Research Database
Displaying 61 - 80 of 93
Towards improving wildland firefighter situational awareness through daily fire behaviour risk assessments in the US Northern Rockies and Northern Great Basin
Year: 2017
Wildland firefighters must assess potential fire behaviour in order to develop appropriate strategies and tactics that will safely meet objectives. Fire danger indices integrate surface weather conditions to quantify potential variations in fire spread rates and intensities and therefore should closely relate to observed fire behaviour. These indices could better inform fire management decisions if they were linked directly to observed fire behaviour. Here, we present a simple framework for relating fire danger indices to observed categorical wildland fire behaviour. Ordinal logistic…
Publication Type: Journal Article
Prescribed Fire in Grassland Butterfly Habitat: Targeting Weather and Fuel Conditions to Reduce Soil Temperatures and Burn Severity
Year: 2017
Prescribed burning is a primary tool for habitat restoration and management in fire-adapted grasslands. Concerns about detrimental effects of burning on butterfly populations, however, can inhibit implementation of treatments. Burning in cool and humid conditions is likely to result in lowered soil temperatures and to produce patches of low burn severity, both of which would enhance survival of butterfly larvae at or near the soil surface. In this study, we burned 20 experimental plots in South Puget Sound, Washington, USA, prairies across a range of weather and fuel conditions to address the…
Publication Type: Journal Article
Evidence of fuels management and fire weather influencing fire severity in an extreme fire event
Year: 2017
Following changes in vegetation structure and pattern, along with a changing climate, large wildfire incidence has increased in forests throughout the western U.S. Given this increase there is great interest in whether fuels treatments and previous wildfire can alter fire severity patterns in large wildfires. We assessed the relative influence of previous fuels treatments (including wildfire), fire weather, vegetation and water balance on fire severity in the Rim Fire of 2013. We did this at three different spatial scales to investigate whether the influences on fire severity changed across…
Publication Type: Journal Article
Does prescribed fire promote resistance to drought in low elevation forests of the Sierra Nevada, California, USA?
Year: 2016
Prescribed fire is a primary tool used to restore western forests following more than a century of fire exclusion, reducing fire hazard by removing dead and live fuels (small trees and shrubs). It is commonly assumed that the reduced forest density following prescribed fire also reduces competition for resources among the remaining trees, so that the remaining trees are more resistant (more likely to survive) in the face of additional stressors, such as drought. Yet this proposition remains largely untested, so that managers do not have the basic information to evaluate whether prescribed…
Publication Type: Journal Article
Wildfire, climate, and perceptions in Northeast Oregon
Year: 2016
Wildfire poses a rising threat in the western USA, fueled by synergies between historical fire suppression, changing land use, insects and disease, and shifts toward a drier, warmer climate. The rugged landscapes of northeast Oregon, with their historically forest- and resource-based economies, have been one of the areas affected. A 2011 survey found area residents highly concerned about fire and insect threats, but not about climate change. In 2014 we conducted a second survey that, to explore this apparent disconnect, included questions about past and future summertime (fire season)…
Publication Type: Journal Article
Review of broad-scale drought monitoring of forests: Toward an integrated data mining approach
Year: 2016
Efforts to monitor the broad-scale impacts of drought on forests often come up short. Drought is a direct stressor of forests as well as a driver of secondary disturbance agents, making a full accounting of drought impacts challenging. General impacts can be inferred from moisture deficits quantified using precipitation and temperature measurements. However, derived meteorological indices may not meaningfully capture drought impacts because drought responses can differ substantially among species, sites and regions. Meteorology-based approaches also require the characterization of current…
Publication Type: Journal Article
Effects of Drought on Forests and Rangelands in the United States: A Comprehensive Science Synthesis
Year: 2016
This assessment provides input to the reauthorized National Integrated Drought Information System (NIDIS) and the National Climate Assessment (NCA), and it establishes the scientific foundation needed to manage for drought resilience and adaptation. Focal areas include drought characterization; drought impacts on forest processes and disturbances such as insect outbreaks and wildfire; and consequences for forest and rangeland values. Drought can be a severe natural disaster with substantial social and economic consequences. Drought becomes most obvious when large-scale changes are observed;…
Publication Type: Report
Models predict longer, deeper U.S. droughts
Year: 2015
Severe, decades-long "megadroughts" that hit the southwestern and midwestern United States over the past millennium may be just a preview of droughts to come in the next century as a result of climate change, new research suggests. According to a new analysis of 17 state-of-the-art climate models and reconstructions of historical drought based on 1000 years of tree-ring data, the regions are heading into a period of unprecedented dryness even if CO2 emissions are dramatically reduced. Under a "business-as-usual" emission scenario, there's an 80% likelihood that at least one decades-long…
Publication Type: Journal Article
The Fire Weather Accuracy and Lightning Ignition Probability System
Year: 2015
Weather forecasts can help identify environmental conditions conducive to prescribed burning or to increased fire danger. These conditions are important components of fire management tools such as fire ignition potential maps, fire danger rating systems, fire behavior predictions, and smoke dispersion modeling. Fire managers use these tools to make decisions on when to conduct prescribed burns, how to manage wildfires, and how to pre-position fire suppression forces. Forecast weather conditions provide variables such as temperature, relative humidity, solar radiation, precipitation (or lack…
Publication Type: Report
The Potential Impact of Regional Climate Change on Fire Weather in the United States
Year: 2015
Climate change is expected to alter the frequency and severity of atmospheric conditions conducive for wildfires. In this study, we assess potential changes in fire weather conditions for the contiguous United States using the Haines Index (HI), a fire weather index that has been employed operationally to detect atmospheric conditions favorable for large and erratic fire behavior. The index summarizes lower atmosphere stability and dryness into an integer value with higher values indicting more fire-prone conditions. We use simulations produced by the North American Regional Climate Change…
Publication Type: Journal Article
The influence of experimental wind disturbance on forest fuels and fire characteristics
Year: 2014
Current theory in disturbance ecology predicts that extreme disturbances in rapid succession can lead to dramatic changes in species composition or ecosystem processes due to interactions among disturbances. However, the extent to which less catastrophic, yet chronic, disturbances such as wind damage and fire interact is not well studied. In this study, we simulated wind-caused gaps in a Pinus taeda forest in the Piedmont of north-central Georgia using static winching of trees to examine how wind damage may alter fuel characteristics and the behavior of subsequent prescribed fire. We found…
Publication Type: Journal Article
Mapping day-of-burning with coarse-resolution satellite fire-detection data
Year: 2014
Evaluating the influence of observed daily weather on observed fire-related effects (e.g. smoke production, carbon emissions and burn severity) often involves knowing exactly what day any given area has burned. As such, several studies have used fire progression maps – in which the perimeter of an actively burning fire is mapped at a fairly high temporal resolution – or MODIS satellite data to determine the day-of-burning, thereby allowing an evaluation of the influence of daily weather. However, fire progression maps have many caveats, the most substantial being that they are rarely mapped…
Publication Type: Journal Article
Correlations between components of the water balance and burned area reveal insights for predicting forest fire area in the southwest United States
Year: 2014
We related measurements of annual burned area in the southwest United States during 1984–2013 to records of climate variability. Within forests, annual burned area correlated at least as strongly with spring–summer vapour pressure deficit (VPD) as with 14 other drought-related metrics, including more complex metrics that explicitly represent fuel moisture. Particularly strong correlations with VPD arise partly because this term dictates the atmospheric moisture demand. Additionally, VPD responds to moisture supply, which is difficult to measure and model regionally due to complex…
Publication Type: Journal Article
The relationship of large fire occurrence with drought and fire danger indices in the western USA, 1984-2008: the role of temporal scale
Year: 2013
The relationship between large fire occurrence and drought has important implications for fire prediction under current and future climates. This study’s primary objective was to evaluate correlations between drought and fire-danger-rating indices representing short- and long-term drought, to determine which had the strongest relationships with large fire occurrence at the scale of the western United States during the years 1984–2008. We combined 4–8-km gridded drought and fire-danger-rating indices with information on fires greater than 404.7 ha (1000 acres). To account for differences in…
Publication Type: Journal Article
Analysis of Meteorological Conditions for the Yakima Smoke Intrusion Case Study, 28 September 2009
Year: 2013
On 28 September 2009, the Naches Ranger District on the Okanogan-Wenatchee National Forest in south-central Washington State ignited an 800-ha prescribed fire. Later that afternoon, elevated PM2.5 concentrations and visible smoke were reported in Yakima, Washington, about 40 km east of the burn unit. The U.S. National Weather Service forecast for the day had predicted good dispersion conditions and winds that would carry the smoke to the less populated area north of Yakima. We undertook a case study of this event to determine whether conditions leading to the intrusion of the smoke plume into…
Publication Type: Report
Relationships between climate and macroscale area burned in the western United States
Year: 2013
Increased wildfire activity (e.g. number of starts, area burned, fire behaviour) across the western United States in recent decades has heightened interest in resolving climate–fire relationships. Macroscale climate–fire relationships were examined in forested and non-forested lands for eight Geographic Area Coordination Centers in the western United States, using area burned derived from the Monitoring Trends in Burn Severity dataset (1984–2010). Fire-specific biophysical variables including fire danger and water balance metrics were considered in addition to standard climate variables of…
Publication Type: Journal Article
Drought-Driven Disturbance History Characterizes a Southern Rocky Mountain Subalpine Forest
Year: 2012
The view that subalpine forest vegetation dynamics in western North America are "driven" by a particular disturbance type (i.e. fire) has shaped our understanding of their disturbance regimes. In the wake of a recent (1990s) landscape-extent spruce beetle (Dendroctonus rufipennis Kirby) outbreak in the southern Rocky Mountains, we re-examined the temporal continuity in disturbance types and interactions and the possible role of drought on their occurrence by reconstructing antecedent disturbances for 11 sites across the Markagunt Plateau, southern Utah, USA. Multiple consistent lines of…
Publication Type: Journal Article
The push and pull of climate change causes heterogeneous shifts in avian elevational ranges
Year: 2012
Projected effects of climate change on animal distributions primarily focus on consequences of temperature and largely ignore impacts of altered precipitation. While much evidence supports temperature-driven range shifts, there is substantial heterogeneity in species' responses that remains poorly understood. We resampled breeding ranges of birds across three elevational transects in the Sierra Nevada Mountains, USA, that were extensively surveyed in the early 20th century. Presence absence comparisons were made at 77 sites and occupancy models were used to separate significant range shifts…
Publication Type: Journal Article
Afternoon Rain More Likely Over Drier Soils
Year: 2012
Land surface properties, such as vegetation cover and soil moisture, influence the partitioning of radiative energy between latent and sensible heat fluxes in daytime hours. During dry periods, soil-water deficit can limit evapotranspiration, leading to warmer and drier conditions in the lower atmosphere. Soil moisture can influence the development of convective storms through such modifications of low-level atmospheric temperature and humidity, which in turn feeds back on soil moisture. Yet there is considerable uncertainty in how soil moisture affects convective storms across the world,…
Publication Type: Journal Article