Research Database
Displaying 141 - 160 of 162
Fuel Treatments and Fire Severity: A Meta-Analysis
Year: 2013
We employed meta-analysis and information theory to synthesize findings reported in the literature on the effects of fuel treatments on subsequent fire intensity and severity. Data were compiled from 19 publications that reported observed fire responses from 62 treated versus untreated contrasts. Effect sizes varied widely and the most informative grouping of studies distinguished three vegetation types and three types of fuel treatment. The resultant meta-analytic model is highly significant (p<0.001) and explains 78% of the variability in reported observations of fuel treatment…
Publication Type: Report
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
Climate stress increases forest fire severity across the western United States
Year: 2013
Pervasive warming can lead to chronic stress on forest trees, which may contribute to mortality resultingfrom fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that highpre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationshipbetween climate and fire was present after accounting for fire defences and injuries, and appeared to influencethe effects of crown and stem injuries. Climate and fire interactions did not vary substantially acrossgeographical regions, major genera and tree sizes. Our…
Publication Type: Journal Article
Fire-mediated pathways of stand development in Douglas-fir/ western hemlock forests of the Pacific Northwest, USA
Year: 2013
Forests dominated by Douglas-fir and western hemlock in the Pacific Northwest of the United States have strongly influenced concepts and policy concerning old-growth forest conservation. Despite the attention to their old-growth characteristics, a tendency remains to view their disturbance ecology in relatively simple terms, emphasizing infrequent, stand-replacing (SR) fire and an associated linear pathway toward development of those old-growth characteristics. This study uses forest stand- and age-structure data from 124 stands in the central western Cascades of Oregon to construct a…
Publication Type: Journal Article
Previous Fires Moderate Burn Severity of Subsequent Wildland Fires in Two Large Western US Wilderness Areas
Year: 2013
Wildland fire is an important natural process in many ecosystems. However, fire exclusion has reduced frequency of fire and area burned in many dry forest types, which may affect vegetation structure and composition, and potential fire behavior. In forests of the western U.S., these effects pose a challenge for fire and land managers who seek to restore the ecological process of fire to ecosystems. Recent research suggests that landscapes with unaltered fire regimes are more ‘‘self-regulating’’ than those that have experienced fire-regime shifts; in self-regulating systems, fire size and…
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
Wildfire severity mediates fluxes of plant material and terrestrial invertebrates to mountain streams
Year: 2012
Wildfire effects upon riparian plant community structure, composition, and distribution may strongly influence the dynamic relationships between riparian vegetation and stream ecosystems. However, few studies have examined the influence of fire on these processes. To that end, we compared the quantity and composition of allochthonous inputs of plant material and terrestrial invertebrates among stream tributaries characterized by various degrees of burn severity 5 years post-fire in the Frank Church Wilderness of central Idaho, USA. The magnitude of inputs of coniferous leaf litter to unburned…
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
Fuel Variability Following Wildfire in Forests with Mixed Severity Fire Regimes, Cascade Range, USA
Year: 2012
Publication Type: Journal Article
Surface fuel treatments in young, regenerating stands affect wildfire severity in a mixed conifer forest, eastside Cascade Range, Washington, USA
Year: 2012
Previous studies have debated the flammability of young regenerating stands, especially those in a matrix of mature forest, and no consensus has emerged as to whether young stands are inherently prone to highseverity wildfire. This topic has recently been addressed using spatial imagery, and weak inferences were made given the scale mismatch between the coarse resolution of spatial imagery and the fine resolution of mechanisms driving fire severity. We collected empirical stand and fire-severity data from 44 regenerating stands that are interspersed in mature, mid-elevation forests in the…
Publication Type: Journal Article
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
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
A Comprehensive Guide to Fuel Management Practices for Dry Mixed Conifer Forests in the Northwestern United States
Year: 2012
This guide describes the benefits, opportunities, and trade-offs concerning fuel treatments in the dry mixed conifer forests of northern California and the Klamath Mountains, Pacific Northwest Interior, northern and central Rocky Mountains, and Utah. Multiple interacting disturbances and diverse physical settings have created a forest mosaic with historically low- to mixed-severity fire regimes. Analysis of forest inventory data found nearly 80 percent of these forests rate hazardous by at least one measure and 20 to 30 percent rate hazardous by multiple measures. Modeled mechanical…
Publication Type: Report
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
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 forestsof the western United States. Tree-ring reconstructions, which suggest that historicaldry forests were park-like with large, old trees maintained by low-severity fires,are from small, scattered studies. To overcome this limitation, we developed spatiallycomprehensive 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 landscapesusing forest…
Publication Type: Journal Article
Meta-analysis of avian and small-mammal response to fire severity and fire surrogate treatments in US fire-prone forests
Year: 2012
Management in fire-prone ecosystems relies widely upon application of prescribed fire and/or fire surrogate (e.g., forest thinning) treatments to maintain biodiversity and ecosystem function. Recently, published literature examining wildlife response to fire and fire management has increased rapidly. However, none of this literature has been synthesized quantitatively, precluding assessment of consistent patterns of wildlife response among treatment types. Using meta- analysis, we examined the scientific literature on vertebrate demographic responses to burn severity (low/moderate, high),…
Publication Type: Journal Article
Short- and Long-term Effects of Fire on Carbon in US Dry Temperate Forest Systems
Year: 2011
Forests sequester carbon from the atmosphere, and in so doing can mitigate the effects of climate change. Fire is a natural disturbance process in many forest systems that releases carbon back to the atmosphere. In dry temperate forests, fires historically burned with greater frequency and lower severity than they do today. Frequent fires consumed fuels on the forest floor and maintained open stand structures. Fire suppression has resulted in increased understory fuel loads and tree density; a change in structure that has caused a shift from low- to high-severity fires. More severe fires,…
Publication Type: Journal Article
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
Both topography and climate affected forest and woodland burn severity in two regions of the western US, 1984 to 2006
Year: 2011
Fire is a keystone process in many ecosystems of western North America. Severe fires kill and consume large amounts of above- and belowground biomass and affect soils, resulting in long-lasting consequences for vegetation, aquatic ecosystem productivity and diversity, and other ecosystem properties. We analyzed the occurrence of, and trends in, satellite-derived burn severity across six ecoregions in the Southwest and Northwest regions of the United States from 1984 to 2006 using data from the Monitoring Trends in Burn Severity project. Using 1,024 fires from the Northwest (4,311,871 ha) and…
Publication Type: Journal Article
Response of antelope bitterbrush to repeated prescribed burning in Central Oregon ponderosa pine forests
Year: 2009
Antelope bitterbrush is a dominant shrub in many interior ponderosa pine forests in the western UnitedStates. How it responds to prescribed fire is not well understood, yet is of considerable concern to wildlifeand fire managers alike given its importance as a browse species and as a ladder fuel in these fire-proneforests. We quantified bitterbrush cover, density, and biomass in response to repeated burning in thinnedponderosa pine forests. Low- to moderate-intensity spring burning killed the majority of bitterbrushplants on replicate plots. Moderately rapid recovery of bitterbrush density…
Publication Type: Journal Article