Considerations on the ecology of wetlands with emphasis on brasilian floodplain ecosystems

Resumo

This essay presents a synthesis of the main aspects of wetland ecology, emphasizing Brazilian systems. Problems regarding the definition of these areas are discussed, and historical considerations on their use by humans are presented. The phenomenon of flooding and drought is considered, in an ecological context, as the principal agent interrupting the successional process, which in these ecosystems is notably maintained in its initial stages. The role of flooding and drought as ecological stress factors for wetland communities is also discussed. In Brazilian wetlands, organisms are adapted at different levels of flood and drought conditions. Plant communities contain many r-strategist species, characterized by their capacity to produce many seeds and their high rate of short-term primary productivity. Special attention is given to the river-floodplain system, as one of the most important wetland systems in Brazil. The role of the flood pulse in the community dynamics of these systems, emphasizing especially the plant communities (phytoplankton, aquatic macrophytes, and floodplain forest, is discussed.