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UBC Theses and Dissertations

Ecological impacts of timber harvest on coastal British Columbia’s riparian plant communities through functional trait analysis Bryn-Thorn, Arlo


Riparian areas are fundamental for the function of headwater streams, as they provide nutritional and physical inputs and processes essential for ecosystem function. I examined how timber harvest affects the riparian shrub and herb communities of headwater streams to better understand the associated impacts on ecological processes in British Columbia’s coastal small-stream ecosystems. By analyzing effects of environmental gradients at three sites each of three intensities of riparian harvest which were complete tree removal (non-buffered), partial tree retention (buffered) and reference sites, shifts in riparian ecological processes were indicated through plant functional trait responses to conditions such as light and temperature; significant differences were found among species and communities trait values. Buffered sites had intermediate trait values between those of the reference and non-buffered sites. Specific leaf area and leaf nitrogen content values were highest at reference sites, intermediate at buffered sites, and lowest at non-buffered sites; stem specific density and leaf carbon content were highest at non-buffered sites and lowest at reference sites. Directional relations of the six focal traits with the three treatments were consistent for the community-weighted values, and most of the eight focal species’ values. These treatment effects were more evident in the physiological plant traits than chemical traits. Buffers of riparian tree retention showed moderating effects to the environmental changes associated with timber harvest that most strongly influence the plant functional traits studied.

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