Research Database
Displaying 101 - 120 of 237
Using Landsat Imagery to Assess Burn Severity of National Forest Inventory Plots
Year: 2021
As the frequency and size of wildfires increase, accurate assessment of burn severityis essential for understanding fire effects and evaluating post-fire vegetation impacts. Remotelysensedimagery allows for rapid assessment of burn severity, but it also needs to be field validated.Permanent forest inventory plots can provide burn severity information for the field validation ofremotely-sensed burn severity metrics, although there is often a mismatch between the size andshape of the inventory plot and the resolution of the rasterized images. For this study, we used twodistinct datasets: (1)…
Publication Type: Journal Article
Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests
Year: 2021
Implementation of wildfire- and climate-adaptation strategies in seasonally dry forests of western North America is impeded by numerous constraints and uncertainties. After more than a century of resource and land use change, some question the need for proactive management, particularly given novel social, ecological, and climatic conditions. To address this question, we first provide a framework for assessing changes in landscape conditions and fire regimes. Using this framework, we then evaluate evidence of change and lack of change in contemporary conditions relative to those maintained by…
Publication Type: Journal Article
Wildfire severity and postfire salvage harvest effects on long-term forest regeneration
Year: 2020
Following a wildfire, regeneration to forest can take decades to centuries and is no longerassured in many western U.S. environments given escalating wildfire severity and warming trends. Afterlarge fire years, managers prioritize where to allocate scarce planting resources, often with limited informationon the factors that drive successful forest establishment. Where occurring, long-term effects of postfiresalvage operations can increase uncertainty of establishment. Here, we collected field data on postfireregeneration patterns within 13- to 28-yr-old burned patches in eastern Washington…
Publication Type: Journal Article
Tribes & Climate Change
Year: 2020
Native Americans rely on tribally important ecosystem services such as traditional foods, hunting, timber production, non-timber forest resources (recreation, water), and cultural resources. Unfortunately, many of these resources may be highly vulnerable to the impacts of climate change. A research team sought to answer the question: Where and which tribally-important ecosystem services will be affected by climate change in the Pacific Northwest? They used projections from climate and vegetation models and stakeholder input to demonstrate a generalizable approach for assessing possible…
Publication Type: Web project page
Fuel treatment effectiveness in the context of landform, vegetation, and large, wind‐driven wildfires
Year: 2020
Large wildfires (>50,000 ha) are becoming increasingly common in semi‐arid landscapes of the western United States. Although fuel reduction treatments are used to mitigate potential wildfire effects, they can be overwhelmed in wind‐driven wildfire events with extreme fire behavior. We evaluated drivers of fire severity and fuel treatment effectiveness in the 2014 Carlton Complex, a record‐setting complex of wildfires in north‐central Washington State. Across varied topography, vegetation and distinct fire progressions, we used a combination of simultaneous autoregression (SAR) and random…
Publication Type: Journal Article
How does tree regeneration respond to mixed‐severity fire in the western Oregon Cascades, USA?
Year: 2020
Dendroecological studies of historical tree recruitment patterns suggest mixed‐severity fire effects are common in Douglas‐fir/western hemlock forests of the Pacific Northwest (PNW), USA, but empirical studies linking observed fire severity to tree regeneration response are needed to expand our understanding into the functional role of fire in this forest type. Recent increases in mixed‐severity fires offered this opportunity, so we quantified the abundance, spatial distribution, species richness, and community composition of regenerating trees across a mixed‐severity fire gradient (unburned–…
Publication Type: Journal Article
Washington State 2020 Forest Action Plan
Year: 2020
Washington has more than 22 million acres of forestland. From the lush rainforests on our coasts, to the rugged sub-alpine forests along the Cascade Crest, to the pine-dominated hillsides surrounding the Columbia Plateau, forests are an integral part of our landscapes and communities, and they provide a wealth of benefits to Washingtonians and the planet. They provide us with sustainable timber and jobs, produce clean air and water, sequester carbon, and support world-class outdoor recreation. Our forests, however, face unprecedented threats that require bold action. Climate change is…
Publication Type: Government Report
Persistent effects of fire severity on ponderosa pine regeneration niches and seedling growth
Year: 2020
Several recent studies have documented how fire severity affects the density and spatial patterns of tree regenerationin western North American ponderosa pine forests. However, less is known about the effects of fireseverity on fine-scale tree regeneration niche attributes such as understory plant composition and cover, surfacefuel abundance, and soil properties, or how these attributes in turn affect regenerating ponderosa pine growth.Using 1-m2 plots centered on 360 ponderosa pine seedlings that regenerated naturally after the Pumpkin Fire in2000 in Arizona, we quantified regeneration niche…
Publication Type: Journal Article
High‐severity wildfire leads to multi‐decadal impacts on soil biogeochemistry in mixed‐conifer forests
Year: 2020
During the past century, systematic wildfire suppression has decreased fire frequency and increased fire severity in the western United States of America. While this has resulted in large ecological changes aboveground such as altered tree species composition and increased forest density, little is known about the long‐term, belowground implications of altered, ecologically novel, fire regimes, especially on soil biological processes. To better understand the long‐term implications of ecologically novel, high‐severity fire, we used a 44‐yr high‐severity fire chronosequence in the Sierra…
Publication Type: Journal Article
Disjunct and decoupled? The persistence of a fire-sensitive conifer soecies in a historically frequent-fire landscape
Year: 2020
Local and regional species extirpations may become more common as changing climate and disturbance regimesaccelerate species’ in situ range contractions. Identifying locations that function as both climate and disturbancerefugia is critical for biodiversity conservation. Here, we investigate the persistence of a disjunct, fire-sensitiveconifer population, yellow-cedar (Callitropsis nootkatensis), in the historically frequent-fire landscape of the BlueMountains in eastern Oregon, USA. We used tree rings to reconstruct multi-century fire histories, which werethen used to compare historical mean…
Publication Type: Journal Article
Fostering collective action to reduce wildfire risk across property boundaries in the American West
Year: 2020
Large-scale, high-severity wildfires are a major challenge to the future social-ecological sustainability of fire-adapted forest ecosystems in the American West. Managing forests to mitigate this risk is a collective action problem requiring landowners and stakeholders within multi-ownership landscapes to plan and implement coordinated restoration treatments. Our research question is: how can we promote collective action to reduce wildfire risk and restore fire-resilient forests in the American West? To address this question we draw on collective action theory to produce an environmental…
Publication Type: Journal Article
Examining post-fire vegetation recovery with Landsat time series analysis in three western North American forest types
Year: 2019
Background: Few studies have examined post-fire vegetation recovery in temperate forest ecosystems with Landsat time series analysis. We analyzed time series of Normalized Burn Ratio (NBR) derived from LandTrendr spectral-temporal segmentation fitting to examine post-fire NBR recovery for several wildfires that occurred in three different coniferous forest types in western North America during the years 2000 to 2007. We summarized NBR recovery trends, and investigated the influence of burn severity, post-fire climate, and topography on post-fire vegetation recovery via random forest (RF)…
Publication Type: Journal Article
Historical patterns of fire severity and forest structure and composition in a landscape structured by frequent large fires: Pumice Plateau ecoregion, Oregon, USA
Year: 2019
Context Lack of quantitative observations of extent, frequency, and severity of large historical fires constrains awareness of departure of contemporary conditions from those that demonstrated resistance and resilience to frequent fire and recurring drought. Objectives Compare historical and contemporary fire and forest conditions for a dry forest landscape with few barriers to fire spread. Methods Quantify differences in (1) historical (1700–1918) and contemporary (1985–2015) fire extent, fire rotation, and stand-replacing fire and (2) historical (1914–1924) and contemporary (2012) forest…
Publication Type: Journal Article
Climate, Environment, and Disturbance History Govern Resilience of Western North American Forests
Year: 2019
Before the advent of intensive forest management and fire suppression, western North American forests exhibited a naturally occurring resistance and resilience to wildfires and other disturbances. Resilience, which encompasses resistance, reflects the amount of disruption an ecosystem can withstand before its structure or organization qualitatively shift to a different basin of attraction. In fire-maintained forests, resilience to disturbance events arose primarily from vegetation pattern-disturbance process interactions at several levels of organization. Using evidence from 15 ecoregions,…
Publication Type: Journal Article
Wild bee diversity increases with local fire severity in a fire‐prone landscape
Year: 2019
As wildfire activity increases in many regions of the world, it is imperative that we understand how key components of fire‐prone ecosystems respond to spatial variation in fire characteristics. Pollinators provide a foundation for ecological communities by assisting in the reproduction of native plants, yet our understanding of how pollinators such as wild bees respond to variation in fire severity is limited, particularly for forest ecosystems. Here, we took advantage of a natural experiment created by a large‐scale, mixed‐severity wildfire to provide the first assessment of how wild bee…
Publication Type: Journal Article
Influence of fire refugia spatial pattern on post-fire forest recovery in Oregon’s Blue Mountains
Year: 2019
Context Fire regimes in many dry forests of western North America are substantially different from historical conditions, and there is concern about the ability of these forests to recover following severe wildfire. Fire refugia, unburned or low-severity burned patches where trees survived fire, may serve as essential propagule sources that enable forest regeneration. Objectives To quantify the influence of fire refugia spatial pattern and other biophysical factors on the process of post-fire tree regeneration; in particular examining both the proximity and density of surrounding refugia to…
Publication Type: Journal Article
Increasing trends in high-severity fire in the southwestern USA from 1984 to 2015
Year: 2019
In the last three decades, over 4.1 million hectares have burned in Arizona and New Mexico and the largest fires in documented history have occurred in the past two decades. Changes in burn severity over time, however, have not been well documented in forest and woodland ecosystems in the southwestern US. Using remotely sensed burn severity data from 1621 fires (>404 ha), we assessed trends from 1984 to 2015 in Arizona and New Mexico in (1) number of fires and total area burned in all vegetation types; (2) area burned, area of high-severity, and percent of high-severity fire in all forest…
Publication Type: Journal Article
Integrating Subjective and Objective Dimensions of Resilience in Fire-Prone Landscapes
Year: 2019
Resilience has become a common goal for science-based natural resource management, particularly in the context of changing climate and disturbance regimes. Integrating varying perspectives and definitions of resilience is a complex and often unrecognized challenge to applying resilience concepts to social–ecological systems (SESs) management. Using wildfire as an example, we develop a framework to expose and separate two important dimensions of resilience: the inherent properties that maintain structure, function, or states of an SES and the human perceptions of desirable or valued components…
Publication Type: Journal Article
Near-future forest vulnerability to drought and fire varies across the western United States
Year: 2019
Recent prolonged droughts and catastrophic wildfires in the western United States have raised concerns about the potential for forest mortality to impact forest structure, forest ecosystem services, and the economic vitality of communities in the coming decades. We used the Community Land Model (CLM) to determine forest vulnerability to mortality from drought and fire by the year 2049. We modified CLM to represent 13 major forest types in the western United States and ran simulations at a 4‐km grid resolution, driven with climate projections from two general circulation models under one…
Publication Type: Journal Article
Predicting increasing high severity area burned for three forested regions in the western United States using extreme value theory
Year: 2019
More than 70 years of fire suppression by federal land management agencies has interrupted fire regimes in much of the western United States. The result of missed fire cycles is a buildup of both surface and canopy fuels in many forest ecosystems, increasing the risk of severe fire. The frequency and size of fires has increased in recent decades, as has the area burned with high severity in some ecosystems. A number of studies have examined controls on high severity fire occurrence, but none have yet determined what controls the extent of high severity fire. We developed statistical models…
Publication Type: Journal Article