n weathering would result in soils of low or high availability of base cations. The presence or absence of ecological zones (large areas of similar environmental conditions consisting of temperature, moisture, and fertility, which are manifested by characteristic vegetative communities) were modeled as multivariate logistic functions of climatic, topographic, and geologic variables. Accuracy of ecozone models ranged from 69- to 95-percent correct classification of sample plots; accuracy of most models was > 80 percent. The most important model variables were elevation, precipitation amount, and lithologic group. A regional map of ecological zones was developed by using a geographic information system to apply the models to a 30-m digital elevation dataset. Overall map accuracy was refined by adjusting the best probability cut levels of the logistic models based on expert knowledge and familiarity of the authors with known ecological zone boundaries throughout the study area. Prelimin

This book outlines a system that subdivides the Earth into a hierarchy of increasingly finer-scale ecosystems that can serve as a consistent framework for ecological analysis and management. The system consists of a three-part, nested hierarchy of ecosystem units and associated mapping criteria. This new edition has been updated throughout with new text, figures, diagrams, photographs, and tables.