Research Database
Displaying 21 - 40 of 59
Fuel Profiles and Biomass Carbon Following Bark Beetle Outbreaks: Insights for Disturbance Interactions from a Historical Silvicultural Experiment
Year: 2023
Anticipating consequences of disturbance interactions on ecosystem structure and function is a critical management priority as disturbance activity increases with warming climate. Across the Northern Hemisphere, extensive tree mortality from recent bark beetle outbreaks raises concerns about potential fire behavior and post-fire forest function. Silvicultural treatments (that is, partial or complete cutting of forest stands) may reduce outbreak severity and subsequent fuel loads, but longevity of pre-outbreak treatment effects on outbreak severity and post-outbreak fuel profiles remains…
Publication Type: Journal Article
Identifying building locations in the wildland–urban interface before and after fires with convolutional neural networks
Year: 2023
Background: Wildland–urban interface (WUI) maps identify areas with wildfire risk, but they are often outdated owing to the lack of building data. Convolutional neural networks (CNNs) can extract building locations from remote sensing data, but their accuracy in WUI areas is unknown. Additionally, CNNs are computationally intensive and technically complex, making them challenging for end-users, such as those who use or create WUI maps, to apply. Aims: We identified buildings pre- and post-wildfire and estimated building destruction for three California wildfires: Camp, Tubbs and Woolsey.…
Publication Type: Journal Article
Lightning-Ignited Wildfires in the Western United States: Ignition Precipitation and Associated Environmental Conditions
Year: 2023
Cloud-to-ground lightning with minimal rainfall (“dry” lightning) is a major wildfire ignition source in the western United States (WUS). Although dry lightning is commonly defined as occurring with <2.5 mm of daily-accumulated precipitation, a rigorous quantification of precipitation amounts concurrent with lightning-ignited wildfires (LIWs) is lacking. We combine wildfire, lightning and precipitation data sets to quantify these ignition precipitation amounts across ecoprovinces of the WUS. The median precipitation for all LIWs is 2.8 mm but varies with vegetation and fire characteristics…
Publication Type: Journal Article
MCDM-Based Wildfire Risk Assessment: A Case Study on the State of Arizona
Year: 2023
The increasing frequency of wildfires has posed significant challenges to communities worldwide. The effectiveness of all aspects of disaster management depends on a credible estimation of the prevailing risk. Risk, the product of a hazard’s likelihood and its potential consequences, encompasses the probability of hazard occurrence, the exposure of assets to these hazards, existing vulnerabilities that amplify the consequences, and the capacity to manage, mitigate, and recover from their consequences. This paper employs the multiple criteria decision-making (MCDM) framework, which produces…
Publication Type: Journal Article
Proportion of forest area burned at high-severity increases with increasing forest cover and connectivity in western US watersheds
Year: 2023
Context In western US forests, the increasing frequency of large high-severity fires presents challenges for society. Quantifying how fuel conditions influence high-severity area is important for managing risks of large high-severity fires and understanding how they are changing with climate change. Fuel availability and heterogeneity influence high-severity fire probability, but heterogeneity is insensitive to some aspects of forest connectivity that are important to potential high-severity fire transmission and thus high-severity area. Objectives To quantify the effects of fuel availability…
Publication Type: Journal Article
A framework for quantifying forest wildfire hazard and fuel treatment effectiveness from stands to landscapes
Year: 2022
Background Wildland fires are fundamentally landscape phenomena, making it imperative to evaluate wildland fire strategic goals and fuel treatment effectiveness at large spatial and temporal scales. Outside of simulation models, there is limited information on how stand-level fuel treatments collectively contribute to broader landscape-level fuel management goals. Our objective here is to present a framework designed to measure fuel treatment effectiveness from stands to landscapes to inform fuel treatment planning and improve ecological and social resilience to wildland fire. Results Our…
Publication Type: Journal Article
Growing impact of wildfire on western US water supply
Year: 2022
Streamflow often increases after fire, but the persistence of this effect and its importance to present and future regional water resources are unclear. This paper addresses these knowledge gaps for the western United States (WUS), where annual forest fire area increased by more than 1,100% during 1984 to 2020. Among 72 forested basins across the WUS that burned between 1984 and 2019, the multibasin mean streamflow was significantly elevated by 0.19 SDs (P < 0.01) for an average of 6 water years postfire, compared to the range of results expected from climate alone. Sig- nificance is…
Publication Type: Journal Article
Spatial and temporal assessment of responder exposure to snag hazards in post-fire environments
Year: 2019
Researchers and managers increasingly recognize enterprise risk management as critical to addressing contemporary fire management challenges. Quantitative wildfire risk assessments contribute by parsing and mapping potentially contradictory positive and negative fire effects. However, these assessments disregard risks to fire responders because they only address social and ecological resources and assets. In this study, we begin to overcome this deficiency by using a novel modeling approach that integrates remote sensing, field inventories, imputation-based vegetation modeling, and empirical…
Publication Type: Journal Article
Decreasing fire season precipitation increased recent western US forest wildfire activity
Year: 2018
Western United States wildfire increases have been generally attributed to warming temperatures, either through effects on winter snowpack or summer evaporation. However, near-surface air temperature and evaporative demand are strongly influenced by moisture availability and these interactions and their role in regulating fire activity have never been fully explored. Here we show that previously unnoted declines in summer precipitation from 1979 to 2016 across 31–45% of the forested areas in the western United States are strongly associated with burned area variations. The number of wetting…
Publication Type: Journal Article
Developing an online tool for identifying at-risk populations to wildfire smoke hazards
Year: 2018
Wildfire episodes pose a significant public health threat in the United States. Adverse health impacts associated with wildfires occur near the burn area as well as in places far downwind due to wildfire smoke exposures. Health effects associated with exposure to particulate matter arising from wildfires can range from mild eye and respiratory tract irritation to more serious outcomes such as asthma exacerbation, bronchitis, and decreased lung function. Real-time operational forecasts of wildfire smoke concentrations are available but they are not readily integrated with information on…
Publication Type: Journal Article
Wildfire smoke cools summer river and stream water temperatures
Year: 2018
To test the hypothesis that wildfire smoke can cool summer river and stream water temperatures by attenuating solar radiation and air temperature, we analyzed data on summer wildfire smoke, solar radiation, air temperatures, precipitation, river discharge, and water temperatures in the lower Klamath River Basin in Northern California. Previous studies have focused on the effect of combustion heat on water temperatures during fires and the effect of riparian vegetation losses on postfire water temperatures, but we know of no studies of the effects of wildfire smoke on river or stream water…
Publication Type: Journal Article
Estimating post-fire debris-flow hazards prior to wildfire using a statistical analysis of historical distributions of fire severity from remote sensing data
Year: 2018
Following wildfire, mountainous areas of the western United States are susceptible to debris flow during intense rainfall. Convective storms that can generate debris flows in recently burned areas may occur during or immediately after the wildfire, leaving insufficient time for development and implementation of risk mitigation strategies. We present a method for estimating post-fire debris-flow hazards before wildfire using historical data to define the range of potential fire severities for a given location based on the statistical distribution of severity metrics obtained from remote…
Publication Type: Journal Article
An Evaluation of the Forest Service Hazardous Fuels Treatment Program—Are We Treating Enough to Promote Resiliency or Reduce Hazard?
Year: 2017
The National Cohesive Wildland Fire Management Strategy recognizes that wildfire is a necessary natural process in many ecosystems and strives to reduce conflicts between fire-prone landscapes and people. In an effort to mitigate potential negative wildfire impacts proactively, the Forest Service fuels program reduces wildland fuels. As part of an internal program assessment, we evaluated the extent of fuel treatments and wildfire occurrence within lands managed by the National Forest System (NFS) between 2008 and 2012. We intersected fuel treatments with historic disturbance rates to assess…
Publication Type: Journal Article
Decade-Long Plant Community Responses to Shrubland Fuel Hazard Reduction
Year: 2017
Fuel hazard reduction treatments such as prescribed fire and mastication are widely used to reduce fuel hazard. These treatments help protect people from wildfire, yet may not be mutually beneficial for people and ecosystems in areas adapted to infrequent crown fire. Short-term studies indicate that some fuel hazard reduction treatments can be detrimental to biodiversity and ecosystem function, suggesting that land managers face an acute dilemma between protecting people or ecosystems. However, the long-term ecological trajectories and fuel hazard outcomes of fuel treatments are poorly…
Publication Type: Journal Article
Return on investment from fuel treatments to reduce severe wildfire and erosion in a watershed investment program in Colorado
Year: 2017
A small but growing number of watershed investment programs in the western United States focus on wildfire risk reduction to municipal water supplies. This paper used return on investment (ROI) analysis to quantify how the amounts and placement of fuel treatment interventions would reduce sediment loading to the Strontia Springs Reservoir in the Upper South Platte River watershed southwest of Denver, Colorado following an extreme fire event. We simulated various extents of fuel mitigation activities under two placement strategies: (a) a strategic treatment prioritization map and (b)…
Publication Type: Journal Article
Regional patterns of postwildfire streamflow response in the Western United States: The importance of scale-specific connectivity
Year: 2017
Wildfires can impact streamflow by modifying net precipitation, infiltration, evapotranspiration, snowmelt, and hillslope run-off pathways. Regional differences in fire trends and postwildfire streamflow responses across the conterminous United States have spurred concerns about the impact on streamflow in forests that serve as water resource areas. This is notably the case for the Western United States, where fire activity and burn severity have increased in conjunction with climate change and increased forest density due to human fire suppression. In this review, we discuss the effects of…
Publication Type: Journal Article
Places where wildfire potential and social vulnerability coincide in the coterminous United States
Year: 2016
The hazards-of-place model posits that vulnerability to environmental hazards depends on both biophysical and social factors. Biophysical factors determine where wildfire potential is elevated, whereas social factors determine where and how people are affected by wildfire. We evaluated place vulnerability to wildfire hazards in the coterminous US. We developed a social vulnerability index using principal component analysis and evaluated it against existing measures of wildfire potential and wildland–urban interface designations. We created maps showing the coincidence of social vulnerability…
Publication Type: Journal Article
Managed wildfire effects on forest resilience and water in the Sierra Nevada
Year: 2016
Fire suppression in many dry forest types has left a legacy of dense, homogeneous forests. Such landscapes have high water demands and fuel loads, and when burned can result in catastrophically large fires. These characteristics are undesirable in the face of projected warming and drying in the western US. Alternative forest and fire treatments based on managed wildfire—a regime in which fires are allowed to burn naturally and only suppressed under defined management conditions—offer a potential strategy to ameliorate the effects of fire suppression. Understanding the long-term effects of…
Publication Type: Journal Article
Assessment of wildland fire impacts on watershed annual water yield: Analytical framework and case studies in the United States
Year: 2016
More than 50% of water supplies in the conterminous United States originate on forestland or rangeland, and are potentially under increasing stress as a result of larger and more severe wildfires. Little is known however about the long-term impacts of fire on annual water yield, and the role of climate variability within this context. We here propose a framework for evaluating wildland fire impacts on streamflow that combines double-mass analysis with new methods (change point analysis, climate elasticity modeling, and process-based modeling) to distinguish between multi-year fire and climate…
Publication Type: Journal Article
Long-term dead wood changes in a Sierra Nevada mixed conifer forest: habitat and fire hazard implications
Year: 2015
Dead trees play an important role in forests, with snags and coarse woody debris (CWD) used by many bird and mammal species for nesting, resting, or foraging. However, too much dead wood can also contribute to extreme fire behavior. This tension between dead wood as habitat and dead wood as fuel has raised questions about appropriate quantities in fire-dependent forested ecosystems. Three plots installed in mixed conifer forest of the central Sierra Nevada in 1929 illustrate how amounts and sizes of dead wood have changed through time as a result of logging and fire exclusion. Diameter of…
Publication Type: Journal Article