Living Laboratory

With its rivers, lakes, forests and plains—not to mention its cityscape—Minnesota is a hotbed for environmental research with global reach.

Living Laboratory

"Land Clearing and the Biofuel Carbon Debt," the globally-cited report by U of M ecologist David Tilman (right), the Nature Conservancy's Joe Fargione (left) and other experts, evolved, in large part, from research on Minnesota's prairie grasses.

At the end of the last ice age more than 10,000 years ago, the glaciers retreated from this region and their meltwaters pooled to form an astonishing feature: Lake Superior, the world’s largest freshwater lake by surface area, holding 10 percent of the world’s surface freshwater.

The glaciers also left tens of thousands of smaller basins that filled with water to make lakes—while the boreal forest, which had fled southward against the cold, returned north into the once-icy landscape. As the land warmed, prairie grasses spread north and east. In the warmest days some 7,000 years ago, they covered what is now the Twin Cities.

But as the climate cooled slightly, deciduous and boreal forest pushed back the prairie. These climate shifts created the Minnesota we know today, “out on the edge of the prairie,” as Garrison Keillor describes it.

We sit in the middle of the continent, at the intersection of three ecosystems: The southernmost boundary of the boreal forest; the northwestern edge of the deciduous forest, stretching in a ribbon from southeast to northwest through the state; and the eastern edge of the prairie rolling 1,000 miles west. Dotted across the landscape are more than 11,000 lakes and the headwaters for three major rivers, with the massive Lake Superior serving as our northeast border.

Such diverse habitats allow for the activities and industries that define life and work in Minnesota, from fishing, skiing and swimming to hunting, farming and forestry.

They also create a prime locale for environmental research, says University of Minnesota Provost Thomas Sullivan. “We have the perfect ecosystems for studying the environment in ways that have applications worldwide.” 

Studies of our state’s forests, at the frontline of climate change, can provide a window into how forests will respond in other places. Research on biofuels made from native prairie grasses is informing the future of biofuels everywhere. And tracking persistent toxic pollutants in the Great Lakes provides a bellwether for how these pollutants behave globally.

Thanks to this dynamic setting, Minnesota researchers see the landscape as an ideal “natural laboratory.”

“In the Duluth area, we have a laboratory in terms of developed versus undeveloped streams,” says Lucinda Johnson, a landscape and aquatic ecologist at the U of M, Duluth. To track the effects of development on streams, Johnson is using the contrast between pristine streams feeding into Lake Superior and those entering the lake near shoreline developments.

The extreme storms and fires that tear through Minnesota woods have created a natural experiment for understanding how the forest recovers afterward, says U of M forest ecologist Lee Frelich. He’s been tracking recovery from a 1999 windstorm that wrought havoc in almost half-a-million acres of trees in Superior National Forest.

“We’re observing whether the forest is going back to what it was or whether it’s moving to some new state,” says Frelich. “It’s too early to tell,” he adds, but such experiments may help researchers make predictions about the future of forests elsewhere.

 Lee FrelichStuck in the Middle of Change

A great deal of the environmental research going on in Minnesota is oriented toward understanding how ecosystems will respond to climate change. And with good reason, says Frelich.

“We have the triple point where [the ecosystems] all come together,” he says. “We’re right in the middle of the continent, and right on these edges, so we think things are going to happen here faster than anywhere else.”

Models predict that boreal forests may retreat 300 miles north under warming. With threats to our deciduous forests from climate change, fragmentation of the habitat, overgrazing by deer, and the spread of invasive species, the woods may all but disappear from the state. Minnesota’s moose population, which relies on forest habitat, is already declining.

During a recent symposium at the Minnesota Landscape Arboretum, Frelich and other academic and government researchers discussed how to manage the state’s ecosystems under climate change. The experts considered the approach of protecting endangered species and maintaining forest habitats by transplanting southerly species further north, and which “assisted colonization” approaches might work the best.

“I think assisted colonization is going to be a much bigger deal for Minnesota than it is in other places,” says Frelich. “We have these really sharp changes where there are completely different species in different parts of the state.” 

Deborah Swackhamer, a founding fellow and former interim director of the Institute on the Environment, says that figuring out how to adapt to climate change is a strong focus at the U of M.

“A lot of people don’t like to talk about adaptation because it sounds like we’re giving up and throwing in the towel,” says Swackhamer. “But it’s definitely going to be one of the strategies.”

Lake Superior is another critical sentinel for climate change. Jay Austin at the U of M, Duluth, has documented warming in Lake Superior that is roughly twice as fast as the regional air temperature increase.

Swackhamer warns that this warming may remobilize persistent organic pollutants like polychlorinated biphenyls—quantities of which have remained sequestered in the lake water since their ban in the 1970s.

“Even a minor 2-degree warming in summer would have a huge impact on the volatilization of chemicals,” she says, pointing to the large-scale implications. “If we see contaminants in Lake Superior, it means they’ve been globally transported. They’re a pretty good canary in the mine.”

Johnson is also working to understand how climate change will affect our ecosystems, specifically the prairie pothole wetlands of western Minnesota. Through a blend of experiments and modeling, Johnson is studying how frogs living in these wetlands will adapt to climate change, especially with the added pressures from herbicides and other types of agricultural runoff.

Her research has shown that some wetlands tend to dry out and stay dry for long periods of time. Since frogs can’t move very far across the landscape in their lifetime, they need groups of wetlands with a variety of water levels to survive. “This will form habitat that is suitable for frogs over a wide variety of climatic conditions,” Johnson explains.

Why should we care about frogs? For starters, says Johnson, they are important food for ducks, which are vital to the hunting economy. And if you’re not a hunter, you should still appreciate them: “They consume tons and tons of mosquitoes.”

Prairie Home-grown

With ever-more food crops grown to make ethanol for fuel, Minnesota has become a major player in the biofuel economy. Going against the grain, so to speak, U of M ecologist David Tilman is looking for alternative biofuels approaches in his research at the Cedar Creek Ecosystem Science Reserve.

In the past year, Tilman has become well known for his biofuels research, though he says he entered the field by accident. “I never planned on being interested in biofuels. But I think early on people were so enamored with the potential of corn ethanol that they weren’t asking the questions that were necessary,” such as how much water, fertilizer and energy are needed to grow crops for ethanol.

“At the same time, we had this long-term experiment at Cedar Creek,” says Tilman, who started out by studying the effects of biodiversity on prairie grass yields, asking how the number of species in a plot affected the amount of biomass that grew.

Switchgrass was a species that was part of his experiment, and the native plant soon emerged as a major candidate for second-generation biofuels: cellulosic ethanol made from the woody parts of plant stems and leaves. Developing processes for making ethanol this way has proved relatively difficult, but this approach has the advantage that the ethanol could be made from plant waste or crops like switchgrass that don’t require irrigation or fertilizer.

“The 16-species plots were always much, much more productive than any of the species growing by themselves,” says Tilman. “We had 238 percent more energy in these plots compared to switchgrass growing by itself.” And, since the plants’ roots remain in the soil, they actually sequester carbon, making the process a net carbon sink.

Now Tilman’s group is testing how fertilization and irrigation affect grass plots. He’s determining the optimum amount of fertilizer that would allow the plants to use it all without creating runoff, and whether plots of prairie grasses might even be useful in helping to capture agricultural runoff from other fields.

“These are sort of off-the-wall ideas,” he says, “but we’re trying to find out if there can be some synergy.”

 Minneapolis skylineAll That, and a Big City

While the varied ecosystems in Minnesota allow research here to be of global relevance, the presence of the Twin Cities metro area also presents an opportunity for studying urban environmental problems that trouble cities everywhere.

U of M civil engineer Paige Novak works with Swackhamer to study the minute concentrations of hormonally active chemicals in our wastewater. One source of these is various pharmaceuticals, especially birth control pills, which end up in urine and make their way to wastewater treatment plants.

Other sources Novak has looked at include facilities that process plant matter, such as paper mills and soybean processing factories, because plants naturally make estrogenic compounds.

The compounds are of concern because they may exert hormonal effects on wildlife, even at low levels. Novak and Swackhamer have found that the two wastewater treatment plants they’ve studied remove about 90 percent of the estrogenic compounds from the water entering the facility. Yet, the remaining 10 percent could still present problems.

“Both of these plants are already doing ‘above and beyond’ levels of treatment,” says Novak. “Now we’re doing studies in the lab to see if we can improve the amount that’s removed.”

Beyond the ideal physical environment, Novak says the state’s progressive stance also supports her research. “We have access to these facilities which are forward thinking,” she says, adding that the wastewater treatment facilities in many other states might not have cooperated.

Swackhamer also values the region’s political and social climate. She believes the combination of landscape, culture and expertise in Minnesota lays a foundation for the U of M’s Institute on the Environment to thrive.

“So much of what has been done in environmental research is to study the problem after it has occurred,” says Swackhamer. “What I really would like to see us do is research that helps us get ahead of the curve, research that will prevent problems—not just to provide solutions to yesterday’s problems.”

JESSICA MARSHALL is a lecturer in the U of M’s School of Journalism and Mass Communication. She is a science and environmental journalist, and the environment correspondent for Discovery News.