The active suppression of wildfires in the 20th Century, as well as land management activities starting from the late 1800s, profoundly altered fire regimes in many areas of the western United States. The accumulation of fuels due to fire suppression in many fire-adapted ecosystems and the consequent increase in the potential for catastrophic, stand-replacing wildfires is of particular concern. The National Fire Plan currently envisions reducing these dangerous fuel accumulations on millions of hectares of federal lands through prescribed fire and other fuels reduction measures and the subsequent reintroduction of pre-suppression fire regimes.

A natural issue concerns the design of efficient fuels management strategies in heterogeneous western ecosystems. Efforts to address this issue are underway, but analysis is hampered by the lack of long time series for individual locations and by the difficulty of drawing conclusions from comparisons of observations of short duration across very diverse landscapes with different management histories.

We address this problem with a case study of the history of fire and land management in the southern Sierra Nevada, focusing in particular on the Sequoia-Kings Canyon National Park and the Sequoia and Sierra National Forests. We compare changes in fire regimes over time under different management regimes for locations with similar climate, topographic, and ecosystem characteristics in neighboring federal land management units. Statistical analyses are performed using comprehensive data on large fire histories and climate records starting from the second decade of the 20th Century, records of recent decades’ land management activities(such as prescribed burning, mechanical thinning, and timber harvesting), and historical accounts of earlier management practices.