Research Database
Displaying 161 - 180 of 247
Winter grazing can reduce wildfire size, intensity and behaviour in a shrub-grassland
Year: 2015
An increase in mega-fires and wildfires is a global issue that is expected to become worse with climate change. Fuel treatments are often recommended to moderate behaviour and decrease severity of wildfires; however, the extensive nature of rangelands limits the use of many treatments. Dormant-season grazing has been suggested as a rangeland fuel treatment, but its effects on fire characteristics are generally unknown. We investigated the influence of dormant-season (winter) grazing by cattle (Bos taurus) on fuel characteristics, fire behaviour and area burned in Wyoming big sagebrush (…
Publication Type: Journal Article
Wildland fire deficit and surplus in the western United States, 1984-2012
Year: 2015
Wildland fire is an important disturbance agent in the western US and globally. However, the natural role of fire has been disrupted in many regions due to the influence of human activities, which have the potential to either exclude or promote fire, resulting in a "fire deficit" or "fire surplus", respectively. In this study, we developed a model of expected area burned for the western US as a function of climate from 1984 to 2012. We then quantified departures from expected area burned to identify geographic regions with fire deficit or surplus. We developed our model of area burned as a…
Publication Type: Journal Article
Projected major fire and vegetation changes in the Pacific Northwest of the conterminous United States under selected CMIP5 climate futures
Year: 2015
Climate change adaptation and mitigation require understanding of vegetation response to climate change. Using the MC2 dynamic global vegetation model (DGVM) we simulate vegetation for the Northwest United States using results from 20 different Climate Model Intercomparison Project Phase 5 (CMIP5) models downscaled using the MACA algorithm. Results were generated for representative concentration pathways (RCPs) 4.5 and 8.5 under vegetation modeling scenarios with and without fire suppression for a total of 80 model runs for future projections. For analysis, results were aggregated by three…
Publication Type: Journal Article
A review of the challenges and opportunities in estimating above ground forest biomass using tree-level models
Year: 2015
Accurate biomass measurements and analyses are critical components in quantifying carbon stocks and sequestration rates, assessing potential impacts due to climate change, locating bio-energy processing plants, and mapping and planning fuel treatments. To this end, biomass equations will remain a key component of future carbon measurements and estimation. As researchers in biomass and carbon estimation, we review the present scenario of aboveground biomass estimation, focusing particularly on estimation using tree-level models and identify some cautionary points that we believe will improve…
Publication Type: Journal Article
Representing climate, disturbance, and vegetation interactions in landscape models
Year: 2015
The prospect of rapidly changing climates over the next century calls for methods to predict their effects on myriad, interactive ecosystem processes. Spatially explicit models that simulate ecosystem dynamics at fine (plant, stand) to coarse (regional, global) scales are indispensable tools for meeting this challenge under a variety of possible futures. A special class of these models, called landscape models (LMs), simulates dynamics at intermediate scales where many critical ecosystem processes interact. The complicated dependencies among climate, disturbance, and vegetation present a…
Publication Type: Journal Article
Development and application of a probabilistic method for wildfire suppression cost modeling
Year: 2015
Wildfire activity and escalating suppression costs continue to threaten the financial health of federal land management agencies. In order to minimize and effectively manage the cost of financial risk, agencies need the ability to quantify that risk. A fundamental aim of this research effort, therefore, is to develop a process for generating risk-based metrics for annual suppression costs. Our modeling process borrows from actuarial science and the process of assigning insurance premiums based on distributions for the frequency and magnitude of claims, generating parameterized probability…
Publication Type: Journal Article
Experimental analysis of fire spread across a two-dimensional ridge under wind conditions
Year: 2015
Results from a laboratory-scale investigation of a fire spreading on the windward face of a triangular-section hill of variable shape with wind perpendicular to the ridgeline are reported. They confirm previous observations that the fire enlarges its lateral spread after reaching the ridgeline, entering the leeward face with a much wider front. Reference fire spread velocities were measured and analysed, putting in evidence the importance of the dynamic effect due to flow velocity and its associated horizontal-axis separation vortex strength without dependence on hill geometry. Similar…
Publication Type: Journal Article
The cost of climate change: Ecosystem services and wildland fires
Year: 2015
Little research has focused on the economic impact associated with climate-change induced wildland fire on natural ecosystems and the goods and services they provide. We examine changes in wildland fire patterns based on the U.S. Forest Service's MC1 dynamic global vegetation model from 2013 to 2115 under two pre-defined scenarios: a reference (i.e., business-as-usual) and a greenhouse gas mitigation policy scenario. We construct a habitat equivalency model under which fuels management activities, actions commonly undertaken to reduce the frequency and/or severity of wildland fire, are used…
Publication Type: Journal Article
Evaluating crown fire rate of spread predictions from physics-based models
Year: 2015
Modeling the behavior of crown fires is challenging due to the complex set of coupled processes that drive the characteristics of a spreading wildfire and the large range of spatial and temporal scales over which these processes occur. Detailed physics-based modeling approaches such as FIRETEC and the Wildland Urban Interface Fire Dynamics Simulator (WFDS) simulate fire behavior using computational fluid dynamics based methods to numerically solve the three-dimensional, time dependent, model equations that govern, to some approximation, the component physical processes and their interactions…
Publication Type: Journal Article
Developing a post-processor to link the Forest Vegetation Simulator (FVS) and the Fuel Characteristic Classification System (FCCS)
Year: 2015
In this project, we developed a Forest Vegetation Simulator (FVS, JFSP Project #) post-processor (FVS2FCCS) to convert FVS simulated treelist and surface fuel data into Fuel Characteristics Classification System (FCCS, JFSP Project #98-1-1-06) fuelbed format (.xml) that can be read and processed by the FCCS to create estimates of surface fire behavior, including reaction intensity (Btu ft-2 min-1 or kJ m2), rate-of-spread (ft min-1 or m min-1), and flame length (ft or m). Post-processors are programs that extend FVS modeling, reporting, and display capabilities. Our post-processor allows…
Publication Type: Report
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
Restoration impacts on fuels and fire potential in a dryland tropical ecosystem dominated by the invasive grass Megathyrsus maximus
Year: 2015
Ecological restoration often attempts to promote native species while managing for disturbances such as fire and non-native invasions. The goal of this research was to investigate whether restoration of a non-native, invasive Megathyrsus maximus (guinea grass) tropical grassland could simultaneously promote native species and reduce fire potential. Megathyrsus maximus was suppressed with herbicide, and three suites of native species—each including the same groundcover and shrub, and one of three tree species—were outplanted in a randomized, complete block design that also included herbicide…
Publication Type: Journal Article
Modeling the direct effect of salvage logging on long-term temporal fuel dynamics in dry-mixed conifer forests
Year: 2015
Salvage logging has been proposed to reduce post-fire hazardous fuels and mitigate re-burn effects, but debate remains about its effectiveness when considering fuel loadings are dynamic, and re-burn occurrence is stochastic, in time. Therefore, evaluating salvage loggings capacity to reduce hazardous fuels requires estimating fuel loadings in unmanipulated and salvaged stands over long time periods. We sampled for snag dynamics, decomposition rates, and fuel loadings within unmanipulated high-severity portions of 7 fires, spanning a 24-year chronosequence, in dry-mixed conifer forests of…
Publication Type: Journal Article
Modeling wildfire regimes in forest landscapes: abstracting a complex reality
Year: 2015
Fire is a natural disturbance that is nearly ubiquitous in terrestrial ecosystems. The capacity to burn exists virtually wherever vegetation grows. In some forested landscapes, fire is a principal driver of rapid ecosystem change, resetting succession ( McKenzie et al. 1996a ) and changing wildlife habitat (Cushman et al. 2011 ), hydrology ( Feikema et al. 2013 ), element cycles ( Smithwick 2011 ), and even landforms (Pierce et al. 2004 ). In boreal forests, for example, recurring wildfi res are the main cause of compositional and spatial patterns ( Wein and MacLean 1983 ), where a fi re-…
Publication Type: Book Chapter
Mapping the daily progression of large wildland fires using MODIS active fire data
Year: 2014
High temporal resolution information on burnt area is needed to improve fire behaviour and emissions models. We used the Moderate Resolution Imaging Spectroradiometer (MODIS) thermal anomaly and active fire product (MO(Y)D14) as input to a kriging interpolation to derive continuous maps of the timing of burnt area for 16 large wildland fires. For each fire, parameters for the kriging model were defined using variogram analysis. The optimal number of observations used to estimate a pixel’s time of burning varied between four and six among the fires studied. The median standard error from…
Publication Type: Journal Article
Modeling Regional-Scale Wildland Fire Emissions with the Wildland Fire Emissions Information System
Year: 2014
As carbon modeling tools become more comprehensive, spatial data are needed to improve quantitative maps of carbon emissions from fire.The Wildland Fire Emissions Information System (WFEIS) provides mapped estimates of carbon emissions from historical forest fires in the United States through a web browser. WFEIS improves access to data and provides a consistent approach to estimating emissions at landscape, regional, and continental scales. The system taps into data and tools developed by the U.S. Forest Serviceto describe fuels, fuel loadings, and fuel consumption and merges information…
Publication Type: Journal Article
The Effectiveness and Limitations of Fuel Modeling Using the Fire and Fuels Extension to the Forest Vegetation Simulator
Year: 2014
Fuel treatment effectiveness is often evaluated with fire behavior modeling systems that use fuel models to generate fire behavior outputs. How surface fuels are assigned, either using one of the 53 stylized fuel models or developing custom fuel models, can affect predicted fire behavior. We collected surface and canopy fuels data before and 1, 2, 5, and 8 years after prescribed fire treatments across 10 national forests in California. Two new methods of assigning fuel models within the Fire and FuelsExtension to the Forest Vegetation Simulator were evaluated. Field-based values for dead and…
Publication Type: Journal Article
Regional projections of the likelihood of very large wildland fires under a changing climate in the contiguous Western United States
Year: 2014
Seasonal changes in the climatic potential for very large wildfires (VLWF ≥ 50,000 ac ~ 20,234 ha) across the western contiguous United States are projected over the 21st century using generalized linear models and downscaled climate projections for two representative concentration pathways (RCPs). Significant (p ≤ 0.05) increases in VLWF probability for climate of the mid-21st century (2031–2060) relative to contemporary climate are found, for both RCP 4.5 and 8.5. The largest differences are in the Eastern Great Basin, Northern Rockies, Pacific Northwest, Rocky Mountains, and Southwest.…
Publication Type: Journal Article
Dry forest resilience varies under simulated climate-management scenarios in a central Oregon, USA landscape
Year: 2014
Determining appropriate actions to create or maintain landscapes resilient to climate change is challenging because of uncertainty associated with potential effects of climate change and their interactions with land management. We used a set of climate informed state-and-transition models to explore the effects of management and natural disturbances on vegetation composition and structure under different future climates. Models were run for dry forests of central Oregon under a fire suppression scenario (i.e., no management other than the continued suppression of wildfires) and an active…
Publication Type: Journal Article
Fire behavior in masticated fuels: A review
Year: 2014
Mastication is an increasingly common fuels treatment that redistributes “ladder” fuels to the forest floor to reduce vertical fuel continuity, crown fire potential, and fireline intensity, but fuel models do not exist for predicting fire behavior in these fuel types. Recent fires burning in masticated fuels have behaved in unexpected and contradictory ways, likely because the shredded, compact fuel created when trees and shrubs are masticated contains irregularly shaped pieces in mixtures quite different from other woody fuels. We review fuels characteristics and fire behavior in masticated…
Publication Type: Journal Article