Description of the Ecoregions of the United States

Compiled by Robert G. Bailey, March 1995

This volume was originally published in 1978 to provide a general description of the ecosystem geography of the Nation as shown on the 1976 map "Ecoregions of the United States." It was first published as an unnumbered publication by the Intermountain Region, USDA Forest Service, Ogden, Utah. It was reprinted in 1980 by the Forest Service, Washington, DC, as Miscellaneous Publication No. 1391. An explanation of the basis for the regions delineated on the map was presented elsewhere (Bailey 1983).

The technique of mapping ecoregions was subsequently expanded to include the rest of North America (Bailey and Cushwa 1981) and the world (Bailey 1989). In 1993, as part of the Forest Service's National Hierarchical Framework of Ecological Units (ECOMAP 1993), ecoregions were adopted for use in ecosystem management. They will also be used in the proposed National Interagency Ecoregion-Based Ecological Assessments. This volume updates the knowledge of the subject. It was my goal in preparing this edition, like its predecessor, not to present information, but to strive for synthesis, i.e., the illustration of interrelationships.

Click on a specific PROVINCE in the list below

100 POLAR DOMAIN
     120 Tundra Division
         124 Arctic Tundra Province
         125 Bering Tundra (Northern) Province
         126 Bering Tundra (Southern) Province
     M120 Tundra Division - Mountain Provinces
         M121 Brooks Range Tundra--Polar Desert Province
         M125 Seward Peninsula Tundra--Meadow Province
         M126 Ahklun Mountains Tundra--Meadow Province
         M127 Aleutian Oceanic Meadow--Heath Province
     130 Subarctic Division
         131 Yukon Intermontane Plateaus Tayga Forest
         135 Coastal Trough Humid Tayga Province
         139 Upper Yukon Tayga Province
     M130 Subarctic Division - Mountain Provinces
         M131 Yukon Intermontane Plateaus Tayga--Meadow Province
         M135 Alaska Range Humid Tayga--Tundra--Meadow
         M139 Upper Yukon Tayga--Meadow Province
200 HUMID TEMPERATE DOMAIN
     210 Warm Continental Division
         212 Laurentian Mixed Forest Province
     M210 Warm Continental Division - Mountain Provinces
         M212 Adirondack-New England Mixed Forest--Coniferous Forest
         --Alpine Meadow Province
     220 Hot Continental Division
         221 Eastern Broadleaf Forest (Oceanic) Province
         222 Eastern Broadleaf Forest (Continental) Province
     M220 Hot Continental Division - Mountain Provinces
         M221 Central Appalachian Broadleaf Forest--Coniferous Forest
         --Meadow Province
         M222 Ozark Broadleaf Forest--Meadow Province
     230 Subtropical Division
         231 Southeastern Mixed Forest Province
         232 Outer Coastal Plain Mixed Forest Province
         234 Lower Mississippi Riverine Forest Province
     M230 Subtropical Division - Mountain Provinces
         M231 Ouachita Mixed Forest--Meadow Province
     240 Marine Division
         242 Pacific Lowland Mixed Forest Province
     M240 Marine Division - Mountain Provinces
         M242 Cascade Mixed Forest--Coniferous Forest
         --Alpine Meadow Province
         M244 Pacific Coastal Mountains Forest--Meadow Province
         M245 Pacific Gulf Coastal Forest--Meadow Province
     250 Prairie Division
         251 Prairie Parkland (Temperate) Province
         255 Prairie Parkland (Subtropical) Province
     260 Mediterranean Division
         261 California Coastal Chaparral Forest and Shrub Province
         262 California Dry Steppe Province
         263 California Coastal Steppe, Mixed Forest,
          and Redwood Forest Province
     M260 Mediterranean Division - Mountain Provinces
         M261 Sierran Steppe--Mixed Forest--Coniferous Forest
         --Alpine Meadow Province
         M262 California Coastal Range Open Woodland-Shrub-
         Coniferous Forest--Meadow Province
300 DRY DOMAIN
     310 Tropical/Subtropical Steppe Division
         311 Great Plains Steppe and Shrub Province
         313 Colorado Plateau Semidesert Province
         315 Southwest Plateau and Plains Dry Steppe and Shrub Province
     M310 Tropical/Subtropical Steppe Division - Mountain Provinces
         M313 Arizona-New Mexico Mountains Semidesert-Open Woodland--
         Coniferous Forest--Alpine Meadow Province
     320 Tropical/Subtropical Desert Division
         321 Chihuahuan Semidesert Province
         322 American Semidesert and Desert Province
     330 Temperate Steppe Division
         331 Great Plains-Palouse Dry Steppe Province
         332 Great Plains Steppe Province
     M330 Temperate Steppe Division - Mountain Provinces
         M331 Southern Rocky Mountain Steppe--Open Woodland--
         Coniferous Forest--Alpine Meadow Province
         M332 Middle Rocky Mountain Steppe--Coniferous Forest--
         Alpine Meadow Province
         M333 Northern Rocky Mountain Forest-Steppe--Coniferous Forest--
         Alpine Meadow Province
         M334 Black Hills Coniferous Forest Province
     340 Temperate Desert Division
         341 Intermountain Semidesert and Desert Province
         342 Intermountain Semidesert Province
     M340 Temperate Desert Division - Mountain Provinces
         M341 Nevada-Utah Mountains Semidesert--Coniferous Forest--
         Alpine Meadow Province
400 HUMID TROPICAL DOMAIN
     410 Savanna Division
         411 Everglades Province
     M410 Savanna Division - Mountain Provinces
         M411 Puerto Rico Province
     420 Rainforest Division
     M420 Rainforest Division - Mountain Provinces
         M423 Hawaiian Islands Province

References 

Appendix 1 - Regional climates, based on the Koppen system 
of classification (1931)

Appendix 2 - Climate diagrams of representative climate stations

Appendix 3 - Approximate area and proportionate extent of ecoregions at 
the province level in the United States

From: Bailey R.G. 1995. Description of the ecoregions of the United States. US Department of Agriculture Forest Service Publication 1391. Washington DC, USA. http://www.fs.fed.us/land/ecosysmgmt/ecoreg1_home.html