The New York Times has an outstanding video, “America’s Disappearing Forests”  documenting the devastating impact of the mountain pine beetle (Dendroctonus ponderosae) on lodgepole pine (Pinus contorta) in the Rocky Mountain states.  The insect has destroyed about 2 million acres of lodgepole pine forests. Since lodgepole pine typically occurs in pure stands (coming in after fire), the insects are in effect wiping out entire forests.

It is becoming clearer that the main cause of the outbreak is the prolonged drought of more than 8 years, and mild winters.  The prolonged drought weakens the ability of the trees to fight off beetle attacks. The mild winters allow higher survival rates in the beetles.  Since the western states will only become warmer and growing seasons longer, there is no end in sight to the outbreak except the death of lodgepole pines.  This does not mean the end of forests in the region, since other species can occupy the space. However, the loss of a dominant species in an arid environment means that it will take a long time, centuries at least, for the forests to recover.

Picture: lodgepole pine mortality due to mountain pine beetle. Photo courtesy of Jerald E. Dewey, USDA Forest Service, bugwood.org.

America’s Disappearing Forests – The New York Times – Video Library

Whitebark pine, Pinus albicaulis, is one of the most characteristic species of high mountains in western North America, and one of the most unusual pines.  Whitebark pine populations are declining steeply throughout the northern Rocky Mountains. The Billings Gazette has an excellent article about the decline of whitebark pine in the northern Rockies. In the Greater Yellowstone Ecosystem, whitebark pine populations have declined from 7% to 24%. In a sign of things to come more than half the trees monitored since 2002 have died. In a monitored area in the panhandle of Idaho, 98% of the trees have died.  Whitebark pine is a species at risk in Canada and a species of special concern in Washington. The cause of the decline is a complex mixture of disease, insects, fire suppression and climate change.

The loss of whitebark pine threatens other species in the Rockies. Grizzly bears depend heavily on the fatty seeds of whitebark pine for fall nutrition. While grizzlies can find other food sources to replace the pine nuts, a lack of seeds may force the bears to wander to lower elevations and come in more contact with humans.

Whitebark pine is also a critically important species for birds, notably Clark’s nutcracker.  Whitebark pines, unlike all other North American pines, have closed cones that have to be pried open by animals. Clark’s nutcracker pries open the cones to get at the rich seeds, dropping many of the seeds in their travels. 

The loss of whitebark pine would be a tragedy for mountain ecosystems throughout the West. But efforts to study and restore the species are fraught with challenges. Most populations of whitebark pine are in roadless areas and at very high elevations. Getting to stands to study them, or to restore populations, is not easy.  Because whitebark pine is not a commercial species, having no timber value, it is hard to come by research funds or restoration money. Centuries of effort will be required to restore whitebark pines, and climate change may quickly overwhelm efforts and restoration.

There will be a lot more information about this interesting and significant species as we develop the species pages at Trees, Climate and People.

Picture: whitebark pine, Pinus albicaulis. Picture by Paul Bolstad.
Map: Whitebark pine, Pinus albicaulis, range

BillingsGazette.com :: Trees on the brink: Whitebark pine face series of threats

Stems and flowers of dwarf mistletoe, Arceuthobium vaginatum, on ponderosa pine, Pinus ponderosa. Coconino National Forest, Arizona. Photo by Tom Kimmerer