United States Forest Service Ecological Subregions of the U.S.A

This data set represents ecological subregions within the conterminous United States. This data set contains regional geographic delineations for analysis of ecological relationships across ecological units. The U.S. Department of Agriculture (USDA), Forest Service, in participation with numerous individuals of Federal and State agencies and nongovernmental organizations (NGOs), has been developing and refining ecological maps of the United States through the process of peer review and successive approximations since 1976 (Bailey 1976). Ecological mapping and descriptions follow the USDA Forest Service's National Hierarchical Framework of Ecological Units (ECOMAP 1993, Cleland et al. 1997). This 2007 map is the first approximation of subregion ecological units developed for the conterminous United States. Alaska, Hawaii, and Puerto Rico were not included because of the additional time that would be needed for coordination and peer review for those areas. Ecological mapping continues for those areas, and they will be included in the near future. This subregional (sections and subsections) presentation represents an effort to develop units that integrate, in an ecologically meaningful way, information from individual disciplines, single purpose maps, and existing regionalizations. This interdisciplinary approach highlighted the need for continued efforts to overcome geopolitical and administrative bias in primary data sources. Development of ecological units and descriptive data is an iterative process that will progress as additional information becomes available and from peer review and comments by users of this information (ECOMAP 2007). Many national, regional, and State sources of information were used in identifying ecological subregions. Some significant sources included Quaternary Geologic Atlas of the United States, U.S. Geological Survey; State Soil Geographic Soil Database, Natural Resources Conservation Service; Ecoregions and Subregions, Environmental Protection Agency; Hammond's Classes of Land Surface Form, U.S. Geological Survey; State Natural Heritage maps and classifications; physiographic maps; land cover types; and State Natural Habitat regions. The data are represented at a scale of 1:3,500,000.