The aim of landscape ecosystem classification and mapping is to distinguish appropritely sized ecosystems - useful and functional land units that differ significantly from one another in abiotic characteristics as well as their related biotic components. This subdivision of a large area into distinctive landscape ecosystems provides a much needed framework for integrated resource management planning; for biological conservation; and for comparison of differences in composition, occurrence, interactions, and productivity of plants and animals among ecosystems on the Allegheny National Forest (ANF).