Diversidade de macrófitas aquáticas em áreas úmidas do Parque Nacional da Lagoa do Peixe, Rio Grande do Sul
Rolon, Ana Silvia
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The Lagoa do Peixe National Park is an important conservation unity, aiming to protect the wetlands, one of the most endangered type of ecosystem in the world. In Southern Brazil around 90% of the wetlands were already lost. The protected ecosystems in the park are ernationally important for biodiversity conservation and it is the unique Ramsar site in Southern Brazil. The existence of areas invaded by Pinus eliotti and the artificial breaching of the lagoon sandbar are severe problems that can threaten the biodiversity in this preservation area. The goal of this study was to evaluate the diversity of aquatic macrophyte present in the park and test some ecological hypothesis about the community diversity of aquatic macrophyte in natural areas and areas under influence of the main problems of the park (pine invasion and the sandbar breaching). To answer this questions a survey was conducted in 32 wetlands situated inside the park between 2007 and 2009. We identified 176 aquatic macrophyte species in the palustrine wetlands of the park. The aquatic macrophyte richness and composition in coastal wetlands are directly related to the isolation degree of these wetlands in relation to the source wetland and other closer wetlands. The wetland area was not a significant factor for the spatial structure of the aquatic macrophyte community. Other determinant factors for the community were habitat diversity and hydroperiod. The influence of those environmental characteristics was different among the macrophyte groups defined as: hydrophytes, palustrine, and amphibious. The presence of pine resulted in a decrease in macrophyte richness, and the species composition in this area is, in a general way, a subset of the species found in natural wetlands. The artificial sandbar breaching did not affect the richness of aquatic macrophytes in the floodplain wetlands of Lagoa do Peixe. However, in this areas affected by the sandbar breaching, the community composition 4 was characterized by a pattern of continuous species replacement during the two-year study. These results provide important information for wetland management in the park.