Initial Establishment of Riparian Vegetation after Disturbance by Debris Flows in Oregon

Abstract

—Three debris flows in the western Oregon Cascades were sampled near the end of the first growing season following disturbance. Vegetative regrowth accounted for 77% of the initial re-establishment of cover, but 67% of the individuals were seedlings Surface deposit characteristics and intensity of scour were the most important influences on debris flow revegetation. Total cover (15%) and vegetative regrowth (14% cover, 28 shoots/ m2) were highest on light intensity scour. Seedling establishment was highest on gravel and fine deposits (2-3% cover, 37-46 seedlingsjm 2). In contrast to previous studies which highlighted the role of seedlings, revegetation patterns in these debris flows were determined by the response of both vegetative sprouts and seedlings.