Last year the Indians seized it for a month. During the winter the farmers took it over for two days.

Tales of the Old West or the Great Plains? No, of Greenbelt National Park, in Prince George's County.

The words "national park" conjure up an image of massive redwoods in Yosemite, or the spectacular geysers of Yellowstone.

Greenbelt Park, however, is 1,100 forested acres (455 hectares, if you've already gone metric) of cool, wooded relief from the shopping malls, garden apartments and industrial sprawl that surround it along the wide traffic arteries of Kenilworth Avenue, Greenbelt Road and Goodluck Road.

A more stark contrast in environments would be hard to imagine. The Kenilworth Avenue-Greenbelt Road intersection on the park's northwest corner is one of the ten most congested in all of Maryland: 61,000 cars whiz through it daily. Not your usual setting for a national park.

Yet only a few hundred feet from those sweltering lanes of traffic lies another world, where the song of the bobwhite, the fragrance of pine, the deep carpet of needles and the cool dampness make the muffled sound of distant traffic melt away.

The park is unique in the vast national park system; the hundreds of holdings of the National Park Service are organized into catergories - national parks, seashores, historical sites and memorials. Only about 30 are designated as "parks," and those are mostly the great lands of the West. Greenbelt Park manager Jim Hankins prefers to call his domain a national park "green area." It represents a trend in the last two decades in the Park Service to develop parkland closer to urban areas. But the trend has not softened the original purpose of conserving plant and animal life in a natural setting. The rangers and technicians who staff the park bring the same training and skills as the rangers at other national parks. And they wear the same familiar green-and-gray uniforms.

The park was recovered from land that once produced tobacco and other crops. As the land wore out and was abandoned near the turn of the century, the trees began to grow back. It's now heavily wooded, and park naturalists expect that within 25 years it will be back to the deciduous forest that existed before the first settlers.

So how do the Indians and farmers fit in?

The park's proximity to Washington has given it a reluctant notoriety. The American Indian Movement's "Longest Walk" settled into the park last summer for almost a month. Last january 110 tractors of American Agricultural Movement's invasion camped there for two days before making their assault on The National's Capital.

Both groups stretched the park facilities and posed planning nightmares. The Indians, at least, gave advance notice that they were coming. Jim Hankins explains that arrangements had been worked out with the Indian leaders through the Department of the Interior - but the campground, which occupies only the southestern quarter of the park, didn't begin to fill the Indians' needs, so they just spread throughout the park."They pretty much insisted that this was an Indian encampment," says Hankins, "and no one else was allowed. They used the whole park, even some of the backwoods areas."

Still, despite the touchiness of the situation and the reluctant decision to close the park to the public, the encampment went off without a hitch. The farmers were a different story. Except for a brief inquiry about the park's facilities a month earlier, they gave no notice of their arrival.

"I told them that we had the campsite and that's all we could accommodate," says Hankins. "That was like pouring water down a duck's back. The first time we knew they were coming here was when they were leaving the Beltway. They arrived here 110 tractors strong."

And the farmers had their own ideas about making camp. Against the wishes of the park authorities, they lined their tractors on the Sweetgum Picnic Area, the only open expanse in the park. "We wanted to get them lined up on the road, but they seemed afraid that they would get blocked, that maybe they'd get circled like a wagon train." The field was frozen, and little damage was done. The caravan moved on in two days, and all was well again.

But when the park isn't being taken over by farmers or Indians, life there is fairly calm - if calm is the word for a million visitors a year. They come to pitch tents in the campsite, hike the 12 miles of nature trails, ride on the bridle trail, picnic and even, on occasion, watch a little Shakespeare.

The campsite stays open all year. "It's rare that we never have someone in there," says Hankins. "In the winter it might be down to three or four, or even one, but there's almost always someone there."

On a summer night, though, even a single vacancy is rare. Judging from the license plates on the cars and campers, it's probably the best place in Prince George's County to meet people from anywhere in America - or would be, if the campsite weren't closed to anyone but campers. "The campers don't come to be attractions," says Hankins. But not all the campers come from far-away places; about 5 percent of them are from the area. Some people find it a painless way to try out first-time camping skills and see if the kids really go for the outdoor business. It's a lot easier to call the whole thing off if home is only a few miles down the road. Not to mention saving gasoline.

If you do go to camp, arrive early: Sites are first-come, first served. On a summer day the 178 spots are usually claimed by mid-morning. For two dollars a night, campers are permitted up to five nights during the summer season and 14 per year.

In the rest of the park, come as you please. There are none of the facilities found in most public parks - tennis courts, ball fields, pools or golf courses. From the park's inception 20 years ago, planners saw a conflict between regimented sports and conservation. The romping on the picnic field is with Frisbees and kites instead of tennis racquets and nine-irons.

If you prefer to escape into the woods, guided interpretive tours are available with a ranger who will describe the flora, fauna and crawling things along the way. Occasionally a "neophyte shakedown" is held, a six-mile hike for rank beginners. If you don't want to wait for a ranger, you can walk the 1.4-mile Dogwood Trail with a self-guiding program. To prove that this is a park for all seasons, guided walks are conducted in winter, too.

For campers there are nightly programs in the campfire circle. Rangers offer a varied bill, telling strange tales of Washington, discussing camp safety or relating the lore of the Indians who first lived in these parts. From time to time these programs are also offered to the non-camping public.

All in all, the park is a delightful chunk of summer camp in the great outdoors. But one threat to the natural setting of this park-for-people, ironically, is the people themselves - not the few who would vandalize; they show up anywhere - but the well-meaning users, who, if they came in droves, could destroy the park.

"Every park has a natural limit to the number of people who can use it without danger," Hankins says. "It's fine line to have people using an area without abusing it." He doesn't foresee a need to close the park or discourage people from coming, though: There are other restraints. One is the limited parking - there are only 300 spaces for non-campers. Limited campsites are another control.

Overuse, however, has forced one change. Park Central Road, which runs two miles down the spine of the park, was closed at its southern entrance on Goodluck Road. Commuters had begun to use it as a bypass around the traffic lights on Kenilworth Avenue. Cars reached such speed that the park authorities were faced with upgrading the road or closing it. Upgrading it to accommodate the traffic would have taken the road away from the bicyclists, joggers and walkers for whom the park is meant.

A more ominous threat, in the long run, could be pressures to carve parkland into ball fields and tennis courts. Such pressures arise occasionally from surrounding towns. Party due to local pressures, the park is under a National Park Service planning study. Public hearings were held in February and will come up again in the fall.

Hankins' job includes planning for the park's future, and his mind is not closed to any possibilities; but he believes that to take scarce green land that can be used for nature and environmental study and turn it into ball fields would be a mistake. Still, he realizes that the decision will ultimately be made by the public.

"We are a people-serving organization," he says, "and the park is for all people."

And if serving the people means more recreational facilities?

A conservationist at heart, he says: "We have a reasonably good park now and ought to be cautious in our changes. Once you develop something, the reversal of it can be expensive or impossible.

He hopes that an advisory group of interested citizens will develop, a sort of "Friends of Greenbelt" that could provide park administrators with a regular flow of advice, support and criticism. Having worked with such a group in his previous post at the Cape Cod. National Seashore, Hankins believes that they can be valuable in linking citizens' desires with how park land is used.

Meanwhile the real life of Greenbelt Park goes on - oblivious, for the most part, to human concerns. The cardinals welcome back the blue jays each spring. The dogwood, laurel and azaleas bloom. The deer, raccoons and red foxes go about their business. And from time to time the Indians and the farmers come by . . . CAPTION: Picture, GATHERING AROUND THE CAMPFIRE AT GREENBELT PARK. By Abbie Rowe, National Park Service.