Rare Tallgrass Prairies Hold Diverse Life Just Beneath the Surface

Tallgrass prairies once spread across the vast plains of America, providing a home to dozens of species of grasses that could grow to the height of a man, hundreds of species of flowers and herds of roaming bison. Yet these prairies also hosted other species--some that weren't as easily seen. Now, scientists have gotten a closer peek at a vitally important community of tallgrass prairies: the diverse assortment of microbes that thrived in the rich soils beneath the grass.

"These soils played a huge role in American history because they were so fertile and so incredibly productive," said Noah Fierer, one of the researchers, in a news release. "They don't exist anymore except in really small parcels. This is our first glimpse into what might have existed across the whole range."

In order to better examine the unique ecosystem that thrived beneath the tallgrass prairie, the researchers examined samples of soil collected from 31 different sites spread across the prairie's historical range. The samples came largely from nature preserves and old cemeteries. Why? Most of the prairie these days has been plowed and replaced by corn, wheat, soybeans and other crops.

"It was very hard to find sites that we knew had never been tilled," said Frierer in a news release. "AS soon as you till a soil, it's totally different. Most gardeners are familiar with that."

After collecting the samples, the researchers used DNA sequencing. This allowed them to characterize the microbial community living in each soil sample. The results revealed that a poorly understood phylum of bacteria, Verrucomicrobia, dominated the microbial communities. In addition, they found that each sample was unique, despite the fact that Verrucomicrobia dominated most. The researchers also used a model to help reconstruct what the soils might have looked like in the past.

Currently, the scientists are hard at work trying to grow Verrucomicrobia in the lab in order to better understand what it does and the conditions that it favors. Learning more about this organism could allow scientists to better improve soil conditions.

"Here's a group that's really critical in the functioning of these soils," said Fierer in a news release. "So if you're trying to have effective prairie restoration, it may be useful to try and restore the below-ground diversity as well."

The findings are published in the journal Science.