LITTLE HABITAT ON THE PRAIRIE - Only remnants remain of the nation's original prairie, and biologists are scrambling to understand and restore what is left

National Wildlife, June-July, 2000 by John Carey

Walt Whitman may have been bewitched by the prairie sunset's "pure luminous color fighting the silent shadows to the last." But for the scientists who study the remnants of America's once vast prairie lands, the real magic comes at dawn. Botanist Kenneth R. Robertson of the Illinois Natural History Survey, for one, likes to recall the splendor of an early summer morning when he ventured out in the darkness before daybreak to survey plants on a small patch of prairie. Striding through tallgrass covered with dew, he soon was soaking wet and oblivious to everything but the task at hand. Suddenly, the sun cut through lifting fog. All around him, thousands of dewy, zigzag-patterned webs of the orb spider glistened in the dawn's early light. "It was just a spectacular, fabulous sight," he says.

The peak working hour for ornithologists, dawn is when the prairie scientist tracks the sights and sounds of bobolinks, meadowlarks and scores of other birds. "The birds are sitting there singing their hearts away, whereas in the afternoon they're all quiet-and you would think there's nothing there," says ecologist Jill Dechant of the U.S. Geological

Survey's Northern Prairie Wildlife Research Center in Jamestown, North Dakota. What's more, early spring mornings bring the booms and foot- stomping dances of male prairie chickens searching for mates, among the most characteristic yet extraordinary of prairie sounds and sights.

Such wonders, however, are small solace for these scientists and others who study and value the habitat, as the prairie itself is in dire need of a metaphorical new dawn. Only remnants are left of the prairie's tallgrass that once carpeted the eastern side of the nation's heartland, the mixed grass that flourished through its midsection and the ribbon of shortgrass that spread before the Rockies. The tallgrass prairie has been hardest hit. Humans have plowed up or paved more than 99.8 percent of the rippling oceans of tallgrass that once covered vast areas from Canada south through the Dakotas to Oklahoma, and from Nebraska east into Indiana-in excess of 90 million acres. "People are still breaking native prairie-which is astounding," says prominent prairie ecologist G. David Tilman of the University of Minnesota.

The loss has been incalculable. "What a thousand acres of Silphiums looked like when they tickled the bellies of the buffalo is a question never again to be answered, and perhaps not even asked," conservation pioneer Aldo Leopold once lamented. Scientifically, the chance to understand the intact habitat-home to hundreds of species of plants, swept by periodic fires, grazed by vast herds of bison and elk and roamed by wolves and grizzlies-is lost. The prairie "is an ecosystem we barely know anything about," sighs Tilman.

But there is some hope. In the past few years, conservationists and scientists have protected new sites, such as a 37,000-acre prairie preserve in Oklahoma, an 11,000-acre preserve in Kansas and a 5,000- acre prairie on a former Army depot in Illinois. And years of painstaking experiments are not only starting to explain why prairies are so diverse but also to offer lessons for the conservation of forests and other habitats as well. "The renewed interest in the prairie has been really kind of incredible," says W. Dan Sverdarsky, wildlife biologist at the University of Minnesota at Crookston.

The prairie's problems began with John Deere's 1837 invention of the self-scouring, steel-bladed plow. For the first time, settlers were able to cut through the dense root systems of prairie plants such as the nine-foot-tall big bluestem. And cut through it they did. By the 1920s, tallgrass prairie was essentially gone. "Breaking prairie was the most beautiful, the most epochal, the most hopeful, and as I look back on it, in one way the most pathetic thing man ever did, for in it, one of the loveliest things ever created began to come to its predestined end," wrote novelist Herbert Quick in 1922. Much of what didn't become farmland was turned into cattle ranches. Even the small remnants that survived in places like cemeteries irrevocably changed due to their isolation and the lack of fire.

In places where most native tallgrass prairie has been lost, scientists and others have been working to restore the original habitat as much as possible. Ironically, that effort often requires the heavy hand of humans-first to replant the original vegetation where needed and then to keep it healthy, sometimes with a complex interplay of fire and grazing. Periodic fires bolster productivity and diversity while killing encroaching shrubs or trees that would otherwise turn prairie into woodland. But fire alone, particularly annual managed burns, can make the prairie less diverse and less productive. One limiting factor in the productivity of grasslands, for example, is the amount of nitrogen in the soil, and burns can make things worse by turning nitrogen in plants into nitrogen gas that is lost to the atmosphere.

The balance can be restored in part by carefully controlled grazing. In recent experiments at the National Science Foundation-funded Konza Prairie Long-Term Ecological Research Program in northeastern Kansas, researchers used fire to deplete the soil of nitrogen in sections of grassland. Then they brought in bison-and the big creatures made the prairie healthier. The degree to which grazing restored the ecosystem's diversity was a surprise for the scientists. They now think the chomping prevents tallgrasses such as big bluestem from hogging the soil nitrogen, thus allowing other species to grow. At the same time, the bison return nutrients to the soil through their manure.