CHEYENNE - A conservation group has asked the federal government to grant endangered species protections to the whitebark pine tree, a high-mountain conifer that environmentalists say is dying in huge numbers in several western states.

The Natural Resources Defense Council announced Tuesday that it has petitioned the U.S. Fish and Wildlife Service and Interior Secretary Dirk Kempthorne to grant protections to the tree, which is found in areas including in the greater Yellowstone ecosystem, Nevada, California and the Northwest.

The NRDC says the trees are threatened by global warming, disease and the mountain pine beetle. More than half of the trees have already died in many parts of its range, while between 80 to 100 percent of the remaining trees are infected with blister rust or beetles and will die eventually, according to the NRDC.

"The whitebark pine really are in really bad trouble from a combination of the threats we've identified," the NRDC's Sylvia Fallon said Tuesday. "And obviously by going forward with the listing, we do think that some intervention is necessary to save the species."

Fallon said some whitebark pines appear to have a natural resistance to blister rust, a fungal disease, and said that some also seem to be less susceptible to attacks from beetles, which feed on mature pines. She said such resistant trees could be propagated and replanted to help the species survive.

"Currently, there are some indications that the species can be restored but there are not enough resources to do that, so a listing petition would require the Fish and Wildlife Service to develop a recovery plan, figure out what the best course of action would be to recover the species, and then put that plan into action," said Fallon, who's based in Washington, D.C.

Fallon said her group doesn't have an estimate of how much such programs would cost.

In the Yellowstone ecosystem, nuts from the whitebark pine provide an important source of food for grizzly bears, Fallon said. Studies have shown when the nuts aren't plentiful, bears tend to move into lower elevations to search for food and have more conflicts with humans, she said.

Bill Crapser, Wyoming state forester, said whitebark pine trees around the state have indeed been getting hit hard by beetles and blister rust. He said he hadn't heard of the group's petition to give the tree federal protection.

He said it would be tough to address problems with the whitebark pine through propagating disease resistant trees and planting them.

"A lot of the whitebark pine is in wilderness areas, real high mountainous areas, where any of that type of work is real expensive and problematic," Crapser said.

Diana Tomback, a professor of biology at the University of Colorado Denver and director of the Whitebark Pine Ecosystem Foundation, said some researchers are hesitant to put the whitebark pine on the endangered species list.

"Whitebark is in trouble. There is no question," Tomback told the Jackson Hole News and Guide for a story in its Tuesday edition. "If being on the endangered species list brings more money for management and restoration of whitebark pine ecosystems and more attention to what is going on, I am completely in favor of it being listed.

"However, if being on the list hampers our ability to execute restoration and management, then that is a problem," she said. "It really comes down to: Will this bring more attention to whitebark pine or will it languish on the list like so many other species?"

An attempt to reach a spokeswoman in the Denver regional office of the Fish and Wildlife Service wasn't immediately successful Tuesday.