Date of this Version
This is the latest of many efforts over the past century to classify North America's natural, undisturbed biological communities as they existed in pre-agrarian times and in many places continue to exist today. Its authors' stated objective is to integrate existing works into a hierarchical synthesis that can lead to a standardized system for researchers, land managers, conservation groups, and government agencies. To that end, the authors have modified and expanded David Brown's earlier classification for the Southwest to cover the continent, defined here as the area from the Panama Canal to the Arctic, including Greenland and some of the West Indies. This explicit system is designed to categorize each biotic community in its worldwide context through the medium of a computer-digitized, statistically testable format that uses plant and animal distributions as well as climatic data.