Invasive species removal and changing fire regimes in a lək̓ʷəŋən Garry oak ecosystem

• Main Author: Lysgaard, Cole
• Other Authors: Mathews, Darcy, Shackelford, Nancy
• Format: Thesis
• Language: English
• Published: 2022
• Subjects: Garry oak; restoration; ecology; Coast Salish; fire; invasive species; oak savanna; First Nations; camas; scotch broom; sweet vernal grass; anthoxanthum odoratum; mill hill regional park; lək̓ʷəŋən; W̱SÁNEĆ; cytisus scoparius; controlled burn; wildfire; cultural landscapes; photo-point monitoring; invasive species removal; climate change; repeat photography; British Columbia; Canada; Garry; Mill Hill
• Online Access: http://hdl.handle.net/1828/13734

This thesis examines restoration of Garry oak ecosystems in Southwestern British Columbia, Canada. Before the arrival of European settlers, Coast Salish peoples practiced intensive stewardship and cultivation practices that heavily shaped Garry oak ecosystems. These long-standing stewardship practices are responsible for the abundance of culturally important plants found in Garry oak ecosystems today. In addition to their cultural value to Coast Salish peoples, Garry oak ecosystems also support unique biodiversity, including numerous at-risk species. These ecosystems and the values they embody came under threat with the arrival of European settlers, who introduced non-native plants and excluded Coast Salish peoples and their stewardship practices from these ecosystems. Today, Garry oak ecosystems have been reduced to a fraction of their pre-colonial distribution and remaining patches are typically heavily invaded by both native and non-native plants. Their cultural and biological values coupled with ongoing degradation has motivated both Indigenous and non-Indigenous land managers to implement restoration programs in Garry oak ecosystems. To inform future restoration efforts, this thesis examines ecological impacts of a long-term restoration program and a wildfire in a lək̓ʷəŋən Garry oak ecosystem at Mill Hill Regional Park near Langford, British Columbia. In Project 1, vegetation responses to a 13-year invasive species removal program were quantified to determine if native plant populations were successfully bolstered by the removal efforts. In Project 2, impacts of an unintended wildfire on the relative cover of native and non-native plants were examined. This attempted to explore potential ecosystem shifts that may occur as wildfires increase in frequency and severity as predicted by climate models. In Project 1, the greatest change observed after invasive species removal was an increase in other introduced species, while increases in native species were not statistically significant. In Project 2, ...