Native grasses offer a bird-friendly alternative to corn for biofuel production, according to new research from Michigan State University in East Lansing.
Biologist Bruce Robertson and colleagues, focused on three varieties of fuel feedstock in southern Michigan: corn, switchgrass, and mixed-grass prairie. They found 1 1/2 times more bird species in tall prairie grasses than in corn crops. Switchgrass ranked in between the two.
“These plants, these birds, are cleaning our water,” Robertson said. “They’re holding down the pest populations.”
In addition to plant type, density was a major factor in bird population. As growth increased, so did the number of bird species, until plant growth became too dense. Robertson says this information is vital for establishing cultivation practices for the emerging biofuel feed stocks.
“We can’t expect farmers, growers and producers to voluntarily forego making as much money as they can,” Robertson said. “We have to explicitly recognize that there are these trade-offs between the economics of a crop and, in this case, biodiversity.”
Robertson urged that public-policy makers implement this approach through incentives, tax breaks and recommendations for growing and harvesting crops in a way to sustain animal populations and preserve ecosystems.
While the study, recently published in Global Change Biology Bioenergy, shows that using native grasses for biofuel production benefits bird species and ecosystems, actual conversion of the plants into biofuel could be a long way off.
“It still is not cost effective at industrial scales to convert plant biomass into ethanol products,” said Randy Jackson, an associate professor at the University of Wisconsin-Madison and project leader at the Great Lakes Bioenergy Research Center.
The U.S. Department of Energy established the regional center, led by the University of Wisconsin-Madison with Michigan State as a major partner, in 2007. Great Lakes is working toward developing technology to convert grasses and other cellulosic plants into biofuel by developing improved plants and processing methods.
The major difference between corn and grasses is how and when they grow, Jackson said. Grasses are a perennial plant, meaning that once the plants are in the ground they continue to grow year after year as opposed to an annual plant such as corn, which has to be reseeded for each growing season. The seeding and tilling process releases carbon, which doesn’t happen with a perennial plant.
Jackson estimated kinks in the conversion process should be worked out within the next five to 10 years. But the larger issue, farmer acceptance and adoption of perennial grass crops, is still an unknown.
“Society has to demand the ecosystem services that they get from these perennial grasses,” Jackson said. “That would manifest itself as fewer subsidies for growing corn and more subsidies for planting perennial grasses.”
In addition to providing a safe haven for bird species, perennial grasses provide other benefits that row crops, such as corn, do not.
“They’re providing pollinating services,” Robertson said. “Corn does not support pollinators. You don’t have food if you don’t have bees.”
