YELLOWSTONE PARK

IT'S a great time of year to visit Yellowstone. The roads to "Old Faithful" and many other top natural attractions are open and clear of snow. Plenty of wildlife photo opportunities with no "bear jams" or "bison backups" to worry about. Traffic is light, and most nearby tourist lodgings are still charging cheaper winter rates.

But the pressures on the world's first national park are mounting, and they are not just from the millions of visitors who come from around the world to see the spectacular sights.

These are pressures from outside the park: logging and mining, residential and commercial construction, oil and gas exploration, geothermal development - all can adversely affect the natural features that make Yellowstone so unique.

John Varley, the park's chief of research, sums it up as "the constant press of civilization on the boundaries of the park."

"There's a dozen resource issues that over a period of a year or two we'll have to deal with as a first priority," says Mr. Varley, who oversees the biggest research operation in the national park system. "Most of those things cycle in their intensity, but they never really go away." In red pencil, at the bottom of his working list, he summarizes these issues as "the witch's brew."

It's a brew of mounting political conflicts as well involving questions of bureaucratic jurisdiction, private property rights, and access to public resources. Above all, it has become a question of philosophy as scientists, politicians, and private conservation organizations see the values that make up Yellowstone in terms - not of boundaries as depicted by lines on a map - but as a larger ecosystem that extends well beyond such boundaries and may require tough trade-offs if the park is to be preserved.

"The Park Service has known for years that most serious threats to the parks were external," says Ed Lewis, executive director of the Bozeman, Mont.-based Greater Yellowstone Coalition. Last month a panel of experts appointed by the National Park Service cited "rising concern about externally generated degradation ... motivated by rapid change in the areas around and near many parks."

"The evolving economics and demographics of America are driving economic, social, and ecological changes in the regions outside unit boundaries. These changes often can impair park resources," said the report, which described the federal parks agency as "beset by controversy, concern, weakened morale, and declining effectiveness." (See accompanying article.)

The Greater Yellowstone Coalition lists these challenges to preserving the park's natural resources:

r Some 7,500 miles of logging roads in the national forests that surround the park.

r Another 800 miles of roads and 150,000 acres of logging planned; 12,000 active and abandoned hard-rock mining claims.

r Some 5 million acres of national forests available for potential gas and oil exploration.

r About 2 million acres around the park, subdivided into plots of 200 acres or less.

r Keen interest in developing geothermal energy, tapping extremely hot water underground.

When a new mine opens just outside the park (a gold, silver, and copper mine is planned two miles from the northeast corner), this can affect water quality. Clear-cut logging can limit habitat for threatened species like the grizzly bear, and logging roads can open up such habitat to illegal hunting. Geothermal development on private land can affect the underground "plumbing" that feeds the park's geysers, hot springs, fumaroles, and mud pots. So can subterranean oil and gas development.

In addition to the extractive industries, people are moving into the region in relatively large numbers. In the 20-county, 28,000-square-mile area known as the "Greater Yellowstone Ecosystem" (see map), population during the 1980s grew at a rate one-third faster than the three states in which Yellowstone National Park lies (Wyoming, Montana, and Idaho).

"If it were the 51st state, Greater Yellowstone would be the fastest-growing state in the nation," Varley observes. "I'm sure that's happy news for chambers of commerce, but for those of us worried about not killing the goose that laid the golden egg, that's a development that concerns us."

That population growth also reflects important economic and social changes for the region. A recent study by the Wilderness Society shows that during the 1980s, "96 percent of the new jobs and 89 percent of the growth in labor income occurred in sectors other than agriculture and the extractive industries." Over the past 20 years, the number of jobs in those traditional industries dropped from 1 in 3 to 1 in 6.

Many people move here to retire or to start new businesses - often in services. To many of them, drawn to a place of uncommon natural beauty, conserving resources like Yellowstone is important.

Three-quarters of the Yellowstone ecosystem, an area larger than West Virginia, is federal land, 20 percent is in private hands, and the rest is controlled by state agencies and Indian tribes. In all, more than 30 agencies have some say in how the land is managed.

Not surprisingly, they don't always agree. For example, the US Geological Survey concluded that some geothermal development could be allowed just north of the park boundary without too much risk. Yellowstone Park superintendent Robert Barbee countered that "any risk, no matter how small, to Yellowstone's geothermal resources is too much." He recommended no such development in an area owned by the controversial Church Universal and Triumphant, and Park Service director James Ridenour concurred.

But US Interior Secretary Manuel Lujan's report to Congress on the matter did not include the Park Service's warning, a situation that led Rep. Bruce Vento (D) of Minnesota, who chairs the congressional subcommittee overseeing parks, to call it "a case study of political manipulation."

The House of Representatives has passed the "Old Faithful Protection Act," which would prevent geothermal development on federal land within 15 miles of the park and would impose a moratorium on such development on private land. The bill awaits Senate action. Republicans are concerned that preventing such development on private land could constitute a government "taking" requiring costly compensation.

On the other hand, some conservation measures here have been so successful that areas and interests outside the park feel threatened. Bison have made such a comeback at Yellowstone that they roam onto grazing land, carrying with them a disease that harms cattle, some biologists say.

The National Park Service, many of whose professionals agree that Yellowstone needs to be treated as a complete ecosystem larger than park boundaries, is caught in the middle.

"Anytime you have a group that faces economic hardship, we're going to hear about it," says one Park Service veteran, who asked not to be named. "You can't operate as a subordinate in a bureaucracy and not realize that you have to make compromises - and we've had to compromise."

The most extreme and perhaps most controversial example of this is the five-year effort by the Greater Yellowstone Coordinating Committee (made up of senior Forest Service and park officials) to produce a "Vision for the Future" of Yellowstone. The 74-page draft plan for protecting the park's resources came under such heavy attack from outside interests that it was reduced to seven pages of what one park official calls "a stream-lined, watered-down version ... almost status quo."

Groups like the "Multiple-Use Land Alliance," which opposes restrictions on the private use of federal lands, take credit for thwarting the "vision document" effort. It also takes credit for forcing from the area, and ultimately from government service, Rocky Mountain regional director Lorraine Mintzmyer, who recently retired charging political interference.

Defining an ecosystem for Yellowstone is difficult scientifically as well as politically. "While few administrative units can operate as an island, the whole concept suffers from vague definitions," says Varley. But the bottom line is that "every time you add to civilization, you detract from wildlife values."