Tuesday, August 5, 2008: 2:30 PM
102 B, Midwest Airlines Center
Michael J. Osland, Wetland and Aquatic Research Center, U.S. Geological Survey, Lafayette, LA, Curtis J. Richardson, Nicholas School of the Environment, Duke University, Durham, NC and Eugenio González, Organization for Tropical Studies, San Pedro, Costa Rica
Background/Question/Methods Cattail (Typha spp.) expansion can greatly modify important wetland ecosystem structure and functions. Although disturbances are frequently used to restrict cattail expansion, the impact and sustainability of such practices are rarely investigated. The objective of this study was to investigate the impact of cattail management on the plant community, soil properties, and avian habitat in a neotropical wetland. Typha domingensis coverage has increased dramatically in the freshwater marshes of Palo Verde National Park (Costa Rica) forming monocultures with culms up to 5 m tall. Park managers currently use a combination of physical disturbance followed by seasonal flooding to reduce cattail expansion and restore avian habitat. In our experiment, cattail management was applied at three levels: control, physical disturbance, and a combination of physical disturbance and grazing. Plant percent cover and recruitment were measured monthly during the first dry season. Plant percent cover was also determined after flooding in the first wet season and will be determined at the end of the second dry season. Additional measurements included avian visitation, soil seed bank composition and emergence, various physical and chemical soil properties, and cattail biomass, height, and density.
Results/Conclusions
Physical disturbance did not alter most soil properties including bulk density. As expected, plant diversity increased, avian diversity increased, and cattail density and cover decreased after disturbance. The seed bank in these wetlands is rich and recruitment was high following cattail removal. Flooding resulted in a shift in plant community composition as flood-tolerant species became more dominant. Physical disturbance appears to be an effective way to restrict cattail expansion in the short-term. However, surveys in subsequent years will help gauge the long-term sustainability of these control efforts.
