For more information on invasive species, these are sites we recommend:
Ontario Invasive Plant Council:
http://www.ontarioinvasiveplants.ca/
Ontario's Invading Species Awareness Program:
http://www.invadingspecies.com/
Government of Ontario:
https://www.ontario.ca/page/invasive-species-ontario
Best Management Practices for Invasive Species:
https://www.scrca.on.ca/wp-content/uploads/2013/06/BMP_Invasive_Species.pdf
Alien invasive species are non-native species that are able to out-compete North American plants in their native habitats. An obvious one to many people is the common reed, Phragmites australis, that has overtaken ditches, ponds, and other wet areas in Lambton County. This is a Eurasian species that forms a dense stand that chokes out native species -physically, as well as by releasing a toxin. There is very little wildlife value in a monoculture of Phragmites. Its spread is decreasing wildlife habitat, biodiversity, and the quality of our wetland ecosystems.
Invasive Species
Many horticultural varieties sold at garden centres are also incredibly invasive if they escape the garden. Periwinkle and lily of the valley will take over the forest understory (there are large patches in Canatara Park and many places on the Howard Watson Nature Trail). We strongly discourage people from planting these species, especially if your property is connected to a natural area. Though you may find these flowers beautiful, they provides no benefit to wildlife and take the place of a native plant that would be a food source.
To get you started in switching your non-native plants to native ones, here is a guide we recommend. It lists a number of common invasive species planted in gardens and offers native alternatives that have similar desirable features (e.g. ground cover, berry producing shrub, etc.).
Plants aren't the only invaders though, non-native animals (insects, mammals, and even fungi) can have great detriment to our natural environments as well. The Emerald Ash Borer is an invasive species from Asia that has wiped out most of our ash tree. The below photo of a forest affected by this insect show how great of an effects it has had on our forests. Note the large sections of dead trees.
The ash borer tunnels into the bark of the tree creating tunnels and chambers that eventually girdle the tree, preventing nutrients and water from flowing to the branches.
