Chapter 16. Invasive Plant Species

Invasive Plant Species

Invasive plant species can displace native vegetation and may have no natural predators in Canada. Without the presence of their natural controls such as insects and diseases, invasive species may grow aggressively and can monopolize large areas by out-competing native trees by producing toxic chemicals and competing for light and nutrients. Another risk involves the possibility of non-native species hybridizing with native vegetation and eventually eliminating native genetic strains. Non-native and invasive species can significantly change ecosystem functioning if effective management practices are not implemented. Invasive plants can be carried to urban areas by vehicle, by wind or water, on pets, or can be intentionally planted in gardens.

Governments, non-profit organizations, regional bodies, or conservation authorities may develop invasive plant strategic management plan to eradicate or prevent invasive plants in urban areas. For example, the City of Calgary’s strategic management plan incorporates numerous strategies: early detection and response, research and development of new eradication strategies, inventorying, prevention, community outreach, and integrated weed management that uses biological, chemical and cultural control methods to eliminate or prevent priority invasive species. Additionally, governments may introduce weed control legislation that prohibits particular plants.

Canadian online resources:

• Alberta Agriculture and Forestry: Invasive plants in Alberta: urban areas
• City of Calgary: Invasive plant prevention and management
• Yukon Invasive Species Council: Yukon Invasive Plants
• City of Halifax: Invasive Species
• Invasive Species Council Manitoba: Strategic Management Plan (2014-2019) (PDF)
• Invasive Species Council of Metro Vancouver: Invasive Species Council of Metro Vancouver
• Government of the Northwest Territories: Invasive Alien Species
• City of Ottawa: Invasive species
• Fédération interdisciplinaire de l’horticulture ornementale du Québec (FIHOQ): Plantes envahissantes
• Saskatchewan Invasive Species Council: Saskatchewan Invasive Species Council
• City of St. John’s: Giant Hogweed

Invasive plant and weed legislation and regulations in Canada:

• Province of Alberta: Weed Control Regulation (PDF)
• Invasive Species Council of BC: Regulations on Invasive Species in BC
• Province of Manitoba: Declaration of Noxious Weeds in Manitoba
• Province of Nova Scotia: Weed Control Act
• Province of Ontario: Invasive Species Act
• Province of Ontario: Weed Control Act
• Province of Prince Edward Island: Weed Control Act
• Province of Saskatchewan: The Weed Control Act

Further reading:

 Francis, R. A. & Chadwick, M. A. (2015). Urban Invasions: non-native and invasive species in cities. Geography, 100(3), 144-151. Retrieved from  https://search.proquest.com/openview/73beff42ad6fb41f7bae64d8c0e434ba/1?pq-origsite=gscholar&cbl=42255

Hawthorne, T. L., Elmore, V., Strong, A., Bennett-Martin, P., Finnie, J., Parkman, J.,. . . Reed, J. (2014). Mapping non-native invasive species and accessibility in an urban forest: A case study of participatory mapping and citizen science in Atlanta, Georgia. Applied Geography, 56, 187-198. https://doi.org/10.1016/j.apgeog.2014.10.005

McMillen, H., Campbell, L. K., & Svendsen, E. S. (2018). Weighing values and risks of beloved invasive species: The case of the survivor tree and conflict management in urban green infrastructure. Urban Forestry & Urban Greening. https://doi.org/10.1016/j.ufug.2018.06.023