|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.
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
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 vegetation, animal life, geology, soils, water, climate,
and human land use, as well as other living and non-living ecosystem components.