Science of Everything: Invasive Species

There’s nothing worse than an unwanted houseguest who eats your food and takes over your living space. Plants experience a similar invasion of their environment. 

Invasive plants are commonly non-native to a region and force out native species or have a negative impact on the functioning of that ecosystem. At first, the new species may provide food, a habitat for animals, and improve the soil quality. But what starts off as a symbiotic relationship can quickly change. Sometimes the new species has traits that are better suited for that environment, so it flourishes and eventually becomes invasive.

Should the more resilient invasive species be allowed to thrive? That’s complicated. While invasive plants may be better suited for an environment, many can’t sustain an ecosystem as well as native plants. For example, the tree of heaven originated in China and Taiwan and was introduced to the United States hundreds of years ago for decorative purposes. It’s now an invasive species. “It doesn’t support the same critters that oaks and maples do, like caterpillars,” warns Dr. Heather Hulton VanTassel, the Executive Director at Three Rivers Waterkeeper. Though insects are often considered a nuisance, their absence would disrupt the food chain. 

Some invasive species are fully grown before the native plants have a chance to sprout. This leaves the native plants to compete for light and moisture, a fight they often lose. Even more concerning, some invasive species actively harm other plants. “Honeysuckle (an invasive shrub) has chemicals in the leaves that change the soil to make it hard for anything else to grow,” says Dr. Beck Swab, Founder of Root & Spiral. 

Is a better solution to eliminate the invasive species? Trying to save the native species while eliminating the invasive ones can be costly and require repeated maintenance. The best solution is one that considers the bigger picture. “Doing the best for the ecological functioning of the landscape as a whole is better than focusing on one species at a time,” says Heather. 

Beck took this holistic approach during their graduate training when they were trying to restore the native vegetation that had been overtaken by honeysuckle. Simply removing the honeysuckle allowed a different invasive species to take over. But combining honeysuckle removal with restoration of flood water to the area was the answer. “The areas that were flooded were getting better, more native species were back in them,” exclaims Beck. The floodwater was essential to the native plants’ survival and kept the invasive species out. 

Having this holistic viewpoint of the ecosystem takes time. “Even when we’re thinking of controlling invasive species, the sanctity of life is still important,” says Beck. So the first solution to an invasive species problem shouldn’t be to eliminate one species over the other. Connecting with nature helps with this mindset. “The more connected to nature you are, the more you’ll want to protect it,” says Heather. As you reconnect with nature, here are some other things you can do to prevent invasive species:

1. When visiting new areas, adhere to all the rules. It may feel silly to wipe your shoes when entering a national park, or buy firewood at a campsite when you have your own, but these rules protect the local ecosystem.
2. Plant native species in your garden. Heather recommends the Bringing Nature Home book for inspiration. Native plant nurseries and conservation groups in your area are valuable resources, too. If you have family in the Cleveland area, tell them about Beck’s native gardening business.
3. Climate change is creating opportunities for invasive species to enter new territories, so taking action can help to prevent it.