Environmental Management

, Volume 34, Supplement 1, pp S27–S38 | Cite as

Perspectives on the Nature and Definition of Ecological Regions

  • James M. Omernik


Among environmental managers, recognition of the importance of integrating management activities across agencies and programs that have different responsibilities for the same geographic areas has created an awareness of the need for a common hierarchical framework of ecological regions (ecoregions) to implement the strategy. Responding to this need in the United States, nine federal agencies have signed a memorandum of understanding on the subject of developing a common framework of ecoregions. However, considerable disagreement over how to define ecoregions and confusion over the strengths and limitations of existing frameworks stand in the way of achieving this goal. This paper presents some perspectives on the nature and definition of ecoregions related to this confusion and provides a brief overview of the weight of evidence approach to mapping ecoregions, using an example initiated by the US Environmental Protection Agency. To effectively implement ecosystem assessment, management, and research at local, regional, and national levels, research is needed to increase our understanding of ecoregions. We must find ways to illustrate the nature of ecoregion boundaries and the variability of characteristics within ecoregions as they relate to management issues. Research must also be conducted on comparing existing frameworks and developing indices of ecological integrity to effectively evaluate their usefulness.

Ecoregions Ecological regions Ecology Ecosystems Ecosystem management Regionalization Environment 



I am grateful to Jerry McMahon, Glenn Griffith, and Susan Christie for their helpful reviews. I also thank Tom Loveland for encouraging me to write this paper. The information in this paper has been funded by the US Environmental Protection Agency and the US Geological Survey. It has been subjected to review by the US EPA National Health and Environmental Effects Research Laboratory’s Western Ecology Division peer review process and approved for publication. Approval does not signify that the contents reflect the views of the Agency.

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Copyright information

© Springer-Verlag New York, Inc. 2004

Authors and Affiliations

  1. 1.U.S. Geological Survey, c/oU.S. Environmental Protection Agency, National Health and Environmental Effects Laboratory, Western Ecology DivisionOregonUSA

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