Invasive Species: What are they?

What are Invasive Species?

Invasive species, also called invasive alien species, are “non-native species that have been introduced from another geographic region and whose introduction or spread negatively impacts native biodiversity, the economy and or society, including human health” (Ontario Invasive Plant Council, 2016).

In addition to the above definition, invasive species often have a combination of three characteristics that make them more challenging to manage than non-native species that are not invasive:

  • Higher rates of seed production
  • Fewer native predators and diseases that keep populations in balance
  • Higher levels of adaptability in a variety of environments. In other words, they are generalist species.

Why should we be so worried about invasive species?

When invasive species enter new ecosystems they can become incredibly problematic predators, competitors, parasites, hybridizers, or diseases that harm native species and habitats. Introduced species are especially problematic when they are spread quickly, either by their own superior dispersal techniques or aided in their spread by humans and climate change. For example, the Emerald Ash Borer was introduced to North America in the late 1990s. In the intervening years, this species of beetle has caused damage and death to tens of millions of native Ash trees throughout the continent. Ash trees are key components of southern Ontario forests, providing essential habitat and food for wildlife and important for pollinators.

The World Conservation Union has stated that invasive species do so much damage to native species that they are the second most significant threat to biodiversity, following only habitat loss.

The ways in which invasive species cause negative impacts to a location are often divided up into three core areas; environmental impacts, social impacts, and economic impacts.

Environmental impacts: Negative impacts on biodiversity, contributes to species extirpation and extinction, increases soil degradation and erosion, eliminates native food sources, alters fire cycles, reduces forest growth, alters soil chemistry, increases the need for pesticides and herbicides.

Social impacts: Human and or animal injury, reduced land and water recreational opportunities, loss of culturally significant species, etc.

Economic impacts: Costs of controlling invasive populations, reduced productivity in forestry, fishing, and agricultural sectors, costs of increased trade restrictions, reductions in property values.

Did you know?: The economic costs of invasive species in Canada is an estimated 36 billion annually!

How do humans play a role in all of this?

Similar to most environmental concerns, humans have played a significant role in the acceleration of invasive species. It is important to keep in mind that the spread of non-native species happens at international, national, regional and local scales, which makes taking precautions as individuals all that much more important.

Humans often bring invasive species into a region. Some are brought to a region as ornamental or medical plants, others come with ships, lumber, and agricultural products, and others are transported from recreational activities such as hiking, riding ATV’s and fishing. Climate change impacts including longer growing seasons and warmer weather are also contributing to increasing the spread of invasive species.

Want to Get Involved?: 

  • Join Oakvillegreen’s Oakville TreeKeepers program to organize an invasive species removal in your neighbourhood.
  • Join Oakville’s Urban Forest Health Ambassador Program.
  • Remove invasive species on your property. Resources here.
  • Share information and resources on invasive species on social media and with friends.
  • Take the time to learn more about invasive species in Ontario.
  • Report invasive species to the proper authorities in your area.
  • Learn to use EDDMapS and track the invasive species in the green spaces near your home.

Sources: – View Points: Invasive Species

Please note that the invasive species information provided on this page is provided for informational purposes only. Please consult the Invading Species Awareness Program or Ontario Invasive Plant Council for more detailed information and be sure to obtain necessary permissions from private property owners and to investigate and adhere to all applicable laws, bylaws and up-to-date management guides before undertaking any invasive species management activities.

Learn more:

Invasive Species: Oakville’s Most Wanted

Reporting Invasive Species

Invasive Species: Minimize Your Impact