Trialing Methods of Invasive Plant Suppression and Native Plant Establishment in Esquimalt Gorge Park, Victoria, BC

Gorge Waterway Nature House Pollinator Meadow Phase 2

Abstract

Pollinator populations face threats from urbanization, making restoration essential for their survival in urban areas. This project aims increase pollinator presence by trialing different methods of invasive species suppression and native plant establishment in a series of test plots in Esquimalt Gorge Park, Victoria, B.C. This acts as Phase 2 of an existing pollinator meadow planted by the Gorge Waterway Action Society (GWAS) in 2020.
Species coverage data was analyzed for Phase 1 of the Pollinator Meadow, along with moisture and light preferences. All test plots were analyzed for their hours and costs per square metre as well as their ratio of native to non-native species coverage to date. Phase 1 is currently the most cost-effective method used, likely due to the increased plot area which allowed resources to have a larger-scale impact. Sticky cinquefoil (Drymocallis glandulosa), woolly sunflower (Eriophyllum lanatum), entire-leaved gumweed (Grindelia stricta), hairy honeysuckle (Lonicera hispidula), Lewis’s mock-orange (Philadelphus lewisii), Pacific ninebark (Physocarpus capitatus), red-flowering currant (Ribes sanguineum), Nootka rose (Rosa nutkana), Henderson’s checker-mallow (Sidalcea hendersonii), and Douglas’ aster (Symphyotrichum subspicatum) increased in percent cover from 2021 to 2022. Yarrow (Achillea millefolium), self-heal (Prunella vulgaris), Western Canada goldenrod (Solidago lepida), and common snowberry (Symphoricarpos albus) also performed well. Entire-leaved gumweed (Grindelia stricta) was the highest performing species.
Invasive species management techniques including mechanical methods, chemical methods, prescribed fire, and native seeding were analyzed for their applicability to the project site. Mechanical methods continue to be the most accessible and plausible management technique for the site, although it is recommended that they be scaled up and timed precisely to be more effective.
Future data collection by GWAS summer students will continue to inform GWAS’s understanding of the most cost-effective and successful techniques used, as well as the species best suited to the site. A list of recommendations for future site management has been provided to GWAS.