Prairie research at the roots of environmental health

What lies beneath the tall prairie grasses at the Arboretum is helping restoration ecologists understand the role prairies can play in improving the health of our environment – from the soil that nourishes our crops to the air that we breathe.

“It’s all the things you can’t see that interest us,” says Chris Kucharik, an ecologist at the Center for Sustainability and the Global Environment and the lead researcher on this project. Specifically, the Wisconsin ecologist wants to understand how prairies – both above and below ground – store carbon from the atmosphere.

The amount of carbon stored in the southern Wisconsin land that had once been prairies has changed over the years, says Kucharik. When farmers began tilling it in the mid-1800s, he explains, they gradually depleted the ground of organic matter, the very material that makes soil so fertile. At the same time, he adds, much of the land’s diverse habitat was lost.

In an effort to restore this biodiversity, in 1985 the government established the federal Conservation Reserve Program (CRP), which pays farmers to turn portions of their farm fields into patches of prairie for 10- to 15-year periods. Today, some 14 million hectares are enrolled.

While this widespread effort has returned many prairie plants to the landscape, Kucharik says more strategic restoration could lead to greater gains, including a temporary offset to carbon dioxide released into the atmosphere by burning fossil fuels and partly responsible for global warming.

“There’s a lot of money being pumped into the federal program and onto the lands. We need to make sure the restoration efforts are doing all that they can.” But he adds, “Restoration ecology is a new science. There is no blueprint on the best ways to restore the land.”

To address this knowledge gap, Kucharik and his students trek across restored prairies, measuring the exchange of carbon dioxide between the atmosphere, plants and soil. They’re primarily interested in carbon sequestration, or how much carbon the soil can accumulate.

Collecting this data is tricky, however, because the ecologists cannot easily see what’s going on underground – which is home to soil microbes and dense root systems that release and store carbon, respectively. To get at the root of the matter, so to speak, they measure fluxes in the amount of carbon dioxide exhaled from the soil. They also monitor soil temperature and moisture, as well as the amount of leafy vegetation above ground – three factors that contribute to the amount of carbon sequestered from the atmosphere.

Interested in the interplay between a prairie’s composition and function, Kucharik also studies carbon sequestration among particular species, namely a tall-growing, wide-bladed grass called switchgrass. Funded by Madison Gas and Electric Company, Kucharik investigates this grass’s potential for not only storing carbon, but also for being used as a renewable, clean energy source.

While Kucharik and his students travel to many sites off campus, they collect some data in their own backyard at the Arboretum. Because this natural laboratory has some of the oldest examples of restored prairies, Kucharik says, “there’s not a better place on the planet to do this work.” An added benefit: Driving there, compared to more distant spots, generates less carbon dioxide.