Human and climatic influences on wildfires ignited by recreational activities in national forests in Washington, Oregon, and California(& nbsp;)

In Washington, Oregon, and California, ignitions from recreational activities accounted for 12% of human-caused wildfires, and 8% of the area burned, from 1992-2020. Wildfires ignited by recreational activities not only increase fire suppression expenditures but have the potential to limit recreational activities traditionally associated with use of fire, such as camping. From 1992-2020, 50% of recreation-caused ignitions in these three states occurred on lands managed by the U.S. Forest Service. The mean annual number of recreation-caused ignitions on national forests in the three states during this period was relatively stable, about 500, whereas recreation-caused ignitions within other jurisdictions decreased by 40%. Improved understanding of the impact of human and climatic factors on recreation-caused ignitions could provide valuable insights for shaping policy and management decisions. We found that mean annual densities of recreation-caused ignitions on national forests were 7 times greater within 1 km of designated campgrounds than >1 km from campgrounds, although 80% of recreation-caused ignitions occured >1 km from designated campgrounds. Ignition density in campgrounds increased non-linearly with overnight visitor density; a doubling of visitor density was associated with a & SIM;40% increase in ignitions. Large (& GE;4 ha) recreation-caused wildfires, especially those ignited in designated campgrounds, tended to occur concurrent with drought and 1-2 years after anomalously wet conditions. These results suggest that accounting for drought in implementation of fire restrictions, and targeting wildfire-prevention awareness to recreational users outside designated campgrounds, might reduce the likelihood of recreation-caused ignitions.