Research Database
Displaying 81 - 100 of 265
Reduced fire severity offers near-term buffer to climate-driven declines in conifer resilience across the western United States
Year: 2023
Increasing fire severity and warmer, drier postfire conditions are making forests in the western United States (West) vulnerable to ecological transformation. Yet, the relative importance of and interactions between these drivers of forest change remain unresolved, particularly over upcoming decades. Here, we assess how the interactive impacts of chang-ing climate and wildfire activity influenced conifer regeneration after 334 wildfires, using a dataset of postfire conifer regeneration from 10,230 field plots. Our findings highlight declining regeneration capacity across the West over the…
Publication Type: Journal Article
Higher burn severity stimulates postfire vegetation and carbon recovery in California
Year: 2023
As the climate continues to warm, the severity of wildfires is increasing. However, the potential impact of higher burn severity on ecosystem resilience and regional carbon balance is still not clear. There are ongoing debates regarding whether increased burn severity stimulates or delays postfire vegetation and carbon recovery. In this study, we utilized remote sensing data to analyze burn severity and vegetation observations, as well as model simulations to assess wildfire carbon emissions and ecosystem carbon fluxes. Our focus was on examining the dynamics of vegetation and carbon flux…
Publication Type: Journal Article
Exploring and Testing Wildfire Risk Decision-Making in the Face of Deep Uncertainty
Year: 2023
We integrated a mechanistic wildfire simulation system with an agent-based landscape change model to investigate the feedbacks among climate change, population growth, development, landowner decision-making, vegetative succession, and wildfire. Our goal was to develop an adaptable simulation platform for anticipating risk-mitigation tradeoffs in a fire-prone wildland–urban interface (WUI) facing conditions outside the bounds of experience. We describe how five social and ecological system (SES) submodels interact over time and space to generate highly variable alternative futures even within…
Publication Type: Journal Article
High-severity fire drives persistent floristic homogenization in human-altered forests
Year: 2023
Ecological disturbance regimes across the globe are being altered via direct and indirect human influences. Biodiversity loss at multiple scales can be a direct outcome of these shifts. Fire, especially in dry forests, is an ecological disturbance that is experiencing dramatic changes due to climate change, fire suppression, increased human population in fire-prone areas, and alterations to vegetation composition and structure. Dry western conifer forests that historically experienced frequent, low-severity fires are now increasingly burning at high severity. Relatively little work has been…
Publication Type: Journal Article
Heading and backing fire behaviours mediate the influence of fuels on wildfire energy
Year: 2023
Background: Pre-fire fuels, topography, and weather influence wildfire behaviour and fire-driven ecosystem carbon loss. However, the pre-fire characteristics that contribute to fire behaviour and effects are often understudied for wildfires because measurements are difficult to obtain. Aims: This study aimed to investigate the relative contribution of pre-fire conditions to fire energy and the role of fire advancement direction in fuel consumption. Methods: Over 15 years, we measured vegetation and fuels in California mixed-conifer forests within days before and after wildfires, with co-…
Publication Type: Journal Article
Drivers of California’s changing wildfires: a state-of-the-knowledge synthesis
Year: 2023
Over the past four decades, annual area burned has increased significantly in California and across the western USA. This trend reflects a confluence of intersecting factors that affect wildfire regimes. It is correlated with increasing temperatures and atmospheric vapour pressure deficit. Anthropogenic climate change is the driver behind much of this change, in addition to influencing other climate-related factors, such as compression of the winter wet season. These climatic trends and associated increases in fire activity are projected to continue into the future. Additionally, factors…
Publication Type: Journal Article
Modeling Wildland Firefighters’ Assessments of Structure Defensibility
Year: 2023
In wildland–urban interface areas, firefighters balance wildfire suppression and structure protection. These tasks are often performed under resource limitations, especially when many structures are at risk. To address this problem, wildland firefighters employ a process called “structure triage” to prioritize structure protection based on perceived defensibility. Using a dataset containing triage assessments of thousands of structures within the Western US, we developed a machine learning model that can improve the understanding of factors contributing to assessed structure defensibility.…
Publication Type: Journal Article
Fire-resistant Plants for Home Landscapes: Reduce Wildfire Risk with Proper Plant Selection and Placement
Year: 2023
In the Pacific Northwest, fires are a natural part of the changing landscape. As homeowners continue to build in the wildland-urban interface, they must take special precautions to protect their lives, homes, and property.One way to do this is to create a defensible space around your home. This is the area between your home or other structures, where potential fuel (materials or vegetation) have been modified, reduced, or cleared to create a barrier and slow the spread of wildfire toward your home. A defensible space also allows room for firefighters to fight the fire safely. Three critical…
Publication Type: Report
Fire refugia are robust across Western US forested ecoregions, 1986–2021
Year: 2023
In the Western US, area burned and fire size have increased due to the influences of climate change, long-term fire suppression leading to higher fuel loads, and increased ignitions. However, evidence is less conclusive about increases in fire severity within these growing wildfire extents. Fires burn unevenly across landscapes, leaving islands of unburned or less impacted areas, known as fire refugia. Fire refugia may enhance post-fire ecosystem function and biodiversity by providing refuge to species and functioning as seed sources after fires. In this study, we evaluated whether the…
Publication Type: Journal Article
Wildland–Urban Interface: Definition and Physical Fire Risk Mitigation Measures, a Systematic Review
Year: 2023
Due to the associated fire risk, the wildland–urban interface (WUI) has drawn the attention of researchers and managers from a range of backgrounds. From a land management point of view, it is important to identify the WUI to determine areas to prioritise for fire risk prevention. It is also important to know the fire risk mitigation measures available to select the most appropriate for each specific context. In this systematic review, definitions of the WUI were investigated and physical mitigation measures for reducing the risk of fire were examined from a land management perspective. The…
Publication Type: Journal Article
The impacts of wildfires of different burn severities on vegetation structure across the western United States rangelands
Year: 2022
Large wildfires have increased in western US rangelands over the last three decades. There is limited information on the impacts of wildfires with different severities on the vegetation in these rangelands. This study assessed the impacts of large wildfires on rangeland fractional cover including annual forbs and grasses (AFG), perennial forbs and grasses (PFG), shrubs (SHR) and trees (TREE) across the western US, and explored relationships between changes in fractional cover and prefire soil moisture conditions. The Expectation Maximization (EM) algorithm was used to group wildfires into…
Publication Type: Journal Article
Interactions Between Fire Refugia and Climate-Environment Conditions Determine Mesic Subalpine Forest Recovery After Large and Severe Wildfires
Year: 2022
Infrequent stand-replacing wildfires are characteristic of mesic and/or cool conifer forests in western North America, where forest recovery within high-severity burn patch interiors can be slow, yet successful over long temporal periods (decades to centuries). Increasing fire frequency and high-severity burn patch size, under a warming climate, however, may challenge post-fire forest recovery, promoting landscape-level shifts in forest structure, composition, and distribution of non-forest patches. Crucial to a delay and/or impediment to this shift, fire refugia (i.e., remnant seed sources)…
Publication Type: Journal Article
Expanding wildland-urban interface alters forest structure and landscape context in the northern United States
Year: 2022
The wildland-urban interface (WUI), where housing intermingles with wildland vegetation, is the fastest-growing land use type in the United States. Given the ecological and social benefits of forest ecosystems, there is a growing need to more fully understand how such development alters the landscape context and structure of these WUI forests. In a space-for-time analysis we utilized land cover data, forest inventory plots, and housing density data over time to examine differences in forest characteristics of the northern US across three WUI change classes: (a) forest that has been in WUI…
Publication Type: Journal Article
Community Engagement With Proactive Wildfire Management in British Columbia, Canada: Perceptions, Preferences, and Barriers to Action
Year: 2022
Wildfires in the wildland-urban interface (WUI) are increasingly threatening lives and livelihoods. These growing impacts have prompted a paradigm shift toward proactive wildfire management that prioritizes prevention and preparedness instead of response. Despite this shift, many communities remain unprepared for wildfires in the WUI due to diverse individual and social-political factors influencing engagement with proactive management approaches. The catastrophic fire seasons of 2017, 2018, and 2021 in British Columbia (BC), Canada, highlighted just how vulnerable communities continue to be…
Publication Type: Journal Article
Comparing particulate morphology generated from human- made cellulosic fuels to natural vegetative fuels
Year: 2022
Background: In wildland–urban interface (WUI) fires, particulates from the combustion of both natural vegetative fuels and engineered cellulosic fuels may have deleterious effects on the environment. Aims: The research was conducted to investigate the morphology of the particulate samples generated from the combustion of oriented strand board (OSB). Findings were compared to the particulate samples collected from the combustion of noble-fir branches. Methods: The exposure conditions were varied to induce either smouldering combustion or flaming combustion of the specimens. Particulate samples…
Publication Type: Journal Article
The contribution of Indigenous stewardship to an historical mixed-severity fire regime in British Columbia, Canada
Year: 2022
Indigenous land stewardship and mixed-severity fire regimes both promote landscape heterogeneity, and the relationship between them is an emerging area of research. In our study, we reconstructed the historical fire regime of Ne Sextsine, a 5900-ha dry, Douglas-fir-dominated forest in the traditional territory of the T’exelc (Williams Lake First Nation) in British Columbia, Canada. Between 1550 and 1982 CE, we found median fire intervals of 18 years at the plot-level and 4 years at the study site-level. Ne Sextsine was characterized by an historical mixed-severity fire regime, dominated by…
Publication Type: Journal Article
The right to burn: barriers and opportunities for Indigenous-led fire stewardship in Canada
Year: 2022
Indigenous fire stewardship enhances ecosystem diversity, assists with the management of complex resources, and reduces wildfire risk by lessening fuel loads. Although Indigenous Peoples have maintained fire stewardship practices for millennia and continue to be keepers of fire knowledge, significant barriers exist for re-engaging in cultural burning. Indigenous communities in Canada have unique vulnerabilities to large and high-intensity wildfires as they are predominately located in remote, forested regions and lack financial support at federal and provincial levels to mitigate wildfire…
Publication Type: Journal Article
A burning issue: Reviewing the sociodemographic and environmental justice aspects of the wildfire literature
Year: 2022
Larger and more severe wildfires are becoming more frequent and impacting different communities and human settlements. Much of the scientific literature and media on wildfires has focused on area of ecosystems burned and numbers of structures destroyed. Equally unprecedented, but often less reported, are the increasing socioeconomic impacts different people and communities face from wildfires. Such information seems to indicate an emerging need to account for wildfire effects on peri-urban or wildland urban interface (WUI) areas, newer socio-demographic groups, and disadvantaged communities.…
Publication Type: Journal Article
Severity patterns of the 2021 Dixie Fire exemplify the need to increase low-severity fire treatments in California’s forests
Year: 2022
Publication Type: Journal Article
Comparing particulate morphology generated from human-made cellulosic fuels to natural vegetative fuels
Year: 2022
Background: In wildland–urban interface (WUI) fires, particulates from the combustion of both natural vegetative fuels and engineered cellulosic fuels may have deleterious effects on the environment. Aims: The research was conducted to investigate the morphology of the particulate samples generated from the combustion of oriented strand board (OSB). Findings were compared to the particulate samples collected from the combustion of noble-fir branches. Methods: The exposure conditions were varied to induce either smouldering combustion or flaming combustion of the specimens. Particulate samples…
Publication Type: Journal Article