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Home › Map Layers › Bailey's Ecoregions and Subregions of the United States, Puerto Rico, and the U.S. Virgin Islands 

Map Layer Info 

Bailey's Ecoregions and Subregions of the United States, Puerto Rico, and 

the U.S. Virgin Islands

What this map layer shows:

Ecoregions defined by common climatic and 

vegetation characteristics, shown as 

domains, divisions, provinces and sections. 

Background Information

Ecoregions are ecosystems of 

regional extent. Bailey's ecoregions 

distinguish areas that share common 

climatic and vegetation 

characteristics. A four-level hierarchy 

is used to differentiate the 

ecoregions, with the broadest 

classification being the domain. 

Domains are groups of related 

climates and are differentiated based 

on precipitation and temperature. 

There are four domains used for 

worldwide ecoregion classification 

and all four appear in the United 

States: the polar domain, the humid temperate domain, the dry domain, and the 

humid tropical domain. Divisions represent the climates within domains and are 

differentiated based on precipitation levels and patterns as well as temperature. 

Divisions are subdivided into provinces, which are differentiated based on 

vegetation or other natural land covers. Mountainous areas that exhibit different 

ecological zones based on elevation are identified at the province level. The finest 

level of detail is described by subregions, called sections, which are subdivisions of 

provinces based on terrain features. 

The purpose of ecological land classification is to provide information for both the 

development of resources and the conservation of the environment. Government 

and private land managers use this information to estimate ecosystem productivity, 

to determine probable responses to land management practices, and to address 

environmental issues over large areas, such as air pollution, forest disease, or 

threats to biodiversity. This map layer was compiled by the USDA Forest Service. 

The Bailey's Ecoregions and Subregions of the United States, Puerto Rico, and the 

U.S. Virgin Islands map layer shows the ecoregion domains, divisions, provinces, 

and sections for this area. Further information on domains, divisions, and provinces 

is available from the USDA Forest Service Rocky Mountain Research Station page 

describing Ecoregions of the United States, and detailed information on sections is 

available through the USDA Forest Service page, Ecological Subregions of the United 

States. 

The National Atlas also includes a map layer showing Omernik's Level III 

Ecoregions, which are defined by a wide variety of characteristics, including 

BIOLOGY

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Ecoregions - Bailey

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Ecoregions - Bailey

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vegetation, animal life, geology, soils, water, climate, and human land use, as well 

as other living and non-living ecosystem components. 

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Last modified: Thursday, 27-Jan-2011 17:11:30 CST 

Bailey's Ecoregions and Subregions of the United States, Puerto Rico, and the U.S. Virgin... Page 2 of 2

http://www.nationalatlas.gov/mld/ecoregp.html 6/12/2011