CONCEPTUALIZED TOPOSEQUENCE OF LAGUNA ATASCOSA NATIONAL WILDLIFE REFUGE IN SOUTH TEXAS

Laguna Atascosa National Wildlife Refuge (LANWR) is the largest protected area of natural habitat in the Lower Rio Grande Valley of Texas. This area is an exclusive complex coastal margin system located 25 miles north of Brownsville along the hypersaline Laguna Madre and is managed to preserve the natural diversity and abundance of an ecologically important mix of waterfowl and wildlife with over 400 species of native, wintering, and migratory birds. Understanding landscape changes in this region is important for the preservation of this unique habitat, which starts with the soils. Soil systems are not static, but are complex systems that are subject to natural influences from hurricanes, drought, and sea-level change. Soil systems are subject to impacts from human modifications such as urbanization, increased agricultural activity, dredging to channel water, and water management. These impacts all influence the health of coastal ecosystems. In response plant communities fluctuate in population and distribution. In this region, the primary anthropogenic threat to the ecological integrity of natural plant communities in recent years has been the increased development of the surrounding coastal areas. The land-use in the Lower Rio Grande valley is increasingly switching from agriculture to commercial and residential development. These land changes have redirected the natural drainage patterns and have reduced the amount of fresh water flowing into LANWR impacting the diversity and extent of important terrestrial and wetland plant communities. Visualization is important for understanding these changes and can be used for land management, environmental resource monitoring, and predicting changes to coastal vegetation patterns where water availability and soil salinity both impact plant community locations and ultimately the wintering and migratory bird populations. To help visualize the system a conceptualized toposequence, or profile, was created by correlating topography, soil type, soil conductivity, and vegetation based on site similarities. The toposequence can then be used to help local refuge authorities conceptualize water flow, soil conductivity changes, and their impact on localized vegetation and ultimately bird populations within the refuge.