Demand for corn-based ethanol is hastening the destruction of North America's Prairie Pothole region, where millions of waterfowl and migratory birds find sanctuary in the shallow wetlands of the Great Plains, according to a new study released by the National Wildlife Federation.

More than 3.2 million acres of prairie potholes were plowed under across portions of Iowa, Minnesota, North Dakota and South Dakota in just three years, from 2005 to 2007, to make room for expanding corn crops, according to data gathered by University of Michigan researchers working on behalf of NWF. Much of that additional corn was grown to meet U.S. mandates for ethanol, which can allow for cleaner combustion and curb certain tailpipe emissions when blended with gasoline.

But the conversion of the seasonally wet grasslands to corn fields comes at a high cost to wildlife, the researchers found. In some areas, species loss has been as high as 30 percent, with particular declines among prairie chickens and birds such as grasshopper sparrows, upland sandpipers and western meadowlarks.

The Prairie Pothole region derives its name from the thousands of small wetlands that dot the landscape. Once covering 25 million acres of the eastern Great Plains, vast acres of potholes have been filled and altered to make room for corn and other row crops. Photo courtesy of the U.S. Global Change Research Program.

Yet even with the known effects on habitat and species, land conversions in the Prairie Pothole region -- which extends as far west as northern Montana and encompasses parts of Alberta, Manitoba and Saskatchewan -- are expected to continue over the next five years as production of blended gasoline expands from 10.57 billion gallons last year to an expected 15 billion gallons in 2015.

And if biofuels demand remains steady, farmers could plant an additional 10.6 million acres of corn each year to meet ethanol mandates, according to researchers with the University of Michigan's School of Natural Resources. "The relationship between ethanol incentives and habitat destruction is fairly clear," states the NWF-commissioned study released last week.

U.S. corn acreage increased 19 percent between 2006 and 2007 alone, primarily due to ethanol production mandates put forth in the Energy Policy Act of 2005, according to data collected by the researchers.

But Chris Thorne, a spokesman for Growth Energy, a trade organization that represents ethanol producers, said the study is misleading and fails to account for more recent trends in corn production.

For instance, corn acreage peaked in 2007 and has been declining ever since "due to better farming practices, better seed variety and better technology," Thorne said. These changes have led to higher per-acre yields, allowing farmers last year to produce 7 percent more corn on 5 million fewer acres.

"The land-use issue is a favorite target for ethanol critics," he said. "But the truth is ... we can meet the obligations of the renewable fuel standards and other mandates without having to plow under another acre."

The NWF study acknowledges a slight decrease in planted acres in 2008, but it notes that overall corn production remains "higher than at any point in the last fifty years."

Growing scrutiny

The study is one of several to raise environmental concerns over the rapid expansion of biofuels since 2005. Criticisms have varied from ethanol refineries' air emissions to questions over whether ethanol provides a true environmental benefit since it requires energy to harvest the feedstock corn and process it into biofuels.

But for many, few impacts weigh heavier than the loss of natural landscapes and the species that rely on them as farmers look to maximize their revenue potential by planting more corn for ethanol.

"If the current trend continues, corn ethanol will increase substantially, and we'll lose the little remaining prairie we have and wildlife species will suffer," said Greg Fogel, a University of Michigan graduate student and one of the lead authors of the study.

The Prairie Pothole region provides some of North America's richest bird habitat. Conversion of shallow prairie wetlands to grow corn for ethanol could have significant effects on migratory birds and other species that have long relied on the region for breeding and feeding. Map courtesy of the Fish and Wildlife Service.

The Michigan study comes on the heels of a Jan. 6 policy paper by Rice University's Baker Institute for Public Policy that details many of the same concerns. "Increases in corn-based ethanol production in the Midwest could cause an increase in detrimental regional environmental impacts," the Rice researchers said.

And in October, a study led by researchers from the Nature Conservancy, U.S. Fish and Wildlife Service, Michigan Technical University and University of Minnesota, found that while the burning of ethanol-blended fuels can reduce greenhouse gas emissions, the land-use requirements for growing corn feedstocks are taking a toll on wildlife habitat (Land Letter, Oct. 8).

That study, published in the journal BioScience, found that the amount of land used to grow corn for ethanol increased by 12 million acres between 2005 and 2008. That includes millions of acres of land formerly set aside under the federal Conservation Reserve Program (CRP), which pays farmers to create or maintain lands in a natural state. Enrollment in the program continues to decline as more farmers plant corn to meet booming ethanol demand.

"The area in the United States devoted to corn crops is increasing, partially at the expense of perennial grasslands, with negative effects on wildlife and water quality," the study concluded.

A rich ecosystem

But the Michigan study is one of the first to narrow the focus to the Prairie Pothole region, which has been identified by conservation groups as the most threatened waterfowl habitat in North America, largely due to the conversion of wetlands and grasslands to plant row crops.

The region's unique topography -- prairie grassland pocked with shallow depressions that collect and store water -- was formed 10,000 years ago when glaciers from the last ice age receded, scouring the landscape and leaving behind large indentations, or "potholes."

An estimated 75 percent of all North American waterfowl use the Prairie Pothole region for breeding and nesting, earning it the nickname of "America's duck factory," said Gary Botzek, executive director at the Minnesota Conservation Federation.

In addition, nearly half of all migratory bird species on the continent use the region's fertile grasslands for breeding, nesting and resting during spring and fall migrations.

Once 25 million acres in size, the Prairie Pothole region has been decimated by two centuries of farming, with some areas losing more than half of their pothole wetlands, according to the University of Michigan study.

"Grassland birds were already in steep decline, making this additional habitat loss quite alarming," Botzek said of the study results. "We need to change course if we want to keep this ecosystem working for the entire nation's benefit."

Potential climate impacts

In addition to loss of wildlife habitat, the dwindling Pothole Prairie could affect climate conditions, the Michigan researchers concluded.

The region's rich prairie soils and plant roots hold vast amounts of carbon. But when those soils are plowed and planted, they can release up to 59.8 tons of CO2 per acre over 50 years of cultivation, the study notes.

"Certainly, when native grasslands are converted to cropland, you lose a substantial amount of the carbon," said Richard Conant, an ecologist at Colorado State University in Fort Collins who has studied the role of carbon offsets. "On a global scale, [plowing the prairie] might not seem very significant. But in terms to the active land sink in the U.S., it could be substantial."

And that makes the potential loss of the prairie to corn crops "a major concern," said Julie Sibbing, the National Wildlife Federation's director of global warming, agriculture and wildlife.

The Agriculture Department has been working with farmers, ranchers and forest managers to maximize agricultural lands' ability to soak up atmospheric CO2. But at the same time, USDA has corn-growing incentives, such as crop insurance that all but guarantees a profit regardless of crop yield -- one of the current policies the study has recommended be changed.

Click here to read the University of Michigan study.

Streater reports from Colorado Springs, Colo.