Research Database
Displaying 161 - 180 of 194
Wildland fire emissions, carbon, and climate: Modeling fuel consumption
Year: 2014
Fuel consumption specifies the amount of vegetative biomass consumed during wildland fire. It is a two-stage process of pyrolysis and combustion that occurs simultaneously and at different rates depending on the characteristics and condition of the fuel, weather, topography, and in the case of prescribed fire, ignition rate and pattern. Fuel consumption is the basic process that leads to heat absorbing emissions called greenhouse gas and other aerosol emissions that can impact atmospheric and ecosystem processes, carbon stocks, and land surface reflectance. It is a critical requirement for…
Publication Type: Journal Article
Wildland firefighter safety zones: a review of past science and summary of future needs
Year: 2014
Current wildland firefighter safety zone guidelines are based on studies that assume flat terrain, radiant heating, finite flame width, constant flame temperature and high flame emissivity. Firefighter entrapments and injuries occur across a broad range of vegetation, terrain and atmospheric conditions generally when they are within two flame heights of the fire. Injury is not confined to radiant heating or flat terrain; consequently, convective heating should be considered as a potential heating mode. Current understanding of energy transport in wildland fires is briefly summarised, followed…
Publication Type: Journal Article
The role of defensible space for residential structure protection during wildfires
Year: 2014
With the potential for worsening fire conditions, discussion is escalating over how to best reduce effects on urban communities. A widely supported strategy is the creation of defensible space immediately surrounding homes and other structures. Although state and local governments publish specific guidelines and requirements, there is little empirical evidence to suggest how much vegetation modification is needed to provide significant benefits. We analysed the role of defensible space by mapping and measuring a suite of variables on modern pre-fire aerial photography for 1000 destroyed and…
Publication Type: Journal Article
Beyond reducing fire hazard: fuel treatment impacts on overstory tree survival
Year: 2014
Fuel treatment implementation in dry forest types throughout the western United States is likely to increase in pace and scale in response to increasing incidence of large wildfires. While it is clear that properly implemented fuel treatments are effective at reducing hazardous fire potential, there are ancillary ecological effects that can impact forest resilience either positively or negatively depending on the specific elements examined, as well as treatment type, timing, and intensity. In this study, we use overstory tree growth responses, measured seven years after the most common fuel…
Publication Type: Journal Article
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
Allowing a wildfire to burn: estimating the effect on future suppression costs
Year: 2013
Where a legacy of aggressive wildland fire suppression has left forests in need of fuel reduction, allowing wildland fire to burn may provide fuel treatment benefits, thereby reducing suppression costs from subsequent fires. The least-cost-plus-net-value-change model of wildland fire economics includes benefits of wildfire in a framework for evaluating suppression options. In this study, we estimated one component of that benefit – the expected present value of the reduction in suppression costs for subsequent fires arising from the fuel treatment effect of a current fire. To that end, we…
Publication Type: Journal Article
Wildland Fire management: Are actively managed forests more resilient than passively managed forests?
Year: 2013
Large areas of federal lands in the western states are currently at high risk of severe wildfire and have many insect and disease problems, indicating a significant decline in forest health and resilience. Although research studies have not been done that would measure whether actively managed forests are more resilient to wildfires than passively managed forests, results from studies of hazardous fuels treatment effectiveness and the economic benefits from avoided costs of future wildfire suppression due to fuels treatment can be used to support an affirmative reply to the question. If a…
Publication Type: Report
Modelling conditional burn probability patterns for large wildland fires
Year: 2013
We present a technique for modelling conditional burn probability patterns in two dimensions for large wildland fires. The intended use for the model is strategic program planning when information about future fire weather and event durations is unavailable and estimates of the average probabilistic shape and extent of large fires on a landscape are needed. To model average conditional burn probability patterns, we organised historical fire data from Yellowstone National Park, USA, into a set of grids; one grid per fire. We captured various spatial relationships inherent in the gridded data…
Publication Type: Journal Article
Powered by Oregon - The potential for woody biomass
Year: 2013
As a fuel, wood has been with us since humans tamed fire. So what’s the big deal? Why the renewed interest in wood as a source of energy? If we imagine a way to power Oregon that is less dependent on fossil fuels, that is built instead on renewable and homegrown sources of energy, then woody fuel should be a significant part of the picture. Why do we import oil or propane to heat a rural town, for instance, when abundant, clean-burning fuel is a few miles away? Using local fuel creates jobs and keeps money at home. Many small Oregon towns could use more of both. Is it sustainable? Yes. In…
Publication Type: Report
The Drivers of Effectiveness of Prescribed Fire Treatment
Year: 2012
Prescribed burning for fuel reduction is a major strategy for reducing the risk from unplanned fire. Although there are theoretical studies suggesting that prescribed fire has a strong negative influence on the subsequent area of unplanned fire (so-called leverage), many empirical studies find a more modest influence. Here, I develop a series of simulations to explore the landscape drivers of leverage. Leverage declines with treatment level in a nonlinear, “decay” relationship, implying diminishing effectiveness. The spatial configuration of the prescribed fire treatment has a major effect:…
Publication Type: Journal Article
A Review of Recent Advances in Risk Analysis for Wildfire Management
Year: 2012
Risk analysis evolved out of the need to make decisions concerning highly stochastic events, and is well suited to analyse the timing, location and potential effects of wildfires. Over the past 10 years, the application of risk analysis to wildland fire management has seen steady growth with new risk-based analytical tools that support a wide range of fire and fuels management planning scales from individual incidents to national, strategic interagency programs. After a brief review of the three components of fire risk – likelihood, intensity and effects – this paper reviews recent advances…
Publication Type: Journal Article
Ecological effects of alternative fuel-reduction treatments: highlights of the National Fire and Fire Surrogate study (FSS)
Year: 2012
The 12-site National Fire and Fire Surrogate study (FFS) was a multivariate experiment that evaluated ecological consequences of alternative fuel-reduction treatments in seasonally dry forests of the US. Each site was a replicated experiment with a common design that compared an un-manipulated control, prescribed fire, mechanical and mechanical + fire treatments. Variables within the vegetation, fuelbed, forest floor and soil, bark beetles, tree diseases and wildlife were measured in 10-ha stands, and ecological response was compared among treatments at the site level, and across sites, to…
Publication Type: Journal Article
Long and Short-Term Effects of Fire on Soil Charcoal of a Conifer Forest in Southwest Oregon
Year: 2012
In 2002, the Biscuit Wildfire burned a portion of the previously established, replicated conifer unthinned and thinned experimental units of the Siskiyou Long-Term Ecosystem Productivity (LTEP) experiment, southwest Oregon. Charcoal C in pre and post-fire O horizon and mineral soil was quantified by physical separation and a peroxide-acid digestion method. The abrupt, short-term fire event caused O horizon charcoal C to increase by a factor of ten to >200 kg C ha−1. The thinned wildfire treatment produced less charcoal C than unthinned wildfire and thinned prescribed fire treatments. The…
Publication Type: Journal Article
The Age of Western Wildfires
Year: 2012
The 2012 wildfire season isn’t over yet, but already this year is shaping up to be the one of the worst on record in the American West. According to the National Interagency Fire Center, with nearly two months still to go in the fire season, the total area already burned this year is 30 percent more than in an average year, and fires have consumed more than 8.6 million acres, an area larger than the state of Maryland. Yet, what defines a “typical” wildfire year in the West is changing. In the past 40 years, rising spring and summer temperatures, along with shrinking winter snowpack, have…
Publication Type: Report
Seasonal variation in surface fuel moisture between unthinned and thinned mixed conifer forest, northern California, USA
Year: 2012
Reducing stand density is often used as a tool for mitigating the risk of high-intensity crown fires. However, concern has been expressed that opening stands might lead to greater drying of surface fuels, contributing to increased fire risk. The objective of this study was to determine whether woody fuel moisture differed between unthinned and thinned mixed-conifer stands. Sections of logs representing the 1000- and 10 000-h fuel sizes were placed at 72 stations within treatment units in the fall (autumn) of 2007. Following snow-melt in 2008, 10-h fuel sticks were added and all fuels were…
Publication Type: Journal Article
Alteration and Recovery of Slash Pile Burn Sites in the Restoration of a Fire-Maintained Ecosystem
Year: 2012
Restoration practices incorporating timber harvest (e.g. to remove undesirable species or reduce tree densities) may generate unmerchantable wood debris that is piled and burned for fuel reduction. Slash pile burns are common in longleaf pine ecosystem restoration that involves hardwood removal before reintroduction of frequent prescribed fire. In this context, long-lasting effects of slash pile burns may complicate restoration outcomes due to unintended alterations to vegetation, soils, and the soil seed bank. In this study, our objectives were to (1) examine alterations to the soil seed…
Publication Type: Journal Article
Health Effects of Wildland Fire Smoke: Insight from Public Health Science Studies
Year: 2012
Due to the composition and dispersion of wildland fire smoke, particulate matter is the principal pollutant of public health concern. Effects will vary based on the source of smoke but predominantly impact local communities in the same way. Studies of the effects of PM from non-fire sources show that long-term exposure can reduce lung function and cause the development of chronic bronchitis. Short-term exposure (hours or days), typical of wildland fire events, can aggravate lung disease, leading to asthma attacks and acute bronchitis. These effects can also increase the susceptibility to…
Publication Type: Report
Fuel Treatment Effectiveness in California Yellow Pine and Mixed Conifer Forests
Year: 2012
We assessed the effectiveness of forest fuel thinning projects that explicitly removed surface and ladder fuels (all but one were combined mechanical and prescribed fire/pile burn prescriptions) in reducing fire severity and tree mortality in 12 forest fires that burned in eastern and southern California between 2005 and 2011. All treatments and fires occurred in yellow pine or mixed conifer forests, in a variety of landscape conditions. Most fires burned under warm, dry conditions, with moderate to high winds. With few exceptions, fire severity measures (bole char height, scorch and torch…
Publication Type: Journal Article
Atmospheric Interactions with Wildland Fire Behaviour II. Plume and Vortex Dynamics
Year: 2012
This paper is the second of two reviewing scientific literature from 100 years of research addressing interactions between the atmosphere and fire behaviour. These papers consider research on the interactions between the fuels burning at any instant and the atmosphere, and the interactions between the atmosphere and those fuels that will eventually burn in a given fire. The first paper reviews the progression from the surface atmospheric properties of temperature, humidity and wind to horizontal and vertical synoptic structures and ends with vertical atmospheric profiles. This second paper…
Publication Type: Journal Article
Climate Change and Disruptions to Global Fire Activity
Year: 2012
Future disruptions to fire activity will threaten ecosystems and human well-being throughout the world, yet there are few fire projections at global scales and almost none from a broad range of global climate models (GCMs). Here we integrate global fire datasets and environmental covariates to build spatial statistical models of fire probability at a 0.58 resolution and examine environmental controls on fire activity. Fire models are driven by climate norms from 16 GCMs (A2 emissions scenario) to assess the magnitude and direction of change over two time periods, 2010–2039 and 2070–2099. From…
Publication Type: Journal Article