Research Database
Displaying 41 - 60 of 116
Landscape‑scale fuel treatment effectiveness: lessons learned from wildland fire case studies in forests of the western United States and Great Lakes region
Year: 2023
Background Maximizing the effectiveness of fuel treatments at landscape scales is a key research and management need given the inability to treat all areas at risk from wildfire. We synthesized information from case studies that documented the influence of fuel treatments on wildfire events. We used a systematic review to identify relevant case studies and extracted information through a series of targeted questions to summarize experiential knowledge of landscape fuel treatment effectiveness. Within a larger literature search, we identified 18 case study reports that included (1) manager…
Publication Type: Journal Article
Dry Live Fuels Increase the Likelihood of Lightning-Caused Fires
Year: 2023
Live fuel moisture content (LFMC) is a key determinant of landscape ignition potential, but quantitative estimates of its effects on wildfire are lacking. We present a causal inference framework to isolate the effect of LFMC from other drivers like fuel type, fuel amount, and meteorology. We show that in California when LFMC is below a critical flammability threshold, the likelihood of fires is 1.8 times as high statewide (2.25% vs. 1.27%) and 2.5 times as high in shrubs, compared to when LFMC is greater than the threshold. This risk ratio is >2 times when LFMC is 10% less than the…
Publication Type: Journal Article
Summer and Fall Extreme Fire Weather Projected to Occur More Often and Affect a Growing Portion of California throughout the 21st Century
Year: 2022
Annual burned area has increased in California over the past three decades as a result of rising temperatures and a greater atmospheric demand for moisture, a trend that is projected to continue throughout the 21st century as a result of climate change. Here, we implement a bias-correction and statistical downscaling technique to obtain high resolution, daily meteorological conditions for input into two fire weather indices: vapor pressure deficit (VPD) and the Canadian Fire Weather Index System (FWI). We focus our analysis on 10 ecoregions that together account for the diverse range of…
Publication Type: Journal Article
Extreme Winds Alter Influence of Fuels and Topography on Megafire Burn Severity in Seasonal Temperate Rainforests under Record Fuel Aridity
Year: 2022
Nearly 0.8 million hectares of land were burned in the North American Pacific Northwest (PNW) over two weeks under record-breaking fuel aridity and winds during the extraordinary 2020 fire season, representing a rare example of megafires in forests west of the Cascade Mountains. We quantified the relative influence of weather, vegetation, and topography on patterns of high burn severity (>75% tree mortality) among five synchronous megafires in the western Cascade Mountains. Despite the conventional wisdom in climate-limited fire regimes that regional drivers (e.g., extreme aridity, and…
Publication Type: Journal Article
Merging prescribed fires and timber harvests in the Sierra Nevada: Burn season and pruning influences in young mixed conifer stands
Year: 2022
Highlights • Mortality of canopy trees was similar between spring and fall prescribed burns in 13-14 year old stands • Fall burns consumed more surface fuel without substantially high levels of canopy damage • Pre-fire pruning Pinus lambertiana and Calocecrus decurrens trees did not clearly reduce tree damage • Gap-based silviculture and prescribed fire can be merged to meet broad ecological goals Abstract In dry, productive forests where historically infrequent high-severity fires are now common, new silvicultural systems will be needed to better align management activity with the ecosystem'…
Publication Type: Journal Article
Contrasting the role of human- and lightning-caused wildfires on future fire regimes on a Central Oregon landscape
Year: 2021
Climate change is expected to increase fire activity in many regions of the globe, but the relative role of human vs. lightning-caused ignitions on future fire regimes is unclear. We developed statistical models that account for the spatiotemporal ignition patterns by cause in the eastern slopes of the Cascades in Oregon, USA. Projected changes in energy release component from a suite of climate models were used with our model to quantify changes in frequency and extent of human and lightning-caused fires and record-breaking events based on sizes of individual fires between contemporary (2006…
Publication Type: Journal Article
Episodic occurrence of favourable weather constrains recovery of a cold desert shrubland after fire
Year: 2021
1. Key to the long-term resilience of dryland ecosystems is the recovery of foundation plant species following disturbance. In ecosystems with high interannual weather variability, understanding the influence of short-term environmental conditions on establishment of foundation species is essential for identifying vulnerable landscapes and developing restoration strategies. We asked how annual environmental conditions affect post-fire establishment of Artemisia tridentata, a shrub species that dominates landscapes across much of the western United States, and evaluated the influence of…
Publication Type: Journal Article
Existing Improvements in Simulation of Fire–Wind Interaction and Its Effects on Structures
Year: 2021
This work provides a detailed overview of existing investigations into the fire–wind interaction phenomena. Specifically, it considers: the fanning effect of wind, wind direction and slope angle, and the impact of wind on fire modelling, and the relevant analysis (numerical and experimental) techniques are evaluated. Recently, the impact of fire on buildings has been widely analysed. Most studies paid attention to fire damage evaluation of structures as well as structure fire safety engineering, while the disturbance interactions that influence structures have been neglected in prior studies…
Publication Type: Journal Article
Weather, Risk, and Resource Orders on Large Wildland Fires in the Western US
Year: 2020
Our results suggest that weather is a primary driver of resource orders over the course of extended attack efforts on large fires. Incident Management Teams (IMTs) synthesize information about weather, fuels, and order resources based on expected fire growth rather than simply reacting to observed fire growth. Background and Objectives: Weather conditions are a well-known determinant of fire behavior and are likely to become more erratic under climate change. Yet, there is little empirical evidence demonstrating how IMTs respond to observed or expected weather conditions. An understanding of…
Publication Type: Journal Article
Long-term effects of fuel treatments, overstory structure, and wildfire on tree regeneration in dry forests of Central Washington
Year: 2020
The long-term effectiveness of dry-forest fuels treatments (restoration thinning and prescribed burning) depends, in part, on the pace at which trees regenerate and recruit into the overstory. Knowledge of the factors that shape post-treatment regeneration and growth is limited by the short timeframes and simple disturbance histories of past research. Here, we present results of a 15-year fuels-reduction experiment in central Washington, including responses to planned and unplanned disturbances.We explore the changing patterns of Douglas-fir regeneration in72 permanent plots (0.1 ha) varying…
Publication Type: Journal Article
The hot-dry-windy index: A new tool for forecasting fire weather
Year: 2020
Accurate predictions of how weather may affect a wildfire’s behavior are needed to protect crews on the line and efficiently allocate firefighting resources. Since 1988, fire meteorologists have used a tool called the Haines Index to predict days when the weather will exacerbate a wildfire. Although the Haines Index is widely believed to have value, it never received rigorous testing on the line. Even Don Haines, the U.S. Forest Service meteorologist who developed the index, has said the Haines Index needs further refinement. Recognizing that a new fire weather prediction tool was needed, a…
Publication Type: Report
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
Tamm Review: Reforestation for resilience in dry western U.S. forests
Year: 2019
The increasing frequency and severity of fire and drought events have negatively impacted the capacity and success of reforestation efforts in many dry, western U.S. forests. Challenges to reforestation include the cost and safety concerns of replanting large areas of standing dead trees, and high seedling and sapling mortality rates due to water stress, competing vegetation, and repeat fires that burn young plantations. Standard reforestation practices have emphasized establishing dense conifer cover with gridded planting, sometimes called 'pines in lines', followed by shrub control and pre-…
Publication Type: Journal Article
Evaluating Model Predictions of Fire Induced Tree Mortality Using Wildfire-Affected Forest Inventory Measurements
Year: 2019
Forest land managers rely on predictions of tree mortality generated from fire behavior models to identify stands for post-fire salvage and to design fuel reduction treatments that reduce mortality. A key challenge in improving the accuracy of these predictions is selecting appropriate wind and fuel moisture inputs. Our objective was to evaluate postfire mortality predictions using the Forest Vegetation Simulator Fire and Fuels Extension (FVS-FFE) to determine if using representative fire-weather data would improve prediction accuracy over two default weather scenarios. We used pre- and post-…
Publication Type: Journal Article
Severe Fire Danger Index: A Forecastable Metric to Inform Firefighter and Community Wildfire Risk Management
Year: 2019
Despite major advances in numerical weather prediction, few resources exist to forecast wildland fire danger conditions to support operational fire management decisions and community early-warning systems. Here we present the development and evaluation of a spatial fire danger index that can be used to assess historical events, forecast extreme fire danger, and communicate those conditions to both firefighters and the public. It uses two United States National Fire Danger Rating System indices that are related to fire intensity and spread potential. These indices are normalized, combined, and…
Publication Type: Journal Article
Short- and long-term effects of ponderosa pine fuel treatments intersected by the Egley Fire Complex, Oregon, USA
Year: 2019
Background Fuel treatments are widely used to alter fuels in forested ecosystems to mitigate wildfire behavior and effects. However, few studies have examined long-term ecological effects of interacting fuel treatments (commercial harvests, pre-commercial thinnings, pile and burning, and prescribed fire) and wildfire. Using annually fitted Landsat satellite-derived Normalized Burn Ratio (NBR) curves and paired pre-fire treated and untreated field sites, we tested changes in the differenced NBR (dNBR) and years since treatment as predictors of biophysical attributes one and nine years after…
Publication Type: Journal Article
High-severity fire: Evaluating its key drivers and mapping its probability across western US forests
Year: 2018
Wildland fire is a critical process in forests of the western United States (US). Variation in fire behavior, which is heavily influenced by fuel loading, terrain, weather, and vegetation type, leads to heterogeneity in fire severity across landscapes. The relative influence of these factors in driving fire severity, however, is poorly understood. Here, we explore the drivers of high-severity fire for forested ecoregions in the western US over the period 2002–2015. Fire severity was quantified using a satellite-inferred index of severity, the relativized burn ratio. For each ecoregion, we…
Publication Type: Journal Article
Human-related ignitions concurrent with high winds promote large wildfires across the USA
Year: 2018
Large wildfires (>40 ha) account for the majority of burned area across the contiguous United States (US) and appropriate substantial suppression resources. A variety of environmental and social factors influence wildfire growth and whether a fire overcomes initial attack efforts and becomes a large wildfire. However, little is known about how these factors differ between lightning-caused and human-caused wildfires. This study examines differences in temperature, vapour pressure deficit, fuel moisture and wind speed for large and small lightning- and human-caused wildfires during the…
Publication Type: Journal Article
Fire and tree death: understanding and improving modeling of fire-induced tree mortality
Year: 2018
Each year wildland fires kill and injure trees on millions of forested hectares globally, affecting plant and animal biodiversity, carbon storage, hydrologic processes, and ecosystem services. The underlying mechanisms of fire-caused tree mortality remain poorly understood, however, limiting the ability to accurately predict mortality and develop robust modeling applications, especially under novel future climates. Virtually all post-fire tree mortality prediction systems are based on the same underlying empirical model described in Ryan and Reinhardt (1988 Can. J. For. Res. 18 1291–7), which…
Publication Type: Journal Article
The Weather Conditions for Desired Smoke Plumes at a FASMEE Burn Site
Year: 2018
Weather is an important factor that determines smoke development, which is essential information for planning smoke field measurements. This study identifies the synoptic systems that would favor to produce the desired smoke plumes for the Fire and Smoke Model Evaluation Experiment (FASMEE). Daysmoke and PB-Piedmont (PB-P) models are used to simulate smoke plume evolution during the day time and smoke drainage and fog formation during the nighttime for hypothetical prescribed burns on 5–8 February 2011 at the Stewart Army Base in the southeastern United States. Daysmoke simulation is…
Publication Type: Journal Article