A picturesque, iconic inhabitant of windy, cold, high-elevation environments across the western United States and southern Canada, the whitebark pine (Pinus abicaulis) is found mostly above 6,000 feet elevation in northern Idaho. As a “keystone” species it promotes biological diversity and ecosystem stability. Mature pines help regulate snowmelt and reduce soil erosion in upper sub-alpine areas. The seedlings are hardy and act as nurse trees to other vegetation. 

Seed dispersal occurs almost exclusively by Clark’s nutcrackers, a bird related to ravens, crows, and jays. In its symbiotic relationship with the tree, the Clark’s nutcracker facilitates its regeneration, distribution and population structure through seed caching. Grizzly bears raid these seed caches for an important food source in many parts of their range, and many other species predate on these caches as well.

The USFWS is concerned that “loss of reproductive trees will lead to a substantial decline in the establishment of new seedlings, meaning new trees will not be able to replace lost trees sufficiently quickly given the species’ long generation time.” (The average age of the WBP’s first cone production is around 40 years.) Increasing mortality from the white pine blister rust, an exotic fungus accidently imported into North America from Asia in the early 20th century, is the major factor leading to its threatened status. By mid-century, this fungus—along with the logging that followed—decimated U.S. populations of another native five-needle pine, the western white pine. 

The USFWS also cites the harmful effects from a combination of climate change and a native insect, the western pine beetle. Before climate change, winters tended to be more severe and deep cold snaps killed most of the beetle’s larvae. According to the USFWS the combination of white pine beetle/climate change, blister rust, and altered fire regimes results in about half of all standing whitebark pine trees in the United States being dead, with most of the mortality happening in the last 20 or so years.