Sustainable by Design

How do we get biomass from the land while preserving—or even benefiting—its living communities? Whichever course we take, researchers at the CALS-led Great Lakes Bioenergy Research Center are determined to put all pros and cons on the table.

“What does it mean, then, if we can basically remove as much debris as possible?” he asks. In a series of studies in different parts of northern Wisconsin, he and a group of collaborators are now trying to find out. Similar to Kucharik’s work at Arlington, they’re examining the effects of intense debris harvesting on forest carbon: How much is released and how much is stored? They’re also measuring the amount of nitrogen forests lose when different amounts of biomass are taken—data that Mladenoff will then use to model impacts on forest productivity long-term.

And that’s the easy part, he adds. Just as worrying, but much harder to assess, is how simplified forest landscapes scoured clean of woody debris will affect the birds, insects, amphibians and mammals that rely on it for habitat. “People are just starting to think about that,” he says.

So does this mean the practice is wrong? Mladenoff definitely has his views on the subject, but he also thinks “right” or “wrong” is somewhat beside the point. “Biofuels may not end up making sense ecologically or economically, but society may still decide to pursue them. Maybe it’s better than going to war with Iran over oil, for example,” he says. “But the way I put it is, we need to know what the trade-offs are. Then society can make a policy decision.”

Jackson agrees, noting that mixtures of plants chock-full of ecological benefits may be something of a mixed bag as well. “It’s pretty clear from our two years of data that the extra services we may get from a diverse system are likely going to be offset by lower productivity overall,” he says. Few, if any, bioenergy crops will probably ever rival King Corn’s sheer biomass-growing power, for one, especially on rich soils like those at Arlington. But even monocultures of switchgrass often are more productive, easier to manage—and thus more attractive to farmers—than mixtures of species.

So what’s needed now is a full accounting, Jackson says. “Okay, the diverse system is less productive. But what does it do to greenhouse gas emissions, carbon accumulation, nitrogen retention?” he says. “Are we seeing extra benefits there, or is maybe the switchgrass monoculture just as good on all those accounts as diverse prairie?”

He believes the sustainability group’s biggest contribution will be to quantify all those trade-offs and present them to farmers, policy makers, land managers and citizens in a way they can easily grasp. And then it will be up to us to decide: Is fuel the utmost goal? Or are ecosystem services also worth pursuing—and paying for? Because like the ladybeetle, what the agricultural landscape looks like, how it functions, matters to us. But unlike her, we have a say in shaping it.