Simulation study of more than 45,000 forest stands provides scientific basis for fuel reduction guidelines
The study, the results of which are published in a recent issue of the Canadian Journal of Forest Research, provides a scientific basis for establishing quantitative guidelines for reducing stand densities and surface fuels. The total number of optimal trees per acre on any given forest will depend on species, terrain and other factors.
“This study proves once again that an ounce of prevention equals a pound of cure,” said U.S. Forest Service Chief Tom Tidwell. “Thinning dense forests reduces the impacts of the catastrophic wildfires we’ve already seen this year and expect to see more and more of in the future. This work helps protect communities, provides jobs and promotes overall better forest health.”
Decades of excluding fire in the Western states have resulted in densely packed stands and a buildup of forest-floor fuels in many dry forests, which can lead to large, continuous crown fires when wildfires do occur. Crown fires are of particular concern to managers because they are challenging to suppress and are capable of causing widespread mortality in stands.
“Most forest managers understand that dry Western landscapes need to be heavily thinned to significantly reduce the threat of crown fires, and our findings now give a sense of just how much thinning is required,” said Morris
To test how effective fuel treatments in the Western states are in reducing the probability and severity of crown fires,
“This kind of simulation modeling allows us to evaluate multiple treatment types across a large number of forest stands and conditions in diverse geographic areas,”
Their simulations suggested that the effectiveness of fuel treatments in the West depends on thinning intensity, with the most intense treatments they studied, which leave 50 to 100 trees per acre, being more effective in reducing the threat of crown fires than less-intense treatments. Thinning to this level, along with the removal of post-treatment debris known as “slash,” made conditions unfavorable for crown fire initiation and reduced the probability of active crown fire.
Findings from the study, in addition to confirming the importance of thinning treatments, can help managers to evaluate the effectiveness of their fuel treatments.
To read the article online, visit http://www.treesearch.fs.fed.us/pubs/38390.
To learn more about the Pacific Wildland Fire Sciences Laboratory, visit http://www.fs.fed.us/pnw/pwfsl.
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About the U.S. Forest Service
The mission of the U.S. Forest Service is to sustain the health, diversity, and productivity of the nation’s forests and grasslands to meet the needs of present and future generations. The agency manages 193 million acres of public land, provides assistance to state and private landowners, and maintains the largest forestry research organization in the world.