Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Nov 10;9(45):eadi4123.
doi: 10.1126/sciadv.adi4123. Epub 2023 Nov 10.

Low-intensity fires mitigate the risk of high-intensity wildfires in California's forests

Xiao Wu  1 , Erik Sverdrup  2 , Michael D Mastrandrea  3 , Michael W Wara  3 , Stefan Wager  2
Affiliations

Low-intensity fires mitigate the risk of high-intensity wildfires in California's forests

Xiao Wu et al. Sci Adv. .

Abstract

The increasing frequency of severe wildfires demands a shift in landscape management to mitigate their consequences. The role of managed, low-intensity fire as a driver of beneficial fuel treatment in fire-adapted ecosystems has drawn interest in both scientific and policy venues. Using a synthetic control approach to analyze 20 years of satellite-based fire activity data across 124,186 square kilometers of forests in California, we provide evidence that low-intensity fires substantially reduce the risk of future high-intensity fires. In conifer forests, the risk of high-intensity fire is reduced by 64.0% [95% confidence interval (CI): 41.2 to 77.9%] in areas recently burned at low intensity relative to comparable unburned areas, and protective effects last for at least 6 years (lower bound of one-sided 95% CI: 6 years). These findings support a policy transition from fire suppression to restoration, through increased use of prescribed fire, cultural burning, and managed wildfire, of a presuppression and precolonial fire regime in California.

PubMed Disclaimer

Figures

Fig. 1.
Fig. 1.. Overview of the quasi-experimental design.
Exposed and unexposed units are defined by fire status within a focal period. We create synthetic controls as a weighted set of unexposed pixels that maintain similar trajectories on fire behaviors and topography, meteorological, disturbance, and vegetation conditions, as the exposed pixel set during the pre-focal period. These synthetic controls are then used as counterfactuals in the evaluation period to estimate the effects of low-intensity fires on future fire frequency and intensity.
Fig. 2.
Fig. 2.. Effects of low-intensity fires on the subsequent fire frequency and intensity up to nine-year lags, grouped by land cover types and fire outcome classes, pooled across focal years 2008–2020.
Two-sided 95% CIs are presented.
Fig. 3.
Fig. 3.. Covariate balance and exposure distribution under the synthetic control quasi-experimental design for the focal year 2008 in different land cover types (conifer and hardwood).
(A and B) show the standardized mean differences of covariate trajectories in the pre-focal period between exposed pixels and synthetic controls, measuring their degree of covariate balance. The covariate balance is substantially improved after implementing synthetic control approaches. (C and D) show the geographic location of exposed (red) and unexposed pixels (blue) that were used to create synthetic controls. The transparency of the blue color represents the synthetic control weights for each unexposed pixel. Results including additional focal years are shown in the Supplementary Materials.
See this image and copyright information in PMC

References

    1. Parks S. A., Abatzoglou J. T., Warmer and drier fire seasons contribute to increases in area burned at high severity in western US forests from 1985 to 2017. Geophys. Res. Lett. 47, e2020GL089858 (2020).
    1. Wang D., Guan D., Zhu S., Kinnon M. M., Geng G., Zhang Q., Zheng H., Lei T., Shao S., Gong P., Economic footprint of California wildfires in 2018. Nat. Sustain. 4, 252–260 (2021).
    1. Burke M., Driscoll A., Heft-Neal S., Xue J., Burney J., Wara M., The changing risk and burden of wildfire in the United States. Proc. Natl. Acad. Sci. U.S.A. 118, e2011048118 (2021). - PMC - PubMed
    1. Williams A. P., Abatzoglou J. T., Gershunov A., Guzman-Morales J., Bishop D. A., Balch J. K., Lettenmaier D. P., Observed impacts of anthropogenic climate change on wildfire in California. Earth's Future 7, 892–910 (2019).
    1. Goss M., Swain D. L., Abatzoglou J. T., Sarhadi A., Kolden C. A., Williams A. P., Diffenbaugh N. S., Climate change is increasing the likelihood of extreme autumn wildfire conditions across California. Environ. Res. Lett. 15, 094016 (2020).