Research Database
Displaying 1 - 20 of 22
A fire deficit persists across diverse North American forests despite recent increases in area burned
Year: 2025
Rapid increases in wildfire area burned across North American forests pose novel challenges for managers and society. Increasing area burned raises questions about whether, and to what degree, contemporary fire regimes (1984–2022) are still departed from historical fire regimes (pre-1880). We use the North American tree-ring fire-scar network (NAFSN), a multi-century record comprising >1800 fire-scar sites spanning diverse forest types, and contemporary fire perimeters to ask whether there is a contemporary fire surplus or fire deficit, and whether recent fire years are unprecedented…
Publication Type: Journal Article
Spatiotemporal Synchrony of Climate and Fire Occurrence Across North American Forests (1750–1880)
Year: 2025
Aim: Increasing aridity has driven widespread synchronous fire occurrence in recent decades across North America. The lack of historical (pre-1880) fire records limits our ability to understand long-term continental fire-climate dynamics. The goal of this study is to use tree-ring reconstructions to determine the relationships between spatiotemporal patterns in historical climate and widespread fire occurrence in North American forests, and whether they are stable through time. This information will address a major knowledge gap required to inform projections of future fire.Location: North…
Publication Type: Journal Article
Return on investments in restoration and fuel treatments in frequent-fire forests of the American west: A meta-analysis
Year: 2024
Arid forests in the American West contend with overly dense stands and a need to reduce fuels and restore more natural fire regimes. Forest restoration efforts include fuel treatments, such as thinning and prescribed burning, that can reduce ground and ladder fuels. Restoration and fuel treatments have emerged as leading wildfire risk-reduction strategies in the American West, yet little is known about the cost-effectiveness of such programs. To evaluate forest restoration and fuel treatment benefits and costs, we conducted a meta-analysis of benefit-cost ratios for restoration benefit types…
Publication Type: Journal Article
Wildfire activity in northern Rocky Mountain subalpine forests still within millennial-scale range of variability
Year: 2023
Increasing area burned across western North America raises questions about the precedence and magnitude of changes in fire activity, relative to the historical range of variability (HRV) that ecosystems experienced over recent centuries and millennia. Paleoecological records of past fire occurrence provide context for contemporary changes in ecosystems characterized by infrequent, high-severity fire regimes. Here we present a network of 12 fire-history records derived from macroscopic charcoal preserved in sediments of small subalpine lakes within a c. 10 000 km2 landscape in the U.S.…
Publication Type: Journal Article
Recent Douglas-fir Mortality in the Klamath Mountains Ecoregion of Oregon: Evidence for a Decline Spiral
Year: 2023
Recent increases in Douglas-fir (Psuedotsuga menziesii var. menziesii) mortality in the Klamath Mountains ecoregion raise concerns about the long-term resilience of Douglas-fir in the ecoregion and increased potential for uncharacteristic wildfire. We used data from the USDA Forest Service Aerial Detection Survey and ninety-six field plots to explore the relationships between physiographic and climate variables and Douglas-fir mortality. Our results provide strong evidence for a decline spiral in which Douglas-fir growing on hot, dry sites (predisposing factor) are further stressed by drought…
Publication Type: Journal Article
Exceptional variability in historical fire regimes across a western Cascades landscape, Oregon, USA
Year: 2023
Detailed information about the historical range of variability in wildfire activity informs adaptation to future climate and disturbance regimes. Here, we describe one of the first annually resolved reconstructions of historical (1500–1900 ce) fire occurrence in coast Douglas-fir dominated forests of the west slope of the Cascade Range in western Oregon. Mean fire return intervals (MFRIs) across 16 sites within our study area ranged from 6 to 165 years. Variability in MFRIs was strongly associated with average maximum summer vapor pressure deficit. Fire occurred infrequently in Douglas-fir…
Fire Effects and Fire Ecology, Fire History, Mixed-Conifer Management, Restoration and Hazardous Fuel Reduction
Publication Type: Journal Article
Trends in forest structure restoration need over three decades with increasing wildfire activity in the interior Pacific Northwest US
Year: 2022
Wildfire is a keystone ecological process in many forests worldwide, but fire exclusion and suppression have driven profound shifts in forest structure (e.g., increased density, canopy cover, biomass) that have contributed to increases in large, high-severity fire in many seasonally dry forests and woodlands of the western United States. Comparisons between contemporary and historic range of variability (HRV) in forest structure can quantify the amount and types of restoration that shift landscapes toward structural conditions that have his- torically fostered resilience to fire. However,…
Publication Type: Journal Article
The Economic Value of Fuel Treatments: A Review of the Recent Literature for Fuel Treatment Planning
Year: 2022
This review synthesizes the scientific literature on fuel treatment economics published since 2013 with a focus on its implications for land managers and policy makers. We review the literature on whether fuel treatments are financially viable for land management agencies at the time of implementation, as well as over the lifespan of fuel treatment effectiveness. We also review the literature that considers the broad benefits of fuel treatments across multiple sectors of society. Most studies find that fuel treatments are not financially viable for land management agencies based on revenue…
Publication Type: Journal Article
The importance of Indigenous cultural burning in forested regions of the Pacific West, USA
Year: 2021
Indigenous communities in the Pacific West of North America have long depended on fire to steward their environments, and they are increasingly asserting the importance of cultural burning to achieve goals for ecological and social restoration. We synthesized literature regarding objectives and effects of cultural burning in this region within an ecosystem services framework. Much scholarly literature focuses on why various species harvested from burned areas were important historically, while tribes and recent research increasingly stress a wide range of ecological and cultural benefits…
Publication Type: Journal Article
The missing fire: quantifying human exclusion of wildfire in Pacific Northwest forests, USA
Year: 2019
Western U.S. wildfire area burned has increased dramatically over the last half‐century. How contemporary extent and severity of wildfires compare to the pre‐settlement patterns to which ecosystems are adapted is debated. We compared large wildfires in Pacific Northwest forests from 1984 to 2015 to modeled historic fire regimes. Despite late twentieth‐century increases in area burned, we show that Pacific Northwest forests have experienced an order of magnitude less fire over 32 yr than expected under historic fire regimes. Within fires that have burned, severity distributions are…
Publication Type: Journal Article
Looking beyond the mean: Drivers of variability in postfire stand development of conifers in Greater Yellowstone
Year: 2018
High-severity, infrequent fires in forests shape landscape mosaics of stand age and structure for decades to centuries, and forest structure can vary substantially even among same-aged stands. This variability among stand structures can affect landscape-scale carbon and nitrogen cycling, wildlife habitat availability, and vulnerability to subsequent disturbances. We used an individual-based forest process model (iLand) to ask: Over 300 years of postfire stand development, how does variation in early regeneration densities versus abiotic conditions influence among-stand structural variability…
Publication Type: Journal Article
Efficacy of resource objective wildfires for restoration of ponderosa pine (Pinus ponderosa) forests in northern Arizona
Year: 2017
Current conditions in dry forests of the western United State have given rise to policy mandates for accelerated ecological restoration on U.S. National Forest System and other public lands. In southwestern ponderosa pine (Pinus ponderosa Laws.) forests, mechanized tree thinning and prescribed fire are common restoration treatments but are not acceptable for all sites. Currently there is much interest in managing naturally ignited fires to accomplish restoration objectives but few studies have systematically examined the efficacy of such “resource objective” wildfires for restoring historical…
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
REVIEW: Searching for resilience: addressing the impacts of changing disturbance regimes on forest ecosystem services
Year: 2016
The provisioning of ecosystem services to society is increasingly under pressure from global change. Changing disturbance regimes are of particular concern in this context due to their high potential impact on ecosystem structure, function and composition. Resilience-based stewardship is advocated to address these changes in ecosystem management, but its operational implementation has remained challenging. We review observed and expected changes in disturbance regimes and their potential impacts on provisioning, regulating, cultural and supporting ecosystem services, concentrating on…
Publication Type: Journal Article
Does wildfire likelihood increase following insect outbreaks in conifer forests?
Year: 2015
Although there is acute concern that insect-caused tree mortality increases the likelihood or severity of subsequent wildfire, previous studies have been mixed, with findings typically based on stand-scale simulations or individual events. This study investigates landscape- and regional-scale wildfire likelihood following outbreaks of the two most prevalent native insect pests in the US Pacific Northwest (PNW): mountain pine beetle (MPB; Dendroctonus ponderosae) and western spruce budworm (WSB; Choristoneura freemani). We leverage seamless census data across numerous insect and fire events to…
Publication Type: Journal Article
Temperate forest health in an era of emerging megadisturbance
Year: 2015
Although disturbances such as fire and native insects can contribute to natural dynamics of forest health, exceptional droughts, directly and in combination with other disturbance factors, are pushing some temperate forests beyond thresholds of sustainability. Interactions from increasing temperatures, drought, native insects and pathogens, and uncharacteristically severe wildfire are resulting in forest mortality beyond the levels of 20th-century experience. Additional anthropogenic stressors, such as atmospheric pollution and invasive species, further weaken trees in some regions. Although…
Publication Type: Journal Article
A state-and-transition simulation modeling approach for estimating the historical range of variability
Year: 2015
Reference ecological conditions offer important context for land managers as they assess the condition of their landscapes and provide benchmarks for desired future conditions. State-and-transition simulation models (STSMs) are commonly used to estimate reference conditions that can be used to evaluate current ecosystem conditions and to guide land management decisions and activities. The LANDFIRE program created more than 1,000 STSMs and used them to assess departure from a mean reference value for ecosystems in the United States. While the mean provides a useful benchmark, land managers and…
Publication Type: Journal Article
Increasing weight of evidence that thinning and burning treatments help restore understory plant communities in ponderosa pine forests
Year: 2015
For more than a century ecosystems around the world have experienced an increase in the dominance of woody species. While the drivers of woody plant proliferation are complex, interactions between climate and land-use change are commonly invoked as primary contributing factors. In ponderosa pine forests of western North America, substantial increases in tree densities are impacting overall forest health and increasing the risk for severe wildfires and insect and disease outbreaks. Addressing this problem through the use of ecological restoration projects is widely advocated. Our objective was…
Publication Type: Journal Article
Eastern Washington Forest Health: Hazards, Accomplishments and Restoration Strategy
Year: 2014
Much of the 10 million acres of forestland in eastern Washington faces serious threats to forest health. Decades of fire suppression and past management practices that changed the species and structure of these forests have put them at higher risk of damage by disease, insects and wildfire.
Publication Type: Report
Historic Variability: Informing Restoration Strategies, Not Prescribing Targets
Year: 2014
The concept of historic range of variability (HRV) is briefly evaluatedwithin the context of its application in ecosystem managementover the past two decades. Despite caveats to the contrary, animplicit assumption continues to emerge of climatic stationarity,and, by corollary, that presettlement centuries provide an appropriatereference period. This is examined from the perspective ofhistoric climate change and ecosystem response. As a means ofdeveloping reference prescriptions and management targets, HRVis generally inappropriate, although if historic periods are usedfor reconstruction that…
Publication Type: Journal Article