Cross Homestake Pass on I-90, or hike into Beehive Basin north of Big Sky, and you’ll see a predominance of dead trees, their needles a vivid coppery color. Mountain pine beetles, the cause of much of this mortality, are native to the Rocky Mountains, and are part of lodgepole pine forests’ natural life cycle. Historically, the beetles have also affected ponderosa, sugar, and western white pines, and two 20th century beetle epidemics killed whitebark pines. All of these species recovered.
Since 2000 however, scientists from Colorado to British Columbia have recorded a significant rise in beetlekilled whitebark pine, in subalpine ecosystems. While the percentage of forest death varies between ranges, this epidemic, combined with the invasive white pine blister rust, has caused unprecedented mortality.
“While, historically, climatic conditions in high elevation whitebark pine habitats have prevented sustained mountain pine beetle outbreaks, today anthropogenic global warming appears to be allowing outbreak populations to expand into these previously inhospitable areas,” according to a 2001 paper on by whitebark experts Jesse Logan and James Powell.