Research Database
Displaying 21 - 40 of 190
Expanding our understanding of nitrogen dynamics after fire: how severe fire and aridity reduce ecosystem nitrogen retention
Year: 2024
Fires release large pulses of nitrogen (N), which can be taken up by recovering plants and microbes or exported to streams where it can threaten water quality. The amount of N exported depends on the balance between N mineralisation and rates of N uptake after fire. Burn severity and soil moisture interact to drive these rates, but their effects can be difficult to predict. To understand how soil moisture and burn severity influence post-fire N cycling and retention in a dryland watershed, we quantified changes in plant biomass, plant N content, soil microbial biomass, inorganic N pools, and…
Publication Type: Journal Article
Factors influencing wildfire management decisions after the 2009 US federal policy update
Year: 2024
Background
The decision making process undertaken during wildfire responses is complex and prone to uncertainty. In the US, decisions federal land managers make are influenced by numerous and often competing factors.
Aims
To assess and validate the presence of decision factors relevant to the wildfire decision making context that were previously known and to identify those that have emerged since the US federal wildfire policy was updated in 2009.
Methods
Interviews were conducted across the US while wildfires were actively burning to elucidate time-of-fire decision factors. Data…
Publication Type: Journal Article
Few large or many small fires: Using spatial scaling of severe fire to quantify effects of fire-size distribution shifts
Year: 2024
As wildfire activity increases and fire-size distributions potentially shift in many forested regions worldwide, anticipating the spatial patterns of burn severity expected with future fire activity is critical for ecological understanding and informing management and policy. Because spatial patterns of burn severity are influenced by a complex mixture of drivers, they remain difficult to predict for any given burned landscape. At broader extents, however, spatial scaling relationships relating high-severity patch size and shape to overall fire size, when combined with scenarios regarding…
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
Demand for Information for Wildland Fire Management
Year: 2024
Significant resources have been devoted to increasing the supply of data and information products for wildland fire management. There has been comparatively less emphasis on understanding the demand for these products. There are large differences in the number of information sources that fire managers use in decision making. We developed a value-of-information model for wildland fire managers to formulate hypotheses about what factors drive these differences. Data from a comprehensive internet survey targeting a well-defined population of the Southwest wildland fire managers are used to test…
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
Generating fuel consumption maps on prescribed fire experiments from airborne laser scanning
Year: 2024
Background. Characterisation of fuel consumption provides critical insights into fire behaviour, effects, and emissions. Stand-replacing prescribed fire experiments in central Utah offered an opportunity to generate consumption estimates in coordination with other research efforts. Aims. We sought to generate fuel consumption maps using pre- and post-fire airborne laser scanning (ALS) and ground measurements and to test the spatial transferability of the ALSderived fuel models. Methods. Using random forest (RF), we empirically modelled fuel load and estimated consumption from pre-…
Publication Type: Journal Article
Bridging scales for landscape-level wildfire adaptation: A case study of the Kittitas Fire Adapted Communities Coalition
Year: 2024
Federal-level strategies or guidance for addressing wildfire risk encourage adaptation activities that span progressively larger scales, often focusing on landscape-level action that necessitates coordination between decision-makers and socially diverse communities. Collaborative organizations are increasingly explored as one approach for coordinating local efforts that address wildfire risk and adaptation, offering a platform for scaling and adjusting federal and state guidance that align with the needs of local landscapes. We conducted semi-structured interviews with members and supporters…
Publication Type: Journal Article
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
Contemporary fires are less frequent but more severe in dry conifer forests of the southwestern United States
Year: 2024
Wildfires in the southwestern United States are increasingly frequent and severe, but whether these trends exceed historical norms remains contested. Here we combine dendroecological records, satellite-derived burn severity, and field measured tree mortality to compare historical (1700-1880) and contemporary (1985-2020) fire regimes at tree-ring fire-scar sites in Arizona and New Mexico. We found that contemporary fire frequency, including recent, record fire years, is still <20% of historical levels. Since 1985, the fire return interval averages 58.8 years, compared to 11.4 years before…
Publication Type: Journal Article
Application of Participatory Process Mapping to Evaluate Environmental Decision-Making and Implementation
Year: 2024
Environmental governance outcomes hinge on the design and implementation of management decisions. Yet, available research methodologies can be limited in their ability to capture the complexity of decision-making and implementation processes and in turn predict and explain environmental governance outcomes. We present participatory process mapping as a method for examining the pathways that emerge and evolve over time that result in natural resource management decisions and on-the-ground outcomes, as perceived by participants in collaborative processes. The approach leverages a large-N…
Publication Type: Journal Article
Estimating the influence of field inventory sampling intensity on forest landscape model performance for determining high-severity wildfire risk
Year: 2024
Historically, fire has been essential in Southwestern US forests. However, a century of fire-exclusion and changing climate created forests which are more susceptible to uncharacteristically severe wildfires. Forest managers use a combination of thinning and prescribed burning to reduce forest density to help mitigate the risk of high-severity fires. These treatments are laborious and expensive, therefore optimizing their impact is crucial. Landscape simulation models can be useful in identifying high risk areas and assessing treatment effects, but uncertainties in these models can limit…
Publication Type: Journal Article
Trees have similar growth responses to first-entry fires and reburns following long-term fire exclusion
Year: 2024
Managing fire ignitions for resource benefit decreases fuel loads and reduces the risk of high-severity fire in fire-suppressed dry conifer forests. However, the reintroduction of low-severity wildfire can injure trees, which may decrease their growth after fire. Post-fire growth responses could change from first-entry fires to reburns, as first-entry fires reduce fuel loads and the vulnerability among trees to fire effects, which may result in trees sustaining less damage during reburns. To determine whether trees had growth responses that varied from first-entry fires to reburns, we cored…
Publication Type: Journal Article
Ladder fuels rather than canopy volumes consistently predict wildfire severity even in extreme topographic-weather conditions
Year: 2024
Drivers of forest wildfire severity include fuels, topography and weather. However, because only fuels can be actively managed, quantifying their effects on severity has become an urgent research priority. Here we employed GEDI spaceborne lidar to consistently assess how pre-fire forest fuel structure affected wildfire severity across 42 California wildfires between 2019–2021. Using a spatial-hierarchical modeling framework, we found a positive concave-down relationship between GEDI-derived fuel structure and wildfire severity, marked by increasing severity with greater fuel loads until a…
Publication Type: Journal Article
Climate limits vegetation green-up more than slope, soil erodibility, and immediate precipitation following high-severity wildfire
Year: 2024
BackgroundIn the southwestern United States, post-fire vegetation recovery is increasingly variable in forest burned at high severity. Many factors, including temperature, drought, and erosion, can reduce post-fire vegetation recovery rates. Here, we examined how year-of-fire precipitation variability, topography, and soils influenced post-fire vegetation recovery in the southwestern United States as measured by greenness to determine whether erosion-related factors would have persistent effects in the longer post-fire period. We modeled relationships between post-fire vegetation and these…
Publication Type: Journal Article
A global outlook on increasing wildfire risk: Current policy situation and future pathways
Year: 2023
Aimto understand how wildfire risk policies are designed to mitigate the impacts of wildfires. Wildfires are a growing threat in many parts of the world, posing significant risks to human life, and the environment. In recent years, wildfires have increased, driven largely by climate change, human activity, and changes in land-use patterns. Wildfire risk adaptation and mitigation measures vary widely between countries and regions around the world. Therefore, it is essential to develop a…
Publication Type: Journal Article
Effects of nurse shrubs and biochar on planted conifer seedling survival and growth in a high-severity burn patch in New Mexico, USA
Year: 2023
The synergistic effects of widespread high-severity wildfire and anthropogenic climate change are driving large-scale vegetation conversion. In the southwestern United States, areas that were once dominated by conifer forests are now shrub- or grasslands after high-severity wildfire, an ecosystem conversion that could be permanent without human intervention. Yet, the reforestation of these landscapes is rarely successful, with a mean planted seedling survival of just 25 %. Given these low rates, we carried out a planting experiment to quantify the impacts of biochar as a soil amendment and…
Publication Type: Journal Article
Prioritizing science efforts to inform decision making on public lands
Year: 2023
Public land management agencies in the US are committed to using science-informed decision making, but there has been little research on the types and topics of science that managers need most to inform their decisions. We used the National Environmental Policy Act to identify four types of science information needed for making decisions relevant to public lands: (1) data on resources of concern, (2) scientific studies relevant to potential effects of proposed actions, (3) methods for quantifying potential effects of proposed actions, and (4) effective mitigation measures. We then used this…
Publication Type: Journal Article
Predicting snag fall in an old-growth forest after fire
Year: 2023
Snags, standing dead trees, are becoming more abundant in forests as tree mortality rates continue to increase due to fire, drought, and bark beetles. Snags provide habitat for birds and small mammals, and when they fall to the ground, the resulting logs provide additional wildlife habitat and affect nutrient cycling, fuel loads, and fire behavior. Predicting how long snags will remain standing after fire is essential for managing habitat, understanding chemical cycling in forests, and modeling forest succession and fuels. Few studies, however, have quantified how fire changes snag fall…
Publication Type: Journal Article
The outsized role of California’s largest wildfires in changing forest burn patterns and coarsening ecosystem scale
Year: 2023
Highlights • We evaluated trends for 1,809 fires that burned 1985–2020 across California forests. • Top 1% of fires by size burned 47% of total area burned across the study period. • Top 1% (18 fires) produced 58% of high and 42% of low-moderate severity area. • Top 1% created novel landscape patterns of large burn severity patches. • These large fires create new opportunities for managing forest resilience. Although recent large wildfires in California forests are well publicized in media and scientific literature, their cumulative effects on forest structure and implications for forest…
Publication Type: Journal Article