'Preliminary descriptions are presented for the 190 section ecological units delineated on the U.S. Department of Agriculture Forest Service 2007 map S2Ecological Subregions: Sections and Subsections of the Conterminous United States. S3 Brief descriptions of the section map units provide an abstract primarily of the climate, physiography, and geologic substrate that combine to form ecosystems with distinctive vegetation and other unique ecological characteristics. Many descriptions are illustrated with a photograph of the landform and vegetation found in the section."

This volume represents a first attempt at holistically classifying and mapping ecological regions across all three countries of the North American continent. A common analytical methodology is used to examine North American ecology at multiple scales, from large continental ecosystems to subdivisions of these that correlate more detailed physical and biological settings with human activities on two levels of successively smaller units. The volume begins with an overview of North America from an ecological perspective, concepts of ecological regionalization. This is followed by descriptions of the 15 broad ecological regions, including information on physical and biological setting and human activities. The final section presents case studies in applications of the ecological characterization methodology to environmental issues. The appendix includes a list of common and scientific names of selected species characteristic of the ecological regions.