13.5

A whitebark pine snag in the Lost River Mountain Range in central Idaho. The slow-growing whitebark can live for 500 years, and sometimes for 1,000 years. The tree is found in the mountains of the western U.S. and Canada, typically at timberline or just below it.

Whitebark pines are an important food source for birds, bears and other species. However, these ancient trees are under attack from an array of forces. The long-standing policy of fire suppression thwarted the low-intensity wildfires that helped maintain healthy whitebark stands by thinning competitors and creating the disturbed sites needed for seedling growth. In addition, white pine blister rust, an exotic disease introduced to western North America a century ago, is attacking whitebarks in virtually all of their range, increasing their susceptibility to the destructive mountain pine beetle. Global warming (if you believe in it) is also having a negative impact on the trees by making the tree's high-altitude home warmer and drier and more hospitable to other tree species and allowing the pine bark beetle a longer active period during which it can damage the tree.

Whitebark pines may become extinct from the mountains of the western United States.