Vaired Effects of Clear-cut Logging on Predators and Their Habitat in Small Streams of the Cascade Mountains, Oregon

Abstract

Assemblages of aquatic vertebrate [Salamanders] and insect predators were inventoried in streams in old-growth and logged coniferous forests in the western Cascades of Oregon to assess effects of clear-cut logging on stream communities. Effects associated with logging depended on stream size, gradient and time after harvest. Clear-cut sections where the stream was still exposed to sunlight (5-17 yr after logging) generally had greater biomass, density and species richness of predators than old-growth (> 450 yr old) forested sections. Increases were greatest in small (1st-order), high gradient (10-16%) streams, where clear-cut sites had greater periphyton production and coarser streambed sediment than old-growth sites of similar size and gradient. Effects on predators were mixed in larger, lower gradient streams, where clear-cut sites showed accumulation of sediment and relatively small increases in periphyton production. Second-growth logged sections (12-35 yr after logging), reshaded by deciduous forest canopy, had lower biomass of trout and fewer predator taxa than old-growth sites.