Developing a Spatial Framework of Common Ecological Regions for the Conterminous United States

 

Gerard McMahon¹, Steve M. Gregonis², Sharon W. Waltman³, James M. Omernik⁴, Thor D. Thorson⁵, Jerry D. Freeouf⁶, Andrew H. Rorick⁷, and James E. Keyes⁸

¹ U.S. Geological Survey, Raleigh, North Carolina 27607, USA
² U.S. Forest Service, Golden, Colorado 80225, USA
³U.S. Geological Survey, 2350 Fairlane Drive, Suite 120, Montgomery, Alabama 36116, USA
⁴ U.S. Environmental Protection Agency, Corvallis, Oregon 97333, USA
⁵ U.S. Department of Agriculture Natural Resources Conservation Service, Portland, Oregon 97204, USA
⁶ U.S. Forest Service, Denver, Colorado 80225, USA
⁷ U.S. Forest Service, Portland, Oregon 97055, USA
⁸ U.S. Forest Service, Washington, DC 20250, USA

ABSTRACT.— In 1996, nine Federal agencies with mandates to inventory and manage the Nation's land, water, and biological resources signed a Memorandum of Understanding entitled "Developing a Spatial Framework of Ecological Units of The United States.'' This spatial framework is the basis for interagency coordination and collaboration in the development of ecosystem management strategies. One of the objectives in this memorandum is the development of a map of common ecological regions for the conterminous United States. The regions defined in the spatial framework will be areas within which biotic, abiotic, terrestrial, and aquatic capacities and potentials are similar. The agencies agreed to begin by exploring areas of agreement and disagreement in three Federal natural-resource spatial frameworks -- the Major Land Resource Areas of the U.S. Department of Agriculture (USDA) Natural Resources Conservation Service, National Hierarchy of Ecological Units of the USDA Forest Service, and Level III Ecoregions of the U.S. Environmental Protection Agency. The explicit intention is that the framework will foster an ecological understanding of the landscape, rather than an understanding based on a single resource, single disciplinary, or single agency perspective. This paper (1) describes the origin, capabilities, and limitations of three major Federal agency frameworks and (2) suggests why a common ecological framework is desirable. The scientific and programmatic benefits of common ecological regions are described, and a proposed process for development of the common framework is presented.