Ecoregions of the Conterminous United States
Abstract
A map of ecoregions of the conterminous United States has been compiled to assist managers of aquatic and terrestrial resources in understanding the regional patterns of the realistically attainable quality of these resources. The ecoregions are based on perceived patterns of a combination of causal and integrative factors including land use, land surface form, potential natural vegetation, and soils. A synoptic approach similar to that used to define these ecoregions is also useful for applications of the map. Initial efforts to use the framework are at the state level of resource management; they center on aquatic ecosystems — mainly attainable ranges in chemical quality, biotic assemblages, and lake trophic state.
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Level II ecoregion delineations were added for each of the 94 studies.
“adding 27 studies and Level II ecoregion delineations for each of the 94 studies”
From Updates to the MANAGE database to facilitate regional analyses of nutrient runoff (2022) · cites this paper as Omernik, 1987
The MANAGE update delineated the Level II EPA ecoregion for each study and presents annual N and P runoff load data for 11 of the 50 Level II ecoregions in the United States and Canada.
“This update also delineated the Level II EPA ecoregion (Omernik 1987;Omernik and Griffith 2014) for each study, presenting annual N and P runoff load data for 11 of the 50 Level II ecoregions in the United States and Canada (Figures 1 and 2).”
From Nutrient Runoff From Agricultural Lands in North American Ecoregions (2025) · cites this paper as Omernik 1987
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Nelson, E., Mendoza, G., Regetz, J., Polasky, S., Tallis, H., Cameron, D., Chan, K. M., Daily, G. C., Goldstein, J., Kareiva, P. M., et al. (2009) · Frontiers in Ecology and the Environment · doi:10.1890/080023 · Cited by 2,389 · see citing works
Ecological Assessments with Algae: A Review and Synthesis
Stevenson, J. (2014) · Journal of Phycology · doi:10.1111/jpy.12189 · Cited by 273 · see citing works
Human and biophysical influences on fire occurrence in the United States
Hawbaker, T. J., Radeloff, V. C., Stewart, S. I., Hammer, R. B., Keuler, N. S., & Clayton, M. K. (2013) · Ecological Applications · doi:10.1890/12-1816.1 · Cited by 143 · see citing works
Wine, M. L., & Cadol, D. (2016) · Environmental Research Letters · doi:10.1088/1748-9326/11/8/085006 · Cited by 96 · see citing works
Columbia River Estuary ecosystem classification—Concept and application
Simenstad, C. A., Burke, J. L., O'Connor, J. E., Cannon, C., Heatwole, D. W., Ramirez, M. F., Waite, I. R., Counihan, T. D., & Jones, K. L. (2011) · Open-File Report · doi:10.3133/ofr20111228 · Cited by 42 · see citing works
Updates to the MANAGE database to facilitate regional analyses of nutrient runoff
Harmel, R. D., Kleinman, P., Hopkins, A. P., Millhouser, P., Ippolito, J. A., & Sahoo, D. (2022) · Agricultural & Environmental Letters · doi:10.1002/ael2.20095 · Cited by 7 · see citing works
“In addition, we determined the Level II ecoregion (Omernik, 1987; Omernik & Griffith, 2014) for each study (Table 2).”
MethodNutrient Runoff From Agricultural Lands in North American Ecoregions
Hopkins, A. P., Harmel, R. D., Kleinman, P. J. A., Sahoo, D., & Ippolito, J. A. (2025) · JAWRA Journal of the American Water Resources Association · doi:10.1111/1752-1688.70004 · Cited by 3 · see citing works
- Authors
- Omernik, J. M.
- Affiliations
- Environmental Protection Agency (US)
- Corresponding author
- Omernik, James M.
- Venue
- Annals of the Association of American Geographers
- Publisher
- Informa UK Limited
- Published
- 1987-03
- Volume
- 77
- Issue
- 1
- Pages
- 118-125
- ISSN
- 0004-5608 (ISSN-L)
- 1467-8306
- OpenAlex
- W2075845155
- Cited by
- 2,695
- References
- 0
- Citations by year
- 2026: 39 · 2025: 79 · 2024: 68 · 2023: 74 · 2022: 80 · 2021: 96 · 2020: 96 · 2019: 92 · 2018: 116 · 2017: 93 · 2016: 99 · 2015: 121 · 2014: 107 · 2013: 118 · 2012: 149
- FWCI
- 35.64
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Annals of the Association of American Geographers (publishedVersion)
- Topics
- Physical Sciences › Environmental Science › Water Science and Technology › Geography and Environmental Studies
- Physical Sciences › Environmental Science › Global and Planetary Change › Land Use and Ecosystem Services
- Physical Sciences › Environmental Science › Management, Monitoring, Policy and Law › Soil and Land Suitability Analysis
- Keywords
- ecoregions, contiguous United States, ecoregion mapping, land use, potential natural vegetation, soil, aquatic ecosystems, water quality, lake trophic state, resource management
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