Research Database
Displaying 1 - 20 of 210
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
Long-term tree population growth can predict woody encroachment patterns
Year: 2025
Recent increases in woody plant density in dryland ecosystems—or “woody encroachment”—around the world are often attributed to land-use changes such as increased livestock grazing and wildfire suppression or to global environmental trends (e.g., increasing atmospheric carbon dioxide). While such changes have undoubtedly impacted ecosystem structure and function, the evidence linking them to woody encroachment is mixed, and the underlying processes are not fully understood. To clarify the role of demographic processes in changing woody plant abundance, we conducted a meta-analysis of tree age…
Publication Type: Journal Article
Resource objective wildfires shifted forest structure and fuels toward pre-fire-exclusion conditions in a remote Arizona wilderness
Year: 2025
BackgroundLarge, severe fires are increasing throughout frequent-fire forests of the western United States due to warming climatic conditions, as well as legacies of early twentieth century land-use practices and anthropogenic fire exclusion. Resource objective (RO) wildfires—where naturally ignited wildfires are allowed to burn to accomplish management objectives—are increasingly accepted due to relatively low cost and flexibility on lands where mechanical treatments are not allowed (e.g., designated wilderness) or economically feasible. We previously implemented a field…
Publication Type: Journal Article
A fire deficit persists across diverse North American forests despite recent increases in area burned
Year: 2025
Rapid increases in wildfire area burned across North American forests pose novel challenges for managers and society. Increasing area burned raises questions about whether, and to what degree, contemporary fire regimes (1984–2022) are still departed from historical fire regimes (pre-1880). We use the North American tree-ring fire-scar network (NAFSN), a multi-century record comprising >1800 fire-scar sites spanning diverse forest types, and contemporary fire perimeters to ask whether there is a contemporary fire surplus or fire deficit, and whether recent fire years are unprecedented…
Publication Type: Journal Article
Finding floral and faunal species richness optima among active fire regimes
Year: 2025
Changing fire regimes have important implications for biodiversity and challenge traditional conservation approaches that rely on historical conditions as proxies for ecological integrity. This historical-centric approach becomes increasingly tenuous under climate change, necessitating direct tests of environmental impacts on biodiversity. At the same time, widespread departures from historical fire regimes have limited the ability to sample diverse fire histories. We examined 2 areas in California's Sierra Nevada (USA) with active fire regimes to study the responses of bird, plant, and bat…
Publication Type: Journal Article
Prescribed fire, managed burning, and previous wildfires reduce the severity of a southwestern US gigafire
Year: 2025
In many parts of the western United States, wildfires are becoming larger and more severe, threatening the persistence of forest ecosystems. Understanding the ways in which management activities such as prescribed fire and managed wildfire can mitigate fire severity is essential for developing effective forest conservation strategies. We evaluated the effects of previous fuels reduction treatments, including prescribed fire and wildfire managed for resource benefit, and other wildfires on the burn severity of the 2022 Black Fire in southwestern New Mexico, USA. The Black Fire burned over 131,…
Publication Type: Journal Article
Increasing wildfire frequency decreases carbon storage and leads to regeneration failure in Alaskan boreal forests
Year: 2025
BackgroundThe increasing size, severity, and frequency of wildfires is one of the most rapid ways climate warming could alter the structure and function of high-latitude ecosystems. Historically, boreal forests in western North America had fire return intervals (FRI) of 70–130 years, but shortened FRIs are becoming increasingly common under extreme weather conditions. Here, we quantified pre-fire and post-fire C pools and C losses and assessed post-fire seedling regeneration in long (> 70 years), intermediate (30–70 years), and short (< 30 years) FRIs, and triple (three fires in < 70…
Publication Type: Journal Article
Combining ecophysiology and combustion traits: a pyro-ecophysiological approach to live fuel moisture prediction in common shrubs
Year: 2025
BackgroundQuantifying fuel moisture content accurately is critical for understanding global vegetation flammability. While models representing changes in dead fuel moisture are relatively advanced, the mechanisms driving fluctuations in live fuel moisture content (LFMC) have been difficult to capture. Living plants make up a large proportion of the fuel complex for wildfires, yet linking plant and combustion science to advance our understanding of wildfire risk has, to date, been limiting. Developing mechanistic approaches to link these two disciplines will confer greater understanding and…
Publication Type: Journal Article
Evidence for strong bottom-up controls on fire severity during extreme events
Year: 2025
BackgroundRecord fire years in recent decades have challenged post-fire forest recovery in the western United States and beyond. To improve management responses, it is critical that we understand the conditions under which management can mitigate severe wildfire impacts, and when it cannot. Here, we evaluated the influence of top-down and bottom-up fire severity forcings on 17 wildfires occurring during two consecutive record-setting years in the eastern Cascade Mountains of Washington State. Despite much of the area having been burned after an extended period of fire…
Fire Effects and Fire Ecology, Fire History, Fuels and Fuel Treatments, Restoration and Hazardous Fuel Reduction
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
Quantifying Western US tree carbon stocks and sequestration from fires
Year: 2025
Background: Forest ecosystems function as the largest terrestrial carbon sink globally. In the Western US, fires play a crucial role in modifying forest carbon storage, sequestration capacity, and the transfer of carbon from live to dead carbon pools. We utilized remeasurements of more than 700,000 trees from 24,000 locations from the US Department of Agriculture Forest Service’s Forest Inventory and Analysis program (FIA) and incorporated supplementary information on wildfires from the Monitoring Trends in Burn Severity dataset. These datasets allowed us to develop models that examined the…
Publication Type: Journal Article
Snow dynamics and forest structure interact to increase wildfire burn severity in the boreal forest
Year: 2025
Climate change in boreal regions is leading to warmer, drier conditions which amplify wildfire activity by altering fuel moisture, weather conditions, as well as the timing and duration of snow cover. Reduced snowpack and earlier snowmelt can lower fuel moisture, extend wildfire seasons, and increase burn severity. However, the effects of snow cover on burn severity under different environmental conditions remain uncertain. We examined how forest structure and snow cover dynamics affect burn severity using structural equation models and remotely sensed burn severity data from 689 wildfires in…
Publication Type: Journal Article
A Systematic Review of Trends and Methodologies in Research on the Effects of Wildfires on the Avifauna in Temperate Forests
Year: 2025
Perceptions of the relationships between forest ecosystems and wildfires have evolved. The ecological role of wildfires is now recognised as essential for maintaining the functionality of fire-adapted forests. Although research on the impact of fire on fauna has grown notably, there is a lack of consensus on its global effects due to the variable responses of faunal communities across taxa. This review provides a bibliometric synthesis of wildfires and their impact on avifauna in temperate forests. It identifies patterns and gaps in research methodologies and offers recommendations for future…
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
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
Offsetting the noise: a framework for applying phenological offset corrections in remotely sensed burn severity assessments
Year: 2025
BackgroundPhenological correction of pre- and post-fire imagery is used to improve remotely sensed burn severity evaluations. Unburned offset values standardize greenness between image pairs; however, efficacy across diverse scenarios remains underexplored.AimsWe evaluated the impact of phenological offset correction methods to support analyst decision-making across fire-prone environments.MethodsWe generated burn severity spectral index values for a dataset of Composite Burn Index (CBI) field plots across the conterminous US. The…
Publication Type: Journal Article
Comparing modeled soil temperature and moisture dynamics during prescribed fires, slash-pile burns and wildfires
Year: 2025
Background: Wildfires, prescribed fires and slash-pile burns are disturbances that occur in many terrestrial ecosystems. Such fires produce variable surface heat fluxes causing a spectrum of effects on soil, such as seed mortality, nutrient loss, changes in microbial activity and water repellency. Accurately modeling soil heating is vital to predicting these second-order fire effects. The process-based Massman HMV (Heat–Moisture–Vapor) model incorporates soil water evaporation, heat transport and water vapor movement, and captures the observed rapid evaporation of soil moisture. Aims:…
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
Insights Into Nature-Based Climate Solutions: Managing Forests for Climate Resilience and Carbon Stability
Year: 2025
Successful implementation of forest management as a nature-based climate solution is dependent on the durability of management-induced changes in forest carbon storage and sequestration. As forests face unprecedented stability risks in the face of ongoing climate change, much remains unknown regarding how management will impact forest stability, or how interactions with climate might shift the response of forests to management across spatiotemporal scales. Here, we used a process-based model to simulate multidecadal projections of forest dynamics in response to changes in management and…
Publication Type: Journal Article
Wildfire disturbance and ecological cascades: Teasing apart the direct and indirect effects of fire on tick populations
Year: 2025
- Wildfires are a significant ecological force in the western United States, reshaping landscapes and ecological communities. However, assessing wildfires' full impact is challenging due to the complexity of fire severity and its varied effects on ecological dynamics. Understanding species-specific responses to disturbances within their environmental context is essential for predicting cascading ecological impacts. Arthropods, including ticks, are particularly sensitive to both abiotic and biotic changes, making them especially vulnerable to the impacts of wildfire.
- In this…
Publication Type: Journal Article