A decline in whitebark pine trees would likely result in more grizzly bear conflicts with people and a smaller grizzly population in Greater Yellowstone, according to conservation groups.

The statement from the Natural Resources Defense Council comes after the group announced Tuesday it will file a petition to protect the tree species under the Endangered Species Act. The group cited numerous threats to the tree, including global climate change, blister rust and the mountain pine beetle.

The organization will file the petition with the U.S. Fish and Wildlife Service and Interior Secretary Dirk Kempthorne.

While grizzly bears can switch diets easily among different food sources, studies have shown clear correlations between whitebark pine cone crops and grizzly bear conflicts, according to Louisa Willcox, senior wildlife advocate with the Natural Resource Defense Council.

Grizzly-human conflicts in Greater Yellowstone increase significantly during years with poor whitebark pine cone crops, because bears are forced to find food at lower elevation habitats.

When bears are up in high-elevation whitebark pine tree habitat during the feeding-frenzy time of year, they are away from a lot of people, Wilcox said. If whitebark disappears “bears will find alternatives in other places,” she said. “What you can anticipate is a lot more human-bear conflicts like we had this year. Bears will not starve, but they will die at high rates.”

Other studies have shown correlations between cone crops and grizzly reproductive success.

“Females that go into their dens fat on whitebark nuts have bigger litters,” Willcox said. “In bad whitebark years, females have smaller litters.”

A ‘frightening future’

Researchers with the U.S. Geological Survey point to Glacier National Park as an example of an ecosystem where grizzly bears survive without whitebark. But, those same scientists say the disappearance of the tree species would remove a significant source of calories from the Greater Yellowstone ecosystem, likely reducing its carrying capacity for the species.

Willcox says places like the Wind River Range, where whitebark pine tree stands seem healthy, could provide additional habitat to keep grizzly population numbers high. Unfortunately, she said Wyoming’s grizzly bear management plan doesn’t include enough protections to keep grizzlies safe outside their current core range.

“If we’re going to keep the same numbers, we’re going to compensate for the loss of habitat productivity in the core [grizzly bear range of the Greater Yellowstone ecosystem],” she said. “Whitebark is the driver here. What we’re looking at here is a pretty frightening future for bears.”

While scientists aren’t sure exactly how much whitebark pine has disappeared in the last decade, some regions such as the northern Rocky Mountains have seen significant declines.

Diana Tomback, a professor of biology at the University of Colorado, Denver and director of the Whitebark Pine Ecosystem Foundation said government agencies in the U.S. and Canada, including the U.S. Fish and Wildlife Service, have already taken note of declining whitebark populations.

Deadly beetles, fungus

In 2004, Fish and Wildlife declared whitebark a species of concern in western Washington State. In Canada, groups are petitioning to protect the tree under the Species At Risk Act, the Canadian version of the Endangered Species Act.

“There’s a recognition across much of whitebark pine’s range that the species is in trouble,” she said.

Tomback said climate change is driving the mountain pine beetle infestation, which is a native species that, under normal climatic circumstances, would die out during years with extreme cold.

While we can still expect cold snaps under a climate-change scenario, Tomback said, the overall trend is for warmer temperatures.

“The beetles will continue to be active taking down the majority of whitebark pine unless the temperatures change and get colder, which they are not likely to do,” she said.

Unlike lodgepole pine, which persists at lower, warmer elevations and has evolved defenses against pine beetles, whitebark has fewer defenses to fight off an infestation. The situation is then compounded by blister rust, a pathogenic fungus that was introduced to the northern Rocky Mountains from Europe or Asia roughly 100 years ago. While blister rust kills slowly, the fungus in combination with a longer infestation of mountain pine beetles could wipe whitebark off the landscape.

“Blister rust plus mountain pine beetle is a synergism that is extremely threatening,” she said.

Tomback said some researchers are hesitant to put the whitebark pine on the Endangered Species List.

“Whitebark is in trouble,” she said. “There is no question. 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,” Tomback continued. “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?”

Bob Keane, a research ecologist with the U.S. Forest Service, said he has mixed feelings about listing the tree.

“This tree is going to need active management in order to keep it on the landscape,” he said. “The Endangered Species Act may not allow that kind of management.”

Keane advocates harvesting seeds from whitebark pines that have survived blister rust infections, raising the seedlings, and then replanting these rust-resistant trees. Keane pointed to designated wilderness areas as a place where replanting trees using this technique isn’t allowed, although that prohibition is due to wilderness designation.

“If we don’t allow planting, we are definitely going to see a decline in wilderness areas,” he said.

Whitebark pine trees benefit a number of animal species besides grizzly bears and act as a pioneer species providing soil stability and shelter from the wind for trees and other vegetation so they can survive near the tree line.

“There are huge die-offs going on, and those resources [available under Endangered Species Act Protection] are necessary if we want to prevent this tree species from disappearing from the region altogether,” said Josh Mogerman, spokesman for the Natural Resources Defense Council. “That’s why we need to step in and help.”

Louise Lasley, public lands director for the Jackson Hole Conservation Alliance, said whitebark pine trees in the Jackson Hole area have declined along with the rest of the northern Rocky Mountains. On some slopes, around Grouse Mountain in particular, “every single whitebark pine tree is dead,” she said

“My first response to this is that I think it is a good thing to have whitebark pine on the endangered species list.”