Karen Castro1, Alec McClay2, Claire Wilson1 and Andrea Sissons1
1Plant Health Risk Assessment Unit, Canadian Food Inspection Agency, Ottawa, Ontario, Canada
2McClay Ecoscience, Ottawa, Ontario, Canada
The numbers of introduced and invasive plant species reported in Canada have both increased by approximately 15% over the past decade. This is one of several key findings in a recent update to a baseline “Invasive Alien Plants in Canada” report produced by the Canadian Food Inspection Agency (CFIA) in 2008. Since then, Canada’s known vascular plant flora increased from 5052 to 5161 species; the number of introduced species increased from 1229 to 1406 species; and the number of invasive species within the pool of introduced species increased from 486 to 555 species. These increases represent current rates of accumulation of introduced and invasive plant species well above the long-term historical averages. While the overall trend is clear, it should be noted that some of the additions or removals of species resulted from changes in taxonomic status or botanical knowledge. The largest numbers of introduced and invasive species are still found in the provinces of Ontario and British Columbia, which also import the largest proportions of products potentially associated with invasive plant introductions. However, the largest percentage increases in introduced and invasive species were recorded in Nunavut and Newfoundland and Labrador. The majority of new introductions into Canada still come from the West Palaearctic region (Europe, North Africa and the Middle East), though the percentage of introductions from that region dropped from 77% to 53%, possibly reflecting some exhaustion of the pool of species not already introduced. Introductions from the East Palaearctic (primarily China and Japan) and Oriental (primarily India and southeast Asia) regions combined, increased from just over 15% to 33%, possibly reflecting increased trade with those regions and some overlap in climate suitability. As Canada’s national plant protection organization, the CFIA is responding to the ever-increasing threat of invasive plants through its invasive plant program, which has undergone significant developments over the past decade. Examples include the creation of an Invasive Plants Policy (2012), an update of Canada’s noxious weed list in the Weed Seeds Order of the Seeds Act (2016), and the addition of 21 regulated pest plants under the Plant Protection Act (2009–2018).