Goldblum, DavidMcDermid, GregLambert, Emily2024-01-302024-01-302024-01-25Lambert, E. (2024). The impacts of clearcutting on understory plants and culturally significant species in coastal western hemlock forests of Vancouver Island (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/118107https://doi.org/10.11575/PRISM/42951The goal of the study is to understand successional changes in an understory plant community after clear-cut timber harvesting. The forest ecosystem is within the Southern Very Wet Hypermaritime biogeoclimatic subzone in the broader Coastal Western Hemlock zone along the west coast of Vancouver Island. The ecosystem is located in Huu-ay-aht First Nations traditional territory, and the subzone falls within various Nuu-chah-nulth First Nations traditional territories. A chronosequence was used to categorize various stages of forest growth in five successional stages: Regeneration, Immature, Thinning, Mature, and Old-growth. Forests censused ranged in age from 1 to 354 years old with old-growth stages described as stands over 250 years. The leaf cover and stem density of understory plant species were recorded within 83 subplots. These metrics were evaluated with regard to environmental variables (slope aspect, elevation, canopy openness, soil pH, A horizon depth, soil profile depth, tree basal area, tree stem density, ground moss cover, and bare ground cover) to determine which, if any, factors influenced understory species composition and structure. Out of 45 species identified, 19 are culturally significant plant species to the Nuu-chah-nulth First Nations. The species restricted to one successional stage were identified, with emphasis on opportunistic species in early stages and rare species in the Old-growth stage. There was a large decrease in many culturally significant species immediately after clearcutting. There was a large decrease in species (stem density, leaf cover, species richness, species diversity) from the Regeneration stage to the Thinning stage (1 to 80 years); however, these values steadily increased thereafter. Plant leaf cover and stem density were influenced by the amount of light reaching the understory. The natural disturbance regime that shade-tolerant plants are adapted to in these old-growth forests is small-scale gap formations, which clearcutting does not mimic. Timber harvesting options are recommended to better mimic the natural disturbance regime in this region, which is optimal for the understory species in this region. Many rare and culturally significant plant species were negatively impacted by clearcutting. Protecting rare plant species in old-growth forests is important for maintaining forest biodiversity and indigenous cultural practices in the future.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.ethnobotanyforest sciencechronosequencesuccessionplant ecologyunderstoryforestrybiogeoclimaticold-growthEducation--SciencesLiterature--Canadian (English)Physical GeographyGeographyEcologyForestry and WildlifeNative American Studiesmaster thesis