Hierarchy of Ecoregions at a Range of Scales

Figure 1 - The upper four levels of ecological units in the Forest Service National Hierarchical Framework consists of Domain, Division, Province, and Section.  Selected ecological units of the Humid Temperate Domain, in the western United States, are progressively revealed to the Section level to illustrate the hierarchical structure, the identification system, and relative sizes of map units at the ecoregion and subregion planning and analysis scales (Hierarchy of ecoregions at a range of scales, Bailey, 1994).