Ecological units are described at the subsection level of the Forest Service National Hierarchical Framework of Ecological Units. A total of 91 subsections are delineated on the 1996 map "Ecological Units of the Northern Region: Subsections," based on physical and biological criteria. This document consists of descriptions of the climate, geomorphology, geology, vegetation, and soils that characterize each subsection. Included is information on sources of natural disturbances, current land use, and ecological relationships of the major components.
Nesser, John A.; Ford, Gary L.; Maynard, C. Lee; Page-Dumroese, Deborah S. 1997. Ecological units of the Northern Region: Subsections. Gen. Tech. Rep. INT-GTR-369. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Research Station. 88 p.