Research Database
Displaying 121 - 140 of 235
Short- and long-term effects of ponderosa pine fuel treatments intersected by the Egley Fire Complex, Oregon, USA
Year: 2019
Background Fuel treatments are widely used to alter fuels in forested ecosystems to mitigate wildfire behavior and effects. However, few studies have examined long-term ecological effects of interacting fuel treatments (commercial harvests, pre-commercial thinnings, pile and burning, and prescribed fire) and wildfire. Using annually fitted Landsat satellite-derived Normalized Burn Ratio (NBR) curves and paired pre-fire treated and untreated field sites, we tested changes in the differenced NBR (dNBR) and years since treatment as predictors of biophysical attributes one and nine years after…
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
Wildland firefighter smoke exposure and risk of lung cancer and cardiovascular disease mortality
Year: 2019
Wildland firefighters are exposed to wood smoke, which contains hazardous air pollutants, by suppressing thousands of wildfires across the U. S. each year. We estimated the relative risk of lung cancer and cardiovascular disease mortality from existing PM2.5 exposure-response relationships using measured PM4 concentrations from smoke and breathing rates from wildland firefighter field studies across different exposure scenarios. To estimate the relative risk of lung cancer (LC) and cardiovascular disease (CVD) mortality from exposure to PM2.5 from smoke, we used an existing exposure-response…
Publication Type: Journal Article
Air-quality challenges of prescribed fire in the complex terrain and wildland urban interface surrounding Bend, Oregon
Year: 2019
Prescribed fires in forest ecosystems can negatively impact human health and safety by transporting smoke downwind into nearby communities. Smoke transport to communities is known to occur around Bend, Oregon, United States of America (USA), where burning at the wildland–urban interface in the Deschutes National Forest resulted in smoke intrusions into populated areas. The number of suitable days for prescribed fires is limited due to the necessity for moderate weather conditions, as well as wind directions that do not carry smoke into Bend. To better understand the conditions leading to…
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
A multi-century history of fire regimes along a transect of mixed-conifer forests in central Oregon, U.S.A
Year: 2019
Dry mixed-conifer forests are widespread in the interior Pacific Northwest, but their historical fire regimes are poorly characterized, in particular the relative mix of low- and high-severity fire. We reconstructed a multi-century history of fire from tree rings in dry mixed-conifer forests in central Oregon. These forests are dominated by ponderosa pine (Pinus ponderosa Lawson & C. Lawson), Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and grand fir (Abies grandis (Douglas ex D. Don) Lindl.). Across four, 30-plot grids of ~800 ha covering a mosaic of dry mixed-conifer forest types…
Publication Type: Journal Article
Assessing relative differences in smoke exposure from prescribed, managed, and full suppression wildland fire
Year: 2019
A novel approach is presented to analyze smoke exposure and provide a metric to quantify health-related impacts. Our results support the current understanding that managing low-intensity fire for ecological benefit reduces exposure when compared to a high-intensity full suppression fire in the Sierra Nevada of California. More frequent use of fire provides an opportunity to mitigate smoke exposure for both individual events and future emission scenarios. The differences in relative exposure between high-intensity, low-intensity, and prescribed burn were significant (P value < 0.01).…
Publication Type: Journal Article
Contributions of fire refugia to resilient ponderosa pine and dry mixed-conifer forest landscapes
Year: 2019
Altered fire regimes can drive major and enduring compositional shifts or losses of forest ecosystems. In western North America, ponderosa pine and dry mixed‐conifer forest types appear increasingly vulnerable to uncharacteristically extensive, high‐severity wildfire. However, unburned or only lightly impacted forest stands that persist within burn mosaics—termed fire refugia—may serve as tree seed sources and promote landscape recovery. We sampled tree regeneration along gradients of fire refugia proximity and density at 686 sites within the perimeters of 12 large wildfires that occurred…
Publication Type: Journal Article
Severe fire weather and intensive forest management increase fire severity in a multi-ownership landscape
Year: 2018
Many studies have examined how fuels, topography, climate, and fire weather influence fire severity. Less is known about how different forest management practices influence fire severity in multi‐owner landscapes, despite costly and controversial suppression of wildfires that do not acknowledge ownership boundaries. In 2013, the Douglas Complex burned over 19,000 ha of Oregon & California Railroad (O&C) lands in Southwestern Oregon, USA. O&C lands are composed of a checkerboard of private industrial and federal forestland (Bureau of Land Management, BLM) with contrasting…
Publication Type: Journal Article
Using Social Media to Predict Air Pollution during California Wildfires
Year: 2018
Wildfires have significant effects on human populations worldwide. Smoke pollution, in particular, from either prescribed burns or uncontrolled wildfires, can have profound health impacts, such as reducing birth weight in children and aggravating respiratory and cardiovascular conditions. Scarcity in the measurements of particulate matter responsible for these public health issues makes addressing the problem of smoke dispersion challenging, especially when fires occur in remote regions. Previous research has shown that in the case of the 2014 King fire in California, crowdsourced data can be…
Publication Type: Journal Article
Developing an online tool for identifying at-risk populations to wildfire smoke hazards
Year: 2018
Wildfire episodes pose a significant public health threat in the United States. Adverse health impacts associated with wildfires occur near the burn area as well as in places far downwind due to wildfire smoke exposures. Health effects associated with exposure to particulate matter arising from wildfires can range from mild eye and respiratory tract irritation to more serious outcomes such as asthma exacerbation, bronchitis, and decreased lung function. Real-time operational forecasts of wildfire smoke concentrations are available but they are not readily integrated with information on…
Publication Type: Journal Article
A Review of Community Smoke Exposure from Wildfire Compared to Prescribed Fire in the United States
Year: 2018
Prescribed fire, intentionally ignited low-intensity fires, and managed wildfires—wildfires that are allowed to burn for land management benefit—could be used as a land management tool to create forests that are resilient to wildland fire. This could lead to fewer large catastrophic wildfires in the future. However, we must consider the public health impacts of the smoke that is emitted from wildland and prescribed fire. The objective of this synthesis is to examine the differences in ambient community-level exposures to particulate matter (PM2.5) from smoke in the United States in relation…
Publication Type: Journal Article
Spatiotemporal patterns of unburned areas within fire perimeters in the northwestern United States from 1984 to 2014
Year: 2018
A warming climate, fire exclusion, and land cover changes are altering the conditions that produced historical fire regimes and facilitating increased recent wildfire activity in the northwestern United States. Understanding the impacts of changing fire regimes on forest recruitment and succession, species distributions, carbon cycling, and ecosystem services is critical, but challenging across broad spatial scales. One important and understudied aspect of fire regimes is the unburned area within fire perimeters; these areas can function as fire refugia across the landscape during and after…
Publication Type: Journal Article
High-severity fire: Evaluating its key drivers and mapping its probability across western US forests
Year: 2018
Wildland fire is a critical process in forests of the western United States (US). Variation in fire behavior, which is heavily influenced by fuel loading, terrain, weather, and vegetation type, leads to heterogeneity in fire severity across landscapes. The relative influence of these factors in driving fire severity, however, is poorly understood. Here, we explore the drivers of high-severity fire for forested ecoregions in the western US over the period 2002–2015. Fire severity was quantified using a satellite-inferred index of severity, the relativized burn ratio. For each ecoregion, we…
Publication Type: Journal Article
The influence of fire history on soil nutrients and vegetation cover in mixed-severity fire regime forests of the eastern Olympic Peninsula, Washington, USA
Year: 2018
The rain shadow forests of the Olympic Peninsula exemplify a mixed-severity fire regime class in the midst of a highly productive landscape where spatial heterogeneity of fire severity may have significant implications for below and aboveground post-fire recovery. The purpose of this study was to quantify the impacts of wildfire on forest soil carbon (C) and nitrogen (N) pools and assess the relationship of pyrogenic carbon (PyC) to soil processes in this mixed-severity ecosystem. We established a 112-year fire chronosequence with nine similar forest stands ranging in time since lastfire (TSF…
Publication Type: Journal Article
Spatiotemporal patterns of unburned areas within fire perimeters in the northwestern United States from 1984 to 2014
Year: 2018
A warming climate, fire exclusion, and land cover changes are altering the conditions that produced historical fire regimes and facilitating increased recent wildfire activity in the northwestern United States. Understanding the impacts of changing fire regimes on forest recruitment and succession, species distributions, carbon cycling, and ecosystem services is critical, but challenging across broad spatial scales. One important and understudied aspect of fire regimes is the unburned area within fire perimeters; these areas can function as fire refugia across the landscape during and after…
Publication Type: Journal Article
How does forest recovery following moderate-severity fire influence effects of subsequent wildfire in mixed-conifer forests?
Year: 2018
Given regional increases in fire activity in western North American forests, understanding how fire influences the extent and effects of subsequent fires is particularly relevant. Remotely sensed estimates of fire effects have allowed for spatial portioning into different severity categories based on the degree of fire-caused vegetation change. Fire effects between minimal overstory tree mortality (< 20%) and complete (or nearly complete) overstory tree mortality (> 95%) are often lumped into a single category referred to as moderate severity. In this paper, we investigated how burned…
Publication Type: Journal Article
Wildfires managed for restoration enhance ecological resilience
Year: 2018
Expanding the footprint of natural fire has been proposed as one potential solution to increase the pace of forest restoration programs in fire‐adapted landscapes of the western USA. However, studies that examine the long‐term socio‐ecological trade‐offs of expanding natural fire to reduce wildfire risk and create fire resilient landscapes are lacking. We used the model Envision to examine the outcomes that might result from increased area burned by what we call “restoration” wildfire in a landscape where the ecological benefits of wildfire are known, but the need to suppress high‐risk fires…
Publication Type: Journal Article
NWCG Smoke Management Guide for Prescribed Fire
Year: 2018
The NWCG Smoke Management Guide for Prescribed Fire contains information on prescribed fire smoke management techniques, air quality regulations, smoke monitoring, modeling, communication, public perception of prescribed fire and smoke, climate change, practical meteorological approaches and smoke tools. The primary focus of this document is to serve as the textbook in support of NWCG’s RX-410, Smoke Management Techniques course which is required for the position of Prescribed Fire Burn Boss Type 2 (RXB2) The Guide is useful to all who use prescribed fire, from private land owners to federal…
Publication Type: Report
Tree traits influence response to fire severity in the western Oregon Cascades, USA
Year: 2018
Wildfire is an important disturbance process in western North American conifer forests. To better understand forest response to fire, we used generalized additive models to analyze tree mortality and long-term (1 to 25 years post-fire) radial growth patterns of trees that survived fire across a burn severity gradient in the western Cascades of Oregon. We also used species-specific leaf-area models derived from sapwood estimates to investigate the linkage between photosynthetic capacity and growth response. Larger trees and shade intolerant trees had a higher probability of surviving fire.…
Publication Type: Journal Article