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Although these indices are useful planning tools, they vary in importance to fire
management. On non-MTC landscapes with aseasonal rainfall, fire danger indices
play a key role alerting managers of severe fire weather conditions, often with long
lead times (Roads et al. 2010 ). In MTC regions where the fire season is more
predictable, they potentially play a less critical role, although large fire events do
generally occur during periods of high burning index (e.g. van Wilgen & Scott
2001 ; McCaw & Hanstrum 2003 ; Trouet et al. 2009 ). Oftentimes, though, the
critical fire parameter is severe winds that are seldom predicted with much lead
time but dominate fire outcomes (Schoenberg et al. 2007 ).
Prefire fuel treatments have long been considered a key step in affecting S , the
probability of fire spread in the wildland environment. Wildland fuel treatments
create patches of landscape with reduced fuel loads. There are multiple objectives.
One is to reduce the probability of fire spread, another is to reduce flame lengths
and thus increase defensible space for fire fighters, and a third is to reduce loss of
resources such as trees. The value of such treatments is a function of fire weather,
as even very recently burned or otherwise treated patches have a low likelihood of
stopping unplanned fires during severe fire weather (Keeley et al. 2009b ; Price &
Bradstock 2010 ).
Prescription burning in forest management is focused on reducing fire intensity
and thus preventing understory fires from becoming crown fires and destroying
trees. One of the longest and more successful programs is in the understory
of giant sequoia ( Sequoiadendron giganteum ) forests in California ( Fig. 13.2 ).
Fig. 13.2 Prescription burn in Sequoiadendron giganteum forest of Kings Canyon National
Park in response to more than a century of fuel accumulation due to highly effective fire
suppression management. (Photo by National Park Service.)
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