Abstract
Much of the coniferous zones in the Western United States where fires were historically frequent have seen large increases in stand densities and associated forest fuels due to 20th century anthropogenic influences. This condition is partially responsible for contemporary large, uncharacteristically severe wildfires. Therefore, considerable effort is under way to reduce the potential for extreme wildfire behavior and effects, especially near communities, by manipulating canopy and surface fuels using mechanical thinning and/or prescribed burning. Treatment effectiveness, however, has been difficult to quantitatively assess, but methods are now available for estimating stand-level canopy and surface fuels with which fire behavior can be more accurately modeled and compared among different fuel treatments. The Sheafman Fuels Reduction Project was recently conducted by the Bitterroot National Forest incorporating various fuel treatments to reduce the probability of high intensity crown fire impacting a watershed adjacent to Pinesdale, MT. Detailed sampling of stand conditions was conducted before and after two treatments: overstory thinning with understory cutting, and understory cutting only. Both were followed by slash burning. Surface fuel loadings were estimated from intercept data, and canopy fuels were estimated from tree data using the FuelCalc program. Pre- and posttreatment fuels data were used to model surface and crown fire behavior using the NEXUS program. A comparison was made between fire behavior computed from treatment mean fuels data and individual plot fuels data. Results indicate that because surface fuels and estimated mid-flame wind speeds increased modestly with treatments, surface fire behavior was not greatly altered until 20-ft wind speeds exceeded 20 mph. Treatment effects on canopy base heights and canopy bulk densities within the small landscape determined the level of estimated treatment effectiveness. Both treatments reduced the probability of crown fire initiation by raising canopy base heights. The likelihood of crown fire spread was appreciably reduced only in the overstory thinning treatment. An examination of plot scale surface and crown fire behavior gave a more detailed assessment of treatment effectiveness than average treatment values.
Parent Publication
Keywords
wildland fire management,
operational fuel reduction treatment,
Bitterroot National Forest,
Montana,
spatial scales,
canopy and surface fuels
Citation
Harrington, Michael G.; Noonan-Wright, Erin; Doherty, Mitchell. 2007. Testing the modeled effectiveness of an operational fuel reduction treatment in a small Western Montana interface landscape using two spatial scales. In: Butler, Bret W.; Cook, Wayne, comps. The fire environment--innovations, management, and policy; conference proceedings. 26-30 March 2007; Destin, FL. Proceedings RMRS-P-46CD. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. CD-ROM. p. 301-314
