Description of the Sections and Subsections of the Interior Highlands of Arkansas and Oklahoma

Journal of the Arkansas Academy of Science Volume 52 Article 10 1998 Description of the Sections and Subsections of the Interior Highlands of Arkansas and Oklahoma Thomas L. Foti Arkansas Natural Heritage Commission George A. Bukenhofer Ouachita National Forest Follow this and additional works at: http://scholarworks.uark.edu/jaas Part of the Geology Commons, Physical and Environmental Geography Commons, and the Soil Science Commons Recommended Citation Foti, Thomas L. and Bukenhofer, George A. (1998) "Description of the Sections and Subsections of the Interior Highlands of Arkansas and Oklahoma," Journal of the Arkansas Academy of Science: Vol. 52 , Article 10. Available at: http://scholarworks.uark.edu/jaas/vol52/iss1/10 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This Article is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact , . Journal of the Arkansas Academy of Science, Vol. 52 [1998], Art. 10 A Description of the Sections and Subsections of the Interior Highlands of Arkansas and Oklahoma Thomas L. Foti Arkansas Natural Heritage Commission, Suite 1500 Tower Building, Little Rock, AR 72201 George A. Bukenhofer Ouachita National Forest, HC64 Box 3467, Heavener, OK 74937 Abstract Sections and subsections of the Interior Highlands of Arkansas and Oklahoma are redefined, mapped and briefly summarized. The map was produced to support the Ozark- Ouachita Highlands Assessment (OOHA), being conducted by the USDA Forest Service. It revises the USDA Forest Service map "Ecological units of the eastern United States, first approximation" by Keys et al. (1995) and the earlier maps of the natural divisions of Arkansas (Foti, 1974; Foti, 1976; Pell, 1983) to reflect new knowledge and to achieve consistency with units recognized in Missouri. Four sections (natural divisions) are defined as opposed to the three of the previous Arkansas natural divisions maps, and new subsections are recognized within most sections. Digital maps of geology, soils and topography were used to create the map in ARC/INFO. The map is accessible through the World Wide Web as a portion of a map of the entire Interior Highlands region of Arkansas, Oklahoma and Missouri on the home page of the Ouachita National Forest at http://www.fs.fed.us/oonf/ooha/welcome.htm. Introduction The Interior Highlands has long been recognized as a distinct physiographic and natural region (Fenneman, 1938; Braun, 1950). It is generally characterized as hilly to mountainous topography on paleozoic substrates dominated by upland hardwood and upland pine-hardwood forests. It is surrounded by plains that are lower in elevation with more recent geological substrates and different vegetation. Vegetation of these plains ranges from tallgrass prairie to lowland pine-hardwood and bottomland hardwood forests. Even though the Interior Highlands region has consistent general characteristics, there are striking differences within it that may occur within distinct geographic areas. Therefore, most descriptions and studies divide the region into smaller, more uniform areas. Authors have generally recognized at least two provinces, the Ozark Mountains and the Ouachita Mountains (Croneis, 1930; Fenneman, 1938; Braun, 1950; Thornbury, 1965; Foti, 1974). Sometimes the Arkansas Valley has been considered a separate province or natural division (Foti, 1976; Pell, 1983; Omernik, 1987). In addition, Omernik (1987) recognized the Boston Mountains as an ecoregion (natural division); previous authors had considered it a subdivision of the Ozark Mountains. These provinces are often subdivided as well (Fig. 1). In order to facilitate agency ecosystem management efforts, the Forest Service developed a new national regionalization framework (Keys et al., 1995; henceforth referred to as Keys et al. Or the Keys map; Fig. 2) based on a national map of ecosystems of North America by Bailey et al. (1994). The new framework is hierarchical like older efforts but is based on a more holistic consideration of land- scape properties than some earlier maps, with climate and soil playing prominent roles along with physiography. The new framework is also explicitly designed to rationally subdivide landscapes down to levels meaningful in ecosystem management, i.e. to units of several acres to a few tens of acres. The older and newer maps coincide most closely at the level of Section (Keys et al., Fig. 2), Province (Fenneman, 1938) and Natural Division (Foti, 1974). Although differences occur at this level, they are usually in the form of one unit in one system equating to two units in another system. The new framework is often more detailed at lower levels in the hierarchy than older maps. The USDA Forest Service has currently underway a project termed the Ozark- Ouachita Highlands Assessment (OOHA; USDA Forest Service, in prep.) that is an attempt to characterize the Interior Highlands region as a whole in order to support revision of Forest Plans on the three National Forests within the region: The Ouachita, the Ozark-St. Francis and the Mark Twain national forests. It was necessary to define regions within the Highlands that were distinct enough to require different management plans. In order to maintain national consistency the OOHA assumed from the outset that the Keys map would provide the regional perspective. Methods Examination of the Keys map (Fig. 2) and comparison with other regional maps such as the Croneis map (1930, Fig. 1) and geological and topographical base maps revealed that sections and subsections and their boundaries are not consistently meaningful and accurate across the assessment Journal of the Arkansas Academy of Science, Vol. 52, 1998 Published by Arkansas Academy of Science, 1998 53 53 r- Journal of the Arkansas Academy of Science, Vol. 52 [1998], Art. 10 A Description of the Sections and Subsections of the Interior Highlands of Arkansas and Oklahoma Fig. 1. Map of physiographic provinces of Arkansas developed by Croneis (1930). area. The Missouri units and their boundaries have been settled for years, so the Keys map simply adopted those, and changes needed for the assessment were very minor. In contrast, the Arkansas units and boundaries required considerable revision because the Keys et al. approach is substantially different from what was done in the past (Croneis, 1930; Foti, 1974) and locally-created maps were not available. The Keys map is of lower quality in Oklahoma because in that state only general regions have been defined (Oklahoma Bio (...truncated)