Drivers of the beta diversity of aquatic plant communities along a latitudinal gradient in southern Brazilian coastal ponds

Abstract

Abstract Questions Is macrophyte beta diversity in temporary ponds generated mainly by turnover along a latitudinal gradient? Is macrophyte beta diversity more strongly correlated with differences in local environmental conditions and climate than geographical distances? Are hydrophytes and helophytes correlated with distinct environmental drivers? Location Southern Brazilian Coastal Plain. Methods Macrophyte communities were studied in 24 ponds distributed along a latitudinal gradient. Beta diversity was calculated with the Sorensen dissimilarity index (and further partitioned into turnover and nestedness components). We assessed the individual correspondence of macrophyte beta diversity with local (water quality and habitat structure; after pre‐selection procedures on each explanatory matrix) and climatic environmental drivers, as well as with the geographical distances, through Mantel correlation tests. Partial Mantel tests were carried out to assess the correspondence of beta diversity with the climatic drivers and geographical distances while controlling for the effect of each explanatory matrix. Separate assessments were carried out for subsets of hydrophytes and helophytes. Results Macrophyte beta diversity was mainly generated by turnover. Mantel tests detected significant correlations of macrophyte beta diversity with climatic rather than with local environmental drivers. Partial Mantel tests detected significant relationships only between macrophyte beta diversity and climate (rather than geographical distances). Helophytes were more strongly correlated with climate than hydrophytes, and geographical distances were significantly correlated to hydrophyte beta diversity only. Conclusions Our results indicate that macrophyte communities in southern Brazilian coastal temporary ponds are mainly assembled by species sorting processes, although the contribution of each assembly mechanism differed between functional groups (spatial processes were more important for hydrophytes than helophytes). The distinct relationships of hydrophytes and helophytes with climate suggest different sensitivity of each functional group to environmental changes in temporary ponds.