02/25/2025
Respect the balance during Invasive Species Week.
Invasive species are plants, animals or other organisms that have been introduced to an area and cause harm within an ecosystem. Since these species have not evolved with natural predators or controls, their growth and spread can outcompete local species and lead to other harmful effects on the local environment. The spread of invasive species can decrease biodiversity, damage soil quality, and have negative economic and social impacts.
Invasive species pose a major challenge, but the City of Toronto is committed to managing invasive species and restoring ecosystems. Through Toronto's Ravine Strategy, the City has substantially increased funding for invasive plant management and the amount of natural parkland managed every year.
Some common invasive species affecting natural areas in Toronto include Common Buckthorn (Rhamnus cathartica), Emerald Ash Borer (Agrilus planipennis), Norway Maple (Acer platanoides), Phragmites (Phragmites australis).
Many woody invasive species like Common Buckthorn and Norway Maple can be managed year-round, though pulling/digging plants out of the ground in the early spring or fall can help with identification and reduce damage to surrounding vegetation.
Many herbaceous invasive species like Garlic Mustard, Dog Strangling Vine, and Goutweed can be hand-pulled during the growing season, but may require repetitive management to exhaust the population.
Forestry staff monitor and manage invasive insects. Potential pest outbreaks are forecasted and assessed through continuous pest monitoring, systematic surveys and data collection with reference to historical patterns.
Read more about best management practices for invasive plants at https://www.toronto.ca/services-payments/water-environment/trees/forest-management/urban-forest-management/.
Image: Common invasive plant species found in Toronto.
