Influences of landscape and climatic factors on aquatic macrophyte richness and composition in ponds

There has been no consensus reached regarding the influences of landscape and climatic factors on aquatic macrophyte assemblages and their functional groups in wetlands. This study aimed to verify: 1) if landscape factors (habitat amount, isolation and land use), physiography and climatic factors (temperature and precipitation) relate to richness and composition of aquatic macrophytes in subtropical ponds; 2) whether these factors relate to functional groups differently (amphibious, emergent, floating and submerged). To accomplish these aims, plants were collected from 40 ponds in two physiographic regions of differing geomorphological age. Landscape variables were measured using GIS tools and FRAGSTATS software. The climatic variables were obtained from the WorldClim database. Habitat amount was negatively related to total species richness, while isolation, agricultural area and precipitation were positively related to it, possibly due to second-order effects, e. g., interspecific interactions or trophic control. Physiography, pond size and diversity of landscape use were related to species composition. Number of patches and pond size were positively related to emergent and floating species, and isolation was negatively associated with the richness of amphibious species, likely due to their dispersal strategies. We conclude that physiography was related to the structure of some aquatic macrophyte functional groups of subtropical ponds.