Much like a lynx or a grizzly bear cub, a healthy whitebark pine tree can be pretty hard to spot in the Northern Rockies. Over the past 40 years, more than half of the whitebark pines in the region have been wiped out. In some remaining pockets, 80 to 100 percent of the trees are dead or dying, plagued by climate-driven beetle outbreaks and a fungus called blister rust.

NRDC filed a petition more than a year ago asking the U.S. Fish and Wildlife Service to list the whitebark pine as an endangered species. The service has yet to respond to the petition, prompting a lawsuit filed today.

The irony of the embattled whitebark pine is that these trees are nature's survivors. They are the first to colonize altitudes where many other trees dare not set roots, growing gnarled and massive despite heavy winds and deep chills, providing shelter and nourishment to other mountain species. Some whitebark pines can grow to be 1,000 years old -- but decades of drought, fire suppression, and recent beetle infestations (made more intense by global warming) are proving to be more than the trees can bear.

Scientist Jesse Logan told told OnEarth last fall: "We're on pace to lose 80 percent of our whitebark pine forests within the next five to ten years. There are a few exceptions ... but the whitebark pine is going to be functionally lost in the Greater Yellowstone ecosystem."

How bad is the loss of a tree? It depends on your perspective. For some people -- even scientists -- the death of an ancient tree can feel like a spiritual loss. For Yellowstone's endangered grizzlies, which rely heavily on whitebark pine seeds to fatten up for the winter, the loss of the tree could affect the bear's survival. And if you like to drink water, the loss of the whitebark pine affects you, too. Healthy whitebark pines trap mountain snow like a fence, prolonging the release of water in the spring and helping maintain Western water supplies.

"While the clock ticks, our mountaintops are turning from green, live trees to red, infested trees, to gray, dead forests," says NRDC wildlife biologist Sylvia Fallon. "And the ripple that this loss will create throughout the ecosystem will be soon to follow. We need to do everything we can to get whitebark pine the attention and resources that it needs."

Photo: Dying whitebark pine trees turn rust red and then gray.