Research Database
Displaying 61 - 80 of 91
Multitemporal LiDAR improves estimates of fire severity in forested landscapes
Year: 2018
Landsat-based fire severity maps have limited ecological resolution, which can hinder assessments of change to specific resources. Therefore, we evaluated the use of pre- and post-fire LiDAR, and combined LiDAR with Landsat-based relative differenced Normalized Burn Ratio (RdNBR) estimates, to increase the accuracy and resolution of basal area mortality estimation. We vertically segmented point clouds and performed model selection on spectral and spatial pre- and post-fire LiDAR metrics and their absolute differences. Our best multitemporal LiDAR model included change in mean intensity values…
Publication Type: Journal Article
Assessing vulnerabilities and adapting to climate change in northwestern U.S. forests
Year: 2017
Multiple climate change vulnerability assessments in the Pacific Northwest region of the USA provide the scientific information needed to begin adaptation in forested landscapes. Adaptation options developed by resource managers in conjunction with these assessments, newly summarized in the Climate Change Adaptation Library of the Western United States, provide an extensive choice of peer-reviewed climate-smart management strategies and tactics. More adaptation options are available for vegetation than for any other resource category, allowing vegetation management to be applied across a…
Publication Type: Journal Article
Who among the elderly is most vulnerable to exposure and health risks of PM2.5 from wildfire smoke?
Year: 2017
Wildfires burn over 7 million US acres annually, according to the US Forest Service. Little is known regarding which subpopulations are more vulnerable to health risks from wildfire smoke, including fine particles. We estimated exposure to fine particles specifically from wildfires and associations between wildfire-specific fine particles and respiratory hospital admissions for subpopulations > 65 years in the Western US (2004-2009). Higher fractions of Blacks and people in urban counties and in California are exposed to > 1 smoke wave (high-pollution episodes from wildfire smoke)…
Publication Type: Journal Article
Predicting post-fire tree mortality for 14 conifers in the Pacific Northwest, USA: Model evaluation, development, and thresholds
Year: 2017
Fire is a driving force in the North American landscape and predicting post-fire tree mortality is vital to land management. Post-fire tree mortality can have substantial economic and social impacts, and natural resource managers need reliable predictive methods to anticipate potential mortality following fire events. Current fire mortality models are limited to a few species and regions, notably Pinus ponderosa and Pseudotsuga menziesii in the western United States. The efficacy of existing mortality models to predict fire-induced tree mortality is central to effective forest management.…
Publication Type: Journal Article
Tree mortality and structural change following mixed-severity fire in Pseudotsuga forests of Oregon’s western Cascades, USA
Year: 2016
Mixed-severity fires are increasingly recognized as common in Pseudotsuga forests of the Pacific Northwest and may be an important mechanism for developing or maintaining their structural diversity and complexity. Questions remain about how tree mortality varies and forest structure is altered across the disturbance gradient imposed by these fires. Therefore, we sampled live and dead trees at 45–1.0 ha plots, each with four 0.10 ha nested subplots, stratified across an unburned, low, moderate and high-severity fire gradient. Burned plots were primarily sampled 10 and 22 years post-fire,…
Publication Type: Journal Article
Assessing Landscape Vulnerability to Wildfire in the USA
Year: 2016
Wildfire is an ever present, natural process shaping landscapes. Having the ability to accurately measure and predict wildfire occurrence and impacts to ecosystem goods and services, both retrospectively and prospectively, is critical for adaptive management of landscapes. Landscape vulnerability is a concept widely utilized in the ecosystem management literature that has not been explicitly defined, particularly with regard to wildfire. Vulnerability more broadly is defined by three primary components: exposure to the stressor, sensitivity to a range of stressor variability, and resilience…
Publication Type: Journal Article
Disturbance, tree mortality, and implications for contemporary regional forest change in the Pacific Northwest
Year: 2016
Tree mortality is an important demographic process and primary driver of forest dynamics, yet there are relatively few plot-based studies that explicitly quantify mortality and compare the relative contribution of endogenous and exogenous disturbances at regional scales. We used repeated observations on 289,390 trees in 3673 1 ha plots on U.S. Forest Service lands in Oregon and Washington to compare distributions of mortality rates among natural disturbances and vegetation zones from the mid-1990s to mid-2000s, a period characterized by drought, insect outbreaks, and large wildfires.…
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
Recent mountain pine beetle outbreaks, wildfire severity, and postfire tree regeneration in the US Northern Rockies
Year: 2014
Widespread tree mortality caused by outbreaks of native bark beetles (Circulionidae: Scolytinae) in recent decades has raised concern among scientists and forest managers about whether beetle outbreaks fuel more ecologically severe forest fires and impair postfire resilience. To investigate this question, we collected extensive field data following multiple fires that burned subalpine forests in 2011 throughout the Northern Rocky Mountains across a spectrum of prefire beetle outbreak severity, primarily from mountain pine beetle (Dendroctonus ponderosae). We found that recent (2001–2010)…
Publication Type: Journal Article
Defining extreme wildland fires using geospatial and ancillary metrics
Year: 2014
There is a growing professional and public perception that ‘extreme’ wildland fires are becoming more common due to changing climatic conditions. This concern is heightened in the wildland–urban interface where social and ecological effects converge. ‘Mega-fires’, ‘conflagrations’, ‘extreme’ and ‘catastrophic’ are descriptors interchangeably used increasingly to describe fires in recent decades in the US and globally. It is necessary to have consistent, meaningful and quantitative metrics to define these perceived ‘extreme’ fires, given studies predict an increased frequency of large and…
Publication Type: Journal Article
Correlations between components of the water balance and burned area reveal insights for predicting forest fire area in the southwest United States
Year: 2014
We related measurements of annual burned area in the southwest United States during 1984–2013 to records of climate variability. Within forests, annual burned area correlated at least as strongly with spring–summer vapour pressure deficit (VPD) as with 14 other drought-related metrics, including more complex metrics that explicitly represent fuel moisture. Particularly strong correlations with VPD arise partly because this term dictates the atmospheric moisture demand. Additionally, VPD responds to moisture supply, which is difficult to measure and model regionally due to complex…
Publication Type: Journal Article
On the use of a firebrand generator to investigate the ignition of structures in WUI fires
Year: 2013
An experimental apparatus has been constructed to generate a controlled and repeatable size and mass distribution of glowing firebrands. The present study reports on a series of experiments conducted in order to characterize the performance of this firebrand generator. Firebrand generator characterization and subsequent structural ignition experiments were performed at the Fire Research Wind Tunnel Facility (FRWTF) at the Building Research Institute (BRI) in Tsukuba, Japan. The firebrand generator was fed with mulch generated from Korean Pine trees. To produce repeatable initial conditions…
Publication Type: Report
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 resulting from fire-caused injuries. Longitudinal analyses of forest plots from across the western US show that high pre-fire climatic water deficit was related to increased post-fire tree mortality probabilities. This relationship between climate and fire was present after accounting for fire defences and injuries, and appeared to influence the effects of crown and stem injuries. Climate and fire interactions did not vary substantially across geographical regions, major genera and tree sizes. Our…
Publication Type: Journal Article
Assessing social vulnerability to climate change in human communities near public forests and grasslands: A framework for resource managers and planners
Year: 2013
Public land management agencies have incorporated the concept of vulnerability into protocols for assessing and planning for climate change impacts on public forests and grasslands. However, resource managers and planners have little guidance for how to address the social aspects of vulnerability in these assessments and plans. Failure to assess social vulnerability to climate change during management planning could compromise land management agencies’ adaptation strategies as well as public support for these strategies. We provide a framework for understanding and assessing social…
Publication Type: Journal Article
Natural tree regeneration and coarse woody debris dynamics after a forest fire in the Western Cascade range
Year: 2013
We monitored coarse woody debris dynamics and natural tree regeneration over a 14-year period after the 1991 Warner Creek Fire, a 3631-ha (8,972-ac) mixed severity fire in the western Cascade Range of Oregon. Rates for tree mortality in the fire, postfire mortality, snag fall, and snag fragmentation all showed distinct patterns by tree diameter and species, with Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) more likely to survive a fire, and to remain standing as a snag, than other common tree species. Natural seedling regeneration was abundant, rapid, and highly variable in space.…
Publication Type: Report
Projected Future Changes in Vegetation in Western North America in the Twenty-First Century
Year: 2013
Rapid and broad-scale forest mortality associated with recent droughts, rising temperature, and insect outbreaks has been observed over western North America (NA). Climate models project additional future warming and increasing drought and water stress for this region. To assess future potential changes in vegetation distributions in western NA, the Community Earth System Model (CESM) coupled with its Dynamic Global Vegetation Model (DGVM) was used under the future A2 emissions scenario. To better span uncertainties in future climate, eight sea surface temperature (SST) projections provided…
Publication Type: Journal Article
Assessing forest vegetation and fire simulation model performance after the Cold Springs wildfire, Washington, USA
Year: 2013
Given that resource managers rely on computer simulation models when it is difficult or expensive to obtain vital information directly, it is important to evaluate how well a particular model satisfies applications for which it is designed. The Forest Vegetation Simulator (FVS) is used widely for forest management in the US, and its scope and complexity continue to increase. This paper focuses on the accuracy of estimates made by the Fire and Fuels Extension (FFE-FVS) predictions through comparisons between model outputs and measured post-fire conditions for the Cold Springs wildfire and on…
Publication Type: Journal Article
Fuels and Fire Behavior Dynamics in Bark Beetle-Attacked Forests in Western North America and Implications for Fire Management
Year: 2012
Declining forest health attributed to associations between extensive bark beetle-caused tree mortality, accumulations of hazardous fuels, wildfire, and climate change have catalyzed changes in forest health and wildfire protection policies of land management agencies. These changes subsequently prompted research to investigate the extent to which bark beetle-altered fuel complexes affect fire behavior. Although not yet rigorously quantified, the results of the investigations, in addition to a growing body of operational experience and research, indicates that predictable changes in surface,…
Publication Type: Journal Article
Mountain pine beetle attack alters the chemistry and flammability of lodgepole pine foliage
Year: 2012
During periods with epidemic mountain pine beetle (Dendroctonus ponderosae Hopkins) populations in lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) forests, large amounts of tree foliage are thought to undergo changes in moisture content and chemistry brought about by tree decline and death. However, many of the presumed changes have yet to be quantified. In this study, we quantified and compared fuel moisture, chemistry, and resulting flammability of bark beetle affected foliage in terms of ignitability, combustibility, consumability, and sustainability at a site in far…
Publication Type: Journal Article
Climate Change, Forests, Fire, Water, and Fish: Building Resilient Landscapes, Streams, and Managers
Year: 2012
Fire will play an important role in shaping forest and stream ecosystems as the climate changes. Historic observations show increased dryness accompanying more widespread fire and forest die-off. These events punctuate gradual changes to ecosystems and sometimes generate stepwise changes in ecosystems. Climate vulnerability assessments need to account for fire in their calculus. The biophysical template of forest and stream ecosystems determines much of their response to fire. This report describes the framework of how fire and climate change work together to affect forest and fish…
Publication Type: Report