Bellevue University Professors and Students Study Unseen Impact of Native Plant Gardens

Chances are you’ve heard that native plant gardens help the environment because they require less watering and provide habitats for pollinator insects like bees and butterflies.

But thanks to a Bellevue University natural sciences research team composed of faculty and students, we now know there’s another reason – native plant gardens support more microbial diversity and beneficial bacteria in the soil in which they’re planted.

In a paper recently published in the scientific journal Urban Ecosystems, the research team found that converting turf grass, what’s traditionally found on lawns and in many community settings, to native gardens could improve the microbial diversity of soil.

Microbial diversity, for the uninitiated, is simply the existence of difference kinds of one-cell organisms, including bacteria. All kinds of different microbes surround us, but they’re too small to be seen by the human eye.

“We live in a microbial world,” commented Dr. John Kyndt, Associate Professor of Microbiology, Nutrition and Sustainability. “Microbes capture carbon from greenhouse gasses, but also produce important gases, like our oxygen. They cycle nutrients.” Bottom line, microbes are important because they create the conditions conducive for human survival and evolution of other living creatures.

Dr. Kyndt and Dr. Tyler Moore, Associate Professor of Biology, along with Bellevue University student Danielle Baldi and Rice University student Christine Humphrey worked from the premise that as native plant gardens enhance the wildlife habitat, they were possibly having an impact on the underlying soil.

“People can see that insects and pollination increase with native gardens,” said Dr. Kyndt. “But changing the soil microbiome might have a more profound impact on sustainability. Dr. Moore agreed, adding that “even a small native plant garden area,” noted Dr. Moore, “can make a rather large difference on the microbial community. And people really hadn’t been looking at that.”

To test their hypothesis, the small but mighty research team first collected small samples of soil from native plant gardens and turf grass areas in two nearby Nebraska communities.

Benjamin Vogt, founder of Monarch Gardens and a well known landscape designer, was one the homeowners whose soil was sampled. “I live on a quarter acre suburban lot right on the edge of Lincoln,” Vogt said, noting that when he moved into the newly constructed home, the builders installed sod. Today, nearly a decade later, Vogt has replaced that sod, mostly with native plants, and has minimal lawn/turf areas.

“Then we had to get the DNA out of the soil,” explained Dr. Moore. “Basically, you take the soil and you get rid of all the non-living material and you blow up the bacteria. Inside of the bacterial cells is where the DNA is.”

The lab work, which was primarily handled by Dr. Kyndt and the students, then commenced. “All three of us did some DNA extraction, some library prep, and some data analysis,” Dr. Kyndt said. The DNA was sequenced in the Bellevue University science labs. The facilities are up to date and equipped with a MiniSeq for Next Generation sequencing, as well as equipment for amplifying and visualizing DNA and the labs have the systems and experience to perform genomic and metagenomic data analysis.

From there, the DNA samples from the native plant areas were compared with the samples from the turf areas. Specifically, the research team looked at the bacterial structure and diversity, and the individual bacterial taxa differences between native plant gardens and adjacent turf grass. Bacterial taxa is a large group of microorganisms organized based on their similarity or relatedness.

The team found several potentially beneficial bacterial taxa, including Kofleria and Gemmatimonas, to be more abundant in native garden soil than in nearby turf. Both of these, the research team said, are key for helping fix and sequester atmospheric carbon that is involved in climate change, into soil. In soil, carbon is critical because it provides nutrient to plants, helps soil store water and provide it to plants, and helps give soil structure so it doesn’t erode.

Gemmatimonas, in particular, the research team found, also acts as a potential “sink,” metabolizing the greenhouse gas nitrous oxide into a form where it can’t escape into the atmosphere or into water.

Both scientists encourage people and communities to explore the impact of native plant gardens rather than simply installing turf as a default landscape choice. ““Native plant gardens can make things more interesting in the areas that you see, like birds and insects, but also in the areas that you can’t see,” said Dr. Moore.

Vogt, the homeowner, author of Prairie Up: An Introduction to Natural Garden Design and native plant landscaper, is one of those on board. “When you just have a lawn, a monoculture, there’s only so much biologic activity that’s going to happen in the soil,” he said. “And every plant makes a difference.”

Ultimately, as the team’s study found, the microbiome from the native garden soil is changed significantly and “by changing the microbiome (of soil), you’re creating a longer-term impact,” said Dr. Kyndt.

And that invisible benefit may be key, because “the smaller the organism gets,” said Dr. Moore. “The more important it is.”