Exotic Plants

What are exotic species?

Voyageurs National Park is home to a large diversity of plants and animals. Unfortunately, not all of these are found naturally in the park. Exotics, or non-natives, are any plant or animal species that are not found in an area naturally and were introduced either intentionally or by accident. While not all exotic species are harmful to the natural ecosystem, many can cause problems to native plants and animals and must be removed. Exotic species are becoming an increasing problem at Voyageurs National Park.

How do exotic plants and animals become successful invaders to an area?

Exotic plants and animals are difficult to control if they become invasive. The term invasive refers to species that spread rapidly through an area and take over the native species living there. The following factors make invasive species successful in an area:

  • Lack of natural predators
  • Produce large numbers of seeds or offspring each year
  • Effective dispersal of seeds or offspring
  • Roots spread quickly
  • Produce toxins or have spines/prickles
  • Can reproduce without seeds (via stems, roots, etc)

How do exotics arrive to a new area?

Exotics are actually native to other areas and must be introduced into a new area. This can happen intentionally or by accident. Some examples of exotics being introduced intentionally are: planting non-native ornamental flowers in gardens or around cabins; releasing fish and wildlife for sporting purposes; and releasing unused fish bait into lakes and streams. However, most exotics are transported by accident. This occurs when small, aquatic creatures are released from a ship’s ballast water; plant seeds are mixed in with crop mixtures; or plants are not cleaned from vehicles and boats before transport.

Which methods are used to remove exotic species?

The most effective method for removing exotics from an area depends on the individual species. Plants and animals do not respond the same way to all treatments. As we learn more about exotic species, new technologies are being developed to quickly eliminate them. The most common removal methods fall into one of three categories:

  • Mechanical – hand pulling, mowing or using a type of equipment; setting traps to catch exotic animals
  • Chemical – applying a pesticide or herbicide
  • Biological – using another living organism to control exotics; an example is releasing loosestrife beetles to eat away invasive purple loosestrife

Why should you care about exotic species?

Many visitors come to Voyageurs National Park for the beautiful scenery and natural landscape. As more exotic species move into the area, they out-compete the native plants and animals living there. Imagine looking across a wetland filled with abundant aquatic plants and animals swimming about. This is a visitor’s ideal view of the park. Now think about that wetland as one giant stand of exotic cattails and no visible wildlife. Exotics are having this effect and must be managed to restore the park’s natural beauty. Visitors can help prevent the spread of exotic species by becoming familiar with those found within the park. Click on the links located below to learn more about exotics in Voyageurs National Park. Inform a park naturalist if you notice these during your visit.


Last updated: June 28, 2017

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