Research Database
Displaying 41 - 60 of 68
Restoring forest structure and process stabilizes forest carbon in wildfire-prone southwestern ponderosa pine forests
Year: 2016
Changing climate and a legacy of fire-exclusion have increased the probability of high-severity wildfire, leading to an increased risk of forest carbon loss in ponderosa pine forests in the southwestern USA. Efforts to reduce high-severity fire risk through forest thinning and prescribed burning require both the removal and emission of carbon from these forests, and any potential carbon benefits from treatment may depend on the occurrence of wildfire. We sought to determine how forest treatments alter the effects of stochastic wildfire events on the forest carbon balance. We modeled three…
Publication Type: Journal Article
Did the 2002 Hayman Fire, Colorado, USA, Burn with Uncharacteristic Severity?
Year: 2016
There is considerable interest in evaluating whether recent wildfires in dry conifer forests of western North America are burning with uncharacteristic severity—that is, with a severity outside the historical range of variability. In 2002, the Hayman Fire burned an unlogged 3400 ha dry conifer forest landscape in the Colorado Front Range, USA, that had been the subject of previous fire history and forest age structure research. We opportunistically leveraged pre-existing data from this research, in combination with post-fire aerial imagery, to provide insight into whether the Hayman Fire’s…
Publication Type: Journal Article
Evaluating Prescribed Fire Effectiveness Using Permanent Monitoring Plot Data: A Case Study
Year: 2016
Since Euro-American settlement, ponderosa pine forests throughout the western United States have shifted from high fire frequency and open canopy savanna forests to infrequent fire and dense, closed canopy forests. Managers at Zion National Park, USA, reintroduced fire to counteract these changes and decrease the potential for high-severity fires. We analyzed existing permanent monitoring plot data collected between 1995 and 2010 to assess achievement of management objectives related to prescribed fire in ponderosa pine forests. Following first entry fire, ponderosa pine (Pinus ponderosa C.…
Publication Type: Journal Article
Latent resilience in ponderosa pine forest: effects of resumed frequent fire
Year: 2013
Ecological systems often exhibit resilient states that are maintained through negative feedbacks. In ponderosa pine forests, fire historically represented the negative feedback mechanism that maintained ecosystem resilience; fire exclusion reduced that resilience, predisposing the transition to an alternative ecosystem state upon reintroduction of fire. We evaluated the effects of reintroduced frequent wildfire in unlogged, fire-excluded, ponderosa pine forest in the Bob Marshall Wilderness, Montana, USA. Initial reintroduction of fire in 2003 reduced tree density and consumed surface fuels,…
Publication Type: Journal Article
Pre-wildfire fuel reduction treatments result in more resilient forest structure a decade after wildfire
Year: 2013
Increasing size and severity of wildfires have led to an interest in the effectiveness of forest fuels treatments on reducing fire severity and post-wildfire fuels. Our objective was to contrast stand structure and surface fuel loadings on treated and untreated sites within the 2002 Rodeo–Chediski Fire area. Data from 140 plots on seven paired treated–untreated sites indicated that pre-wildfire treatments reduced fire severity compared with untreated sites. In 2011, coarse woody debris loading (woody material >7.62 cm in diameter) was 257% higher and fine woody debris (woody material <7…
Publication Type: Journal Article
Spatially extensive reconstructions show variable-severity fire and heterogeneous structure in historical western United States dry forests
Year: 2012
Aim Wildfire is often considered more severe now than historically in dry forests of the western United States. Tree-ring reconstructions, which suggest that historical dry forests were park-like with large, old trees maintained by low-severity fires,are from small, scattered studies. To overcome this limitation, we developed spatially comprehensive reconstructions across 927,000 ha in four landscapes, using anew method based on land surveys from c. 1880. Location Dry forests of the western United States. Methods We reconstructed forest structure for four large dry-forest landscapes using…
Publication Type: Journal Article
Temporal dynamics and decay of coarse wood in early seral habitats of dry-mixed conifer forests in Oregon’s Eastern Cascades
Year: 2012
Early seral forest habitats are increasingly valued for the unique structural resources they provide in many western US forests. Coarse woody detritus (CWD) are a significant feature of this developmental stage and are highly dynamic, suggesting these environments exhibit temporally diverse structural conditions prior to forest canopy closure. In dry-mixed conifer forests, snags are hypothesized to decay slower than logs making long-term dynamics in these forests dependent on snag fall, breakage and the decay rates of both standing and surface CWD. We estimated snag fall and breakage rates…
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
Fuel treatment impacts on estimated wildfire carbon loss from forests in Montana, Oregon, California, and Arizona
Year: 2012
Using forests to sequester carbon in response to anthropogenically induced climate change is being considered across the globe. A recent U.S. executive order mandated that all federal agencies account for sequestration and emissions of greenhouse gases, highlighting the importance of understanding how forest carbon stocks are influenced by wildfire. This paper reports the effects of the most common forest fuel reduction treatments on carbon pools composed of live and dead biomass as well as potential wildfire emissions from six different sites in four western U.S. states. Additionally, we…
Publication Type: Journal Article
Mastication and Prescribed Fire Influences on Tree Mortality and Predicted Fire Behavior in Ponderosa Pine
Year: 2012
The purpose of this study was to provide land managers with information on potential wildfire behavior and tree mortality associated with mastication and masticated/fire treatments in a plantation. Additionally, the effect of pulling fuels away from tree boles before applying fire treatment was studied in relation to tree mortality. Fuel characteristics and tree mortality data were gathered before and after treatments in a 25-year-old ponderosa pine (Pinus ponderosa C. Lawson) plantation. A random block design was used with three treatments plus a control at each of four blocks. Four plots…
Publication Type: Journal Article
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
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
Simulating effects of climate change and ecological restoration on fire behaviour in a south-western USA ponderosa pine forest
Year: 2012
Global climate change has the potential to affect future wildfire activity, particularly in south-western USA ponderosa pine forests that have been substantially altered by land-use practices and aggressive fire suppression. Using two regional general circulation models for the A1B greenhouse gas emission scenario, Australia's CSIRO:MK3 and Germany's MPIM:ECHAMS, we predicted fire behaviour under the 80th, 90th and 97th percentiles of future fire-weather conditions at a study site on the Kaibab National Forest, Arizona. We then altered the fuel structure by simulating alternative ecological…
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
Principal short-term findings of the National Fire and Fire Surrogate study
Year: 2012
Principal findings of the National Fire and Fire Surrogate (FFS) study are presented in an annotated bibliography and summarized in tabular form by site, discipline (ecosystem component), treatment type, and major theme. Composed of 12 sites, the FFS is a comprehensive multidisciplinary experiment designed to evaluate the costs and ecological consequences of alternative fuel reduction treatments in seasonally dry forests of the United States. The FFS has a common experimental design across the 12-site network, with each site a fully replicated experiment that compares four treatments:…
Publication Type: Report
Photo Series for Quantifying Natural Fuels Volume XI : Eastern Oregon Sagebrush - Steppe and Spotted Owl Nesting Habitat in the Pacific Northwest
Year: 2012
Three series of photographs display a range of natural conditions and fuel loadings for sagebrush-steppe types that are ecotonal with grasses, western juniper, and ponderosa pine in eastern Oregon, and one series of photographs displays a range of natural conditions and fuel loadings for northern spotted owl nesting habitat in forest types in Washington and Oregon. Each group of photos includes inventory information summarizing vegetation composition, structure, and loading; woody material loading and density by size class; forest floor depth and loading; and various site characteristics. The…
Publication Type: Report
Estimating Consumption and Remaining Carbon in Burned Slash Piles
Year: 2012
Fuel reduction treatments to reduce fire risk have become commonplace in the fire adapted forests of western North America. These treatments generate significant woody debris, or slash, and burning this material in piles is a common and inexpensive approach to reducing fuel loads. Although slash pile burning is a common practice, there is little information on consumption or even a common methodology for estimating consumption. As considerations of carbon storage and emissions from forests increase, better means of quantifying burn piles are necessary. This study uses two methods, sector…
Publication Type: Journal Article
Reducing hazardous fuels on nonindustrial private forests: factors influencing landowner decisions
Year: 2011
In mixed-ownership landscapes, fuels conditions on private lands have implications for fire risk on public lands and vice versa. The success of efforts to mitigate fire risk depends on the extent, efficacy, and coordination of treatments on nearby ownerships. Understanding factors in forest owners’ decisions to address the risk of wildland fire is therefore important. This research uses logistic regression to analyze mail survey data and identify factors in forest owners’ decisions to reduce hazardous fuels in the ponderosa pine (Pinus ponderosa) ecosystem on the east side of Oregon. Results…
Publication Type: Journal Article
Assessing Fuel Treatment Effectiveness After the Tripod Complex Fires
Year: 2011
Over the past 50 years, wildfire frequency and area burned have increased in the dry forests of western North America. To help reduce high surface fuel loads and potential wildfire severity, a variety of fuel treatments are applied. In spite of the common use of these management practices, there have been relatively few opportunities to quantitatively measure their efficacy in wildfires. That changed with the 2006 Tripod Complex fires in the Okanogan-Wenatchee National Forest in Washington—one of the largest fire events in Washington state over the past five decades. A serendipitous…
Publication Type: Report
Ponderosa Pine Biomass Relationships Vary with Site Treatment and Site Productivity
Year: 2011
Allometric equations, which express biomass as a function of tree size, are often used to estimate the amount of fuel in a site’s canopy. Most managers assume that one allometric equation per species is sufficient, or that any error introduced by extrapolation is irrelevant. This work showed, however, that the allometric biomass relationship for ponderosa pine likely changes over space and time. The researchers concluded that for maximum accuracy, allometric equations for ponderosa pine should account for stand management history and site productivity. Thinned trees replaced their foliage…
Publication Type: Report