THE GRAVELLY RANGE, MONTANA -- Amid imitation wolf howls, tribal "war dancing" in the buff and calls for a return to the pristine past, the annual Earth First convention fizzled to an end this week, leaving many wondering whether the loose-knit ecological organization will soon split between radical activists and mainstream environmentalists.

Fewer than half of the expected 500 people came here for the week of open-air seminars and spontaneous discussions given at the "Round River Roundup," and most of those seemed more interested in a romanticized oneness with nature than in embracing "ecotage," or ecological sabotage such as driving spikes in trees and ruining road-grading equipment.

"We have to turn back the clock on 3,000 years of planetary abuse or it's all been just one big Ghost Dance," said Lone Wolf Circles, a former motorcyclist from Los Angeles and now prominent Earth First activist whose blond hair and handlebar mustache belie his adopted Native American name.

The rendezvous was the 11th such Earth First convention since the amorphous group of ecological radicals appeared in the mid-1970s. Set in a meadow ringed with aspen and Douglas fir in the panoramic foothills of the Gravelly Range west of Yellowstone National Park, this year's meeting attracted a mixture of ecological activists from across the country and Canada.

Compared to those at previous Earth First conventions, attendees this year seemed to be younger; most were white and college-age. Many were off on "meaningful" summer vacations, wending their way from the Rainbow People's gathering in Minnesota to the Redwood Summer protest in northern California.

With a few exceptions, the movement's hard core of ecological radicals, including Dave Foreman, were conspicuous by their absence, suggesting to some that the movement may soon split into ultra-activists devoted to "stopping the machine" and incrementalists opposed to the continued use of "ecotage," the activity that has made Earth First synonymous with spiking trees to deter logging and draining oil from heavy-duty road-working equipment so that engines will seize. Foreman was arrested last year in an FBI sting on charges of attempting to cut power lines to a nuclear reactor in Arizona.

The theory of such acts of destruction to slow or stop development was first expounded in "The Monkey Wrench Gang," a 1975 novel by the late Edward Abbey that remains the bible of Earth Firsters.

In the course of the rollicking novel, a marijuana-smoking Jewish girl from New York and her lover, a Scotch-sipping, older doctor from New Mexico, team up with a fallen Mormon river-rafter from Utah and his new-found, psychopathic assistant, a Vietnam veteran obsessed with guns and explosives.

Financed by the doctor, the four blow up bridges, dams, coaling stations and everything else they perceive as detracting from the natural beauty and flow of the Colo- rado River until they are caught by the law. Throughout the novel, Abbey spells out how best to sabotage various development schemes.

The characters in the book became the models for radical Earth Firsters, but now, eco-radicals, Rainbow People, New Agers, feminists, gays and other groups all claim to fall under the Earth First umbrella.

"The problem with Earth First is that it looks like an organization, but it isn't," said one participant in the roundup. "Anyone who wants to can say they belong."

Foresters, loggers and miners have labeled members of the group "ecological terrorists" and are increasingly ready to counter Earth First antics with violence. Earth First members, for example, have said they have been shot at, but hunters have asserted that the demonstrators had come between them and game.

"We are here to ensure the health and welfare of all concerned," said one of the numerous police officers guarding access to the roundup site. Concern that the Earth First conventioneers would bring drugs and guns with them contributed to police apprehension; keeping local ranchers and timber-industry employees from attacking the meeting was another worry.

"We have to expand our horizons," Darryl Cherney told reporters at the rendezvous. "We have to go beyond strictly wilderness issues to dealing with systematic social change." Cherney received national attention when a pipe bomb exploded in a car carrying him and Earth First activist Judi Bari in Oakland in May. They claimed the bombing was in retaliation for their work in organizing Redwood Summer protests against the lumber industry, but they were arrested for investigation of explosives possession and transportation because police suspected they were carrying a device that accidentally went off. On Tuesday, prosecutors announced that charges will not be filed against Cherney and Bari, which Cherney's lawyer, Douglas Horngrad, said was "confirmation of Judi and Darryl's innocence."

At the roundup, which concluded Monday, Cherney was joined by others who want to include animal, feminist, minority and international issues on the group's agenda, a concept anathema to the "ecotage" old guard whose position on AIDS and the famine in Ethiopia suggests that such catastrophes were nature's way of keeping world population down.

Several seminars were indicative of the attendees' changing priorities. In one, a sort of witnessing session entitled "Deep Ecology and Action" led by Lone Wolf Circles and attended by about 60 people, the idea of "adopting" a piece of wilderness for long-term concern seemed to evoke a better response than one man's complaint that he had expected less talk and more "action."

But too much action, as in the case of a New York lawyer who attempted to present a seminar on political assassination, was grounds for eviction. Organizers of the roundup asked him to leave, and some attendees suggested he was an agent provocateur whose proposed seminar was designed to give Earth First a worse reputation.

But there also was disappointment that the seminars focused almost exclusively on wilderness concerns and did not address the fact that about 75 percent of Americans, including nearly everyone camped on the mountain, are urbanites.

"Traditionally, a lot of environmentalist groups have ignored the automobile," said Philip Capo, a member of the San Francisco-based Urban Ecology group, which claims affiliation with Earth First. "The attitude has been to just keep driving up to the wilderness all the time, ignore the car, and maybe make it go solar in 50 years. That is not dealing with the situation. We cannot have cities and civilization without huge tracts of wilderness. And we cannot have places where people live, in the short term, without livable cities. We have to work for both."

Capo delivered this message to an audience of two.