"Understanding how to establish and manage grasslands that can provide more than biomass is an important challenge for developing sustainable, production-scale bioenergy plantings.”

HICKORY CORNERS, Mich. - A new study conducted at the Michigan State University W.K. Kellogg Biological Station (KBS) has revealed that species diversity has no substantial impact on production of switchgrass and prairie grass, two grasses that are being evaluated for cellulosic bioenergy production.

A paper on the project, co-authored by Kay Gross, a professor in the MSU Department of Plant Biology and the director of KBS, and Timothy Dickson, an assistant professor at the University of Nebraska-Omaha, was published in September in PLoS One.

The project was developed to test findings from experimental biodiversity and productivity studies, which commonly find a positive correlation between the number of plant species and biomass produced. Gross said that there are distinct challenges to applying these findings to bioenergy plantings, however.

"A number of things will constrain how well results from biodiversity experiments will translate to large-scale agriculture," Gross said. "Typically, the experimental studies use high seeding rates and involve hand weeding, two things you won't find in large agricultural operations. Growers are worried about cost when managing their crops, so they're going to seed as little as possible."

The two studies reported in the paper compared how the number of species related to biomass production in switchgrass and prairie grass plantings. One study compared switchgrass and prairie fields planted for conservation and other purposes. The other was a field experiment in which switchgrass was grown alone and in combination with various prairie species. In both studies, the team found that there was no relationship between the amount of biomass produced and the number of species.

"What we've seen is that you can get high biomass production using inexpensive seed but not much diversity," Gross said. "But bioenergy plantings have the potential to provide a number of ecosystem services besides biomass production. For example, diverse bioenergy plantings may provide habitat for pollinators or other beneficial insects, as well as high biomass. Understanding how to establish and manage grasslands that can provide more than biomass is an important challenge for developing sustainable, production-scale bioenergy plantings."

The study was funded by the Department of Energy Great Lakes Bioenergy Research Center, the Department of Energy Office of Energy Efficiency and Renewable Energy, the National Science Foundation's Long Term Ecological Research program, the University of Nebraska-Omaha and Michigan State University.