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Short-term responses of songbirds to alternate harvesting methods in a high elevation forest Leupin, Ernest E.

Abstract

Silvicultural alternatives to clearcutting have been promoted in forests of British Columbia to attempt to simulate short-term natural disturbances typical of certain forest types as these cuts are hypothesized to mitigate negative impacts on wildlife dependent on forests. However, the potential effects of these harvesting activities have not been studied enough to evaluate their success in mitigating wildlife impacts. I examined the response of songbirds breeding in high elevation, Engelmann spruce-subalpine fir forests (Sicamous Creek Research Forest) to alternative forms of forest harvesting using the variable circular method of point counting to determine relative abundance. The experimental harvesting treatments at Sicamous created openings (perforations) in the original forest that ranged in size from 10ha clearcuts to small gaps (0.01 ha) resulting from the harvest of selected trees. The community of songbirds that breed in the Sicamous Creek Research Forest was monitored over a five-year period that included both pre- and post-harvest conditions. The original songbird community remained relatively unchanged after harvest and among the various treatments. Few new species colonized the newly created habitats (openings) and did so in very small numbers. Golden-crowned kinglet declined significantly post-harvest in harvested areas with the most pronounced declines in selection and 10 ha treatments. Conversely, dark-eyed junco responded positively to the harvesting and increased in abundance in all harvested treatments. In general, the creation of a variety of habitats through alternative harvesting methods appears to lessen impacts and allow much of the songbird community to persist in high elevation forests. This persistence may be related to an evolutionary adaptation of songbirds to small-scale disturbances typical of high elevation forests that alternative harvesting methods simulate. Future research should focus on long-term monitoring to determine reproductive success in the various harvesting techniques.

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