The importance of local environmental, hydrogeomorphological and spatial variables for beta diversity of macrophyte assemblages in a Neotropical floodplain

SCHNEIDER, BERENICE; MARCHESE, MERCEDES; ESPÍNOLA, LUIS A.; CUNHA, EDUARDO R.; THOMAZ, SIDINEI M.

JOURNAL OF VEGETATION SCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Año: 2019 vol. 30 p. 269 - 280

1100-9233

Questions: Understanding the processes that determine the variation in community composition (β-diversity) is a major challenge in ecology, evolution, and conservation. Here we assess the importance of abiotic variables associated with local environ- mental features, hydrogeomorphology, and space to explain β-diversity patterns in macrophytes by addressing the following questions: (1) Which are the sets of envi- ronmental, hydrogeomorphological, and spatial variables that contribute significantly to the spatial variation of macrophytes? (2) Which are their relative contributions to explaining the total β-diversity, nestedness and turnover of macrophyte assemblages?Study Site: Middle Paraná River floodplain, Argentina.Methods: We sampled 20 lakes at low and high water levels in the Middle Paraná River floodplain. To investigate the relationship of total β-diversity, turnover and nestedness with explanatory variables, we used the constrained analysis of principal coordinates (CAP). We used variation partitioning to assess the proportion of the variation related to each subset of variables (environmental, hydrogeomorphological and spatial).Results: Among four alternatives considered to explain the spatial structure, the dis- tance between lakes by watercourses best described the spatial organization of β- diversity. Species turnover was largely explained by hydrogeomorphological variables, followed by spatial descriptors, whereas nestedness was exclusively re- lated to spatial variables.Conclusions: In the Middle Paraná River floodplain β-diversity of macrophyte com- munities is partly shaped by turnover (mainly driven by the hydrogeomorphology of the floodplain) and nestedness (resulting from dispersal limitation by watercourses), but it also seems to be randomly organized (possibly because of random colonization and extinction, due to disturbances such as floods). Our work indicates that environ- mental pressures reflect differences between macrophyte communities of lakes with different geomorphological and hydrographical conditions. This suggests that certain ecological processes (such as species sorting) are driven at a higher degree by hy- drogeomorphology than by local environment.