students gather samples in prairie restoration project Credit: Northern Illinois University.
Recent Northern Illinois University graduate Karley Chantos-Davidson (left) and biology professors Nick Barber (center) and Wes Swingley (right) take soil samples at the Nachusa Grasslands preserve.

Reclaiming prairie aids soil microbiome

Study finds Nachusa Grasslands restoration also improves soil.

Summer in Nachusa Grasslands in Illinois brings purple coneflowers and big bluestem grass. Although invisible to the naked eye, something amazing is happening beneath the array of flora at the 4,000-acre preserve near Dixon, Ill., according to Northern Illinois University scientists.

In a new study published in the journal of Environmental Microbiology, Northern Illinois University biological sciences professors Nick Barber and Wes Swingley said they have found evidence that the soil microbiome is reaping the benefits of nearly three decades of carefully managed tallgrass prairie restoration at Nachusa.

"Diverse bacterial communities are recolonizing the soils," Swingley said. "These communities closely resemble those in untouched natural prairies, despite no direct efforts at reclaiming soil functions."

Owned and operated by The Nature Conservancy, the Nachusa Grasslands preserve consists of large remnant prairie, woodlands and wetlands reconnected through habitat restoration to create one of the largest and most biologically diverse grasslands in Illinois.

"It's particularly noteworthy that restoration efforts at Nachusa are producing successes that extend beyond plant and animal biodiversity," Barber said.

"We found strong evidence that, over time, bacterial communities in the soil of sites restored with native prairie plants come to resemble the communities found in remnant prairies," he added, noting that very little was previously known about what was happening to bacteria in the soil of restored grasslands.

"This is exciting news, because it means the restoration is working at this foundational level," Barber said. "Not only do we see beautiful plant diversity, but underneath the plants, we find diversity in the soil, with bacteria that are recolonizing and recovering on their own to resemble what once lived in prairie systems throughout Illinois."

Restoration and management of natural ecosystems is a critical strategy in mitigating global biodiversity loss -- a crisis that some scientists believe is a greater threat to the planet than climate change. Prairies are highly diverse ecosystems that, as drivers of clean air and water, also contribute to the health of people and the planet.

While North American tallgrass prairies once stretched from southern Canada to Texas, they now represent one of the most widely destroyed ecosystems on Earth, with more than 90% of the original prairie lost, the university said. In Illinois, more than 99% of the prairie has vanished, replaced primarily by row-crop agriculture.

Starting in the late 20th century, restoration efforts targeting these lost prairie ecosystems became widespread, although they still represent islands in a sea of farmland. Basic questions also linger over what the goals of restoration should be, how fully a tallgrass prairie can be restored and how quickly recovery can be accomplished.

"Our work shows that restoration of a single element of the ecosystem -- namely plants -- can have beneficial effects downstream in other areas," Swingley said.

"We found that some soil microbial groups recovered from agricultural states within the first three years after restoration, whereas full recovery of known prairie microbial groups took 15-20 years," he added. "This is a shockingly fast recovery."

Restoration efforts typically include the re-establishment of diverse native plant communities, control of exotic plant species and implementation of regular activities that mimic natural periodic disturbances, such as fire and animal grazing. Bison were reintroduced to the Nachusa Grasslands in 2014 to re-establish their historical impacts as native grazers.

While microorganisms within soil are tiny, they play large roles in the environment, providing nutrients to plants and forming the base of a food web. Yet, very little detail is known about the roles different soil bacteria and fungi play.

"Soil often gets the short shrift," Swingley said. "Scientists don't really know what each microbe in the soil is doing and how they are all working together — and these are important questions for ecology as well as for agriculture."

For their study at Nachusa, the scientists characterized soil bacterial and archaeal communities in 13 tallgrass prairie plots ranging in restoration age from one to 27 years old. Using a combination of field, laboratory and computational techniques, soil communities were compared to one another as well as to local remnant prairies and nearby farm fields using DNA sequencing.

"All lines of evidence point to the soil in older restorations most closely resembling local remnants," Swingley said. "It's a profoundly positive result of decades of hard work by The Nature Conservancy and managers at Nachusa."

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