Identifying Reference Conditions for Prescribed Fire Management of Mixed Confier Forests in Yosemite National Park, California

摘要

A guiding policy for management of landscapes inside national parks (NPS) calls for maintenance of natural conditions and processes. This policy assumes that natural and unnatural influences on landscape change are distinguishable and that natural processes can maintain a desired landscape structure. Current policy guidelines permit natural change to proceed within limits, while managers are directed to arrest or reverse unnatural or anthropogenic change. An important need for fire and resource managers implementing this policy in forests highly altered by a century or more of fire suppression is quantitative information on pre-fire suppression reference conditions. Managers use information on reference conditions for both understanding how fire suppression has changed ecosystems, and for identifying restoration goals and management treatments if contemporary conditions are outside the range of desired conditions. A critical need for knowledge of reference conditions for mixed conifer forests was identified by fire and resource managers in developing Yosemite National Park's Fire Management Plan. Fire suppression in YNP has dramatically altered the mixed conifer forest landscape. Exclusion of fire for a century or more has caused an increase in forest density, an increase in live and dead forest fuels, and a shift in forest composition towards more fire intolerant tree species.