Research Database
Displaying 1 - 20 of 222
Canadian forests are more conducive to high-severity fires in recent decades
Year: 2025
Canada has experienced more-intense and longer fire seasons with more-frequent uncontrollable wildfires over the past decades. However, the effect of these changes remains unknown. This study identifies driving forces of burn severity and estimates its spatiotemporal variations in Canadian forests. Our results show that fuel aridity was the most influential driver of burn severity, summer months were more prone to severe burning, and the northern areas were most influenced by the changing climate. About 6% (0.54 to 14.64%) of the modeled areas show significant increases in the number of days…
Publication Type: Journal Article
Fire directly affects tree carbon balance and indirectly affects hydraulic function: consequences for post-fire mortality in two conifers
Year: 2025
- The mechanistic links between fire-caused injuries and post-fire tree mortality are poorly understood. Current hypotheses differentiate effects of fire on tree carbon balance and hydraulic function, yet critical uncertainties remain about the relative importance of each and how they interact.
- We utilize two prescribed burns with Douglas-fir and ponderosa pine to examine: the relative evidence for fire-caused changes in hydraulic function and carbon dynamics, and how such impacts relate to fire injuries; which impacts most likely lead to post-fire mortality; and how these…
Publication Type: Journal Article
State of Wildfires 2024–2025
Year: 2025
Climate change is increasing the frequency and intensity of extreme wildfires globally, yet our understanding of these high-impact events remains uneven and shaped by media attention and regional research biases. The State of Wildfires project systematically tracks global and regional fire activity of each annual fire season, analyses the causes of prominent extreme wildfire events, and projects the likelihood of similar events occurring in future climate scenarios. This, its second annual report, covers the March 2024 to February 2025 fire season. During the 2024–2025 fire season, fire-…
Publication Type: Journal Article
Insights provided by a new searchable repository for post-fire hydrology studies and associated data
Year: 2025
BackgroundAs the number and size of wildfires increase worldwide, so too has the realization that wildfires and hydrology are closely linked. The field of post-fire hydrology has been growing in recent decades, but the resultant datasets and studies are spread across disparate repositories and can be difficult for researchers and decision-makers to access.ResultsTo help address this issue, we have created searchable lists of literature, datasets, and models related to post-fire hydrology which can be accessed—and added to—by any interested members of the…
Publication Type: Journal Article
Integrated fire management as an adaptation and mitigation strategy to altered fire regimes
Year: 2025
Altered fire regimes are a global challenge, increasingly exacerbated by climate change, which modifies fire weather and prolongs fire seasons. These changing conditions heighten the vulnerability of ecosystems and human populations to the impacts of wildfires on the environment, society, and the economy. The rapid pace of these changes exposes significant gaps in knowledge, tools, technology, and governance structures needed to adopt informed, holistic approaches to fire management that address both current and future challenges. Integrated Fire Management is an approach that combines fire…
Publication Type: Journal Article
Long-term influence of prescribed burning on subsequent wildfire in an old-growth coast redwood forest
Year: 2025
Background: Prescribed burning is an effective tool for reducing fuels in many forest types, yet there have been few opportunities to study forest resilience to wildfire in areas previously treated. In 2020, a large-scale high-intensity wildfire burned through an old-growth coast redwood (Sequoia sempervirens) forest with a mixed land management history, providing a rare opportunity to compare early post-wildfire data between areas with and without previous application of prescribed burning. The purpose of this study was to analyze the differences between these two treatments in…
Publication Type: Journal Article
Wildfires drive multi-year water quality degradation over the western United States
Year: 2025
Wildfires can dramatically alter water quality, resulting in severe implications for human and freshwater systems. However, regional-scale assessments of these impacts are often limited by data scarcity. Here, we unify observations from 1984–2021 in 245 burned watersheds across the western United States, comparing post-fire signals to baseline levels from 293 unburned basins. Organic carbon and phosphorus exhibit significantly elevated levels (p ≤ 0.05) in the first 1–5 years post-fire, while nitrogen and sediment show significant increases up to 8 years post-fire. During peak post-…
Publication Type: Journal Article
A Negative Fire–Vegetation Feedback Substantially Limits Reburn Extent Across the North American Boreal Biome
Year: 2025
The North American boreal biome (NAB) is warming at 2–4 times the mean global rate, contributing to increasing wildfire activity. The degree to which this trend alters biome-level feedbacks to global climate depends on how strongly bottom-up feedbacks between fire and vegetation dampen the effects of climate drivers. As young vegetation recovering from fire covers a growing portion of the landscape, it could resist reburning, buffering against further increases in fire. Resistance to reburning could be particularly strong in the NAB, where slow post-fire fuel accumulation is sometimes…
Publication Type: Journal Article
Post-fire delayed tree mortality in mesic coniferous forests reduces fire refugia and seed sources
Year: 2025
Context: Ecological functions provided by fire refugia are critical for supporting conifer forest resiliency under increased fire activity across the western United States. The spatial distribution and persistence of fire refugia over time are uncertain as fire-injured trees continue to die over subsequent years post-fire.Objectives: We examined how post-fire delayed tree mortality affects the spatial distribution and attributes of fire refugia at patch and landscape scales following high-severity wildfires.Methods: To explore changes in fire…
Publication Type: Journal Article
Near real-time indicators of burn severity in the western U.S. from active fire tracking
Year: 2025
BackgroundTimely information on wildfire burn severity is critical to assess and mitigate potential post-fire impacts on soils, vegetation, and hillslope stability. Tracking individual fire spread and intensity using satellite active fire data provides a pathway to near real-time (NRT) information. Here, we generated a large database (n = 2177) of wildfire events in the western United States (U.S.) between 2012 and 2021 using active fire detections from the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor on the Suomi National Polar-orbiting Partnership (SNPP) satellite and…
Publication Type: Journal Article
Changing fire regimes in the Great Basin USA
Year: 2025
Wildfire is a natural disturbance in landscapes of the Western United States, but the effects and extents of fire are changing. Differences between historical and contemporary fire regimes can help identify reasons for observed changes in landscape composition. People living and working in the Great Basin, USA, are observing altered fire conditions, but spatial information about the degree and direction of change and departure from historical fire regimes is lacking. This study estimates how fire regimes have changed in the major Great Basin vegetation types over the past 60 years with…
Publication Type: Journal Article
Short-term impacts of operational fuel treatments on modelled fire behaviour and effects in seasonally dry forests of British Columbia, Canada
Year: 2025
Background: In response to increasing risk of extreme wildfire across western North America, forest managers are proactively implementing fuel treatments.Aims: We assessed the efficacy of alternative combinations of thinning, pruning and residue fuel management to mitigate potential fire behaviour and effects in seasonally dry forests of interior British Columbia, Canada.Methods: Across five community forests, we measured stand attributes before and after fuel treatments in 2021 and 2022, then modelled fire behaviour and effects using the…
Publication Type: Journal Article
Mapping Delayed Canopy Loss and Durable Fire Refugia for the 2020 Wildfires in Washington State Using Multiple Sensors
Year: 2025
Fire refugia are unburned and low severity patches within wildfires that contribute heterogeneity that is important to retaining biodiversity and regenerating forest following fire. With increasingly intense and frequent wildfires in the Pacific Northwest, fire refugia are important for re-establishing populations sensitive to fire and maintaining resilience to future disturbances. Mapping fire refugia and delayed canopy loss is useful for understanding patterns in their distribution. The increasing abundance of satellite data and advanced analysis platforms offer the potential to map fire…
Publication Type: Journal Article
Complexities in post-wildfire governance: lessons from Colorado’s 2020 wildfires
Year: 2025
Background: The increasing size and severity of western U.S. wildfires in recent years has generated greater attention towards post-wildfire response and recovery. Post-fire governance requires coordinating response and recovery capacities across jurisdictions, landscapes, and time scales. The presence of wildfire on federal public lands necessitates federal agency involvement in both suppression and recovery efforts, and program coordination with lower levels of government and non-governmental organizations. Using semi-structured interviews, we investigated experiences of leaders across the…
Publication Type: Journal Article
Anthropogenic warming drives earlier wildfire season onset in California
Year: 2025
Annual wildfire area in California has rapidly grown in recent decades, with increasingly negative impacts on people. The fire season is also lengthening, with an earlier onset. This trend has been hypothesized to be driven by anthropogenic warming, but it has yet to be quantitatively attributed to climate drivers. Using a comprehensive fire occurrence dataset, we analyze fire season onset and climate controls on its variability and change during 1992–2020 in 13 California ecoregions. Northern California ecoregions show stronger trends toward earlier onset compared to more arid southern…
Publication Type: Journal Article
Planted seedling regeneration using gap-based silviculture without herbicide in a wildfire-impacted forest of the Sierra Nevada
Year: 2025
Gap-based silviculture, which we define as the creation and maintenance of multi-aged stands through the periodic harvesting of discrete canopy gaps, provides a potential mechanism for converting previously high-graded stands into more heterogeneous, multi-aged structures. An advantage of small canopy gaps, relative to even-aged regeneration methods, is their potential to suppress shrub competition while allowing seedling growth without the use of herbicides or other means of managing shrub competition. While this idea has been proposed in principle, it has not been tested. The objective of…
Publication Type: Journal Article
Fire gives avian populations a rapid and enduring boost in protected forests of California
Year: 2025
BackgroundFire can impact ecosystems and species over both short and long timeframes, resulting in pervasive impacts on the structure of avian communities. While recent research has highlighted the strong impact of fire on bird communities in the short term, there remains a need for understanding long-term population processes following fire, particularly in forested landscapes that are burning more frequently than in the past century. We analyzed avian response to fire using point-count data from 1999–2019 within national parks of the Sierra Nevada Inventory & Monitoring Network,…
Publication Type: Journal Article
Increasing Hydroclimatic Whiplash Can Amplify Wildfire Risk in a Warming Climate
Year: 2025
On January 7 and 8, 2025, a series of wind-driven wildfires occurred in Los Angeles County in Southern California. Two of these fires ignited in dense woody chaparral shrubland and immediately burned into adjacent populated areas–the Palisades Fire on the coastal slopes of the Santa Monica Mountains and the Eaton fire in the foothills of the San Gabriel Mountains. Both fires ultimately eclipsed the traditionally-defined “wildland-urban interface” boundaries by burning structure-to-structure as an urban conflagration. The scope of the devastation is staggering; at the time of writing, the…
Publication Type: Report
Small-scale fire refugia increase soil bacterial and fungal richness and increase community cohesion nine years after fire
Year: 2025
Small-scale variation in wildfire behavior may cause large differences in belowground bacterial and fungal communities with consequences for belowground microbial diversity, community assembly, and function. Here we combine pre-fire, active-fire, and post-wildfire measurements in a mixed-conifer forest to identify how fine-scale wildfire behavior, unburned refugia, and aboveground forest structure are associated with belowground bacterial and fungal communities nine years after wildfire. We used fine-scale mapping of small (0.9–172.6 m2) refugia to sample soil-associated burned and…
Publication Type: Journal Article
Mobile radar provides insights into hydrologic responses in burn areas
Year: 2025
Background. Wildfires often occur in mountainous terrain, regions that pose substantial challenges to operational meteorological and hydrologic observing networks. Aims. A mobile, postfire hydrometeorological observatory comprising remote-sensing and in situ instrumentation was developed and deployed in a burnt area to provide unique insights into rainfall-induced post-fire hazards. Methods. Mobile radar-based rainfall estimates were produced throughout the burn area at 75-m resolution and compared with rain gauge accumulations and basin response variables. Key results. The mobile radar was…
Publication Type: Journal Article