Stream bank restoration in Sequoia sempervirens (coast redwood) forests

Stream bank stabilization structures, or revetment, can impact riparian systems by confining watercourses to the point where natural functions are limited. Removal of existing revetment may have considerable impacts on stream bank stability however. The effect of revetment and revetment removal was measured on three streams in forests dominated by Sequoia sempervirens (coast redwood) in northern California. Data regarding species richness, cover, and density were collected using randomly located transects on three treatments; “no-revetment”, “revetment-intact”, and “revetment removed.” Results were compared between treatments using ANOVA at a 0.05 level of significance. On all three sites, species richness, vegetation cover, and tree density were found to be higher on the “no-revetment” treatment compared to the “revetment-intact” treatment. Results from the “revetment-removed” treatment were more site-specific. Vegetation parameters on transects where revetment had been removed ranged between the parameters measured on the “no-revetment” transects and the “revetment-intact” transects. Superior recovery following revetment removal is likely due to greater recovery time, less habitat alterations prior to removal, and a higher degree of stream bank restoration effort following revetment removal.