Thesis Defence: Ecological Integrity Assessment for Monitoring Conservation Status and Restoration Success in Antelope Brush (Purshia tridentata) Ecosystems
May 12 at 1:00 pm - 5:00 pm
Jef Vreys, supervised by Dr. Jason Pither, will defend their thesis titled “Ecological Integrity Assessment for Monitoring Conservation Status and Restoration Success in Antelope Brush (Purshia tridentata) Ecosystems” in partial fulfillment of the requirements for the degree of Master of Science in Biology.
An abstract for Jef Vreys’s thesis is included below.
Defences are open to all members of the campus community as well as the general public. Registration is not required for in-person defences.
Abstract
Antelope brush (Purshia tridentata) ecosystems in the South Okanagan are among British Columbia’s most at-risk shrub-steppe habitats, yet systematic monitoring and assessment tools tailored to their unique conditions have been lacking. In this thesis, I address three primary objectives: (1) designing consistent, repeatable vegetation monitoring protocols for antelope brush systems; (2) creating clear ecological integrity standards using a NatureServe Ecological Integrity Assessment (EIA) framework adapted for local conditions; and (3) applying these protocols to evaluate the ecological integrity of antelope brush ecosystems across multiple sites in the South Okanagan. To achieve these goals, I used British Columbia’s Terrestrial Ecosystem Mapping (TEM) data to delineate assessment areas and classify ecosystems under the Biogeoclimatic Ecosystem Classification (BEC) system. I tailored NatureServe’s EIA modules—originally developed for Washington State—to better align with the small patch sizes, fire regimes, and common invasive species found in the South Okanagan. I collected field data during two rounds of sampling in 2023 and 2024. I generated overall integrity ranks for each site and used these results to guide management recommendations. Additionally, I compared the 2023 and 2024 findings to assess year-to-year changes, and I compared current conditions to those reported in a 2012 report covering some of the same sites. Sites with lower Landscape Context scores tended to exhibit lower Condition scores. Sites with lower Landscape Context scores generally had correspondingly lower Condition scores, and no site received an EIA rank above B-. Although some discrepancies were observed—possibly linked to different sampling windows and methods—both historical and current data suggest these ecosystems retain some level of resilience despite ongoing pressures from development and invasive species. I demonstrate the potential for using Landscape Context and Condition scores as criteria to inform the restoration potential of targeted sites. My proposed protocol provides a standardized, science-based approach to monitoring antelope brush habitats, enabling land managers and conservation practitioners to track ecological integrity over time.
