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ALBUQUERQUE—Cellulosic biofuels extracted from native switchgrass could lend a helping hand to imperiled birds that depend on vanishing prairies in the Midwest.
With palm oil plantations overrunning Indonesian rainforests and corn-based ethanol in the U.S. spurring new deforestation abroad, it may seem like biofuels and biodiversity don't mix. That's why ecologist Bruce Robertson at Michigan State University's W. K. Kellogg Biological Station and his colleagues wanted to know how birds and bugs would fare if the U.S. switches from corn-based ethanol production to cellulosic biofuels based on grasses. The U.S. Environmental Protection Agency is pushing these biofuels to help achieve further reductions in greenhouse gas emissions. Switchgrass has been singled out for biofuel production because of its low water requirements and high nutrient efficiency, along with the fact that it is native to the U.S.
Robertson and his team went bird-watching in native prairie, switchgrass plantations and cornfields in Michigan. In the latter, bird diversity was limited to horned larks, killdeer and cowbirds. Large plots of switchgrass, on the other hand, supported 19 of the 20 bird species found on native prairie, including the Henslow's sparrow and the bobolink, and were used as a stopover by migratory birds. The team also found more insect species on switchgrass than on corn—although they still fared worse than those in the native prairie.
"Switchgrass production is going to have some measurable biodiversity benefits both for [insect] and grassland bird populations," Robertson said Tuesday at the Ecological Society of America meeting, held here this week. He added that the switchgrass harvest could occur in the fall, after the birds' breeding season, which would reduce its ecological impact. "As a monoculture," he warns, "it may not be a good place for them to survive and reproduce in the long term."
Max Henschell of Michigan Technological University, who has also studied birds in switchgrass, agrees with the findings. "Switchgrass," he says, "will definitely be better than corn." He suggests that interspersing native broadleaf vegetation in switchgrass monocultures could boost bird numbers even further.