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Level IV Ecoregions of the Conterminous United States

Metadata Updated: March 22, 2024

Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources. They are designed to serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components. These general purpose regions are critical for structuring and implementing ecosystem management strategies across federal agencies, state agencies, and nongovernment organizations that are responsible for different types of resources within the same geographical areas. The approach used to compile this map is based on the premise that ecological regions can be identified through the analysis of patterns of biotic and abiotic phenomena, including geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another. A Roman numeral hierarchical scheme has been adopted for different levels for ecological regions. Level I is the coarsest level, dividing North America into 15 ecological regions. Level II divides the continent into 50 regions (Commission for Environmental Cooperation Working Group, 1997). At Level III, the continental United States contains 105 regions whereas the conterminous United States has 85 (U.S. Environmental Protection Agency, 2005). Level IV ecoregions are further subdivisions of Level III ecoregions. Methods used to define the ecoregions are explained in Omernik (1995, 2004), Omernik and others (2000), and Gallant and others (1989). Literature cited: Commission for Environmental Cooperation Working Group, 1997, Ecological regions of North America- toward a common perspective: Montreal, Commission for Environmental Cooperation, 71 p. Gallant, A. L., Whittier, T.R., Larsen, D.P., Omernik, J.M., and Hughes, R.M., 1989, Regionalization as a tool for managing environmental resources: Corvallis, Oregon, U.S. Environmental Protection Agency, EPA/600/3-89/060, 152p. Omernik, J.M., 1995, Ecoregions - a framework for environmental management, in Davis, W.S. and Simon, T.P., eds., Biological assessment and criteria-tools for water resource planning and decision making: Boca Raton, Florida, Lewis Publishers, p.49-62. Omernik, J.M., Chapman, S.S., Lillie, R.A., and Dumke, R.T., 2000, Ecoregions of Wisconsin: Transactions of the Wisconsin Academy of Science, Arts, and Letters, v. 88, p. 77-103.Omernik, J.M., 2004, Perspectives on the nature and definitions of ecological regions: Environmental Management, v. 34, Supplement 1, p. s27-s38. Comments and questions regarding the Level III and IV Ecoregions should be addressed to Glenn Griffith, USGS, c/o US EPA., 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4465, email:griffith.glenn@epa.gov Alternate: James Omernik, USGS, c/o US EPA, 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4458, email:omernik.james@epa.gov

Access & Use Information

License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

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Dates

Metadata Date April 16, 2013
Metadata Created Date March 22, 2024
Metadata Updated Date March 22, 2024
Reference Date(s) April 16, 2013 (publication)
Frequency Of Update asNeeded

Metadata Source

Harvested from Environmental Dataset Gateway ISO Geospatial Metadata

Additional Metadata

Resource Type Dataset
Metadata Date April 16, 2013
Metadata Created Date March 22, 2024
Metadata Updated Date March 22, 2024
Reference Date(s) April 16, 2013 (publication)
Responsible Party U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory (NHEERL) (Point of Contact)
Contact Email
Guid {90263ACC-6C39-45C6-B006-E253837A8E65}
Access Constraints Use Constraints: None. Please check sources, scale, accuracy, currentness and other available information. Please confirm that you are using the most recent copy of both data and metadata. Acknowledgement of the EPA would be appreciated., Access Constraints: None.
Bbox East Long -65.345754
Bbox North Lat 51.604869
Bbox South Lat 22.896808
Bbox West Long -127.886770
Coupled Resource
Frequency Of Update asNeeded
Harvest Object Id 1d3816f7-24d3-49e3-a70a-954d73cc431a
Harvest Source Id 9b3cd81e-5515-4bb7-ad3c-5ae44de9b4bd
Harvest Source Title Environmental Dataset Gateway ISO Geospatial Metadata
Licence https://edg.epa.gov/EPA_Data_License.htm
Licence Url https://edg.epa.gov/EPA_Data_License.htm
Lineage This lineage was generated by the FGDC CSDGM to 19139 transformation
Metadata Language eng; USA
Metadata Type geospatial
Old Spatial {"type": "Polygon", "coordinates": [[[-127.88677, 22.896808], [-65.345754, 22.896808], [-65.345754, 51.604869], [-127.88677, 51.604869], [-127.88677, 22.896808]]]}
Progress underDevelopment
Spatial Data Service Type
Spatial Reference System
Spatial Harvester True

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