Effects of clearcutting and riparian buffers on the yield of adult aquatic macroinvertebrates from headwater streams.

摘要

We studied the emergence of Ephemeroptera, Plecoptera and Trichoptera (EPT) from headwater streams in Pacific Northwest conifer forests (five locations in the Willamette National Forest in Oregon, USA) with emergence traps. We analysed the effects of silvicultural management (clear felling and riparian buffering) on insect species assemblages as a measure of the quantity of food resource available to insectivorous predators. Canopy removal increased the biomass and density of total EPTs and all feeding guilds except scrapers. Buffering does not change EPT yield from that of the mature forest (perhaps it decreases it), but the EPT community composition within the buffers becomes similar to that of adjacent clearcuts. Differences in community composition attributed to changes in elevation were more substantial than differences caused by silvicultural management. Forty percent of the species collected were restricted to one or another of the five sites..