Spatial correlates of floristic and structural variation in a Neotropical wetland forest

Despite the ecological importance of wetland forests, their classification is still unsatisfactory, partly due to insufficient knowledge about the environmental drivers of their spatial heterogeneity. We examined the spatial variation of six community attributes in a tropical wetland forest and analyzed the underlying causes by using linear distance measures and geomorphological zonation as proxies of environmental heterogeneity. The study was conducted in a wetland forest located on a coastal plain of southern Mexico. Vegetation was sampled in two distinct landforms: coastal lagoon and river channel. For each plot we determined two other proxies of environmental variation, namely distance to the sea, and distance to closest water body. We assessed the effects of these environmental factors on wetland forest attributes through linear modelling. Except for species richness, all other attributes were heterogeneous across space, with aboveground biomass showing the largest variation. Overall, forest structural attributes in plots located along the highly dynamic main river channel were higher than those recorded around a relatively stable coastal lagoon, suggesting better conditions for wetland forest development in the former area. Models consistently included geomorphological zone, as well as distance proxies in most of them, with variable effects on community attributes. The spatial variation of this wetland forest was associated with different combinations of environmental proxies, with geomorphology being a key driver of this variability. A thorough understanding of the factors driving the spatial variation of wetland forests will lead to a more sensible ecological classification.