Impacts of livestock grazing on the probability of burning in wildfires vary by region and vegetation type in California

Katherine J Siegel; Luke Macaulay; Matthew Shapero; Theresa Becchetti; Stephanie Larson; Fadzayi E Mashiri; Lulu Waks; Laurel Larsen; Van Butsic

doi:10.1016/j.jenvman.2022.116092

Impacts of livestock grazing on the probability of burning in wildfires vary by region and vegetation type in California

J Environ Manage. 2022 Nov 15:322:116092. doi: 10.1016/j.jenvman.2022.116092. Epub 2022 Aug 30.

Authors

Katherine J Siegel¹, Luke Macaulay², Matthew Shapero³, Theresa Becchetti⁴, Stephanie Larson⁵, Fadzayi E Mashiri⁶, Lulu Waks⁷, Laurel Larsen⁸, Van Butsic⁹

Affiliations

¹ Department of Environmental Science, Policy, & Management, University of California-Berkeley, CA, 94720, USA. Electronic address: ksiegel@ucar.edu.
² University of Maryland Extension, College Park, MD, 20742, USA.
³ University of California Cooperative Extension, Ventura County, CA, 93003-5401, USA.
⁴ University of California Cooperative Extension, San Joaquin and Stanislaus Counties, CA, 95358, USA.
⁵ University of California Cooperative Extension, Sonoma County, CA, 95403, USA.
⁶ University of California Cooperative Extension, Mariposa and Merced Counties, CA, 95338, USA.
⁷ Sonoma County Regional Parks, CA, 95403, USA.
⁸ Department of Geography, University of California-Berkeley, CA, 94720, USA.
⁹ Department of Environmental Science, Policy, & Management, University of California-Berkeley, CA, 94720, USA.

PMID: 36055100
DOI: 10.1016/j.jenvman.2022.116092

Abstract

Wildfire activity has recently increased in California, impacting ecosystems and human well-being. California's rangelands are complex social-ecological systems composed of multiple ecosystems and the people who live and work in them. Livestock grazing has been proposed as a tool for reducing wildfire activity. Here, we explore how grazing affects wildfire at large spatial scales, assessing burn probability on rangelands with different grazing levels. We collected grazing data by surveying 140 large private landowners in three social-ecological regions: California's North Bay, Central Coast, and Central Valley and Foothills. Using pre-regression matching and mixed effects regression, we calculate the burn probability from 2001 to 2017 in points sampled from grazed and ungrazed properties in each region in grasslands, shrub/scrublands, and forests. We find that in the Central Coast and North Bay, annual burn probability decreases as stocking levels increase across all vegetation types, with reductions of 0.008-0.036. In the Central Valley and Foothills, the relationship is complex, with burn probability increasing over some grazing levels and variations in the effect of higher stocking densities. Our results indicate that livestock grazing may reduce annual burn probability in some regions and ecosystems in California, providing the first large-scale assessment of this relationship.

Keywords: California; Grazing; Matching; Rangelands; Wildfire.

MeSH terms

Animals
Ecosystem
Forests
Livestock*
Probability
Wildfires*