Whether they are called invasive, nonnative alien, exotic, or nonindigenous, introduced species are those that evolved elsewhere and have been purposely or accidentally relocated . While some species have invaded habitats on their own (e.g., migrating wildlife, plants and animals rafting on floating debris), human exploration and colonization have dramatically increased the diversity and scale of invasions by exotic species. Introduced species often find no natural enemies in their new habitat and therefore spread easily and quickly.

Forests provide natural pathways for invasive species. Some of the problematic terrestrial species within the CLOCA jurisdiction include the following:

• Native to Europe
• Also called European buckthorn
• Naturalized in much of Southern Ontario
• First introduced as an ornamental shrub
• Produces seed at a young age
• Prolific seed production, dispersed by birds
• Resprouts from cut stumps
• Usually successful with repeated control measures

• Native to Europe
• Toronto and Ottawa are the main areas of abundance for the species
• Introduced probably for medicinal use and as a green vegetable
• Garlic mustard reproduces by seed production only
• Forms monocultures and displaces native spring flora
• A biennial plant (flowers every 2nd year)
• Success with control measures

• Native to Europe
• Member of the Milkweed family
• One story suggests its introduction as a research plot escapee during testing as a possible filler for lifejackets during WWII
• Reproduces by windborne seed and spreading underground rhizomes
• Forms dense mats
• Quickly becoming a problematic species in Southern Ontario first noticed by CLOCA in 1997
• Difficult to control

CLOCA, in partnership with the nine Oak Ridges Moraine Conservation Authorities is working toward developing a strategy to address all invasive species. Sustaining Biodiversity is a document produced by the Ontario Invasive Plants Working Group, and will form the backbone of comprehensive invasive species strategy for the nine Conservation Authorities.

Other invasive species that are threatening our forest health, but have not yet been located within this region are the Asian Longhorned Beetle and the Emerald Ash Borer. The Canadian Food Inspection Agency (CFIA) is the lead agency when it comes to these two invasive insects. If you think you have discovered either of these insects on your property, please call your local CFIA office.

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