U.S. Joint Fire Science Program


Date of this Version


Document Type



Fire Science Brief, Issue 67, September 2009


US government work.


In July 1994, a low-intensity surface fire that had been burning on Storm King Mountain in Colorado suddenly intensifi ed, shifting to the shrub canopy and rapidly advancing upslope. Caught off guard, 14 firefi ghters were trapped and lost their lives in the South Canyon Fire. A major contributing factor to this tragedy was lack of awareness of the behavior of fire in live fuels, in this case Gambel oak. Researchers have for decades sought to understand live fuel moisture variability and how it affects the behavior of fi re in carefully controlled laboratory conditions, in prescribed fires, and in wildfires. The overriding question, one which has not yet been definitively answered, is this: Under what conditions will a surface fire enter green, moist canopy foliage to sustain a high-intensity, rapidly spreading crown fire? And given the importance of live moisture variability on fire behavior, how do we interpret live fuel moisture information gathered by satellite sensors or from field sampling for its application to describing fire behavior and predicting fire danger? A recent synthesis of our state of knowledge of fire behavior in live fuels, and an assessment of the utility and limitations of the models in widespread use, will be useful to those charged with interpreting the information and transforming it into sound management decisions. The delicate tradeoff is to ensure firefighter and public safety while effectively suppressing or containing wildfi re or planning prescribed burns.