Research and Publications
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We used 26,907 California’s wildfire ignitions to run automatic simulations. The Fire Behavior Index (FBI), Terrain Difficulty Index (TDI) and IAA were determined using size-based and fire behavior outputs from each simulation. Initial attack success was evaluated by comparing simulations with real fire sizes. Binary models were calibrated and validated to predict success based on IAA, FBI and TDI, and suppression response time.
The IAA effectively identified fires exceeding suppression capacity. Higher levels of IAA, FBI and TDI were associated with reduced success odds, IAA=5 giving a 90% decrease in the odds of initial attack success. Response time and its interaction with terrain difficulty were also influential. The IAA is a powerful index to feed DSSs, prioritizing fire response and predicting the probability of control at a small size.
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We measured forb composition and other community characteristics at different scales in 17 sites across eastern Oregon with paired plots across seeding boundaries. We quantified differences associated with seeding overall. We also investigated the potential for seeding outcomes to relate to biotic interactions based on abundance of major functional groups, species traits related to competition, microsite features relating to competition, and soil texture. Finally, we tested the generality of our paired plot results across the study area by accounting for a broader range of management and environmental factors with a matching analysis using a large independent vegetation dataset. Paired plot comparisons suggested negative relationships between seeding and forb density. Biotic interactions with major functional groups were not strongly associated with forb community differences due to seeding, with the exception of a negative relationship between native annual forb abundance and increasing invasive annual grass cover. Few biotic interactions were related to seeding outcomes, though native annual forb abundance was negatively associated with higher invasive annual grass cover. Traits related to competition were not strongly related to species seeding response. Soil texture affected several forb community characteristics, including sometimes altering seeding outcomes. Increasing sand content was associated with lower perennial forb diversity and abundance, and annual forb richness decreased with higher sand content in seeded, but not unseeded, sites. The regional-level matching analysis, which controlled for the effects of management and environmental factors, generally supported the paired plot comparisons by showing that crested wheatgrass seeding was associated with lower invasive annual grass cover and lower total and perennial forb cover and richness.
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We measured herbaceous biomass response to cattle grazing spanning 18 yr (2007–2024) on burned Wyoming big sagebrush steppe in southeastern Oregon. Treatments were applied in a randomized complete block design, including no grazing on burned (nonuse) and unburned (control) sagebrush steppe; and cattle grazing at low (low), moderate (moderate), and high (high) stocking. All grazed treatments were by deferred rotation. Deferred rotation consisted of grazing during the active growing season (mid-May–early June) once every 3 yr followed by 2 yr of grazing during summer herbaceous dormancy (July, August, or September). Herbage was sorted by herbaceous functional group, which included an early season bunchgrass, tall perennial bunchgrasses, perennial forbs, cheatgrass, and annual forbs. Both standing crop and annual net primary production (ANPP, current year’s growth) of functional groups were evaluated by repeated measures analysis. Standing crop decreased as grazing intensity increased but recovered with 1 or 2 yr of grazing rest. Herbaceous functional group ANPP did not differ among the burned treatments (grazed and nonuse), and total and perennial bunchgrass production were all greater than the control. Grazing intensity in the deferred rotation program did not affect long-term ANPP. Annual weather events account for ANPP variability measured for the various grazed and ungrazed treatments.
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We compared vegetation recovery spanning 20 yr following prescribed fire on mid-succession and late-succession western juniper woodlands on Steens Mountain, Oregon. Our objective was to evaluate vegetation dynamics between early (first decade) and later successional (second decade) time periods after fire. The first decade after fire vegetation on burned mid-succession sites were codominated by native herbaceous perennials and sprouting shrub species and on late-succession sites vegetation was codominated by nonnative cheatgrass and snowbrush. During the second decade after fire, vegetation composition converged and both mid-succession and late-succession sites were codominated by herbaceous perennials, mountain big sagebrush, round-leaf snowberry, and snowbrush. Herbaceous and shrub vegetation composition of both burned woodland phases proved to be highly resilient to fire, the difference was that native shrub-herbaceous recovery on late-succession sites required about twice as much time as mid-succession sites. The resilience of both mid-succession and late-succession woodland sites was likely a product of ecological site characteristics (e.g., elevation and precipitation zone) that affords a competitive advantage for native perennial species over invasive annuals.
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The Bureau of Land Management (BLM) plans to expand its network of LFBs in the Great Basin by over 17 000 km. However, uncertainties remain regarding their effectiveness in reducing wildfire-related impacts. To address this knowledge gap, we estimate avoided wildfire costs attributable to fuel breaks in the Twin Falls BLM District of south-central Idaho. Our analysis focuses on the 2019 Pothole fire, which was contained in part due to the presence of LFBs. By developing a counterfactual simulated scenario in which the fire did not intersect the fuel breaks and using historic data on suppression expenditures, postfire rehabilitation costs, and grazing-related forage losses, we estimate the net economic benefits associated with fuel break presence. This case study provides actionable insights for land managers by quantifying the potential cost savings from fuel break infrastructure. Our findings indicate that in the northern Great Basin, LFBs may significantly reduce wildfire management costs, supporting their strategic deployment as part of a broader landscape-scale fire mitigation approach.
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This study investigates the key drivers influencing prescribed fire effects across 16 sites in northern and central California, with particular emphasis on how operational decisions by fire practitioners shape burn outcomes. Data from the California Prescribed Fire Monitoring Program revealed that prescribed fires reduced total fuel loads by an average of 60 %, with greater consumption of postfrontal smoldering fuels (coarse fuels, 65 %) compared to frontline spreading fuels (fine fuels, 49.0 %).
Crown scorch height showed a strong relationship to crown base height (R2 = 0.37–0.86), suggesting that practitioners use crown base height as a visual indicator to control fireline intensity and avoid crown damage. This relationship may partially explain fuel consumption patterns, as crown avoidance strategies can influence fire behavior and intensity. Additionally, we documented a compensatory relationship between live and dead fuel moisture content across burn seasons, indicating that practitioners strategically select burning windows that maintain fireline intensity within controllable parameters regardless of season.
Our findings demonstrate that human decisions fundamentally modify prescribed fire behavior to maintain safety parameters, often constraining outcomes to conservative ranges that may compromise treatment effectiveness. Understanding and accounting for these human factors is crucial to encouraging a more effective use of prescribed fires in the future. We recommend that future research explicitly include operational parameters and practitioner decision-making processes in assessing prescribed fire science, balancing safety considerations with goals for ecological restoration.
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Protection of human life and property is an accepted priority of wildfire management, yet there has been little consideration of how fire management strategies balance these two objectives. International comparisons present an important opportunity to explore differences in how human life or property are impacted by contrasting wildfire regimes and management responses. We analyse public data (1999–2020) on fatalities and property losses in Australia and the USA, two countries heavily affected by socially disastrous wildfires. The annual ratio between house losses and fatalities differs markedly between the two countries, with the USA experiencing a 2.5-fold higher rate of house loss per fatality than Australia. This difference potentially reflects contrasting wildfire adaptation strategies between these two countries: the USA approach relies on mass evacuations and fire suppression, whereas the Australian approach is centred on building design and reducing wildland fuel loads. Further international comparative research is required to understand how biophysical and management regimes influence the impacts of wildfire on human life and property.
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It’s no secret that wildland fires kill trees, but are more trees killed by fire when they are already stressed from drought? New research from the U.S. Department of Agriculture, Forest Service indicates that prefire drought can increase tree mortality after fire, even with the same level of tree damage.
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We analyzed fire statistics (1910–2021) alongside climate and weather data, stratifying the state by 10 ecoregions. Northern forests had the strongest correlation with the proximate factor fuel aridity, ultimately due to climate. Fire rotation intervals exceeded 100 years, implicating woody fuel accumulation as an additional factor. Lightning ignitions occurred in decadal bursts, with dense strike events potentially overwhelming fire-fighting resources. Lower elevation/latitude foothill ecoregions experienced highest fire activity following wet winters and springs, implicating control by herbaceous fuel loads and a negative effect of global warming on future fires. Human ignitions dominate in these ecoregions, and population growth contributes to expansion of powerlines, a major ignition source. While climate change may increase fire activity in forested ecoregions, its role is less pronounced in non-forested ecoregions, where human ignition sources are the dominant factor.
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While species diversity and cover of lifeforms did not differ on and off fuel breaks, species composition and regeneration strategy of dominant shrubs differed significantly. Sites in fuel breaks were dominated by fast-growing subshrubs that regenerate from seeds and are more readily dispersed into sites—species that are typical indicators of the coastal sage scrub community. Sites off fuel breaks were characterized by a mix of resprouting and seeding shrubs typically associated with the chaparral community. Fuel breaks established by bulldozers during wildland firefighting have impacts on chaparral composition because the actions of the dozer remove soil seed banks and damage resprout “banks” (lignotubers). The permanence of these changes is likely to be related to the frequency and severity of fire suppression actions.