UNINTENDED CONSEQUENCES: EFFECTS OF EUROPEAN FIRE MANAGEMENT ON AQUATIC SYSTEMS

Fire history research supports the ethnography, ethnohistory, and archeology of Native California societies that document planned vegetation management through the use of fire. For at least the past 3000 years, and possibly extending back as far as 10,000 years, the fire recurrence for much of California was on the order of 10 to 30 years. Plant and animal communities evolved under this managed fire regime to the conditions that most individuals now consider natural and wild. This use of fire for vegetation management was rapidly replaced with a system of fire suppression and neglect following the arrival of European-Americans. In addition to the now well-publicized effect of larger, hotter wildland fires, recent fire management has altered the biomass of vegetation and the average sizes of individual trees in many watersheds. This may result in profound consequences to fluvial aquatic systems. Many aquatic species now considered threatened, including anadromous salmon, filled niches that were favored under Native California management. Input of the physical habitat elements of wood, water, and sediment has changed under European-American control. Successful suppression of fire reduces the total water yield and summer base flow. When fires do occur they are frequently large and intense, removing mature trees as well as the understory, setting the system up for post-fire floods and debris flows that simplify in-stream structures to the detriment of many species of fish and amphibians. Without management activities that attempt to mimic the results of Native California societies the fluvial aquatic system will continue to evolve to conditions that no longer favor species that once dominated the landscape.