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Fuel Treatment Patterns
It’s the Mission Impossible of Western ponderosa pine forest management — millions of acres of overcrowded, drought stressed, small diameter trees ready to go up in flames in catastrophic wildfires. You have enough money to conduct ecologically sound thinning treatments on only 10 to 20 percent of the landscape. Your mission, should you choose to accept it: prevent destructive crown fires while allowing for the return of naturally occurring low intensity fires. And stay within budget.
We are not likely to see Tom Cruise in this adventure, but Research Forester Mark Finney and his team members from the Forest Service Rocky Mountain Research Station’s Fire Sciences Laboratory are ready to try an innovative approach to reducing the threat of catastrophic wildfire. Finny’s team has developed a sophisticated computer modeling program called FARSITE.
FARSITE works with variables such as prevailing wind patterns and speeds, topography (landscape slopes), vegetation types and densities, and temperature and moisture conditions to make predictions about fire behavior in a given landscape. The computer model simulates fire growth and spread rates based on inputs of data gathered from studies in a particular forest. Researchers can change certain variables to simulate thinning, restoration projects, fire breaks and other treatments. FARSITE then makes predictions of how well treatments are likely to perform on the ground.
Finney’s research suggests that intensive treatments on 10 to 20 percent of the landscape can be effective in reducing the threat of crown fires if the treatments are arranged in spatial patterns that that disrupt a fire’s forward spread rate. The following figure shows highly simplified simulations of fire spread rates through different treatment patterns.
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Models of actual landscapes bear little resemblance to the simplified patterns shown in the figures above. Features such as previous treatments, roads, and meadows are all factored into landscape scale treatment strategies. FARSITE models treatment patterns that modify fire growth and behavior by slowing forward fire spread rates, thus allowing fires to burn with less intensity and minimizing crown fire.
Studies are underway to test the effectiveness of fuel treatment pattern regimens modeled by FARSITE. Mission Impossible: the clock is ticking as the 2003 fire season begins. Nature may soon put Finney’s theories to the ultimate test.
References
Agee, James K. et al. “The Use of Shaded Fuel Breaks in Landscape fire Management.” 2000. Forest Ecology and Management 127.
Finney, Mark A. “Design of Regular Landscape Fuel Treatment Patterns
for Modifying Fire Growth and Behavior.” 2001. Forest Science 47
(2). http://www.cnr.berkeley.edu/wfrg/main/lecture01/Finney.pdf
5/9/03.
