Influences on Wildfires Ignited by Recreational Activities in Oregon, Washington, and California
Fire is strongly linked to outdoor recreation in the United States. Recreational uses of fires, whether in designated campgrounds or the backcountry, include warmth, cooking, and fostering a comfortable atmosphere. However, through inattention, negligence, or bad luck, recreational fires sometimes ignite wildfires. From 1992 through 2020, such ignitions accounted for an estimated 12% of human-caused wildfires and 8% of the area burned by those wildfires in Washington, Oregon, and California. 76% of the recreation-caused ignitions occurred on public lands: 50% on lands managed by the U.S. Forest Service, 15% on other federal lands, and 11% on state, county, or local lands.
With the aim of informing strategies to limit the risk of recreation-caused ignitions, we evaluated whether the density of wildfires ignited by recreation or ceremony on U.S. Forest Service lands, and the size of such wildfires, is influenced by proximity to designated campgrounds, visitor density, previous and current drought conditions, and the type of vegetation surrounding the ignition point. With respect to recreation-caused ignitions, we tested the common assumption that large wildfires tend to be enabled by wet conditions in the prior growing season where vegetation is not continuous, and by dry conditions in the current growing season where vegetation is abundant and the climate generally limits flammability. We accounted for the potential effects of ecoregion on these associations given that vegetation composition, climate, and historical fire-return intervals and sizes vary among ecoregions.