White-bark pine ravaged throughout Yellowstone

The clear, high peaks of the greater Yellowstone region once were studded with huge stands of majestic white-bark pine forests, some of the trees 1,000 years old.

A decade or so ago, big pockets of rust started appearing as the green pine needles succumbed to infestation and disease. Since then, it's become worse: Unable to fend off invading armies of mountain pine beetles, large swaths of the forest have simply died. An alarming part of the high-elevation landscape across the mountains of Wyoming, eastern Idaho and southern Montana is gradually turning eerie and gray.

"You get a picture of how breathtaking it is from the air," said Louisa Willcox, a senior researcher with the Natural Resources Defense Council, which has completed a first-ever aerial survey of the greater Yellowstone ecosystem to document the extent of the threat to the region's white-bark pine forests. "All the gray you see in the eastern part of Yellowstone Park and the Absaroka Mountans are gray ghosts [of dead trees]. Basically, white-bark pine [there] is functionally gone, functionally lost."