Second-Entry Burns Reduce Mid-Canopy Fuels and Create Resilient Forest Structure in Yosemite National Park, California

Hankin, Lacey E.; Anderson, Chad

doi:10.3390/f13091512

Cited by 4 publications

(1 citation statement)

References 68 publications

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“…These forest conditions can increase rates and size of high-severity fire (Steel et al 2015;Stephens et al 2015;Boisramé et al 2017). Higher tree densities have also been associated with reduced forest health (Hankin and Anderson 2022) and widespread bark beetle-induced tree mortality (Fettig et al 2007). Historical forest structure created and maintained by frequent lightning ignitions and Indigenous burning promoted ecosystem resilience by minimizing competition and resisting highseverity wildfire (North et al 2022).…”

Section: Introductionmentioning

confidence: 99%

How forest management changed the course of the Washburn fire and the fate of Yosemite’s giant sequoias (Sequoiadendron giganteum)

et al. 2023

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Background The Washburn fire started on July 7, 2022 in the lower Mariposa Grove in Yosemite National Park, posing immediate threats to the iconic giant sequoias (Sequoiadendron giganteum), critical Pacific fisher (Pekania pennanti) habitat, and the community of Wawona. The wildfire quickly gained national attention and the public followed Yosemite’s firefighting efforts closely. In the aftermath of the Washburn fire, we evaluate how decades of fire management and recent roadside thinning in the Park shaped the tactics and outcomes of this wildfire. Fuels reduction and prescribed fire have been at the core of Yosemite’s fire management program since the 1970s and much of this activity has been concentrated in the two areas where firefighting operations were most successful in protecting key resources. We use long-term fire effects monitoring data, airborne light detection and ranging data, and operational perspectives to link together science, management, and fire operations. Results Successful initial attack and suppression efforts kept fire out of the Mariposa Grove and the community, where topography and the distribution of heavy fuels largely drove fire behavior throughout the course of the fire. We demonstrate the cumulative effects of decades of fuels treatments in reducing two major drivers of fire behavior – tree density and fuel load – and highlight substantially lower ladder fuels and fire severity in treatment units compared to untreated areas within the Washburn fire footprint. Conclusions We show how repeated prescribed fire and fuels treatments can promote forest structure indicative of frequent-fire regimes, moderate extreme fire behavior, improve the ability to protect key resources of concern, and increase human safety in the face of unplanned wildfire. Strategically placed prescribed fire and fuels treatments surrounding the Washburn fire were key considerations in wildfire suppression tactics and were instrumental in protecting the Mariposa Grove.

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Section: Introductionmentioning

confidence: 99%

How forest management changed the course of the Washburn fire and the fate of Yosemite’s giant sequoias (Sequoiadendron giganteum)

et al. 2023

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Consistently heterogeneous structures observed at multiple spatial scales across fire-intact reference sites

Chamberlain,

Cova,

Cansler

et al. 2023

Forest Ecology and Management

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When do contemporary wildfires restore forest structures in the Sierra Nevada?

Chamberlain,

Bartl-Geller,

Cansler

et al. 2024

fire ecol

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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 pine and mixed conifer (YPMC) forests of California’s Sierra Nevada. We quantified the degree to which forest structures in first-entry burned areas (previously unburned since ~ 1900s) and unburned controls aligned with restoration targets derived from contemporary reference sites. We also identified environmental conditions that contributed to more restorative fire effects. Results Relative to unburned controls, structural patterns in first-entry burned areas aligned more closely with reference sites. Yet, across all burn severities, first-entry wildfires were only moderately successful at meeting targets for canopy cover (48% total area) and ladder fuels (54% total area), and achieving these targets while also producing tree clump and opening patterns aligning with reference sites was less common (16% total area). Moderate-severity patches had the highest proportion of restorative fire effects (55–64% total area), while low- and high-severity patches were either too dense or too open, respectively. Our models (and publicly-available mapped predictions) indicated a higher probability of restorative effects within 1 km of previous fires, within the mid-upper climate range of the YPMC zone, and under moderate fire intensities (~ 1–2 m flame lengths). Conclusions First-entry wildfires can sometimes restore structural conditions by reducing canopy cover and ladder fuels and increasing structural heterogeneity, especially within moderate-severity patches. However, these initial fires represent just one step toward restoring dry forest ecosystems. Post-fire landscapes will require additional low- to moderate-intensity fires and/or strategic management interventions to fully restore structural conditions. In yet unburned forests, managers could prioritize mechanical treatments at lower elevations, early-season burning at mid to high elevations, and resource objective wildfires in landscapes with mosaics of past wildfires.

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Second-Entry Burns Reduce Mid-Canopy Fuels and Create Resilient Forest Structure in Yosemite National Park, California

Cited by 4 publications

References 68 publications

How forest management changed the course of the Washburn fire and the fate of Yosemite’s giant sequoias (Sequoiadendron giganteum)

How forest management changed the course of the Washburn fire and the fate of Yosemite’s giant sequoias (Sequoiadendron giganteum)

Consistently heterogeneous structures observed at multiple spatial scales across fire-intact reference sites

When do contemporary wildfires restore forest structures in the Sierra Nevada?

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