Content Description
Abstract: 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. By recognizing the spatial differences in the capacities and potentials of ecosystems, ecoregions stratify the environment by its probable response to disturbance (Bryce, Omernik, and Larsen, 1999). Ecoregions are general purpose regions that 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 in the same geographical areas (Omernik and others, 2000). A Roman numeral hierarchical scheme has been adopted for different levels of ecological regions. Level I is the coarsest level, dividing North America into 15 ecological regions. Level II divides thecontinent into 52 regions (Commission for Environmental Cooperation Working Group, 1997). At level III, the continental United States contains 104 ecoregions and the conterminous United States has 84 ecoregions (U.S. Environmental Protection Agency [USEPA], 2003). Level IV ecoregions are further subdivisions of level III ecoregions. Methods used to define the USEPA's ecoregions are explained in Omernik (1995), Omernik and others (2000), and Gallant and others (1989). The approach used to compile the ecoregions of Arkansas is based on the premise that ecological regions can be identified through the analysis of the spatial patterns and the composition of biotic and abiotic characteristics that affect or reflect differences in ecosystem quality and integrity (Wiken, 1986; Omernik, 1987, 1995). These characteristics include geology, physiography, climate, soils, land use, wildlife, fish, hydrology, and vegetation (including "potential natural vegetation" defined by Ku:chler(p. 2, 1964) as "vegetation that would exist today" if human influence ended and "the resulting plant succession" was "telescoped into a single moment"). The relative importance of each characteristic varies from one ecological region to another regardless of ecoregion hierarchical level. In Arkansas, there are 7 level III ecoregions and 32 level IV ecoregions; all but four of these level IV ecoregions are also found in ecologically similar parts of adjacent states (Chapman and others, 2002, 2004a, 2004b; Griffith, Omernik, and Azevedo, 1998). Arkansas' ecological diversity is strongly related to regional physiography, geology, soil, climate, and land use. Elevated karst plateaus, folded mountains, agricultural valleys, forested uplands, and bottomland forests occur. Fire-maintained prairie was once extensive in several parts of the state. The ecoregion were compiled at a scale of 1:250,000, and depict revisions and subdivisions of earlier level III ecoregions that wereoriginally compiled at a smaller scale (U.S. Environmental Protection Agency, 2003; Omernik, 1987). It is part of a collaborative project primarily between USEPA Region 6, USEPA-National Health and Environmental Effects Research Laboratory (Corvallis, Oregon), and the Multi-Agency Wetland Planning Team (MAWPT), which comprises representatives of six Arkansas state agencies (Arkansas Natural Heritage Commission, Arkansas Soil and Water Conservation Commission, Arkansas Game and Fish Commission, Arkansas Department of Environmental Quality, Arkansas Forestry Commission, and University of Arkansas Cooperative Extension Service). Collaboration and consultation also occurred with the U.S. Army Corps of Engineers (USACE), U.S. Department of Agriculture-Natural Resources Conservation Service (NRCS), U.S. Geological Survey (USGS), U.S. Fish and Wildlife Service, USGS-Earth Resources Observation Systems Data Center, and University of Arkansas-Center for Advanced SpatialTechnologies. This project is associated with an interagency effort to develop a common framework of ecological regions (McMahon and others, 2001). Reaching that objective requires recognition of the differences in the conceptual approaches and mapping methodologies applied to develop the most common ecoregion-type frameworks, including those developed by the U.S. Department of Agriculture-Forest Service (Bailey and others, 1994), the USEPA (Omernik 1987, 1995), and the U.S. Department of Agriculture-Soil Conservation Service (1981). As each of these frameworks is further refined, their differences are becoming less discernible. Each collaborative ecoregion project, such as this one in Arkansas, is a step toward attaining consensus and consistency in ecoregion frameworks for the entire nation.Comments and questions regarding the Level III and IV Ecoregions of Arkansas should be addressed to Alan Woods, Oregon State University, c/o US EPA., 200 SW 35th Street, Corvallis, OR 97333, (541) 754-4469, email: woods.alan@epa.gov, or to James Omernik, USGS, c/o US EPA, 200 SW 35th Street, Corvallis, OR 97333, (541) 754-4458, email: omernik.james@epa.gov.
Purpose: The purpose of this data set is to assist managers of aquatic and terrestrial resources in understanding the regional patterns of the realistically attainable quality of these resources.
Supplemental Information: Procedures_Used:1) All ecoregion delineations are digitized from the U.S.G.S. 1:250,000 base maps. Prior to digitizing each base map must be initialized to orient the map and relate it in geographic coordinates to the surface of the earth. When the registration tics are entered at the start of digitizing a transformation error of <0.003 must be achieved in order to insure a high level of registration accuracy. The person responsible for digital data entry completes a data sheet describing coverage name, date of entry, and whether a topology for the coverage is established.2) After each 1:250,000 base map has been digitized, a topology for each coverage is established. This function creates unique identities.3) Next each base map is tested for polygon errors through an internal editing function. Errors are corrected for unlabeled polygons, unclosed polygons, or polygons with more than one label. Topology is reestablished for each coverage and tested again until no error are indicated.4) The digital coverage is then plotted at the same scale as the original base map. This coverage is overlaid on a light table with the original and visually inspected for replication of original lines with digitized lines. Two individuals independently inspect the coverage for accuracy.Reviews_Applied_to_Data1. Lines and map were reviewed by multiple state and federal personnel2. Revised lines were reviewed by Alan Woods, OSU, and Glenn Griffith, Dynamac, Inc., c/o US EPA3. Revisions were reviewed by Alan Woods, OSU, and Glenn Griffith, Dynamac, Inc., c/o US EPALiterature Cited: Bailey, R.G., Avers, P.E., King, T., and McNab, W.H., editors, 1994, Ecoregions and subregions of the United States (map): Washington, D.C., U.S. Department of Agriculture-Forest Service, map scale 1:7,500,000.Bryce, S.A., Omernik, J.M., and Larsen, D.P., 1999, Ecoregions - a geographic framework to guide risk characterization and ecosystem management: Environmental Practice, v. 1, no. 3, p. 141-155.Chapman, S.S., Griffith, G.E., Omernik, J.M., Comstock, J.A., Beiser, M.C., and Johnson, D., 2004a, Ecoregions of Mississippi (color poster with map, descriptive text, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey, map scale 1:1,000,000.Chapman, S.S., Kleiss, B.A., Omernik, J.M., Foti, T.L., and Murray, E.O., 2004b, Ecoregions of the Mississippi Alluvial Plain (color poster with map, descriptive text, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey, map scale 1:1,150,000.Chapman, S.S., Omernik, J.M., Griffith, G.E., Schroeder, W.A., Nigh, T.A., and Wilton, T.F., 2002, Ecoregions of Iowa and Missouri (color poster with map, descriptive text, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey, map scale 1:1,800,000.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, 152 p.Griffith, G., Omernik, J., and Azevedo, S., 1998, Ecoregions of Tennessee (color poster with map, descriptive text, summary tables, and photographs): Reston, Virgnia, U.S. Geological Survey, scale 1:940,000.Ku:chler, A.W., 1964, Potential natural vegetation of the conterminous United States (map and manual): American Geographical Society, Special Publication 36, map scale 1:3,168,000.McMahon, G., Gregonis, S.M., Waltman, S.W., Omernik, J.M., Thorson, T.D., Freeouf, J.A., Rorick, A.H., and Keys, J.E., 2001, Developing a spatial framework of common ecological regions for the conterminous United States: Environmental Management, v. 28, no. 3, p. 293-316.Omernik, J.M., 1987, Ecoregions of the conterminous United States (map supplement): Annals of the Association of American Geographers, v. 77, p. 118-125, map scale 1:7,500,000.Omernik, J.M., 1995, Ecoregions - a framework for environmental management, in Davis, W.S., and Simon, T.P., editors, 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 Sciences, Arts, and Letters, v. 88, p. 77-103.U.S. Department of Agriculture-Soil Conservation Service, 1981, Land resource regions and major land resource areas of the United States: Agriculture Handbook 296, 156 p.U.S. Environmental Protection Agency, 2003, Level III ecoregions of the continental United States (revision of Omernik, 1987): Corvallis, Oregon, USEPA-National Health and Environmental Effects Research Laboratory, Western Ecology Division, Map M-1, various scales.Wiken, E., 1986, Terrestrial ecozones of Canada: Ottawa, Environment Canada, Ecological Land Classification Series no. 19, 26 p.Arc Attributes:LNTYPE = item representing the Level III or IV Ecoregion line type4 = level IV ecoregion boundary3 = level III ecoregion boundary9 = state boundaryPolygon Attributes: ECO = item representing Level III or IV Ecoregion labelECO_NAME = item representing Level III or IV Ecoregion nameECO ECO_NAME35 South Central Plains35a Tertiary Uplands35b Floodplains and Low Terraces35c Pleistocene Fluvial Terraces35d Cretaceous Dissected Uplands35g Red River Bottomlands35h Blackland Prairie36 Ouachita Mountains36a Athens Plateau36b Central Mountain Ranges36c Central Hills, Ridges, and Valleys36d Fourche Mountains36e Western Ouachitas37 Arkansas Valley37a Scattered High Ridges and Mountains37b Arkansas River Floodplain37c Arkansas Valley Hills37d Arkansas Valley Plains38 Boston Mountains38a Upper Boston Mountains38b Lower Boston Mountains39 Ozark Highlands39a Springfield Plateau39b Dissected Springfield Plateau Elk River Hills39c White River Hills39d Central Plateau
Content Status
Progress: In work
Update Frequency: As needed
Content Keywords
Theme Keywords: ISO 19115 Topic Category, environment, EPA GIS Keyword Thesaurus, Biology, Ecology, Ecosystem, Land, Natural Resources, None, Level III and IV ecoregions
Place Keywords: Arkansas