This map is commonly called Bailey's ecoregions and shows ecosystems of regional extent in the United States, Puerto Rico, and the U.S. Virgin Islands, based on conditions in 1994. Four levels of detail are included to show a hierarchy of ecosystems. The largest ecosystems are domains, which are groups of related climates and which are differentiated based on precipitation and temperature. Divisions represent the climates within domains and are differentiated based on precipitation levels and...