What makes a Species Invasive?

While we tend to focus on wildflowers, especially the early blooming ones, we should also remember what is invasive. This early in the year, many of the plants that are green would be considered invasive species. But what makes them invasive and how did they get here? We’re going to learn about it today.

To be considered an invasive species, a species must inflict harm and have negative impacts on the environment around it. An invasive species can be a plant, an animal or even small things like bacteria or fungus. To be considered invasive, a species must cause environmental harm, economic harm, or impact human health according to an article on environmentalscience.org.

Many species have been transported by humans. Once in their new environment, they either die or thrive. The ones that thrive are the invasive species. They have no natural predators in their new environment which leads to the species multiplying out of control. When they took the wolves out of Yellowstone, the deer population skyrocketed.

"Native Great Lakes Unionid Mussel encrusted with Zebra Mussels" by NOAA Great Lakes Environmental Research Laboratory is licensed under CC BY-SA 2.0

“Native Great Lakes Unionid Mussel encrusted with Zebra Mussels” by NOAA Great Lakes Environmental Research Laboratory is licensed under CC BY-SA 2.0

One example of an invasive species you might know is the Zebra Mussels that we are working to keep out of our lakes. The zebra mussels are invasive and will kill off the native species of mussels in any body of water. They are originally from the Caspian sea region in Asia and were transported to the great lakes on intercontinental boats according to the Iowa DNRopens PDF file . There is a lack of predators who eat the mussels and they change the entirety of the ecosystem they infest. This makes them an invasive species.


Another example is your common lawn grass. While it’s not an invasive species because it’s not bad for humans, it’s not great at keeping the soil in place. Iowa was once 80 percent prairie land but is now less than 0.01 percent prairie. The root systems on prairie plants are so extensive, they will reach at least 6 feet into the ground. This helps keep the good soil in place but your common lawn grass only has root systems four inches deep. While the lawn grass will keep the soil where it needs to be, it’s much less efficient about it than the prairie roots.