The structure of most virgin forests in the western United States reflects a past disturbance history that includes forest fire. James K. Agee, an expert in the emergent field of fire ecology, analyzes the ecological role of fire in the creation and maintenance of natural western forests, focusing primarily on forest stand development patterns. His discussion of the natural fire environment and the environmental effects of fire is applicable to a wide range of temperate forests. James K. Agee is professor of forest ecology in the College of Forest Resources at the University of Washington, Seattle. He recently completed a five-year term as chair of the Division of Ecosystem Science and Conservation, and he continues to teach and conduct research on forest and fire ecology. Before coming to the University of Washington, he was a forest ecologist and research biologist for the National Park Service in Seattle and San Francisco. Agee received his Ph.D. from the University of California, Berkeley, in 1973. He is the author of more than 100 technical reports and professional papers in forest and fire ecology, and he has extensive experience with fire research and management in the Pacific Coast states. He has been a trustee for the Washington chapter of The Nature Conservancy, was chair to the Washington Natural Heritage Council, and associate editor of Northwest Science. Fire Ecology of Pacific Northwest Forests By James K. Agee ISLAND PRESS Copyright © 1993 James K. Agee All rights reserved. ISBN: 978-1-55963-230-0 Contents ABOUT ISLAND PRESS, Title Page, Copyright Page, Dedication, PREFACE, ACKNOWLEDGMENTS, CHAPTER 1 - THE NATURAL FIRE REGIME, CHAPTER 2 - THE NATURAL FIRE ENVIRONMENT, CHAPTER 3 - THE CULTURAL FIRE ENVIRONMENT, CHAPTER 4 - METHODS FOR FIRE HISTORY, CHAPTER 5 - FIRE EFFECTS ON VEGETATION, CHAPTER 6 - ENVIRONMENTAL EFFECTS OF FIRE, CHAPTER 7 - SITKA SPRUCE, COAST REDWOOD, AND WESTERN HEMLOCK FORESTS, CHAPTER 8 - PACIFIC SILVER FIR AND RED FIR FORESTS, CHAPTER 9 - SUBALPINE ECOSYSTEMS, CHAPTER 10 - MIXED-CONIFER/ MIXED-EVERGREEN FORESTS, CHAPTER 11 - PONDEROSA PINE AND LODGEPOLE PINE FORESTS, CHAPTER 12 - NORTHWEST WOODLANDS, CHAPTER 13 - FIRE IN OUR FUTURE, APPENDIX A - COMMON CONVERSION FACTORS, APPENDIX B - NAMES OF PLANTS MENTIONED IN TEXT, GLOSSARY, REFERENCES, INDEX, ABOUT THE AUTHOR, CHAPTER 1 THE NATURAL FIRE REGIME DISTURBANCE IS AN INTEGRAL PROCESS in natural ecosystems, and management of forest ecosystems must take into account the chance of natural disturbance by a variety of agents. In some situations, such as park or wilderness management, natural disturbance may be required by law or policy to maintain natural ecosystems. In others, natural disturbance may wreak havoc with specific management goals, such as wood production or maintenance of a specific wildlife habitat. Fire is a ubiquitous disturbance factor in both space and time, and it cannot be ignored in long- term planning. Its effects can be integrated into land management planning through an understanding of how fire affects the site and the landscape. Today's plant communities reflect species assemblages in transition, each reacting with different lag times to past changes in climate, and each migrating north or south, up or downslope. Many species have not closely coevolved with the other species they are found growing with today, because of differential rates of migration over past millennia. Each species, however, may have coevolved for much longer periods with particular processes associated with it. Fires have been associated with most species of angiosperms and gymnosperms through much or all of their evolutionary development. THE PALEOPYRIC IMPERATIVE Fire is by no means a recent phenomenon. As long as plant biomass has been present on the earth, lightning has ignited fires, and the myriad ecological effects have been repeated time and again. The history of fire extends well back into the Paleozoic Era, hundreds of million years before the present and long before the angiosperms existed on earth. The Carboniferous Period, so named because of the extensive coal deposits formed during that time, have extensive amounts of fusain (Komarek 1973, Beck et al. 1982). Fusain is a fossil charcoal produced by fires that is almost completely inert, allowing it to survive through the geologic eras (Harris 1958). Fusain has little volatile content and glows on combustion, in contrast to coalified plant tissue, which burns with a smoky flame (Harris 1981). Wildfire was probably a regular occurrence on the earth during and since the Mesozoic (Cope and Chaloner 1985), when gymnosperms dominated the earth and angiosperms developed. Fire may have been associated with the extinction of dinosaurs. A catastrophe following a large meteorite striking the earth is now a widely accepted theory for the significant deposition of iridium at the Cretaceous-Tertiary (K-T) boundary, also as