Research Database
Displaying 21 - 40 of 212
Prescribed fire, managed burning, and previous wildfires reduce the severity of a southwestern US gigafire
Year: 2025
In many parts of the western United States, wildfires are becoming larger and more severe, threatening the persistence of forest ecosystems. Understanding the ways in which management activities such as prescribed fire and managed wildfire can mitigate fire severity is essential for developing effective forest conservation strategies. We evaluated the effects of previous fuels reduction treatments, including prescribed fire and wildfire managed for resource benefit, and other wildfires on the burn severity of the 2022 Black Fire in southwestern New Mexico, USA. The Black Fire burned over 131,…
Publication Type: Journal Article
Long-term influence of prescribed burning on subsequent wildfire in an old-growth coast redwood forest
Year: 2025
Background: Prescribed burning is an effective tool for reducing fuels in many forest types, yet there have been few opportunities to study forest resilience to wildfire in areas previously treated. In 2020, a large-scale high-intensity wildfire burned through an old-growth coast redwood (Sequoia sempervirens) forest with a mixed land management history, providing a rare opportunity to compare early post-wildfire data between areas with and without previous application of prescribed burning. The purpose of this study was to analyze the differences between these two treatments in…
Publication Type: Journal Article
A cellular necrosis process model for estimating conifer crown scorch
Year: 2025
Fire-caused tree mortality has major impacts on forest ecosystems. One primary cause of post-fire tree mortality in non-resprouting species is crown scorch, the percentage of foliage in a crown that is killed by heat. Despite its importance, the heat required to kill foliage is not well-understood. We used the “lag” model to describe time- and temperature-dependent leaf cell necrosis as a method of predicting leaf scorch. The lag model includes two rate parameters that describe 1) the process of cells accumulating non-lethal damage, and 2) damage becoming lethal to the cell. To parameterize…
Publication Type: Journal Article
Optimising disaster response: opportunities and challenges with Uncrewed Aircraft System (UAS) technology in response to the 2020 Labour Day wildfires in Oregon, USA
Year: 2024
BackgroundThe expanding use of Uncrewed Aircraft System (UAS) technology in disaster response shows its immense potential to enhance emergency management. However, there is limited documentation on the challenges and data management procedures related to UAS operation.AimsThis manuscript documents and analyses the operational, technical, political, and social challenges encountered during the deployment of UAS, providing insights into the complexities of using these technologies in disaster situations.MethodsThis manuscript documents and…
Publication Type: Journal Article
Nonstructural carbohydrates explain post-fire tree mortality and recovery patterns
Year: 2024
Trees use nonstructural carbohydrates (NSCs) to support many functions, including recovery from disturbances. However, NSC’s importance for recovery following fire and whether NSC depletion contributes to post-fire delayed mortality are largely unknown. We investigated how fire affects NSCs based on fire-caused injury from a prescribed fire in a young Pinus ponderosa (Lawson & C. Lawson) stand. We assessed crown injury (needle scorch and bud kill) and measured NSCs of needles and inner bark (i.e., secondary phloem) of branches and main stems of trees subject to fire and at an…
Publication Type: Journal Article
Moderating effects of past wildfire on reburn severity depend on climate and initial severity in Western US forests
Year: 2024
Rising global fire activity is increasing the prevalence of repeated short-interval burning (reburning) in forests worldwide. In forests that historically experienced frequent-fire regimes, high-severity fire exacerbates the severity of subsequent fires by increasing prevalence of shrubs and/or by creating drier understory conditions. Low- to moderate-severity fire, in contrast, can moderate future fire behavior by reducing fuel loads. The extent to which previous fires moderate future fire severity will powerfully affect fire-prone forest ecosystem trajectories over the next century. Further…
Publication Type: Journal Article
When do contemporary wildfires restore forest structures in the Sierra Nevada?
Year: 2024
Background: Following a century of fire suppression in western North America, managers use forest restoration treatments to reduce fuel loads and reintroduce key processes like fire. However, annual area burned by wildfire frequently outpaces the application of restoration treatments. As this trend continues under climate change, it is essential that we understand the effects of contemporary wildfires on forest ecosystems and the extent to which post-fire structures are meeting common forest restoration objectives. In this study, we used airborne lidar to evaluate fire effects across yellow…
Publication Type: Journal Article
Landsat assessment of variable spectral recovery linked to post-fire forest structure in dry sub-boreal forests
Year: 2024
Forest disturbances such as wildfires can dramatically alter forest structure and composition, increasing the likelihood of ecosystem changes. Up-to-date and accurate measures of post-disturbance forest recovery in managed forests are critical, particularly for silvicultural planning. Measuring the live and dead vegetation post-fire is challenging because areas impacted by wildfire may be remote, difficult to access, and/or dangerous to survey. The difficulties of post-fire monitoring are compounded by the global increase in the frequency and severity of disturbances, as expansion of…
Publication Type: Journal Article
Thinning and Managed Burning Enhance Forest Resilience in Northeastern California
Year: 2024
Understanding and quantifying the resilience of forests to disturbances are increasingly important for forest management. Historical fire suppression, logging, and other land uses have increased densities of shade tolerant trees and fuel buildup in the western United States, which has reduced the resilience of these forests to natural disturbances. One way to mitigate this problem is to use fuel treatments such as stand thinning and prescribed burning. In this study, we investigated changes in forest structure in the Lassen and Plumas National Forests of northern California following a large…
Publication Type: Journal Article
A fast spectral recovery does not necessarily indicate post-fire forest recovery
Year: 2024
BackgroundClimate change has increased wildfire activity in the western USA and limited the capacity for forests to recover post-fire, especially in areas burned at high severity. Land managers urgently need a better understanding of the spatiotemporal variability in natural post-fire forest recovery to plan and implement active recovery projects. In burned areas, post-fire “spectral recovery”, determined by examining the trajectory of multispectral indices (e.g., normalized burn ratio) over time, generally corresponds with recovery of multiple post-fire vegetation types, including trees and…
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
Stand diversity increases pine resistance and resilience to compound disturbance
Year: 2024
BackgroundDrought, fire, and insects are increasing mortality of pine species throughout the northern temperate zone as climate change progresses. Tree survival may be enhanced by forest diversity, with growth rates often higher in mixed stands, but whether tree defenses are likewise aided remains in question. We tested how forest diversity-productivity patterns relate to growth and defense over three centuries of climate change, competition, wildfire, and bark beetle attack. We used detailed census data from a fully mapped 25.6-ha forest dynamics plot in California, USA to…
Publication Type: Journal Article
Fire severity drives understory community dynamics and the recovery of culturally significant plants
Year: 2024
Anthropogenic influences are altering fire regimes worldwide, resulting in an increase in the size and severity of wildfires. Simultaneously, throughout western North America, there is increasing recognition of the important role of Indigenous fire stewardship in shaping historical fire regimes and fire-adapted ecosystems. However, there is limited understanding of how ecosystems are affected by or recover from contemporary “megafires,” particularly in terms of understory plant communities that are critical to both biodiversity and Indigenous cultures. To address this gap, our collaborative…
Publication Type: Journal Article
Prefire Drought Intensity Drives Postfire Recovery and Mortality in Pinus monticola and Pseudotsuga menziesii Saplings
Year: 2024
Increasing frequency of droughts and wildfire are sparking concerns that these compounded disturbance events are pushing forested ecosystems beyond recovery. An improved understanding of how compounded events affect tree physiology and mortality is needed given the reliance of fire management planning on accurate estimates of postfire tree mortality. In this study, we use a toxicological dose-response approach to quantify the impact of variable-intensity drought and fire on the physiology and mortality of Pinus monticola and Pseudotsuga menziesii saplings. We show that the…
Publication Type: Journal Article
A Review of the Occurrence and Causes for Wildfires and Their Impacts on the Geoenvironment
Year: 2024
Wildfires have short- and long-term impacts on the geoenvironment, including the changes to biogeochemical and mechanical properties of soils, landfill stability, surface- and groundwater, air pollution, and vegetation. Climate change has increased the extent and severity of wildfires across the world. Simultaneously, anthropogenic activities—through the expansion of urban areas into wildlands, abandonment of rural practices, and accidental or intentional fire-inception activities—are also responsible for a majority of fires. This paper provides an overall review and critical appraisal of…
Climate Change and Fire, Fire Effects and Fire Ecology, Smoke and Air Quality, Soils and Woody Debris
Publication Type: Journal Article
The impacts of rising vapour pressure deficit in natural and managed ecosystems
Year: 2024
An exponential rise in the atmospheric vapour pressure deficit (VPD) is among the most consequential impacts of climate change in terrestrial ecosystems. Rising VPD has negative and cascading effects on nearly all aspects of plant function including photosynthesis, water status, growth and survival. These responses are exacerbated by land–atmosphere interactions that couple VPD to soil water and govern the evolution of drought, affecting a range of ecosystem services including carbon uptake, biodiversity, the provisioning of water resources and crop yields. However, despite the…
Publication Type: Journal Article
Wildfire management decisions outweigh mechanical treatment as the keystone to forest landscape adaptation
Year: 2024
BackgroundModern land management faces unprecedented uncertainty regarding future climates, novel disturbance regimes, and unanticipated ecological feedbacks. Mitigating this uncertainty requires a cohesive landscape management strategy that utilizes multiple methods to optimize benefits while hedging risks amidst uncertain futures. We used a process-based landscape simulation model (LANDIS-II) to forecast forest management, growth, climate effects, and future wildfire dynamics, and we distilled results using a decision support tool allowing us to examine tradeoffs between alternative…
Publication Type: Journal Article
Disentangling drivers of annual grass invasion: Abiotic susceptibility vs. fire-induced conversion to cheatgrass dominance in the sagebrush biome
Year: 2024
Invasive annual grasses are often facilitated by fire, yet they can become ecologically dominant in susceptible locations even in the absence of fire. We used an extensive vegetation plot database to model susceptibility to the invasive annual grass cheatgrass (Bromus tectorum L.) in the sagebrush biome as a function of climate and soil water availability variables. We built random forest models predicting cheatgrass presence or dominance (>15 % relative cover) under unburned (37,219 plots) and burned conditions (6340 plots). We mapped predicted probability of cheatgrass…
Publication Type: Journal Article
Drought before fire increases tree mortality after fire
Year: 2024
Fire and drought are expected to increase in frequency and severity in temperate forests due to climate change. To evaluate whether drought increases the likelihood of post-fire tree mortality, we used a large database of tree survival and mortality from 32 years of wildland fires covering four dominant western North American conifers. We used Bayesian hierarchical modeling to predict the probability of individual tree mortality after fire based on species—Pinus contorta (lodgepole pine), Abies concolor (white fir), Pseudotsuga menziesii (Douglas-fir), and Pinus…
Publication Type: Journal Article
Long-term frequent fire and cattle grazing alter dry forest understory vegetation
Year: 2024
Understanding fire and large herbivore interactions in interior western forests is critical, owing to the extensive and widespread co-occurrence of these two disturbance types and multiple present and future implications for forest resilience, conservation and restoration. However, manipulative studies focused on interactions and outcomes associated with these two disturbances are rare in forested rangelands. We investigated understory vegetation response to 5-year spring and fall prescribed fire and domestic cattle grazing exclusion in ponderosa pine stands and reported long-term responses,…
Publication Type: Journal Article