Research Database
Displaying 21 - 40 of 110
Abiotic Factors Modify Ponderosa Pine Regeneration Outcomes After High-Severity Fire
Year: 2024
Large high-severity burn patches are increasingly common in southwestern US dry conifer forests. Seed-obligate conifers often fail to quickly regenerate large patches because their seeds rarely travel the distances required to reach core patch area. Abiotic factors may further alter the distance seeds can travel to regenerate a patch, which would change expected post-fire regeneration patterns. We used the presence and density of ponderosa pine regeneration as a proxy for seed dispersal to quantify the effect of abiotic factors on seed dispersal into high-severity patches. We established 45…
Publication Type: Journal Article
Mortality attributable to PM 2.5 from wildland fires inCalifornia from 2008 to 2018
Year: 2024
In California, wildfire risk and severity have grown substantially in the last several decades. Research has characterized extensive adverse health impacts from exposure to wildfire-attributable fine particulate matter (PM2.5), but few studies have quantified long-term outcomes, and none have used a wildfire-specific chronic dose-response mortality coefficient. Here, we quantified the mortality burden for PM2.5 exposure from California fires from 2008 to 2018 using Community Multiscale Air Quality modeling system wildland fire PM2.5 estimates. We used a concentration-response function for PM2…
Publication Type: Journal Article
Bacterial Emission Factors: A Foundation for the Terrestrial-Atmospheric Modeling of Bacteria Aerosolized by Wildland Fires
Year: 2024
Wildland fire is a major global driver in the exchange of aerosols between terrestrial environments and the atmosphere. This exchange is commonly quantified using emission factors or the mass of a pollutant emitted per mass of fuel burned. However, emission factors for microbes aerosolized by fire have yet to be determined. Using bacterial cell concentrations collected on unmanned aircraft systems over forest fires in Utah, USA, we determine bacterial emission factors (BEFs) for the first time. We estimate that 1.39 × 1010 and 7.68 × 1011 microbes are emitted for each Mg of biomass consumed…
Publication Type: Journal Article
Repeated fuel treatments fall short of fire-adapted regeneration objectives in a Sierra Nevada mixed conifer forest, USA
Year: 2024
Fire exclusion over the last two centuries has driven a significant fire deficit in the forests of western North America, leading to widespread changes in the composition and structure of these historically fire-adapted ecosystems. Fuel treatments have been increasingly applied over the last few decades to mitigate fire hazard, yet it is unclear whether these fuel-focused treatments restore the fire-adapted conditions and species that will allow forests to persist into the future. A vital prerequisite of restoring fire-adaptedness is ongoing establishment of fire-tolerant tree species, and…
Publication Type: Journal Article
Mental Health and Traumatic Occupational Exposure in Wildland Fire Dispatchers
Year: 2024
Wildland fire dispatchers play a key role in wildland fire management and response organization; however, to date, wildland fire studies have largely focused on the physical hazards and, to a lesser extent, mental health hazards of wildland firefighting operational personnel, and dispatcher studies have primarily focused on 911 and police dispatchers. Studies of other dispatchers have provided some limited insight into potential strains impacting this workforce, including work-related fatigue, burnout, and traumatic exposure. However, the specific job hazards that are faced by wildland fire…
Publication Type: Journal Article
Factors Associated with Concurrent Tobacco Smoking and Heavy Drinking within a Women Firefighters’ Sample
Year: 2024
Studies showed that tobacco use and excessive alcohol consumption frequently occur, and both are significant causes of preventable morbidity and mortality. Data were collected as part of a national online study of the health of women in the fire service. Multinomial logistic regression was employed to determine factors associated with smoking and drinking characteristics. A total of 2330 women firefighters completed questions regarding tobacco and alcohol use; 3.2% (n = 75) were concurrent users, 0.9% (n = 22) were smokers only, 49.4% (n = 1150) were heavy drinkers only, and 46.5% (n = 1083)…
Publication Type: Journal Article
Exploring spatial heterogeneity in synergistic effects of compound climate hazards: Extreme heat and wildfire smoke on cardiorespiratory hospitalizations in California
Year: 2024
Extreme heat and wildfire smoke events are increasingly co-occurring in the context of climate change, especially in California. Extreme heat and wildfire smoke may have synergistic effects on population health that vary over space. We leveraged high-resolution satellite and monitoring data to quantify spatially varying compound exposures to extreme heat and wildfire smoke in California (2006–2019) at ZIP Code Tabulation Area (ZCTA) level. We found synergistic effects between extreme heat and wildfire smoke on daily cardiorespiratory hospitalizations at the state level. We also found spatial…
Publication Type: Journal Article
Montane springs provide regeneration refugia after high-severity wildfire
Year: 2024
In the mountainous regions of the Western United States, increasing wildfire activity and climate change are putting forests at risk of regeneration failure and conversion to non-forests. During periods with unfavorable climatic conditions, locations that are suitable for post-fire tree regeneration (regeneration refugia) may be essential for forest recovery. These refugia could provide scattered islands of recovering forest from which broader forest recovery may be facilitated. Spring ecosystems provide cool and wet microsites relative to the surrounding landscape and may act as regeneration…
Publication Type: Journal Article
Quantifying wildland fire resources deployed during the compound threat of COVID-19
Year: 2024
Fire agencies across the United States must make complex resource allocation decisions to manage wildfires using a national network of shared firefighting resources. Firefighters play a critical role in suppressing fires and protecting vulnerable communities. However, they are exposed to health and safety risks associated with fire, smoke inhalation, and infectious disease transmission. The COVID-19 pandemic further complicated these risks, prompting fire agencies to propose resource management adaptations to minimize COVID-19 exposure and transmission. It is unclear if and how the pandemic…
Publication Type: Journal Article
Thinning and prescribed burning increase shade-tolerant conifer regeneration in a fire excluded mixed-conifer forest
Year: 2024
Fire exclusion and past management have altered the composition, structure, and function of frequent-fire forests throughout western North America. In mixed-conifer forests of the California Sierra Nevada, fire exclusion has exacerbated the effects of drought and endemic bark beetles, resulting in extensive mortality of fire-adapted pine species. Thinning and prescribed fire are widely used in these forests to reduce fuels, moderate fire behavior, and restore ecosystems. Tree regeneration influences future forest composition and structure, and therefore future resilience to disturbances, but…
Publication Type: Journal Article
A Preliminary Case Study on the Compounding Effects of Local Emissions and Upstream Wildfires on Urban Air Pollution
Year: 2024
Interactions between urban and wildfire pollution emissions are active areas of research, with numerous aircraft field campaigns and satellite analyses of wildfire pollution being conducted in recent years. Several studies have found that elevated ozone and particulate pollution levels are both generally associated with wildfire smoke in urban areas. We measured pollutant concentrations at two Utah Division of Air Quality regulatory air quality observation sites and a local hot spot (a COVID-19 testing site) within a 48 h period of increasing wildfire smoke impacts that occurred in Salt Lake…
Publication Type: Journal Article
Fuel constraints, not fire weather conditions, limit fire behavior in reburned boreal forests
Year: 2024
Fire frequency in boreal forests has increased via longer burning seasons, drier conditions, and higher temperatures. However, fires have historically self-regulated via fuel limitations, mediating the effects of changes in climate and fire weather. Early post-fire boreal forests (10–15 years postfire) are often dominated by mixed conifer-broadleaf or broadleaf regeneration, considered less flammable due to the higher foliar moisture of broadleaf trees and shrubs compared to their more intact conifer counterparts. However, the strength of self-regulation in the context of changing fire…
Publication Type: Journal Article
Limited availability of health risk communication related to community smoke exposure from prescribed burns in the United States: a review
Year: 2024
Prescribed burns are used to maintain wildland ecosystems and decrease fuel loads and associated wildfire hazard. Prescribed burns may produce enough smoke to cause adverse health outcomes. The aim of this review is to understand what communication materials exist for disseminating health risk information related to prescribed burn smoke and challenges to developing such communication. We examined United States peer-reviewed literature from PubMed, Scopus, and Web of Science databases and conducted an environmental scan of grey literature including materials from federal, and several US state…
Publication Type: Journal Article
Mortality Burden From Wildfire Smoke Under Climate Change
Year: 2024
Wildfire activity has increased in the US and is projected to accelerate under future climate change. However, our understanding of the impacts of climate change on wildfire smoke and health remains highly uncertain. We quantify the past and future mortality burden in the US due to wildfire smoke fine particulate matter (PM2.5). We construct an ensemble of statistical and machine learning models that link variation in climate to wildfire smoke PM2.5, and empirically estimate smoke PM2.5-mortality relationships using georeferenced data on all recorded deaths in the US from 2006 to 2019. We…
Publication Type: Report
Quantifying the smoke-related public health trade-offs of forest management
Year: 2023
Prescribed burning can mitigate extreme wildfire risk and reduce total smoke emissions. Yet prescribed burns’ emissions may also contribute to smoke exposures in nearby communities. Incorporating public health considerations into forest management planning efforts may help reduce prescribed burn-related exposure impacts. We present a methodological framework linking landscape ecology, air-quality modelling and health impact assessment to quantify the air-quality and health impacts of specific management strategies. We apply this framework to six forest management scenarios proposed for a…
Publication Type: Journal Article
Topographic information improves simulated patterns of post-fire conifer regeneration in the southwest United States
Year: 2023
The western United States is projected to experience more frequent and severe wildfires in the future due to drier and hotter climate conditions, exacerbating destructive wildfire impacts on forest ecosystems such as tree mortality and unsuccessful post-fire regeneration. While empirical studies have revealed strong relationships between topographical information and plant regeneration, ecological processes in ecosystem models have either not fully addressed topography-mediated effects on the probability of plant regeneration, or the probability is only controlled by climate-related factors,…
Publication Type: Journal Article
The persistence of smoke VOCs indoors: Partitioning, surface cleaning, and air cleaning in a smoke-contaminated house
Year: 2023
Wildfires are increasing in frequency, raising concerns that smoke can permeate indoor environments and expose people to chemical air contaminants. To study smoke transformations in indoor environments and evaluate mitigation strategies, we added smoke to a test house. Many volatile organic compounds (VOCs) persisted days following the smoke injection, providing a longer-term exposure pathway for humans. Two time scales control smoke VOC partitioning: a faster one (1.0 to 5.2 hours) that describes the time to reach equilibrium between adsorption and desorption processes and a slower one (4.8…
Publication Type: Journal Article
Long-term mortality burden trends attributed to black carbon and PM2·5 from wildfire emissions across the continental USA from 2000 to 2020: a deep learning modelling study
Year: 2023
Background
Long-term improvements in air quality and public health in the continental USA were disrupted over the past decade by increased fire emissions that potentially offset the decrease in anthropogenic emissions. This study aims to estimate trends in black carbon and PM2·5 concentrations and their attributable mortality burden across the USA.
Methods
In this study, we derived daily concentrations of PM2·5 and its highly toxic black carbon component at a 1-km resolution in the USA from 2000 to 2020 via deep learning that integrated big data from satellites, models, and surface…
Publication Type: Journal Article
Climate and fire impacts on tree recruitment in mixed conifer forests in Northwestern Mexico and California
Year: 2023
Frequent-fire forests were once heterogeneous at multiple spatial scales, which contributed to their resilience to severe fire. While many studies have characterized historical spatial patterns in frequent-fire forests, fewer studies have investigated their temporal dynamics. We investigated the influences of fire and climate on the timing of conifer recruitment in old-growth Jeffrey pine-mixed conifer forests in the Sierra San Pedro Martir (SSPM) and the eastern slope of Sierra Nevada. Additionally, we evaluated the impacts of fire exclusion and recent climate change on recruitment levels…
Publication Type: Journal Article
Less fuel for the next fire? Short-interval fire delays forest recovery and interacting drivers amplify effects
Year: 2023
As 21st-century climate and disturbance dynamics depart from historic baselines, ecosystem resilience is uncertain. Multiple drivers are changing simultaneously, and interactions among drivers could amplify ecosystem vulnerability to change. Subalpine forests in Greater Yellowstone (Northern Rocky Mountains, USA) were historically resilient to infrequent (100–300 year), severe fire. We sampled paired short-interval (<30-year) and long-interval (>125-year) post-fire plots most recently burned between 1988 and 2018 to address two questions: (1) How do short-interval fire, climate,…
Publication Type: Journal Article