Research and Publications
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Seventeen of the 18 case studies occurred in the western United States, and all were primarily focused on forested ecosystems. Surface fire behavior was more commonly observed in areas treated for fuel reduction than in untreated areas, which managers described as evidence of treatment effectiveness. Reduced fire intensity diminished fire effects and supported fire suppression efforts, while offering the potential to use wildfires as a fuel treatment surrogate.
This study found that wildfires burned more area of non-forest lands than forest lands at the scale of the conterminous and western U.S. and the Department of Interior (DOI). In an agency comparison, 74% of DOI burned area occurred on non-forest lands and 78% of U.S. Forest Service burned area occurred on forested lands. Landscape metrics revealed key differences between forest and non-forest fire patterns and trends in total burned area, burned patch size, distribution, and aggregation over time across the western U.S. Opposite fire patterns emerged between non-forest and forest burns when analyzed at the scale of federal agency jurisdictions. In addition, a fire regime departure analysis comparing current large fire probability with historic fire trends identified certain vegetation types and locations experiencing more fire than historically. These patterns were especially pronounced for cold desert shrublands, such as sagebrush where increases in annual area burned, and fire frequency, size, and juxtaposition have resulted in substantial losses over a twenty-year period.
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Streamflow often increases after fire, but the persistence of this effect and its importance to present and future regional water resources are unclear. This paper addresses these knowledge gaps for the western United States (WUS), where annual forest fire area increased by more than 1,100% during 1984 to 2020. Among 72 forested basins across the WUS that burned between 1984 and 2019, the multibasin mean streamflow was significantly elevated by 0.19 SDs (P < 0.01) for an average of 6 water years postfire, compared to the range of results expected from climate alone. Significance is assessed by comparing prefire and postfire streamflow responses to climate and also to streamflow among 107 control basins that experienced little to no wildfire during the study period. The streamflow response scales with fire extent: among the 29 basins where >20% of forest area burned in a year, streamflow over the first 6 water years postfire increased by a multibasin average of 0.38 SDs, or 30%. Postfire streamflow increases were significant in all four seasons. Historical fire–climate relationships combined with climate model projections suggest that 2021 to 2050 will see repeated years when climate is more fire-conducive than in 2020, the year currently holding the modern record for WUS forest area burned. These findings center on relatively small, minimally managed basins, but our results suggest that burned areas will grow enough over the next 3 decades to enhance streamflow at regional scales. Wildfire is an emerging driver of runoff change that will increasingly alter climate impacts on water supplies and runoff-related risks.
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In this study we illustrate the value of social data compiled at the community scale to guide a local wildfire mitigation and education effort. The four contiguous fire-prone study communities in North Central Washington, US, fall within the same jurisdictional fire service boundary and within one US census block group. Across the four communities, similar attitudes toward wildfire were observed. However, significant differences were found on the measures critical to tailoring wildfire preparation and mitigation programs to the local context such as risk mitigation behaviors, reported barriers to mitigation, and communication preferences across the four communities.
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In general, we find that treating near housing units can provide the greatest level of protection relative to treating more remote wildlands to reduce transmission potential. Treating on federal lands to reduce federal transmission was highly effective at reducing exposure from federal fires and at expanding opportunities for beneficial fire but contributed comparatively little to reducing housing exposure from all fires. We find that treatment extents as low as 2.5–5% can yield significant benefits with spatially optimized strategies, whereas the random strategy did not perform comparably until reaching a much larger treatment extent. Increasing risk tolerance for housing exposure expanded the area suitable for managed fire, while decreasing risk tolerance for beneficial fire opportunity and flame length probability shrunk the area suitable for managed fire.
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This study expands on a 2011 tribal research needs assessment with a survey to identify tribal natural resource professionals’ research needs, access to research findings, and interest in participating in research. Information needs identified in our survey includes forest health, water quality, culturally significant species, workforce and tribal youth development, cultural importance of water, and invasive species. Additionally, postfire response and valuation, resilience and long-term forestry, protecting and curating tribal data, and Indigenous burning were more important research needs for tribal members than for nontribal members. This study can inform forestry research planning efforts and establish research priorities and collaborations that are aligned with needs identified by tribal natural resource managers.
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Our results imply that a 50% reduction in forest basal area could reduce drought-driven tree mortality by 20%–80%. The largest impacts of density reduction are seen in areas with high current basal area and places that experience high temperatures and/or severe multiyear droughts. These interactions between competition and drought are critical to understand past and future patterns of tree mortality in the context of climate change, and provide information for resource managers seeking to enhance dry forest drought resistance.
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Our results suggest that emissions from wildfires will substantially increase in future decades; however, increased levels of forest thinning could substantially reduce those emissions and harmful health impacts from large wildfires. We also found that increased use of prescribed burning could reduce the health impacts associated with large wildfires but would also increase the frequency of low levels
of emissions. Furthermore, the modeling results suggested that individual prescribed fires could have substantial health impacts if dispersion conditions are unfavorable. Our results suggest that increased management is likely to yield important benefits given expected increases in wildfire activity associated with climate change. However, there remain many challenges to projecting the effects of alternative
management regimes, especially ones that involve substantial increases in intentional burning.
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This report describes the full range of costs associated with wildland fire in the Western United States (U.S.) to help inform leaders and policymakers working to improve wildfire response and mitigation. Wildfire cost information has, in the past, primarily focused on suppression costs and structure losses; however, as this report shows, there are many other types of costs relating to values such as human health, water supply, transportation, the labor market, and local economics, among others. These less-recognized costs are massive in aggregate.
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Most studies find that fuel treatments are not financially viable for land management agencies based on revenue generated from forest products, biomass, or carbon credits at the time of implementation. Fuel treatments also tend to not be financially viable based on future management costs savings (fire suppression and rehabilitation costs) or averted losses in forest products from wildfire over the lifespan of treatment effectiveness. Similarly, most studies that consider benefits beyond those accruing to land management agencies find that the benefits from any single category (e.g., damage to structures and infrastructure, critical watersheds, air quality, or ecosystem values) are not sufficient to offset treatment costs. Overall, the recent literature suggests that fuel treatment projects are more likely to have benefits that exceed costs if they generate benefits in multiple categories simultaneously. The literature also documents tremendous variability in benefits and costs across regions and between projects within regions, which poses a challenge to reaching general conclusions about the benefits and costs of fuel treatments at programmatic scales, and suggests that practitioners should proceed with caution when trying to extrapolate the benefits and costs for a prospective fuel treatment project from estimates reported in the previous literature.