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How Invasive Plants Can Bully Natives Underground

Close-up of white bush honeysuckle blossom

It may sound a little doom and gloom, but the very same blooms that are filling our noses with smells of sweet nectar this summer may be damaging our environment in unexpected ways.

This grim news has a silver lining, however. Research conducted at Indiana University Bloomington suggests an interesting solution to this problem may be found by looking underground.

The Problem With Invasives

A plant is a plant, right? Wrong. Invasive plant species are a serious threat to the native plants not only of Indiana, but of the entire country.

Because they are not from here, invasive plants have few enemies in the form of herbivores and pathogens. This allows them to flourish and essentially bully their way into the ecosystem, replacing our once biologically diverse landscapes with a low diversity span of flora.

Sarah Shannon, a native of San Jose, Calif., entered the plant world in 2001 at the University of California Davis. In 2007, she made her way to Indiana University, where she has spent the last several years studying invasive plants and how they affect native species under Dr. Heather Reynolds.

Her main research questions encapsulate how invasive plants affect the soil living organisms and chemical properties and how those changes, in turn, can affect native plants.

This Black Box

"It's sort of this black box, this interaction that we can‘t see," Shannon says. "We can‘t see how [plants] are interacting below-ground and that‘s what is so fascinating."

Her research has focused on the "feedback" between native and non-native species. Positive feedback is when a plant sends chemical signals into the soil in a way that benefits itself. Negative feedback, on the other hand, occurs when a plant sends chemical signals into the soil that benefit neighboring plants. While we don't yet know the chemistry underlying this, we do know about the above-ground results.

The Takeaway

The take-home message here is that landscaping with invasives like bush honeysuckle and privet can have impacts beyond what we can see. Even though it may not seem like one invasive plant in your yard could do harm, it might very well be preventing natives from germinating and growing.

By telling us how invasive plants impact the soil and surrounding plants, Shannon‘s research can help land managers and home gardeners alike make more environmentally-friendly choices.

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