STRONG CITY, Kan. - It's easy to envision the world that pioneers encountered while looking at a herd of bison grazing at Tallgrass Prairie National Preserve in east-central Kansas.

Little has changed over the decades on the landscape of the only national park dedicated to protecting this dwindling ecosystem, which once covered 40 percent of the United States. Today, less than 4 percent remains of the original tallgrass prairie. Most of what's left is in the Flint Hills of eastern Kansas and the Osage Hills of northeastern Oklahoma.

Patches of the prairie are burned in the spring, and the early growth offers vibrant shows of wildflowers. By September and October, visitors can walk among grasses that reach chest high in damp years. But after a blistering summer with little rain, this year's show of foliage is knee-high in all but the wettest areas.

The ground was too rocky to plow in this stretch of the Flint Hills, so named for a type of quartz that litters the ground. And so this nearly 11,000-acre patch was saved - a landscape created through a combination of limited rainfall, grazing and fires that routinely sweep across the land. Only a few trees survive these conditions, and they grow mainly along the springs that dot the area.

Early explorers called the landscape the "Great American Desert." But later settlers realized the land was fertile and tilled the fields. And so it mostly disappeared. Homogenous fields of corn, wheat, soybeans and a type of grain sorghum called Milo replaced the prairie that once teemed with hundreds of species of plants like switchgrass and blue sage.

"So what was seen as a hazard for settlers 150 years ago is a benefit for us now," said Eric Patterson, the lead park ranger.

On the mostly unplowed prairie that became the park nearly 15 years ago, early settlers made use of the land much the same way as American Indians before them. But instead of hunting the millions of buffalo that once grazed upon the prairie, the settlers made use of the land to fatten cattle.

One early rancher grew so wealthy he used the area's limestone to build a grand four-level ranch home and barn on the land in the 1880s. A new visitor's center is under construction, but for now, most of the 23,000 visitors that come to the preserve each year start their tour in the ranch house, watching a short movie in the home's former dining room. Period furniture fills the rooms of the partially restored home.

From there, visitors can wander among the ranch buildings, hike more than 40 miles of trail or fish in some of the preserve's ponds.

Bus tours - the only way to drive through the park - are usually offered once or twice a day and last about 90 minutes.

Patterson hands out binoculars so visitors can get a closer look at a herd of 16 bison during one stop on the bumpy trip. All but the babies were captured two years ago at Wind Cave National Park in South Dakota and relocated here.

At another stop on a high point that challenges Kansas' flat-as-a-pancake reputation, visitors can glimpse views of rolling hills that stretch out 15 to 20 miles in any direction. Lizards and skinks scamper among the rocks. Butterflies flit among the flowers, and crickets chirp.

"It's kind of a cerebral," Patterson muses. "It's one of those environments that challenges you to reach out for it. It's almost like it wants you to be a part of its discovery. You have to look close or it's not going to really tell you much."

After the hazy skies of summer are replaced with clear, fall skies, visitors can catch stunning views of the stars, far away from the city lights. While the ranch house and barn close in the evening, the trails are open 24 hours a day. No camping is allowed in the park, but there is camping available nearby or visitors can choose fancier digs such as the Grand Central Hotel in nearby Cottownwood Falls.

"It's very serene," Amber Smyers, 26, a Kansas native who lives in Seattle, said after the bus tour ended.

Her friend, Jessica Cutting, 27, also of Seattle, had visited numerous national parks - from little-known ones in Alaska to the popular destination of Yellowstone and the Grand Canyon.

"It was pretty," she said. "I think there is beauty in everything."

But this isn't the typical national park experience, the rangers readily acknowledge. There are no stunning mountain views, canyons or waterfalls to behold. Much of the magic is underground, where the plant's roots reach 15 to 25 feet into the soil.

As awareness grew that the land was unique, Congress voted in November 1996 to create the Tallgrass Prairie National Preserve. There was resistance to the move from residents who feared federal intrusion and that the land would be taken off the tax rolls. Landowners put up signs reading, "Private Land in Private Hands" and "Say No to National Parks."

Former U.S. Sen. Nancy Landon Kassebaum came up with the idea of a public-private partnership. The National Park Service owns just 34 acres of the land; the bulk is owned by the Nature Conservancy, an environmental group, that handles grazing leases and taxpaying.

"It's really an experiment in how you can operate a national park and have the bulk of the property be in nonprofit, private ownership," Patterson said. "So far so good."

Other efforts have cropped up to save and tell the story of the tallgrass prairie and the flint-filled hills. About 55 miles to the north in Manhattan, the college town for Kansas State University, a $24.5 million center that will chronicle the geology, biology and cultural history of the Flint Hills is on track to open to visitors in April. In northern Oklahoma, visitors can see the 40,000-acre Tallgrass Prairie Preserve, a Nature Conservancy project and the largest preserved tract of native tallgrass prairie.

It all makes the words of D.W. Wilder, the one-time editor of the Hiawatha World in Kansas, seem at least a little prophetic. He wrote nostalgically in 1884 of the already dwindling prairie in an editorial the National Park Service now uses in its brochures.

"Whenever you stop on the prairie to lunch or camp, and gaze around, there is a picture such as poet and painter never succeeded in transferring to book or canvas." He lamented that people should have saved a park "ten thousand acres broad - the prairie as came from the hand of God, not a foot or an inch desecrated by 'improvements' and 'cultivation.' It is only a memory now."

If you go

TALLGRASS PRAIRIE NATIONAL PRESERVE: Strong City, Kan.; http://www.nps.gov/tapr/index.htm or 620-273-8494. You cannot drive through the park, but bus tours are available most days at 11 a.m. daily through Oct. 30; call to check the schedule. Hiking trails are open 24 hours a day.