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Submodule 2: Invasive Species Defined
Many Non-native Species are Actually Good and Useful
The focus of this learning module is invasive species - those non-native organisms that cause ecological damage (or have potential to cause damage) to their new environment. There are, however, many non-native species in the US that are quite beneficial to Americans. Let's look at a few examples:
Corn -- not native to the US, yet beneficial to
Americans. (photo courtesy Agricultural
Research Service)
- Most major food crops including corn, wheat, barley, potatoes, and soybeans. It's easier to list the common agricultural crops that are native to the U.S.: cranberry, pecan, sunflower, tobacco, and a few legumes – that's it!
- Many common horticultural plants including iris, willow trees, and lilac bushes.
- Livestock including cattle, pigs, sheep, and chickens.
- Pets including dogs and cats.
- European honeybees for pollinating most US crops.
- Organisms introduced for biological control of invasive species such as fish introduced to control aquatic weeds or fungus introduced to control a weed in California.
In addition, many indigenous U.S. species have been intentionally spread far beyond their native ranges with beneficial results. Rainbow trout, striped bass, and Pacific salmon in the Great Lakes are some examples.
Most of these beneficial non-indigenous species are not invasive and are used to improve the environment and serve humankind. Unfortunately, even these “beneficial” species can sometimes become a nuisance in their new environment. An example is feral cats that have become a problem in many communities; they rapidly reproduce which increases their numbers, and they kill other animals including pet cats and wild birds.
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