Non-native and invasive. Are they the same thing?

By Greta Solbrig on July 15, 2024 in Blog

When scientists discuss the environment, they can throw around some confusing lingo. Sometimes it seems as though science has its own language, making important topics difficult to understand. Scientific information should be accessible to the public, and accessibility starts with understanding.

Perhaps when hiking with friends or buying landscape plants for your yard, you have heard the terms “non-native” or “invasive.” These words were most likely used to indicate that a species is generally negative and doesn’t belong. Many think that these words are synonymous, and they are often mistakenly used interchangeably, but they have different meanings in relation to ecological impact.

The term non-native seems to have a negative connotation, but just because a species did not originate in an area does not mean it necessarily is causing problems. There are many non-native species that we interact with almost daily. The grass in your lawn, many trees used in urban plantings and even the produce grown in backyard gardens are all examples of benign non-native plants. Ring-necked Pheasants (Phasianus colchicus), long ago introduced from Asia, are now found across North America and are considered so desirable that the species is often taken into account when considering plantings or other habitat restoration work. The same is true for Gray Partridge (Perdix perdix), another popular game bird. Though they’re both non-native (and while it would be preferable we still had our native prairie chickens), they are creating outdoor recreation opportunities and positive economic impact. 

Native and non-native species that have a negative impact on the surrounding ecosystem or economy are considered invasive. These species, local or introduced, can spread rapidly if uncontrolled and will deprive native species of nutrients or physical space. Big offenders like exotic bush honeysuckle, zebra mussels or the emerald ash borer might first come to mind. But consider the Eastern red cedar (Juniperus virginiana). Native to Iowa and a common find across the state, cedar belongs on the landscape but can also cause problems if it takes hold in certain places. Cedars can invade prairies, changing the habitat structure and making it unusable for the species that depend on open grasslands. If uncontrolled, the native species can dominate the area and turn a prairie into a woodland. Even though this species is within its normal geographic range, it can still negatively impact surrounding species, so is sometimes considered “invasive.”

It's true that most invasive species are usually non-native. A plant or animal might not behave invasively in its native range, but when away from its natural predators or other controls, it can grow unchecked. It’s worth mentioning that many of our non-native invasive species were deliberately brought or released here. Crown vetch, oriental bittersweet, European starlings and reed canary grass are just a few of the examples where we learned hard lessons. Non-native invasives can also sneakily hitch a ride on vehicles, equipment, shoe treads or shipments, so it’s always important to consider what you might be unknowingly spreading around.  

Now when you hear these terms, you will be better able to distinguish which species truly pose a threat to your environment and that non-native is not necessarily negative.