Research Database
Displaying 1 - 20 of 41
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
Are wildfire risk mitigators more prepared to evacuate? Insights from communities in the Western United States
Year: 2025
As the realized experiences of wildfires threatening communities increase, the importance of proactive evacuation preparation and wildfire risk mitigation on private property to reduce the loss of lives and property is shaping wildfire policy and programs. To date, research has focused on pre-wildfire evacuation preparation and risk mitigation independently. This paper examines the substitutability or complementarity of these proactive risk-reducing actions. If mitigation and evacuation preparedness are substitutes, wildfire education programs may take a life-over-property approach. However,…
Publication Type: Journal Article
The national Fire and Fire Surrogate study: Effects of fuel treatments in the Western and Eastern United States after 20 years
Year: 2025
The national Fire and Fire Surrogate (FFS) study was initiated more than two decades ago with the goal of evaluating the ecological impacts of mechanical treatments and prescribed fire in different ecosystems across the United States. Since then, 4 of the original 12 sites remain active in managing and monitoring the original FFS study which provides a unique opportunity to look at the long-term effects of these treatments in different regions. These sites include California (Blodgett Forest Research Station), Montana (Lubrecht Experimental Forest), North Carolina (Green River Game Land), and…
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
Evaluating fuelbreak strategies for compartmentalizing a fire-prone forest landscape in Alberta, Canada
Year: 2025
Large wildfires, the dominant natural disturbance type in North American forests, can cause significant damage to human infrastructure. One well-known approach to reduce the threat of wildfires is the strategic removal of forest fuels in linear firebreaks that segment forest landscapes into distinct compartments. However, limited human and financial resources can make it difficult to plan compartmentalization effectively. In this study, we developed a simulation-optimization approach to assist with the planning of wildfire risk mitigation efforts in the Red Rock-Prairie Creek area of Alberta…
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
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
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
Trees in Fire-Maintained Forests Have Similar Growth Responses to Drought, but Greater Stomatal Conductance Than Trees in Fire-Excluded Forests
Year: 2025
In the western US, increased tree density in dry conifer forests from fire exclusion has caused tree growth declines, which is being compounded by hotter multi-year droughts. The reintroduction of frequent, low-severity wildfire reduces forest density by removing fire-intolerant trees, which can reduce competition for water and improve tree growth response to drought. We assessed how lower forest density following frequent, low-severity wildfire affected tree stomatal conductance and growth response to drought by coring and measuring competition surrounding ponderosa pines (Pinus…
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
High fire hazard Wildland Urban Interface (WUI) residences in California lack voluntary and mandated wildfire risk mitigation compliance in Home Ignition Zones
Year: 2025
Wildfire structure losses are increasing globally and particularly in California, USA. Losses can be mitigated in part by changes to the Home Ignition Zone (HIZ), including both home hardening and defensible space. In the United States, there are local, nation-wide, and industry-based home mitigation standards that are enforced or recommended. We explore the standards implementation (California code and two voluntary standards) at 176 participating residences in three Santa Cruz Mountains and two Sierra Nevada Mountains sites. Overall most residences had little compulsory or recommended…
Publication Type: Journal Article
Mechanical mastication and prescribed burning reduce forest fuels and alter stand structure in dry coniferous forests
Year: 2025
Mechanical thinning is often prescribed in dry coniferous forests to reduce stand density, ladder fuels, and canopy fuels before using prescribed burning to manage surface fuels. Mechanical mastication is a tool for thinning forests where commercial thinning is not viable. We evaluated the effects of mastication-based thinning – with and without subsequent prescribed burning – on forest structure and fuels in dry coniferous forests of the Pacific Northwest, USA. We thinned stands by masticating small-diameter trees and depositing the resulting slash on the forest floor. We then used…
Publication Type: Journal Article
Preventing Human-Caused Wildfire Ignitions on Public Lands: A Review of Best Practices
Year: 2025
Effective interventions to prevent human-caused ignitions on public lands play a critical role in social and ecological adaption to wildfire. While wildfire prevention spending generates a high return on investment, funding and capacity to support such programing within federal, state, and local land and fire management agencies remains limited. One avenue for ensuring that available funding and staffing for prevention is used to strategically maximize impact is the documentation of best practices, grounded in empirical data, that can provide indicators for effective intervention with…
Publication Type: Journal Article
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
Ladder fuels rather than canopy volumes consistently predict wildfire severity even in extreme topographic-weather conditions
Year: 2024
Drivers of forest wildfire severity include fuels, topography and weather. However, because only fuels can be actively managed, quantifying their effects on severity has become an urgent research priority. Here we employed GEDI spaceborne lidar to consistently assess how pre-fire forest fuel structure affected wildfire severity across 42 California wildfires between 2019–2021. Using a spatial-hierarchical modeling framework, we found a positive concave-down relationship between GEDI-derived fuel structure and wildfire severity, marked by increasing severity with greater fuel loads until a…
Publication Type: Journal Article
The Efficacy of Red Flag Warnings in Mitigating Human-Caused Wildfires across the Western United States
Year: 2024
Red flag warnings (RFWs) are issued by the U.S. National Weather Service to alert fire and emergency response agencies of weather conditions that are conducive to extreme wildfire growth. Distinct from most weather warnings that aim to reduce exposure to anticipated hazards, RFWs may also mitigate hazards by reducing the occurrence of new ignitions. We examined the efficacy of RFWs as a means of limiting human-caused wildfire ignitions. From 2006 to 2020, approximately 8% of wildfires across the western United States and 19% of large wildfires (≥40 ha) occurred on days with RFWs. Although the…
Publication Type: Journal Article
Repeated fuel treatments fall short of fire-adapted regeneration objectives in a Sierra Nevada mixed conifer forest, USA
Year: 2024
Fire exclusion over the last two centuries has driven a significant fire deficit in the forests of western North America, leading to widespread changes in the composition and structure of these historically fire-adapted ecosystems. Fuel treatments have been increasingly applied over the last few decades to mitigate fire hazard, yet it is unclear whether these fuel-focused treatments restore the fire-adapted conditions and species that will allow forests to persist into the future. A vital prerequisite of restoring fire-adaptedness is ongoing establishment of fire-tolerant tree species, and…
Publication Type: Journal Article
Climate change mitigation-adaptation relationships in forest management: perspectives from the fire-prone American West
Year: 2024
Minimizing negative impacts of climate change on human and natural systems requires mitigation of greenhouse gas emissions and adaptation to new climate conditions. Forestry provides grounds to study the relationship between these two concepts: carbon flux and storage are ecosystem services of forests, while forests are growing increasingly vulnerable to climate-driven disturbances. We examined the practice and interplay of mitigation and adaptation in the American West, which is a testbed for the conceptual balance between carbon cycling and growing climate-related risk given its abundance…
Publication Type: Journal Article
Unlocking the potential of Airborne LiDAR for direct assessment of fuel bulk density and load distributions for wildfire hazard mapping
Year: 2024
Large-scale mapping of fuel load and fuel vertical distribution is essential for assessing fire danger, setting strategic goals and actions, and determining long-term resource needs. The Airborne LiDAR system can fulfil such goal by accurately capturing the three-dimensional arrangement of vegetation at regional and national scales. We developed a novel method to estimate multiple metrics of fuel load and vertical bulk density distribution for any type of vegetation. The approach uses Beer-Lambert law for inverting the ALS point cloud into vertical plant area density profiles, which are…
Publication Type: Journal Article
Managing fire-prone forests in a time of decreasing carbon carrying capacity
Year: 2024
Changing climatic conditions are increasing overstory tree mortality in forests globally. This restructuring of the distribution of biomass is making already flammable forests more combustible, posing a major challenge for managing the transition to a lower biomass state. In western US dry conifer forests, tree density resulting from over a century of fire-exclusion practices has increased the risk of high-severity wildfire and susceptibility to climate-driven mortality. Reducing dead fuel loads will require new approaches to mitigate risk to the remaining live trees by preparing forests to…
Publication Type: Journal Article