Wilderness areas offer value to society as a source of scientific information. We used fire perimeter records from the upper South Fork Flathead River watershed (Montana) to characterize the area burned one or more times during three periods: the pre-fire exclusion period (1889-1934), the fire exclusion period (1935-1980), and the fire management period (1981-2017). We also quantified the effects of a recent reburn on forest structure and fuels using a before-after-control-impact study design. Total area burned and area burned multiple times depended strongly on time period. The active fire regime during the fire management period mirrored total area burned and area reburned in the pre-exclusion period. At once-burned sites, fuel loads for most fuel types increased or were stable from 2011 to 2015, reflecting ongoing deposition of fire-killed branches and trees. In contrast, the second fire either reduced or maintained surface fuels in 2015 relative to 2011 levels. Seedlings decreased significantly in the twice-burned plots while there was no change in once-burned plots; live overstory tree densities were stable over time in both once- and twice-burned plots. Managers can use the results presented here to inform the design and monitoring of forest landscape restoration prescriptions.
Larson, Andrew J.; Berkey, Julia K.; Maher, Colin T.; Trull, Wyatt; Belote, R. Travis; Miller, Carol. 2020. Fire history (1889-2017) in the South Fork Flathead River Watershed within the Bob Marshall Wilderness (Montana), including effects of single and repeat wildfires on forest structure and fuels. In: Hood, Sharon M.; Drury, Stacy; Steelman, Toddi; Steffens, Ron, [eds.]. Proceedings of the Fire Continuum-Preparing for the future of wildland fire; 2018 May 21-24; Missoula, MT. Proceedings RMRS-P-78. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 139-156.