Long-term human habitation introduces morphological and chemical changes to soil as a result of cultural, economic, and stewardship practices. These cultural soils, or Anthrosols, are recognized globally. On the Northwest Coast of North America, Indigenous marine and terrestrial land stewardship practices are recognized on present-day landscapes. Increased awareness of these stewardship practices is informed by Indigenous knowledge, ecological legacies, ethnographic studies, and archaeological evidence. This research was undertaken to better understand how lək̓ʷəŋən (Straits Salish) stewardship of a cultural landscape affected the development of soil across a village-garden gradient. On Vancouver Island, British Columbia, Indigenous cultivation of culturally important root foods was interrupted by colonization and its pervasive effects, so an additional research aim was to investigate how cultural soils remain after being disconnected from traditional stewardship. There is a growing global understanding that Indigenous management of ecosystems plays a key role in ecological health. At the regional scale, Songhees First Nation are interested in learning about their soils to inform future restoration efforts and connect youth with their land and culture. The lək̓ʷəŋən Ethnoecology and Archaeology Project (LEAP) is a collaborative research project with the Songhees First Nation to learn more about the physical remains of lək̓ʷəŋən stewardship: soils are a key part of the project. Community knowledge, ethnographic sources, and ecological legacies informed the archaeological excavation and soil sampling in this research. Archaeological excavation was utilized to understand the pedologic and archaeological setting of the site. Soil samples were analyzed for physical and chemical properties to see if a statistical difference between on and off-site samples could be detected. Data from the archaeological excavation were recorded and interpreted. A gradient of influence does exist across the village-garden; the village has a strong physical and chemical signature that can be seen through archaeological excavation, macroscopic remains in the soil, and elevated levels of phosphorous, calcium, and soil pH. Results from the garden are less clear, previous ecological studies and archaeological surveys show evidence of lək̓ʷəŋən stewardship—culturally important plant species and burial cairns are present. However, within the soil, the macroscopic remains and soil chemistry signatures are not as strong as the village which indicates that the health of lək̓ʷəŋən gardens facilitates their continued ecological functioning which ultimately may obscure earlier soil signatures of stewardship. Archaeological investigation alone does not always show the full scope of Indigenous terrestrial management practices. Incorporating present-day community knowledge, ecological legacies of plant cultivation, and utilizing soil chemical data are important to understanding the interconnections between people and their environments across cultural landscapes. Current work on the ecological legacies of plant cultivation can be assisted by investigating the soil as a site that also undergoes co-development with Indigenous stewardship. / Graduate

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, introduced Anthoxanthum odoratum was facilitated by fire while native Camassia spp. were reduced by it. Taken together, these results demonstrate the complexity of restoring Indigenously managed ecosystems where multiple introduced species have existed for long periods. Invasive species, specifically Anthoxanthum odoratum, showed greater responses to removal efforts and wildfire than native species. Intensive, long-term restoration programs that utilize multiple tools, including low-intensity fire, invasive removal, herbicide, and seeding of native species appear necessary to bolster native species without unintentional facilitation of introduced species. Coast Salish peoples and stewardship practices were integral in maintaining these ecosystems before the arrival of European settlers and should play a key role in their restoration today, though traditional practices will likely need adapted to account for environmental changes caused by colonization. Furthermore, to avoid continuing the cultural damage that began with colonization, it is vital that Coast Salish First Nations lead or be directly involved in restoration of these ecosystems, which continue to hold irreplaceable cultural value. / Graduate / 2023-01-14