Historic range of variability of mountain forest ecosystems: concepts and applications

Concepts of historical range of variability (HRV) have taken on an increasingly important role in resource planning and the management of mountain forest ecosystems. This essay draws on examples from the study of the history of disturbance ecology in the Colorado Rocky Mountains and the southern Andes to examine key HRV concepts and their applications. These case studies show that historical perspectives can reduce the chances of major future surprises in ecosystem conditions related to climatic variation, which often overrides many of the effects of management practices. They demonstrate the long-lasting legacy effects of relatively infrequent but severe disturbances in the past that shaped the present landscape and its potential response to future climatic variation. Finally, the case studies illustrate the importance of conducting area-specific research in potential management areas rather than simply extrapolating research findings from studies of historic range of variability of forest ecosystems conducted elsewhere. Key words: climatic variation, disturbance, Rocky Mountains, Andes, Patagonia, Ponderosa pine, landscape, ecosystem management, fire