AS Yellowstone National Park prepares for its unofficial opening to vacationers Memorial Day weekend, this place of beauty and wonder faces unusual challenges.
It's not just the increasing numbers of traffic-jammed visitors armed with video cameras to record the wildlife, the thermal pools, and each other. Or the constant battle with potholes pocking the hundreds of miles of two-lane roads after a rough winter in the northern Rockies. Or even the approaching summer fire season.
These days, the politically touchy question is: Should Yellowstone be treated as something without clear boundaries, a larger ecosystem including other government jurisdictions and parcels of private property deserving protection for their unique environmental qualities?
''Yellowstone is not an island,'' says park superintendent Mike Finley, who has jumped into the fray in a way uncharacteristic for a guy in a Smokey Bear hat.
Yellowstone bison have been wandering across park borders and onto neighboring ranches, some of them carrying a disease that threatens cattle. Wolves, reintroduced to the park earlier this year, also are seen as a threat to ranchers.
Meanwhile, there are plans for a large gold mine just outside the park that critics -- including Mr. Finley -- warn could be environmentally damaging for years to come.
The controversy over such issues is not just regional or even national. Founded 123 years ago as the world's first national park, Yellowstone is listed as a ''World Heritage Site'' under an international treaty. The treaty stipulates that the United States protect the park from ecological threats -- including those outside of Yellowstone.
In February, 14 conservation organizations asked the World Heritage Committee (which is located in Paris and is part of United Nations Educational, Scientific, and Cultural Organization -- UNESCO) to investigate whether Yellowstone should be included on the ''List of World Heritage in Danger.''
In response, World Heritage Centre director Bernd von Droste last month reminded the US Interior Department that ''if proposed developments will damage the integrity of Yellowstone National Park, the [United States] has responsibility to act beyond the National Park boundary.''
While the park itself covers 2.2 million acres, the ''greater Yellowstone ecosystem,'' as park officials and environmental advocates call it, encompasses some 18 million to 22 million acres in Wyoming, Montana, and Idaho. Most of this is federal land, including national forests open to grazing, logging, and mining. About 20 percent is private property, where vacation homes and other development is popping up -- particularly in the river valleys.
Pressures on the park these days are symbolized by efforts to revive and protect two animal species: bison and wolves.
At the turn of the century, there were fewer than 100 bison here. Now, the Yellowstone herd numbers between 3,500 and 4,000.
The problem for nearby ranchers is that some of the bison carry the brucellosis bacteria, which can cause spontaneous abortions in cattle. (The irony is that the disease was first introduced to bison, elk, and antelope by domestic cattle in the 19th century.)
In the winter, some bison migrate across the park boundary into Montana. A group of 100 or so recently could be seen moving steadily along the Madison River toward Yellowstone's west entrance.
Although laboratory tests show bison can contribute to the transmission of brucellosis to cattle, this has never been documented in the wild. Still, state and federal agencies have ordered that hundreds of bison outside the park be shot.
In January, Montana sued the US departments of agriculture and interior for what officials there see as a dangerous invasion. ''Potential conflicts between Yellowstone National Park bison outside of park boundaries and private interests in Montana include damage to fences, consumption of hay, physical hazard to people, transmission of brucellosis to cattle, and transmission of undulant fever to humans,'' states the Montana complaint.
Meanwhile, US Sen. Conrad Burns (R) of Montana (a former livestock auctioneer) earlier this month introduced legislation calling for the capture and slaughter or neutering of all Yellowstone bison that test positive for the bacteria. The rest of the bison would be quarantined under the Burns bill. A committee of federal agency representatives, plus wildlife and livestock officials from Montana, Wyoming, and Idaho, is trying to sort out scientific fact from assertion.
Aside from the question of disease, there are differences of opinion over the park's ''carrying capacity'' for bison. In a letter to President Clinton last December, Montana Gov. Marc Racicot (R) asserted that the number of bison in the park today is ''way more than the park's available forage can support.'' The federal National Biological Service, on the other hand, does not believe that Yellowstone is being overgrazed by bison.
''Unfortunately, science is not dictating this problem -- emotion is,'' says park superintendent Finley. ''I see two real victims in this controversy,'' he adds. ''One is the ranchers in the tri-state area, and the other is the bison itself.''
Like bison, wolves are now a reminder here that Yellowstone is one of the last intact temperate ecosystems with virtually all of its native wildlife species present.
Late last month, 14 adult wolves were released from pens in Yellowstone, where they had been brought from Canada. Radio-collared and checked daily by aircraft, they have been feeding on elk and bison, forming packs, and preparing to bear offspring.
Early this month, US Fish and Wildlife Service biologist Joe Fontaine came upon a new litter of eight pups near Red Lodge, Mont., about 40 miles outside the park.
This was good news for those trying to help the gray wolf recover from its status as an endangered species. The goal of the recovery plan is to have 10 packs of about 10 wolves each reproducing in the area for three consecutive years by the year 2002.
Another group of 15 Canadian wolves was brought to central Idaho as part of the wolf recovery program. At the same time, wolves have been entering Montana from the north on their own since the early 1980s with the first documented litter of pups in 1986.
''What we're trying to do is accelerate what appears to be a natural process,'' says Wayne Brewster of the Yellowstone Center for Resources at park headquarters.
Natural process or not, the idea of wolves sharing habitat with humans draws strong reactions. Park visitors now can look forward to a glimpse of this elusive animal or perhaps the sound of its howl. (Fifteen percent of visitors to Denali National Park in Alaska see wolves.)
But ranchers are wary. Cattlemen's groups are suing the federal government. The Wyoming state legislature passed a law setting a bounty on wolves, which Gov. Jim Geringer (R) vetoed. An unemployed carpenter has been charged with killing and beheading the mate of the female that bore the litter near Red Lodge. Last week, the mother wolf and her pups were moved back into a pen inside Yellowstone. When strong enough to survive on their own, these wolves will be released again.
''People get very emotionally involved with wolves -- either for or against,'' says Mr. Brewster. ''And that's very frustrating.''
Meanwhile, the broader debate over the Yellowstone ecosystem continues. For several years in a row, a few lawmakers from other parts of the country have tried to generate interest in a ''Northern Rockies Ecosystem Protection Act.'' This would strengthen protection of more than 20 million acres of federal land in Montana, Idaho, Wyoming, Oregon, and Washington -- including Yellowstone.
The proposal is not expected to go anywhere, particularly since no lawmaker from any of the affected states supports it. To show what they think of the idea (and particularly its lead proponent, Rep. Carolyn Maloney (D) of New York) members of the Montana House of Representatives passed a resolution to have wolves reintroduced into Central Park.