Climate & Fire & Adaptation
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We investigate priorities and effectiveness of wildfire suppression using a novel empirical strategy that compares 1,500 historical fire perimeters with the spatial distribution of assets at risk to identify determinants of wildfire suppression efforts. We find that fires are more likely to stop spreading as they approach homes, particularly when those homes are of higher value. This effect of threatened assets persists after controlling for physical factors (fuels, landscape, and weather) using outputs from a state-of-the-art wildfire simulation tool, and the probability that fire spread will be halted is affected by characteristics of homes 1–2 km from a fire’s edge. Our results provide evidence that wildfire suppression can substantively affect outcomes from wildfires but that some groups may benefit more from wildfire management than others.
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Drawing on recent syntheses of the scientific evidence, this paper examines “myths” commonly used to
oppose climate- and wildfire-adaptation of fire-prone forests. We use an established framework
designed to counter science denial by recognizing the fallacy for each myth. Fallacies are false
arguments; there are several kinds of fallacies, including cherry picking (selecting only a portion of
facts to support a conclusion), false dichotomies or oversimplification (claiming only two possible
outcomes), circular arguments, or straw man (misdirection) arguments. Learning to recognize
logical fallacies and other characteristics of science denial is an essential component of any
assessment of arguments for and against proposed actions
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Recent literature reviews and syntheses provide valuable references for land management practitioners and stakeholders engaged in designing, evaluating, and implementing scientifically credible wildfire- and climate-adaptation strategies. These syntheses are supported by thousands of peer-reviewed articles that evaluated the benefits and constraints of restoring fire to fire-dependent forest landscapes. This working paper summarizes key insights from the review of studies, described in detail below, that documented unprecedented, human-caused fire exclusion and its impacts on fire-dependent forest landscapes in western North America.
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Results suggest that dry forest species are undergoing an active range shift driven by both changing recruitment and mortality, and that increasing temperatures and drought threaten the long-term viability of many of these species in their current range. While four of the five species examined were experiencing some declines, Pinus edulis is currently most vulnerable. Management actions such as reducing tree density may be able to mitigate some of these impacts. The framework we present to estimate range-wide demographic rates can be applied to other species to determine where range contractions are most likely.
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We focused on three metrics that are important for forest management objectives for the area: forest carbon storage, area burned at high severity, and total area burned by wildfire. Management explained a substantial amount of variance in the short term for area burned at high severity and longer term carbon storage, while climate explained the most variance in total area burned. Our results suggest that simulated extensive management activities will not meet all the desired management objectives. Both the extent and intensity of forest management will need to increase significantly to keep pace with predicted climate and wildfire conditions.
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This study quantifies the climate drivers that influence wildfire and climate stress-driven tree mortality, including a separate insect-driven tree mortality, for the contiguous United States for current (1984–2018) and project these future disturbance risks over the 21st century. We find that current risks are widespread and projected to increase across different emissions scenarios by a factor of >4 for fire and >1.3 for climate-stress mortality. These forest disturbance risks highlight pervasive climate-sensitive disturbance impacts on US forests and raise questions about the risk management approach taken by forest carbon offset policies. Our results provide US-wide risk maps of key climate-sensitive disturbances for improving carbon cycle modeling, conservation and climate policy.
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At both sites climatic water deficit (CWD), a cumulative measure of moisture stress, and mean annual temperature increased during the 2010 decade and CWD was the highest in 2020 relative to any time during the past 40 years. Although Great Basin bristlecone pine mortality has not previously been attributed to bark beetles, we observed recent (i.e., 2013 to 2020) bark beetle-attacked trees at both sites, coincident with the timing of increasing temperature and CWD. Few adult beetles were produced, however, and our results support previous research that Great Basin bristlecone pine is a population sink for bark beetles. Because bark beetles are likely not self-sustaining in Great Basin bristlecone pine, bark beetle-caused mortality of this iconic species will most likely occur when it grows mixed with or near other pine species that support bark beetle population growth. We found Ips confusus and Dendroctonus ponderosae attacking Great Basin bristlecone pine in areas where their host trees, P. monophylla and P. flexilis, were also growing. These results suggest that the presence of these infested conifers likely contributed to Great Basin bristlecone pine mortality. We highlight several factors that may be used for prioritizing future research and monitoring to facilitate development of management strategies for protecting this iconic species.
Check back for upcoming virtual workshop opportunities and curriculum materials.
Engage your students in hands-on activities to explore climate change and wildfire in the Southwest! This standards-aligned curriculum unit developed in coordination with the USDA Southwest Climate Hub uses experiments, games, demonstrations, and a group project to introduce students to how increased temperature and changes in precipitation affect wildfire risk in ecosystems. In this workshop, you will hear from an expert in the field, participate in a Q&A session, and then get training to implement these lessons in your classroom. Participating teachers will receive a $50 stipend and the opportunity to win raffle prizes.
2020 California fire season: A year like no other, a return to the past, or harbinger of the future?
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The 2020 fires were part of an accelerating decades-long trend of increasing burned area, fire size, fire severity and socio-ecological costs in California. In fire-prone forests, the management emphasis on reducing burned area should be replaced by a focus on reducing the severity of burning and restoring key ecosystem functions after fire. There have been positive developments in California vis-à-vis collaborative action and increased pace and scale of fuel management and pre- and postfire restoration, but the warming climate and other factors are rapidly constraining our options.
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This study reports on preliminary investigations into recent and unexpected Great Basin bristlecone pine mortality at two sites, including the potential roles of weather-induced stress and bark beetles. At both sites climatic water deficit (CWD), a cumulative measure of moisture stress, and mean annual temperature increased during the 2010 decade and CWD was the highest in 2020 relative to any time during the past 40 years. Although Great Basin bristlecone pine mortality has not previously been attributed to bark beetles, we observed recent (2013-20) bark beetle-attacked trees at both sites, coincident with the timing of increasing temperature and CWD. Few adult beetles were produced, however, and our results support previous research that Great Basin bristlecone pine is a population sink for bark beetles. Because bark beetles are likely not self-sustaining in Great Basin bristlecone pine, bark beetle-caused mortality of this iconic species will most likely occur when it grows mixed with or near other pine species that support bark beetle population growth. We found Ips confusus and Dendroctonus ponderosae attacking Great Basin bristlecone pine in areas where their host trees were also growing. These results suggest that the presence of these infested conifers likely contributed to Great Basin bristlecone pine mortality. We highlight several factors that may be used for prioritizing future research and monitoring to facilitate development of management strategies for protecting this iconic species.