Research Database
Displaying 101 - 120 of 1306
A novel methodology to assess fuel treatment effectiveness: application to California’s forests
Year: 2025
Background. Fuel treatments are increasingly used to mitigate wildfire risks. Aims. Proposing a novel, scalable and transferable methodology, this study investigates which treatment is (more) effective at a regional scale. Methods. This research evaluates the effectiveness of fuel treatments in California forests using the Fuel Treatment Effectiveness Monitoring (FTEM) database, which provides a binary (yes/no) assessment of treatment efficacy based on a structured subjective evaluation process. Proposed methodology enables scaling up site-specific treatment outcomes to the regional…
Publication Type: Journal Article
Aspen impedes wildfire spread in southwestern United States landscapes
Year: 2025
Aspen (Populus tremuloides) forests are generally thought to impede fire spread, yet the extent of this effect is not well quantified in relation to other vegetation types. We examined the influence of aspen cover on interpolated daily fire spread rates, the relative abundance of aspen at fire perimeters versus burn interiors, and whether these relationships shifted under more fire-conducive atmospheric conditions. Our study incorporated 314 fires occurring between 2001 and 2020 in the southwestern United States and a suite of gridded vegetation, topography, and fire weather…
Publication Type: Journal Article
Mapping Community Capacity to Reduce Vulnerability to Wildfire in Colorado, USA
Year: 2025
Communities can face significant risk from wildfire, often compounded by climate change and legacies of industrial forest management. Policies and collaborative approaches for managing wildfire risk have evolved to include greater roles and responsibilities for these communities, yet local communities often lack the capacity to plan and implement actions to reduce risk of, respond to, and recover from wildfire. In this paper, we explore spatial patterns of local capacity relative to wildfire risk across the state of Colorado, USA, with the aim of informing efforts to reduce vulnerability.…
Publication Type: Journal Article
Contextualizing recent increases in Canadian boreal wildfire activity: decadal burn rates still within historical variability of the two past centuries
Year: 2025
With approximately 15 million hectares burned, the 2023 wildfire season in Canada was exceptional. However, it remains unclear whether such recent increases in burned areas exceed the range of variability observed over past centuries. The objective of this study was to leverage available dendrochronological reconstructions of decadal burn rates to contextualize their recent increase within their historical variability over the past two centuries. We compared decadal burn rate reconstructions based on dendrochronological data (1800s–2023) for five large eastern and western Canadian boreal…
Publication Type: Journal Article
Effect of Recent Prescribed Burning and Land Management on Wildfire Burn Severity and Smoke Emissions in the Western United States
Year: 2025
Wildfires in the western US increasingly threaten infrastructure, air quality, and public health. Prescribed (“Rx”) fire is often proposed to mitigate future wildfires, but treatments remain limited, and few studies quantify their effectiveness on recent major wildfires. We investigate the effects of Rx fire treatments on subsequent burn severity across western US ecoregions and particulate matter (PM2.5) emissions in California. Using high-resolution (30-m) satellite imagery, land management records, and fire emissions data, we employ a quasi-experimental design to compare Rx fire-treated…
Publication Type: Journal Article
Air Quality Impacts of the January 2025 Los Angeles Wildfires: Insights from Public Data Sources
Year: 2025
Smoke from the Los Angeles (LA) wildfires that started on January 7, 2025 caused severe air quality impacts across the region. Government agencies released guidance on assessing personal risk, pointing to publicly available data platforms that present information from monitoring networks and smoke plume outlines. Additional satellite-based products provide supporting information during dynamic wildfire smoke events. We evaluate the regional air quality impacts of the fires through publicly available fine particulate matter (PM2.5) and nitrogen dioxide (NO2) observations from regulatory…
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
Drivers of fire severity in repeat fires: implications for mixed-conifer forests in the Sierra Nevada, California
Year: 2025
BackgroundWhile the reintroduction of recurring fire restores a key process in frequent-fire adapted forests, the ability to significantly shift the structure and composition of departed contemporary forests has not been clearly demonstrated. Our study utilized an extensive network of field plots across three short-interval successive fires occurring in the northern Sierra Nevada, California. We evaluated the influence of plot-level forest structure and composition, topography, and weather on fire severity in a third successive fire (i.e., second reburn). Additionally, we assessed the range…
Publication Type: Journal Article
Evolution and change in wildfire mitigation approaches: Social fragmentation and recreational development in rural contexts
Year: 2025
The social diversity of human populations living in or near wildfire-prone lands are an important influence on the scale at which wildfire mitigation action can occur among residential populations at increasing risk from wildfire. The research presented in this paper explores how fire adaptation programs or strategies designed to foster private landowners’ mitigation action proliferate across a landscape through in-depth case study of interacting contexts operating in neighboring human “communities.” We utilize and expand existing concepts for gauging the local social context influencing…
Publication Type: Journal Article
Motivating parents to protect their children from wildfire smoke: the impact of air quality index infographics
Year: 2025
Background. Wildfire smoke events are increasing in frequency and intensity due to climate change. Children are especially vulnerable to health effects even at moderate smoke levels. However, it is unclear how parents respond to Air Quality Indices (AQIs) frequently used by agencies to communicate air pollution health risks. Methods. In an experiment (3 × 2 × 2 factorial design), 2,100 parents were randomly assigned to view one of twelve adapted AQI infographics that varied by visual (table, line, gauge), index type (AQI [0-500], AQHI [1-11+]), and risk…
Publication Type: Journal Article
Extremely large fires shape fire severity patterns across the diverse forests of British Columbia, Canada
Year: 2025
Warming and drying conditions are driving increases in wildfire size and annual area burned across the forests of British Columbia, Canada. The impact of increasing fire activity on these forests remains unclear as examination of concurrent changes to fire severity is lacking. Here, we assess how fire severity patterns change with the amplification of wildfire size across the bioregions of British Columbia using fire severity mapping from 1986 to 2021. First, we examine trends in extremely large fires (i.e., largest 5% of fires) and their influence on annual area burned; then we examine…
Publication Type: Journal Article
Big trees burning: Divergent wildfire effects on large trees in open- vs. closed-canopy forests
Year: 2025
Wildfire activity has accelerated with climate change, sparking concerns about uncharacteristic impacts on mature and old-growth forests containing large trees. Recent assessments have documented fire-induced losses of large-tree habitats in the US Pacific Northwest, but key uncertainties remain regarding contemporary versus historical fire effects in different forest composition types, specific impacts on large trees within closed versus open canopies, and the role of fuel reduction treatments. Focusing on the 2021 Schneider Springs Fire, which encompassed 43,000 ha in the eastern Cascade…
Publication Type: Journal Article
Increasing global human exposure to wildland fires despite declining burned area
Year: 2025
Although half of Earth’s population resides in the wildland-urban interface, human exposure to wildland fires remains unquantified. We show that the population directly exposed to wildland fires increased 40% globally from 2002 to 2021 despite a 26% decline in burned area. Increased exposure was mainly driven by enhanced colocation of wildland fires and human settlements, doubling the exposure per unit burned area. We show that population dynamics accounted for 25% of the 440 million human exposures to wildland fires. Although wildfire disasters in North America, Europe, and Oceania have…
Publication Type: Journal Article
Climate Change Effects on Interacting Disturbances in Forest Ecosystems
Year: 2025
Drought, wildfire, wind, insects, and pathogens can interact across space and time to shape forest ecosystems. Although subdisciplines in ecology have long studied individual disturbances, their interactions remain poorly understood, particularly under climate change. Further, inconsistent terminology used to describe these interactions compounds this gap. To address this challenge, we first develop a unifying framework and then review the literature to synthesize climate change effects on the seven classes of forest disturbance interactions. Climate change alters the impacts of disturbance…
Publication Type: Journal Article
Human Mediation of Wildfires and Its Representation in Terrestrial Ecosystem Models
Year: 2025
Increasing wildfires are causing global concerns about ecosystem functioning and services. Although some wildfires are caused by natural ignitions, it is also important to understand how human ignitions and human-related factors can contribute to wildfires. While dynamic global vegetation models (DGVMs) have incorporated fire-related modules to simulate wildfires and their impacts, few models have fully considered various human-related factors causing human ignitions. Using global examples, this study aims to identify key factors associated with human impacts on wildfires and provides…
Publication Type: Journal Article
The western North American forestland carbon sink: will our climate commitments go up in smoke?
Year: 2025
Pathways to achieving net-zero and net-negative greenhouse-gas (GHG) emission targets rely on land-based contributions to carbon (C) sequestration. However, projections of future contributions neglect to consider ecosystems, climate change, legacy impacts of continental-scale fire exclusion, forest accretion and densification, and a century or more of management. These influences predispose western North American forests (wNAFs) to severe drought impacts, large and chronic outbreaks of insect pests, and increasingly large and severe wildfires. To realistically assess contributions of future…
Publication Type: Journal Article
Impact of Thinning Strategy, Surface Fuel Loading and Burning Conditions on Fuel Treatment Efficacy in Ponderosa Pine Dominated Forests of the Southern Rocky Mountains
Year: 2025
Managers across the western US seek effective fuel treatment strategies to mitigate hazardous fuel loads and risks of high severity fire in dry conifer forests. Conventional fuel hazard reduction treatments emphasis reducing canopy fuel continuity and surface fuel loading using an even spaced, thin-from-below approach, with pile or broadcast burning of residual surface fuels. Such treatments often result in forest structures that differ from the historical conditions. Ecological restoration treatments emphasize enhancing structural heterogeneity but may produce less fire-resistant stands…
Publication Type: Journal Article
Optimizing woody fuel treatments to reduce wildfire risk to sagebrush ecosystems in the Great Basin of the western US
Year: 2025
The sagebrush biome in the western United States is a focus of widespread conservation concern due to multiple interacting threats including larger, more severe wildfires. Given the immense scale of the region and limited resources, prioritizing restoration treatments is essential for optimizing risk reduction and managing for resilient ecosystems. We leveraged work identifying sagebrush areas suitable for woody fuel treatments based on resilience to disturbance and resistance to annual grass invasion (R&R) and areas of sagebrush mapped as high conservation value. We used wildfire…
Publication Type: Journal Article
Intensifying Fire Season Aridity Portends Ongoing Expansion of Severe Wildfire in Western US Forests
Year: 2025
Area burned by wildfire has increased in western US forests and elsewhere over recent decades coincident with warmer and drier fire seasons. However, high–severity fire—fire that kills all or most trees—is arguably a more important metric of fire activity given its destabilizing influence on forest ecosystems and direct and indirect impacts to human communities. Here, we quantified area burned and area burned severely in western US forests from 1985 to 2022 and evaluated trends through time. We also assessed key relationships between area burned, extent and proportion burned severely…
Publication Type: Journal Article
Extreme Weather Magnifies the Effects of Forest Structure on Wildfire, Driving Increased Severity in Industrial Forests
Year: 2025
Despite widespread concern over increases in wildfire severity, the mechanisms underlying this trend remain unclear, hampering our ability to mitigate the severity of future fires. There is substantial uncertainty regarding the relative roles of extreme weather conditions, which are exacerbated by climate change, and forest management, in particular differences between private industrial timber companies and public land agencies. To investigate the effects of extreme weather and forest management on fire severity, we used light detection and ranging (LiDAR) data to characterize pre-fire…
Publication Type: Journal Article