Historical patterns of wildfire ignition sources in California ecosystems

International Journal of Wildland Fire
By:  and 



State and federal agencies have reported fire causes since the early 1900s, explicitly for the purpose of helping land managers design fire-prevention programs. We document fire-ignition patterns in five homogenous climate divisions in California over the past 98 years on state Cal Fire protected lands and 107 years on federal United States Forest Service lands. Throughout the state, fire frequency increased steadily until a peak c. 1980, followed by a marked drop to 2016. There was not a tight link between frequency of ignition sources and area burned by those sources and the relationships have changed over time. Natural lightning-ignited fires were consistently fewer from north to south and from high to low elevation. Throughout most of the state, human-caused fires dominated the record and were positively correlated with population density for the first two-thirds of the record, but this relationship reversed in recent decades. We propose a mechanistic multi-variate model of factors driving fire frequency, where the importance of different factors has changed over time. Although ignition sources have declined markedly in recent decades, one notable exception is powerline ignitions. One important avenue for future fire-hazard reduction will be consideration of solutions to reduce this source of dangerous fires.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Historical patterns of wildfire ignition sources in California ecosystems
Series title International Journal of Wildland Fire
DOI 10.1071/WF18026
Volume 27
Issue 12
Year Published 2018
Language English
Publisher International Association of Wildland Fire
Contributing office(s) Western Ecological Research Center
Description 19 p.
First page 781
Last page 799
Country United States
State California
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