The North American prairie once covered 170 million acres, making it the largest ecosystem on the continent, as well as the most biologically diverse. Today, 96% of that prairie is gone. Many property owners and rural communities are seeking to restore native prairie plants, but after years of topsoil loss, pesticides, or invasive plants, they’re finding the soil is missing one key ingredient—fungi smaller than a period at the end of this sentence.
Dr. Liz Koziol, a research professor at the University of Kansas, studies arbuscular mycorrhizal fungi (AMF) and their role in the success of native prairie plants. “Some of these [native prairie] plants can live longer than humans, and AMF associate with them for this time,” she said. “Their relationships are decades and decades long.”
In fact, AMF have symbiotic relationships with more than 80% of land plants. They live in the soil and survive by inserting themselves into the plant’s roots. From there, they help the plant take up nutrients and water. In exchange, they harvest some of the plant’s carbon—the same as a human would after fertilizing and watering a garden.
“Many plants can’t survive without the help of their fungi,” said Dr. Gail Wilson, a professor at Oklahoma State University who also studies AMF. “You don’t want to put plants in if there aren’t fungi there.”
In a study of 54 prairie plant species, Koziol found that planting native prairie plants with their traditional AM fungi increased their chances of surviving by 40%. With AMF, the plants also grew three times larger in the first year. Koziol notes that it’s especially the late-successional prairie plants—the ones that are slow to return after a site has been disturbed—that need fungi in the soil.
Restoration Spaces May Be Missing Fungi
Although AMF are tiny, they are particularly vulnerable—to tilling, sunlight and pesticides. An old field that has some native prairie plants may still have fungi. But other areas, such as anywhere that Round-Up has been sprayed or the topsoil has been removed, may not.
“If you have no plants for quite a while or have non-native plants that don’t form associations with fungi, then the fungi die because they don’t have a way to get carbon,” Wilson says. “The fungi need the plant and the plant needs the fungi. If you mess that up, you can’t get either to grow… The biggest challenge in native plant restoration is getting the soil back to being healthy enough to support the plants.”
Native and Non-native Fungi
The relationship between AMF and plants isn’t unique to prairies. For some gardeners and farmers, using fungi to help plant growth is more appealing than relying on fertilizer or genetic modification. AMF soil amendments can be purchased in garden stores and online. But many commercial products use fungi that are easy to cultivate in a lab—because of their aggressive growth.
Koziol, whose work focuses on fungi native to prairie ecosystems, expressed concern about introducing non-native fungi to the soil. She points to a recent study in Saskatchewan, Canada, where researchers found non-native fungi changed or suppressed native fungi in certain sites. Areas without healthy, diverse native fungi were particularly vulnerable.
“We’ve clearly seen adverse effects from adding non-native plants,” says Wilson. “Why take the chance of adding a kudzu below ground?”
The Benefits of Restoration
But for landowners and communities willing to seek out native fungi, the benefits of restoring not just a few grasses but a fully diverse prairie ecosystem can be huge. Plants like rattlesnake master, coneflowers and milkweed need their fungi, and insects need the plants.
“Having a fully restored plant system means pollen for bees and food for animals,” Koziol says. “If you only have plants that don’t need AMF, then you don’t have a full system. You’ll go months without food or blooms for pollinators.”
Brad Guhr, an education coordinator and prairie restorationist at Kansas’s Dyck Arboretum agrees. “The more diversity you can build into that system, the better off it will be. It will attract more wildlife. It will be more resilient.”
Resilience is especially important in the face of invasive plants. A fully restored prairie is less vulnerable to invasives than a partially restored one.
How Property Owners Can Reintroduce Native Fungi to the Soil
If you want to restore native prairie plants to your property or community, you may need to remove invasives first. Wilson said the best way to do this is to till Round-Up into the earth, even though it’s bad for the soil and you’ll need to add back beneficial fungi. Soil amendments with AMF may be called bio-fertilizer, fungal mix, mycorrhizae mix or a microbial inoculant.
If your soil needs a boost, Wilson said, “Do your homework. Look for media that are from grasslands or your region. There are good companies out there.”
The scarcity of native prairie fungal mixes led Koziol to start MycoBloom, a business that sells AMF from unaltered prairies in the Great Lakes region.
For new plantings, she’ll use a seed drill or broadcast the inoculant over the soil and till it into the top four inches. Sometimes she plants inoculated plugs that she’s grown in her greenhouse. She will also use a “side-dressing” approach, where she buries a few tablespoons of fungal amendment near existing plants or at the bottom of a hole for new seedlings.
“If you get fungi established, the restoration should be low input and long-term success,” Wilson said. “It makes for a lower budget on your project.”
For property owners who don’t live in a prairie ecosystem, working with fungi and plants native to their region could still be beneficial. Most recently, Koziol has been helping an organic vegetable farmer use AMF to harness soil fertility without adding fertilizer. They’re applying the same methods she’s used for native restoration. So far, she said, the results have been great.
Phoebe McIlwain Bright is a science and environmental writer who often writes about ecology.