Introduction to EcoRegions

Introduction to EcoRegions

Omernik (1987) invented EcoRegion maps and the U.S. EPA modified them to support environmental projects. There are ongoing efforts to refine the maps, primarily by subdividing ecoregions to more accurately reflect field observations. The maps serve as a spatial framework for monitoring ecosystems and ecosystem components.  EcoRegions denote areas within which ecosystems (and the type, quality, and quantity of environmental resources) are generally similar. By recognizing the spatial differences in the capacities and potentials of ecosystems, ecoregions stratify the environment by its probable response to disturbance (Bryce et al. 1999). These general purpose regions are critical for structuring and implementing ecosystem management strategies across federal agencies, state agencies, and nongovernmental organizations that are responsible for different types of resources within the same geographical areas (Omernik et al. 2000, McMahon et al. 2001).

EcoRegion Level III US - courtesy of ArcheWild Native Nurseries 15x11

The maps show that ecological regions are identifiable through the analysis of biotic and abiotic feature patterns that show differences in ecosystem quality and integrity (Wiken 1986; Omernik 1987, 1995). These features include geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another. Level I is the coarsest level, dividing North America into 15 ecological regions, whereas Level II subdivides the continent into 50 classes (CEC 1997, 2006). Level III (shown above), a subdivision of Level II, has been even further subdivided into Level IV regions for the contiguous United States.

EcoRegions are also used by open-pollinated, local-ecotype (OPLE©) nurseries to match plant genetics to a particular project.  It is now widely accepted that plants grown from seeds collected in California (e.g. Asclepias tuberosa) are not genetically fit to be used in upstate New York.  Yet many ‘native’ nurseries are buying seed with unknown or foreign genetics and selling them into local markets as native plants; This is rife with many issues, including the effects of outbreeding depression on local, indigenous populations.

Below is a Level IV EcoRegion map for New Jersey and surrounding areas.

ArcheWild EcoRegion Level IV New Jersey
ArcheWild EcoRegion Level IV New Jersey

ArcheWild uses the Level IV EcoRegion map in its accession database to record the ecoregion from which seeds are or were collected and this ecoregion designation becomes part of the labelling system for its plants.  This allows customers to match our genetic stock to the location and even the type of project.  ArcheWild grows and stocks over twenty (20) different ecotypes of little bluestem, for example, to allow restoration experts to better match the plant to the project.  The ideal scenario is to grow plants from seed collected in close proximity of the site.  The picture below depicts the Level IV EcoRegions from which ArcheWild commonly collects seed.  The darker shades denote a higher number of accessions from that EcoRegion.

ArcheWIld Accession Heat Map
ArcheWIld Accession Heat Map

Learn more about EcoRegions

Bryce, S.A., J.M. Omernik, and D.P. Larsen. 1999. Ecoregions – a geographic framework to guide risk characterization and ecosystem management: Environmental Practice 1(3):141-155.

Commission for Environmental Cooperation. 1997. Ecological regions of North America: toward a common perspective. Commission for Environmental Cooperation, Montreal, Quebec, Canada. 71p. Map (scale 1:12,500,000). Revised 2006.

Gallant, A.L., E.F. Binnian, J.M. Omernik, and M.B. Shasby. 1995. Ecoregions of Alaska. U.S. Geological Survey Professional Paper 1567. U.S. Government Printing Office, Washington D.C. 73p.

Griffith, G.E., S.B. Bryce, J.M. Omernik, and A. Rogers. 2007. Ecoregions of Texas. Texas Commission on Environmental Quality. Austin, TX. 125p.

Griffith, G.E., J.M. Omernik, C.M. Rohm, and S.M. Pierson. 1994. Florida regionalization project. EPA/600/Q-95/002. U.S. Environmental Protection Agency, Environmental Research Laboratory, Corvallis OR. 83p.  73 p.

Griffith, G.E., J.M. Omernik, T.F. Wilton, and S.M. Pierson. 1994. Ecoregions and subregions of Iowa: A framework for water quality assessment and management. The Journal of the Iowa Academy of Science 101(1):5-13.

McMahon, G., S.M. Gregonis, S.W. Waltman, J.M. Omernik, T.D. Thorson, J.A. Freeouf, A.H. Rorick, and J.E. Keys. 2001. Developing a spatial framework of common ecological regions for the conterminous United States. Environmental Management 28(3):293-316.

Omernik, J.M. 1987. Ecoregions of the conterminous United States. Map (scale 1:7,500,000). Annals of the Association of American Geographers 77(1):118-125.

Omernik, J.M. 1995. Ecoregions: A spatial framework for environmental management. In: Biological Assessment and Criteria: Tools for Water Resource Planning and Decision Making. Davis, W.S. and T.P. Simon (eds.), Lewis Publishers, Boca Raton, FL. p. 49-62.

Omernik, J.M., S.S. Chapman, R.A. Lillie, and R.T. Dumke. 2000. Ecoregions of Wisconsin. Transactions of the Wisconsin Acadamy of Sciences, Arts, and Letters 88:77-103.

Omernik, J.M. 2004. Perspectives on the nature and definition of ecological regions. Environmental Management 34(Supplement 1):S27-S38.

Wiken, E. 1986. Terrestrial ecozones of Canada. Environment Canada. Ecological Land Classification Series No. 19. Ottawa, Canada.