Grasses feather nests of at-risk birds

MICHIGAN STATE (US) — Threatened bird populations will be better protected if efforts are made to develop biofuel from native perennials like grass, instead of ethanol staple corn.

Federal mandates and market forces both are expected to promote rising biofuel production, but the consequences of turning more acreage over to row crops for fuel are a serious environmental concern.

Ethanol in America is chiefly made from corn, but scientists are focusing on how to cost-effectively process cellulosic sources such as wood, corn stalks, and grasses.

The low cost and energy inputs involved with planting, fertilizing, and watering grasses promise substantial environmental benefits, according to new research published in the journal GCB (Global Change Biology) Bioenergy.

“Native perennial grasses might provide an opportunity to produce biomass in ways that are compatible with the conservation of biodiversity and important ecosystem services such as pest control,” says Bruce Robertson, adjunct professor of entomology at Michigan State University.

“This work demonstrates that next-generation biofuel crops have potential to provide a new source of habitat for a threatened group of birds.”

With its rich variety of ecosystems, including historic prairie, southern Michigan offers a convenient place to compare bird populations in 20 sites of varying size for each of the three fuel feedstocks.

Because grassland birds have suffered more dramatic population losses than any other group of North American birds, their future is of significant concern, Robertson says.

In the first such empirical comparison and the first to simultaneously study grassland bird communities across habitat scales, Robertson and colleagues found that bugs and the birds that feed on them thrive more in mixed prairie grasses than in corn.

Almost twice as many species made their homes in grasses, while plots of switchgrass, a federally designated model fuel crop, fell between the two in their ability to sustain biodiversity.

The larger the plot of any type, the greater the concentration of birds supported, Robertston says.

But if grasslands offer conservation and biofuel opportunities, the biodiversity benefits could decrease as biofuel grass feedstocks are bred and cultivated for commercial uniformity.

The research was funded by the U.S. Department of Energy Great Lakes Bioenergy Research Center with support from The Nature Conservancy’s Great Lakes Fund for Partnership in Conservation Science and Economics.

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