Research Database
Displaying 981 - 1000 of 1416
Are high-severity fires burning at much higher rates recently than historically in dry-forest landscapes of the Western USA.
Year: 2015
Dry forests at low elevations in temperate-zone mountains are commonly hypothesized to be at risk of exceptional rates of severe fire from climatic change and land-use effects. Their setting is fire-prone, they have been altered by land-uses, and fire severity may be increasing. However, where fires were excluded, increased fire could also be hypothesized as restorative of historical fire. These competing hypotheses are not well tested, as reference data prior to widespread land-use expansion were insufficient. Moreover, fire-climate projections were lacking for these forests. Here, I used…
Publication Type: Journal Article
First Approximations of Prescribed Fire Risks Relative to Other Management Techniques Used on Private Lands
Year: 2015
Fire is widely recognized as a critical ecological and evolutionary driver that needs to be at the forefront of land management actions if conservation targets are to be met. However, the prevailing view is that prescribed fire is riskier than other land management techniques. Perceived risks associated with the application of fire limits its use and reduces agency support for prescribed burning in the private sector. As a result, considerably less cost-share support is given for prescribed fire compared to mechanical techniques. This study tests the general perception that fire is a riskier…
Publication Type: Journal Article
Soil Moisture Affects Growing-Season Wildfire Size in the Southern Great Plains
Year: 2015
The increasing availability of soil moisture data presents an opportunity for its use in wildfire danger assessments, but research regarding the influence of soil moisture on wildfires is scarce. Our objective was to identify relationships between soil moisture and wildfire size for Oklahoma wildfires during the growing (May-October) and dormant seasons (November-April). We hypothesized that soil moisture influences wildfire size when vegetation is growing but is less important when most vegetation is dead or dormant. Soil moisture, as fraction of available water capacity (FAW), and commonly…
Publication Type: Journal Article
Long-Term Growth of Sierra Nevada Mixed Conifer in Response to Mechanized Thinning, Slash Mastication, and Prescribed Fire
Year: 2015
Thinning implemented with a cut-to-length system accompanied by on-site slash mastication and dispersal and followed by prescribed underburning were evaluated for their influences on individual tree and stand level growth in eastern Sierran mixed conifer. California white fir (Abies concolor var. lowiana [Gord.] Lemm.) dominated stand composition with Jeffrey pine (Pinus jeffreyi Grev. & Balf.) and sugar pine (Pinus lambertiana Dougl.) moderately represented while incense-cedar (Libocedrus decurrens Torr.) and California red fir (Abies magnifica A. Murr.) were exceedingly minor…
Publication Type: Journal Article
Modeling spatial and temporal dynamics of wind flow and potential fire behavior following a mountain pine beetle outbreak in a lodgepole pine forest
Year: 2015
Patches of live, dead, and dying trees resulting from bark beetle-caused mortality alter spatial and temporal variability in the canopy and surface fuel complex through changes in the foliar moisture content of attacked trees and through the redistribution of canopy fuels. The resulting heterogeneous fuels complexes alter within-canopy wind flow, wind fluctuations, and rate of fire spread. However, there is currently little information about the potential influence of different rates and patterns of mortality on wind flow and fire behavior following bark beetle outbreaks. In this study, we…
Publication Type: Journal Article
Particulate and trace gas emissions from prescribed burns in southeastern U.S. fuel types: Summary of a 5-year project
Year: 2015
Management of smoke from prescribed fires requires knowledge of fuel quantity and the amount and composition of the smoke produced by the fire to minimize adverse impacts on human health. A five-year study produced new emissions information for more than 100 trace gases and particulate matter in smoke for fuel types found in the southern United States of America using state-of-the-art instrumentation in both laboratory and field experiments. Emission factors for flaming, smoldering, and residual smoldering were developed. Agreement between laboratory and field-derived emission factors was…
Publication Type: Journal Article
Spatiotemporal dynamics of recent mountain pine beetle and western spruce budworm outbreaks across the Pacific Northwest Region
Year: 2015
Across the western US, the two most prevalent native forest insect pests are mountain pine beetle (MPB; Dendroctonus ponderosae; a bark beetle) and western spruce budworm (WSB; Choristoneura freemani; a defoliator). MPB outbreaks have received more forest management attention than WSB outbreaks, but studies to date have not compared their cumulative mortality impacts in an integrated, regional framework. The objectives of this study are to: (1) map tree mortality associated with MPB and WSB outbreaks by integrating forest health aerial detection surveys (ADS; 1970–2012), Landsat time series (…
Publication Type: Journal Article
Hillslope erosion two and three years after wildfire, skyline salvage logging, and site preparation in southern Oregon, USA
Year: 2015
Harvest of dead timber following wildfire is contentious because of a perception that the benefits are outweighed by environmental costs. One primary concern is the potential for increased erosion susceptibility associated with timber extraction (i.e. salvage logging) and site preparation. We measured erosion at the Timbered Rock Fire in southwestern Oregon on replicated sites that were either salvage logged on private land or non-salvage logged on adjacent public lands. Sediment was collected from silt fences placed in locations with relatively uniform hillslope surface conditions beginning…
Publication Type: Journal Article
Put the wet stuff on the hot stuff': The legacy and drivers of conflict surrounding wildfire suppression
Year: 2015
Existing research demonstrates that wildfire events can lead to conflict among local residents and outside professionals involved in wildfire management or suppression. What has been missing in thewildfire literature is a more explicit understanding of the social dynamics that influence such conflict in rural or agricultural communities and their long-term legacy for future wildfire management. Authorsconducted interviews with local residents of a southeastern Washington community in 2012 to better understand conflict surrounding management of the 2006 Columbia Complex Fire. We utilize…
Publication Type: Journal Article
Spatially and socially segmenting private landowner motivations, properties, and management: A typology for the wildland urban interface
Year: 2015
Throughout North America, rapid exurban development is increasing the spatial extent and population density of the wildland urban interface (WUI), exacerbating problems of wildfire risk and biodiversity loss. To address these issues, policy and planning tools need to be targeted toward different types of WUI landowners in the different types of landscape locations they occupy. We developed a typology of WUI landowners in the Willamette Valley foothills of Oregon, USA. We used market segmentation techniques on mail survey data (n = 939) to develop a typology of four types of WUI landowners in…
Publication Type: Journal Article
Post-fire seeding with ryegrass: implications for understory plant communities and overall effectiveness
Year: 2015
Seeding following high-severity wildfires is motivated by the goals of increasing vegetative cover and decreasing bare soil in order to minimise soil erosion and exotic plant invasions. We compared the ground cover and vegetation response of seeded versus non-seeded areas located in the Warm Fire in northern Arizona, where post-fire seeding treatments with Italian ryegrass (Lolium perenne spp. multiflorum (L.)) were conducted in 4000 ha of high-severity burned areas. Over the course of the study, we observed no significant difference between seeded and non-seeded plots in percentage of bare…
Publication Type: Journal Article
The effects of burn entry and burn severity on ponderosa pine and mixed conifer forests in Grand Canyon National Park
Year: 2015
Over a century of fire exclusion in frequent-fire ponderosa pine and dry mixed conifer forests has resulted in increased tree densities, heavy surface fuel accumulations and an increase in late successional, fire-intolerant trees. Grand Canyon National Park uses prescribed fires and wildfires to reduce fire hazard and restore ecosystem processes. Research is needed to determine post-fire vegetation response thus enabling future forest succession predictions. Our study focussed on the effects of burn entry and burn severity on species composition and regeneration in two forest types: ponderosa…
Publication Type: Journal Article
Temporal fuel dynamics following high-severity fire in dry mixed conifer forests of the eastern Cascades, Oregon, USA
Year: 2015
Fire-resilient landscapes require the recurrent use of fire, but successful use of fire in previously burned areas must account for temporal fuel dynamics. We analysed factors influencing temporal fuel dynamics across a 24-year spatial chronosequence of unmanipulated dry mixed conifer forests following high-severity fire. Duff and litter accumulated as bark sloughed from snags and leaves senesced from recovering vegetation, averaging 14.6 Mg ha–1 and 22.1 Mg ha–1 at our 24-year post-fire site, respectively. 1-h fuels increased linearly, averaging 1.1 Mg ha–1 at our 24-year post-fire site,…
Publication Type: Journal Article
A Wildfire-relevant climatology of the convective environment of the United States
Year: 2015
Convective instability can influence the behaviour of large wildfires. Because wildfires modify the temperature and moisture of air in their plumes, instability calculations using ambient conditions may not accurately represent convective potential for some fire plumes. This study used the North American Regional Reanalysis to develop a climatology of the convective environment specifically tied to large fire events. The climatology is based on the period 1979–2009 and includes ambient convective available potential energy (CAPE) as well as values when surface air is warmed by 0.5, 1.0 or 2.0…
Publication Type: Journal Article
The economic benefit of localised, short-term, wildfire-potential information
Year: 2015
Wildfire-potential information products are designed to support decisions for prefire staging of movable wildfire suppression resources across geographic locations. We quantify the economic value of these information products by defining their value as the difference between two cases of expected fire-suppression expenditures: one in which daily information about spatial variation in wildfire-potential is used to move fire suppression resources throughout the season, and the other case in which daily information is not used and fire-suppression resources are staged in their home locations all…
Publication Type: Journal Article
Location, timing and extent of wildfire vary by cause of ignition
Year: 2015
The increasing extent of wildfires has prompted investigation into alternative fire management approaches to complement the traditional strategies of fire suppression and fuels manipulation. Wildfire prevention through ignition reduction is an approach with potential for success, but ignitions result from a variety of causes. If some ignition sources result in higher levels of area burned, then ignition prevention programmes could be optimised to target these distributions in space and time. We investigated the most common ignition causes in two southern California sub-regions, where humans…
Publication Type: Journal Article
Relations between soil hydraulic properties and burn severity
Year: 2015
Wildfire can affect soil hydraulic properties, often resulting in reduced infiltration. The magnitude of change in infiltration varies depending on the burn severity. Quantitative approaches to link burn severity with changes in infiltration are lacking. This study uses controlled laboratory measurements to determine relations between a remotely sensed burn severity metric (dNBR, change in normalised burn ratio) and soil hydraulic properties (SHPs). SHPs were measured on soil cores collected from an area burned by the 2013 Black Forest fire in Colorado, USA. Six sites with the same soil type…
Publication Type: Journal Article
Toward an integrated system for fire, smoke and air quality simulations
Year: 2015
In this study, WRF-Sfire is coupled with WRF-Chem to construct WRFSC, an integrated forecast system for wildfire behaviour and smoke prediction. WRF-Sfire directly predicts wildfire spread, plume and plume-top heights, providing comprehensive meteorology and fire emissions to chemical transport model WRF-Chem, eliminating the need for an external plume-rise model. Evaluation of WRFSC was based on comparisons between available observations of fire perimeter and fire intensity, smoke spread, PM2.5 (particulate matter less than 2.5 μm in diameter), NO and ozone concentrations, and plume-top…
Publication Type: Journal Article
Fuel accumulation and forest structure change following hazardous fuel reduction treatments throughout California
Year: 2015
Altered fuel conditions coupled with changing climate have disrupted fire regimes of forests historically characterised by high-frequency and low-to-moderate-severity fire. Managers use fuel treatments to abate undesirable fire behaviour and effects. Short-term effectiveness of fuel treatments to alter fire behaviour and effects is well documented; however, long-term effectiveness is not well known. We evaluated surface fuel load, vegetation cover and forest structure before and after mechanical and fire-only treatments over 8 years across 11 National Forests in California. Eight years post…
Publication Type: Journal Article
Effect of mastication and other mechanical treatments on fuel structure in chaparral
Year: 2015
Mechanical fuel treatments are a common pre-fire strategy for reducing wildfire hazard that alters fuel structure by converting live canopy fuels to a compacted layer of dead surface fuels. Current knowledge concerning their effectiveness, however, comes primarily from forest-dominated ecosystems. Our objectives were to quantify and compare changes in shrub-dominated chaparral following crushing, mastication, re-mastication and mastication-plus-burning treatments, and to assess treatment longevity. Results from analysis of variance (ANOVA) identified significant differences in all fuel…
Publication Type: Journal Article