Fire severity in intermittent stream drainages, western Cascade Range, Oregon

We quantified fire severity patterns within intermittent stream drainages in a recently burned area of the central western Cascades, Oregon. Aerial photographs were used to estimate post fire live canopy cover within streamside and upland zones on the southeast and southwest-facing slopes of 33 watersheds. Live canopy cover did not differ significantly between streamside and upland zones in the watersheds. Fire severity data obtained from aerial photographs were highly correlated with fire severity data obtained in the field in six of the watersheds, confirming that aerial photograph estimates of live canopy cover reflected actual conditions on the ground. While previous studies indicate that fire severity may be lower along perennial streams, the results of this study suggest that fire severity in intense events may be similar between intermittent stream channels and adjacent upland areas. At the landscape scale, differences in fire severity along streams of different sizes may influence the mosaic of post fire vegetation and contribute to overall structural diversity in forests of mountainous landscapes. Fire regime information obtained in this and related studies may be used to guide forest management activities that are modeled after natural disturbance processes and seek to balance commodity production and ecosystem protection.