|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