24% of vascular plants are exotic in Canada

Photo: Canada Thistle, Cirsium arvense © Edward Willet

Photo: Canada Thistle, Cirsium arvense © Edward Willet

One of the issues highlighted in the Wild Species reports is the large number of non-native species in Canada. Exotic species are species that have been moved beyond their natural range as a result of human activity. Exotic species have thus been introduced to Canada, both deliberately and accidentally, from around the world. In addition, exotic species can also include native species that have been moved from regions of the country in which they traditionally occur, to regions in which they are not naturally found (to another province or territory for example). Whether from abroad, or from a different part of Canada, exotic species can cause problems for native species in a variety of ways, including competition for space and resources, predation, hybridization and introduction of new diseases.

The ranking system used by the National General Status Working Group includes a category specifically for the exotic species. Exotic species have been purposefully excluded from all other categories so that we are able to track them. In the Wild Species 2010 report, of the 11,950 species assessed, a total of 1426 species were exotic at the national level in Canada. Most of the exotic species were vascular plants (1252 species), representing 89% of all exotic species assessed in the report. Vascular plants have the highest proportion of exotic species of any other groups covered in this report: 24% of species of vascular plants established in the wild in Canada are exotic. Other taxonomic groups with many exotic species were the spiders (70 species) and the ground beetles (54 species). The list of all the scientific names of these exotic species can be found in the databases of the Wild Species reports, available on this website.

 

Number of exotic species established in Canada for the taxonomic groups assessed in the Wild Species 2010 report.
Taxonomic groupNumber of exotic species
Macrolichens
1
Mosses
4
Vascular plants
1252
Freshwater mussels
0
Spiders
70
Dragonflies and damselflies
0
Predaceous diving beetles
0
Ground beetles
54
Lady beetles
7
Bumble bees
0
Black flies
0
Horse flies
0
Mosquitoes
3
Selected macromoths
7
Butterflies
2
Crayfishes
2
Amphibians
0
Reptiles
2
Birds
11
Mammals
11
TOTAL
1426

 

Governments in Canada are collaborating and have developed a national strategy on exotic species, called An Invasive Alien Species Strategy for Canada. This national strategy plays an important role in preventing new invasions, detecting and responding to new invasive alien species and in managing established invasive alien species through eradication, containment and control. The species that are ranked as exotic by the National General Status Working Group in the Wild Species reports could be used in this strategy. The Wild Species reports represent one of the most comprehensive sources of information to identify which exotic species are present in Canada. The strategy can use the Wild Species reports to do further analysis on the impact these exotic species have on our ecosystems. Other initiatives, such as the Plants of Canada Database website, which uses the information from the Wild Species reports as a starting point, are targeting specifically the vascular plants.