Wildfire is a critical component to the ecology of forests in the Pacific Northwest—although the frequency and severity of these wildfires vary across forest type. The drier Ponderosa pine forests east of the Cascades historically observed fires on every few years to decades while subalpine Douglas fir-Western hemlock forests west of the Cascades would observe fires every few centuries or longer. Wildfires help recycle nutrients, remove fuel, promote new herbaceous growth and allow for new cohorts of trees to establish. However, while wildfires are natural and integral components to forest ecosystems, they can pose a threat to human lives, property and infrastructure. 

    Much of the management related to wildfire mitigation in fire-prone forests consists thinning, or the removal of hazardous fuels near the wildland urban interface and critical infrastructure. Prescribed fire is often used as a management tool in drier, frequent-fire forests. While the moist mixed-conifer forest types in the Clackamas River Basin are characterized by an infrequent, high severity fire regime—there is evidence that changing climate conditions and drought can increase the susceptibility of the basin to larger and more frequent wildfires in the future.