Some Forest Areas Benefit
Even From Extreme Fire
A recent U.S. Forest Service study shows that the Rodeo-Chediski Fire typically burned with less severity in areas that had undergone management treatments such as controlled burns or thinning.

The "Rodeo-Chediski Fire Effects Summary Report, August 2002" written by the Apache-Sitgreaves National Forests demonstrates that forest treatments are beneficial even when there is an extreme fire-behavior event during a record-breaking drought.

Lloyd Wilmes, the assistant fire management officer on the Apache-Sitgreaves National Forests, says it is clear from the report that forest management treatments reducing tree crown densities, raising canopy heights and reducing ground surface fuels can result in more low-intensity fires that provide sustainable wildlife habitat.

"Such fires provide openings in tree canopies, reduce choked, brushy understory and help regenerate vegetation and forage that is necessary for a wildlife population to be healthy and thrive," Wilmes says.

To compile the report, the Forest Service took all vegetative, fuel and prescribed fire treatments within the Rodeo-Chediski Fire area for the past 15 years and overlaid them on a burn severity map. The resulting overlay map shows the level of burning within each particular management treatment area.

Forest Service personnel currently use one or more of five methods to treat forest habitats.

1) Fuel treatments consisting of thinning, chipping and pile burning to reduce flammable materials.

2) Prescribed fire treatments utilizing broadcast burning to reduce fuel loads and regenerate grasses and shrubs.

3) Pre-commercial treatments consisting of thinning, chipping and/or lopping small trees.

4) Commercial treatments including large-diameter tree removal, seed cutting, regeneration, and thinning.

5) Salvage treatments involving removing salvageable trees and accumulated fuels after a wildfire.

The report states that with one exception, pre-commercial thinning, each treatment type showed a significantly smaller percentage of its area in the high-severity burn classification than those areas that were not treated.

Additionally, the moderate- and high-severity percentages together were significantly smaller than the low and unburned classifications in similar treatment types. This observation is also substantiated by data gathered from monitoring plots established within treated and untreated areas.

The report shows that prescribed fires were an effective tool in protecting some forested areas within the Rodeo-Chediski Fire because they reduced fuels that contributed to the spread and intensity of fire. This type of treatment was more effective where it had occurred in the past 10 years.

The report further states that the overall effectiveness of a prescribed fire is related to the year the burn was done, the size of the area treated, its ability to reduce live and dead fuels within the area treated, and the general stand condition. Those stands that had significant brush species regenerating in the understory burned with higher intensities than those more recently treated with prescribed fire.

Experts point out that properly administered, consistent treatments on forest habitats reduce the potential for catastrophic wildfire events. "Using treatment activities as a forest management tool is good for the forest, good for wildlife and also good for users of the forest, including recreationists and people who depend on it for their livelihood," Wilmes says.

The Forest Service report also shows that forested areas with brushy understories occurred on more than half of the area burned, and contributed to some of the highest burn severities during the fire. Because of these findings, Forest Service personnel are recommending that prescribed fires be implemented with high enough intensities and with a frequency interval necessary to keep fuel loads in check.

The fire severity map graphically depicts low-severity burn areas that correlate with past fuel and timber management activities. Although the extent of survival rates for existing tree stands will not be determined for three years or more, their probability for survival is enhanced, given their current condition. This contrasts the stark mortality shown in the majority of untreated stands.

The study demonstrates that past management practices also influenced the fire's behavior at many intervals during its progression. Previously accomplished work lowered the intensities of the fire, diminished the rate spread and altered the direction of the prominent spread significantly.

For instance, the report shows that the eastern flank of the fire that threatened Show Low and Pinetop-Lakeside was controlled because of fuel reduction treatments that had occurred previously in the area.

Fires did spread through previously burned areas, but they flanked around the treated areas first, giving firefighters additional time to enact protection measures that saved many houses and other structures.

The report points out additional benefits such as lowering rehabilitation costs in treated areas while also reducing costly erosion.

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