Ecological Divisions


Ecological Divisions are sub-continental landscapes reflecting both climate and biogeographic history, modified from Bailey (1995 and 1998) at the Division scale.  Continent-scaled climatic variation, reflecting variable humidity and seasonality (e.g., Mediterranean vs. dry continental vs. humid oceanic) are reflected in these units, as are broad patterns in phytogeography (e.g., Takhtajan 1986).  The division lines were modified by using ecoregions established by The Nature Conservancy (Groves et al. 2002) and World Wildlife Fund (Olson et al. 2001) throughout the Western Hemisphere.  These modified divisional units aid the development of ecological systems and vegetation classification units because regional patterns of climate, physiography, disturbance regimes, and biogeographic history are well described by each Division.  Examples of these Divisions include the Inter- Mountain Basins, the North American Warm Desert, the Western Great Plains, the Eastern Great Plains, the Laurentian and Acadian region, the Rocky Mountains, and the Atlantic and Gulf Coastal Plain (Comer and Schulz 2007).  

Data Layer Description




United States


How you might make use of this data layer

This subcontinental framework places the United States within a global ecological context, and serves to organize information on the array of characteristic terrestrial ecosystems and species habitats that occur within each.  Being ecologically based, and regional in scale, it forms natural regions suitable for multi-agency, multi-state conservation partnerships aimed at ecological assessment, planning, management, and monitoring.

How to get more information

Bailey, R.G.  2009.  Ecosystem Geography: From Ecoregions to Sites second edition.  Springer, New York Inc., New York. 251 pp.

Bailey, R.G.  1998.  Ecoregion Map of North America: Explanatory Note.  USDA Forest Service Misc.Publ. 1548.

Comer, P., and K. Schulz. 2007. Standardized Ecological Classification for Meso-Scale Mapping in Southwest United States. Rangeland Ecology and Management 60 (3) 324-335.

Comer, P., D. Faber-Langendoen, R. Evans, S. Gawler, C. Josse, G. Kittel, S. Menard, M. Pyne, M. Reid, K. Schulz, K. Snow, and J. Teague.  2003. Ecological Systems of the United States: A Working Classification of U.S. Terrestrial Systems. NatureServe, Arlington VA.

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