Geographically Isolated Wetlands of the Coterminous United States

Abstract:

It has been suggested that “geographically isolated” wetlands (GIWS) are important landscape elements involved in hydrologic, biogeochemical, and biological functioning, and that their influence, under certain circumstances, can significantly affect other waters of the Unites States. The presence of wetland connectivity with waters of the United States remains an important determination. At the national level we have had estimates of the abundance of GIWs, but no spatially explicit calculations or data, frustrating efforts to quantify the presence and effects of connectivity at significant and relevant scales. Using the National Wetland Inventory and the National Hydrography Dataset, we quantified the abundance and spatial extent of GIWs across the coterminous United States. Approximately 15% of the wetlands of the coterminous United States were identified as putative “geographically isolated” wetlands, almost one million discrete wetlands covering ~65,000 km². We provide analyses of the types, distributions, and regional extent of these systems and explore connectivity measures associated with adjacency and so-called isolation. This geospatial database will be made available for analyses.