The Noble Whitebark

Here on the northern rim of Greater Yellowstone, great ranges of mountains rise into the cobalt sky like dragons teeth. Climb into the high country of the Montana Rockies and you enter the realm of the Whitebark Pine (Pinus albicans). Long-lived, slow-growing, sturdy and hardy, these iconic trees are an integral part of Greater Yellowstone’s mountain ecosystem.

Whitebarks grow only at high elevations in western North America. These five-needle pines are often found in association with dark, pointy Subalpine fir (Abies lasiocarpa) and are closely related to Limber pine (Pinus flexilis).

Whitebarks grow fat and short, forming bushy growth that is often made up of several trunks. Stout trees like these tend to hold snow in drifts, helping conserve snowpack and lengthen the time it takes to melt off, thus preserving high-country snows into summer.

The only way to reliably tell Whitebarks from Limbers is by their cones. Limbers have large, woody cones, the largest of any tree in Greater Yellowstone, while Whitebarks produce small, sticky purple cones which, when ripe, are loaded with edible pine nuts.

Whitebark pine nuts are the most important food source for grizzly bears in Greater Yellowstone. This is a unique association between bears and trees, with help from squirrels and Clark's Nutcrackers that collect and store the seeds and cones. Bears depend in a big way on these rich, fatty pine nuts to make it through hibernation. In the late summer and early fall, bears swarm the Whitebark groves, knocking cones out of trees and picking out the nuts or raiding the caches of cones and nuts made by birds and squirrels.

When you enter a Whitebark pine forest you can easily see the results of climate change. The needles on the Whitebark trees are a rusty red, if indeed they have any needles left at all. Look across a high elevation forest from a peak in the Absaroka or Gallatin range, and you see red everywhere. According to retired USGS biologist David Mattson, in 10 to 15 years the Whitebark Pine will be functionally extinct in Greater Yellowstone.

Since the 1980s, Whitebarks (and Limbers) have been dying across the Yellowstone Ecosystem from a combination of an invasive pathogen called white pine blister rust, an epidemic of pine bark beetles, and extreme weather events. The blister rust, while not a symptom of climate change, did result from human meddling (it probably got to North America on a shipment of plants from Asia). The bark beetles, however, have invaded the Whitebark forest solely due to warming temperatures. These native insects normally cannot survive the cold winters at high elevations in the Rockies.

Climate change is happening faster at higher elevations (and higher latitudes), thus allowing the beetles to attack Whitebarks that have little defense against them. The one-two punch of beetles and blister rust is delivering the death blow to these spectacular trees.

Few scientists predicted the swiftness of the demise of the Whitebarks. Attempting to predict the rate and the effects of climate change and related events is like trying to predict which way the cars on a crashing train will roll. Forest ecosystems and weather systems are more complex than we can know, and the added chaos of climate change is leading to unpredictable consequences.

In the 1990s my wife and I hiked the Indian Ridge trail into the Spanish Peaks Wilderness of Montana. We walked through what may have been the most beautiful Whitebark Pine forest we had ever seen, and called it the "Enchanted Forest." When I backpacked that trail in 2012, the Whitebark forest was unrecognizable. All the trees were dead and most had blown over, forcing trail crews to recut the trail through all the thick dead trunks. Elsewhere on Indian Ridge, another patch of healthy Whitebarks had been destroyed by a recent avalanche.

Extreme weather events like windstorms, avalanches and severe wildfires are also taking out Whitebarks, which grow so slowly that, even were they to grow back, it could take a century to replace a ruined forest. I did, amazingly, find some healthy patches of Whitebark high on Indian Ridge, loaded with sticky purple cones and that, of course, is where I found fresh bear tracks on the trail.

Forest destruction like that I saw on Indian Ridge is shocking and produces a visceral reaction in me. It's like witnessing the loss of something you never knew how much you loved until it was gone. It's also an in-your-face display of the power of human-induced climate change, a process that is ramping up as we draw well past the 400 ppm mark of CO2 in Earth's atmosphere.

Trees, bears, squirrels, birds, humans...which will be the next to face the abyss of extinction? Or can we, the only species with power to decide, amend our wasteful ways for the sake of all?

 

~Phil Knight