3.7: Invasive or Exotic Species
pg. 101
Invasive Species: a non-native species that has a negative impact on the
natural environment.
Non-native Species
Non-native species can arrive in an ecosystems in many different ways.
- Boats and travelers from other countries
- Seeds and cuttings of exotic plants for gardens
- The intentional introduction to solve other problems
Some non-native and exotic species do not succeed because they cannot
tolerate the new environment.
Some species are successful, because there are few predators or diseases to
limit their growth.
In some situations native species cannot compete with the newly introduced
species. This will lead to a problem, the new species increases rapidly and
may become invasive. Invasive species grow rapidly and have a negative
impact on the environment.
A Plan Gone Wrong
Canadian Beaver – introduced into South America in the 1940’s to start a fur
trade industry failed when the beaver pelts did not generate a thick enough
fur to be of any value. The beaver population grow out of control because of
lack of hunting and trapping. The beavers performed their natural niche by
cutting down trees and creating dams in the rivers.
Foxes were introduced to prey on the beavers to decrease the population.
This had a negative effect also. The foxes hunted the native rabbits, instead
of the beavers. Rabbits were important to the development of fertile soil.
The lack of rabbit droppings led to infertile soil unbalancing the ecosystem.
Invasive Species in Canada
There are more than 3000 invasive species found in Canada, 185 are found
in the Great lakes region. The Borer Beetle, native to Eastern Asia, has had a
negative impact on economy, ecology, tourism, and health of a region.
Canada is force to spend millions of dollars to control these species each
year.
Controlling Introduced Species
1. Chemical control is the use of pesticides to protect trees, crops,
fisheries, and human health. Pesticides are effective yet they pollute
the environment and kill native species also.
2. Mechanical control includes human – made barriers to prevent
invasive species from moving into and out of an area. Pulling and
digging up invasive plants or trapping insects are also examples.
3. Biological control means that a predator or infectious agent is
introduced to kill or harm the invasive species.
Check Your Learning:
Questions 1 – 5, pg. 103
Wrap Up:
- Invasive species are non-native species whose introduction is harmful to
ecosystems.
- Invasive species may negatively affect our health and economy.
- Invasive species can sometimes be controlled using chemical, mechanical,
or biological methods.