Fire Behavior and Fuel Reduction Treatments

Wildfire illustration

Weather, topography, and fuels influence the behavior of wildfire in the central Sierra Nevada mountains. Wildfire suppression personnel have no control over weather and topography. Fuels, however, can be modified through a variety of treatments to slow or affect the spread of wildfire. The less fuel present, the lower the fire behavior intensity should be with all other factors remaining the same.

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Key influences on fire regimes: (1) vegetation, (2) topography, (3) climate, and (4) humans.

Connectivity of fuel treatments, to reduce available fuel, is vital to construct the defense system to protect against or lessen the severity of wildfire. Prioritization and development of fuel treatments is driven by factors including grant funding availability and requirements, success in obtaining grant funding, and project management availability for project planning and implementation.

The range of possible fuel reduction treatments include fuel breaks and defensible fire profile zone (DFPZ) construction, shredding, biomass treatments, mastication, thinning, prescribed burning, and goat and cattle grazing.

Wildfires that display extreme fire behavior conditions can be expected to cross fire defense systems/fuel breaks in certain situations. Regardless of this expectation, strategically placed fire defense systems aid in significantly controlling wildfires where they come into contact with fuel breaks. This concept proved true in the 2015 Oak Fire near Old Oak Ranch and Sierra Outdoor School. Two fast moving fires started just after 1 p.m. on September 8, 2015, merging into one fire that ran into a recently completed shaded fuel break, allowing air and ground suppression resources to stop the fire at 108 acres, preventing a major fire from occurring. Two days later over 70,000 acres burned in the Butte Fire, serving as a stark reminder of what can happen under extreme conditions.