SDE Feature Class
Biology, Land, Selected State, Conterminous United States, Ecosystem, location, environment, United States, US Ecoregion Levels III and IV, North American (CEC) Ecoregion Levels I, II, III, North Dakota, Natural Resources, Conservation, biota, Ecology, boundaries, Environment
Ecoregions by state were extracted from the seamless national shapefile. 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 52 regions (Commission for Environmental Cooperation Working Group, 1997). At Level III, the continental United States contains 104 regions whereas the conterminous United States has 84 (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, EPA6003-89060, 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 Ecoregions should be addressed to Glenn Griffith, Dynamac Corporation, co US EPA., 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4465, email:email@example.com Alternate: James Omernik, USGS, co US EPA, 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4458, email:firstname.lastname@example.org
Ecoregion maps assist managers of aquatic and terrestrial resources to understand the regional patterns of the realistically attainable quality of these resources
There are no credits for this item.
The State of North Dakota has compiled this data according to conventional cartographic standards, using what is thought to be the most reliable information available. This data is intended to make results of research available at the earliest possible date, but is not intended to constitute final or formal publication. The State of North Dakota makes every effort to provide virus-free files but does not guarantee uncorrupted files. The State of North Dakota does not guarantee this data to be free from errors, inaccuracies, or viruses, and disclaims any responsibility or liability for interpretations or decisions based on this data.
Standard Technical Controls
Although ecoregion polygons and attributes have been checked for accuracy, some errors may remain. Polygons along state borders were reviewed and updated, May 2010.
Level IV ecoregions are not complete for California and Arizona, as of May, 2010. For these states, the polygons are for Level III or lower. The field 'US_L4CODE" contains placeholder information derived from "US_L3CODE". Ecoregions were digitized at 1:250,000 scale and are intended for large geographic extents (i.e. states, multiple counties, or river basins). Use for smaller areas, such as individual counties or a 1:24,000 scale map boundary, is not recommended.
Data were collected using methods that have unknown accuracy (EPA National Geospatial Data Policy [NGDP] Accuracy Tier 10). For more information, please see EPA's NGDP at <http:epa.govgeospatialpolicies.html> <http:epa.govgeospatialpolicies.html>)
1) U.S.G.S. 1:250,000 topographic maps are used to delineate the ecoregions. The lines drawn are manually digitized or scanned to produce georeferenced electronic files. 2) All base maps are joined together and errors along the edges are resolved. 3) Topology is established and the maps are reviewed for accuracy, completeness, and conformity with the original lines. Corrections are made as needed and topology regenerated. 4) Attributes are added. 5) Maps are plotted for visual inspection by two individuals and necessary changes made. 6) Ecoregions from all available states are merged and dissolved to identify and correct inconsistencies. 7) Polygons of the corrected seamless ecoregion features are extended beyond the coastal borders. 8) State and Ecoregion datasets are intersected. 9) Topology errors removed. 10) Final QA
The state borders were derived from the dtl_st.sdc on the ArcGIS DVD provided by ESRI. It was modified by removing Alaska and Hawaii polygons and all but the State field, adding some coastal islands based on imagery or NHDPlus areas, and restoring topology (removing internal gaps and small overlaps). The EPA regions were added to this custom geodatabase (dtl_48plyf) prior to the intersection process with the seamless ecoregion data.
Internal feature number.
Sequential unique whole numbers that are automatically generated.
Coordinates defining the features.