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Learning From the Past: Retrospective Analyses of Fire Behavior in Yosemite and Sequoia-Kings Canyon National Parks

Carol Miller and Brett Davis - Aldo Leopold Wilderness Research Institute

Yosemite Fire

Decades of fire suppression in both Yosemite and Sequoia-Kings National Parks have altered natural fire regimes, vegetation and wildlife habitat. Fires are suppressed for a variety of reasons including air quality concerns inside and outside the parks, risks to cultural resources, structures in park developments, private in-holdings, and the adjacent WUI. To alleviate the negative impacts of fire suppression, both parks have implemented fire restoration policies. Although restoration of fire as a natural process is one of the highest priorities for both parks, this objective has not been met and the parks are far from restoring natural fire regimes (Yosemite National Park 2003). Measuring the difference between the natural frequency of wildland fires and the number of years fire has been suppressed provides an indication of how far current vegetation deviates from natural conditions and how to prioritize fuel management activities. Both parks have fire management plans (Yosemite NP, Sequoia-Kings Canyon NP) which delineate extensive zones where the option of allowing fires to burn exists. But, for the reasons listed above, most fires are still suppressed. These fire management decisions are always made with some degree of uncertainty surrounding their environmental and social consequences. An adaptive management approach with explicit monitoring of management actions has been recommended (Committee of Scientists, 1999) for informing these kinds of decisions but has proven difficult. Measuring the effects of fires that are allowed to burn is relatively straight-forward, but measuring the impacts of fire suppression is much less so. We believe that retrospective case studies can be used to systematically evaluate the consequences of these suppression decisions.


This 3-year project used fire behavior modeling to quantify the consequences of past suppression decisions. Results from this research will improve the prioritization and planning of fuels management activities, allow managers to track the cumulative effects of suppression, and communicate tradeoffs to the public.

Black Mountain Fire

We used retrospective fire behavior modeling and risk-benefit assessments for suppressed lightning ignitions that have occurred since 1994 in the two Parks. We determined where lightning ignitions would have spread had they not been suppressed and we assessed the effects that would have resulted from these fires. Results from our analyses were compiled and presented in a GIS data library that allows easy reference for managers during the fire season when making the decision whether or not to suppress, when preparing Stage III Wildland Fire Implementation Plan (WFIP) analyses, and when developing appropriate management response on suppression incidents. Furthermore, the project developed methodologies and step-by-step procedures for conducting these retrospective analyses so that Park fire management staff can update and add to this information resource annually. The information and understanding generated by this research will improve the prioritization and planning of fuels management activities by supplementing the Fire Return Interval Departure analysis that is routinely done by both Parks. The results of our analyses will allow park managers to frame future decisions and cost-benefit analyses in the context of past experiences, to track the cumulative effects of suppression, and to communicate tradeoffs to the public and other governmental entities.

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Joint Fire Science Program

This project is supported by the Joint Fire Science Program.