The characteristics of woody debris and sediment distribution in headwaterstreams, southeastern Alaska

Large woody debris (LWD), fine woody debris (FWD), fine organic debris (FOD ), and sediment deposition were measured in 15 steep headwater streams with five management and disturbance regimes. Clear-cut channels logged in 1995 contained large accumulations of logging residue that initially provided s ites for sediment storage. Half of the LWD in clear-cut channels was recrui ted during and immediately after logging. Woody debris from logging activit ies remains in young growth conifer channels 37 years after logging. Number s of LWD in clear-cut and young conifer channels were significantly higher than in old-growth channels, although numbers of FWD pieces were not signif icantly different because of higher recruitment from old-growth stands. Cha nnels that experienced recent (1979 and (or) 1993) and earlier (1961 and (o r) 1979) scour and runout of landslides and debris flows contained less LWD and FWD, although large volumes of LWD and FWD were found in deposition zo nes. The volumes of sediment stored in young alder and recent landslide cha nnels were higher than in the other channels. Because of the recruitment of LWD and FWD from young alder stands, the ratio of sediment stored behind w oody debris to total sediment volume was higher in young alder channels com pared with recent landslide channels. Numbers of LWD and FWD pieces in all streams were significantly correlated with the volumes of sediment stored b ehind woody debris. Timber harvesting and soil mass movement influence the recruitment, distribution, and accumulation of woody debris in headwater st reams; this modifies sediment storage and transport in headwater channels.