrix-based variation partitioning analysis, and the generalized dissimilarity model (GDM) was applied to identify its main drivers. Plant community composition differed significantly between the two zones (PERMANOVA, R 2 = 0.18, p < 0.01). The overall β-diversity was predominantly composed of the turnover component, which accounted for 60.59% and 55.84% of the total dissimilarity in the natural and human-impacted zones, respectively. Accordingly, the process shaping this dominant component shifted from environmental filtering in the natural zone to dispersal limitation in the human-impacted zone. The GDM analyses showed that, in the natural coastal wetland zone, β-diversity was primarily driven by environmental factors, particularly salinity (54.73%; p = 0.02) and elevation (30.23%; p = 0.04), whereas in the human-impacted zone, spatial distance (54.26%; p = 0.04) was the main driver. Our results demonstrate that anthropogenic disturbances reconfigure the dominant assembly processes, shifting plant community β-diversity from environmental filtering to dispersal limitation. These findings have implications for the conservation of coastal wetlands; that is, conservation efforts should target areas with intact vegetation communities spanning from the sea to the land. • Species turnover dominates community assembly in both natural and human-disturbed coastal wetlands. • Environmental filtering in natural zones versus dispersal limitation in human-disturbed zones. • Community structure is primarily governed by gradients in salinity and elevation.