Focus on Whitebark Pine

Whitebark pine is a perfectly adapted alpine tree. It grows at or near the timberline throughout the mountains of the Pacific Northwest. Since it doesn’t compete well with other conifers in wet or shady locations or on north facing slopes, you will find it in open, dry and sunny locations on ridgetops or south facing slopes.  Whitebark pine is the only stone pine that grows in North America. The stone pines have large wingless seeds. Other stone pines grow in Europe, China and Korea. These edible seeds are called “pine nuts,” which you can buy in grocery stores if you can afford them.

You can identify whitebark pine by counting the number of needles in each bundle. Whitebark pine needles grow in bundles of five. Western white pine also has 5 needles per bundle, so it’s easy to confuse it with whitebark pine. However, if you see any cones, and can tell eggs from bananas, it’s easy to tell them apart. Whitebark cones are about the size and shape of eggs, while western white pine cones are about the size and shape of bananas.

The most remarkable thing about Whitebark pine is its relationship to the Clark’s nutcracker. Unlike the cones of most other native pines in the Northwest, which open and disperse their winged seeds, white bark pine cones remain on the tree and do not open when they mature. This is where the eating habits of the Clark's nutcracker play an essential role in the life cycle of the Whitebark pine. These birds easily pull apart the cones to get the seeds and bury them in the ground for eating later. Or perhaps they fancy themselves as tree planters. It’s just that they often get hungry and return to eat some of the seeds. In either case, they don’t eat all of the seeds they “plant,” so some of them germinate and continue the life cycle of the pines. This paradigm case of mutualism benefits both the nutcrackers and the whitebark pines. However, nutcrackers don’t get all of the whitebark seeds. They are also a favorite of Steller’s jays, Douglas squirrels, golden-mantled squirrels and chipmunks.

By the way, the feeding habit of nutcrackers is why you seldom find any whitebark pine cones on the ground, just cone fragments left by the nutcrackers. This can make it more difficult to tell a whitebark pine from a western white pine. If you are at the timberline, it’s probably a whitebark. If it’s a small tree, it may not be producing cones yet, so good luck. Looking at the needles may help. Whitebark needles are green, while western white pine needles are blue-green.

The scientific name of whitebark pine is Pinus albicaulis. The common and scientific names describe the whitebark pine. Albicaulis means "white stemmed." To remember the name, think of it as the "Albino-bark Pine." Other common names: Pitch pine, scrub pine, and creeping pine. John Muir called it "Dwarf Pine."

If you go looking for whitebark pine, you may be disappointed. Like other white pines, whitebark pine has been decimated by white pine blister rust. You can see their ghostly, white forms still standing in large areas, for example, above Mount Hood Meadows. White pine blister rust is a disease caused by an Asian fungus, which was introduced to North America over 100 years ago. It has caused serious damage to the white pines all across the U.S. In the Northwest, white pine blister rust has infected large areas of whitebark pine. The fungus first attacks the needle, then the branches, and eventually the trunk of the tree.

Whitebark pines tested for resistance to blister rust.
Some survive, others, not so much.

White pine blister rust has a fascinating life history. It requires two host species to complete its life cycle. One is a white pine. The other can be a variety of plants from the Ribes genus, locally, usually shrubs like currants and gooseberries. The infected shrubs infect the trees, and the trees in turn infect more shrubs. If you remove one of the hosts, the fungus cannot reproduce. Years ago, the Forest Service sent out summer workers to clear affected areas of the shrubs necessary to complete the life cycle of the fungus. Unsurprisingly, that effort failed. More recently, efforts have been underway to develop genetic strains of whitebark pine that are resistant to the disease. For details on this effort, see this post on the Dorena Genetic Resource Center. 

Whitebark pines just don’t seem to be able to catch a break. Recently, the mountain pine beetle has attacked large areas of whitebark pine. More outbreaks are likely as winters become warmer allowing pine beetles to survive in areas where they were once killed by cold winters. Due to the decline in whitebark pine from blister rust and beetles, it is now listed as an endangered species on the IUCN Red List. Climate change may prove to be the biggest challenge to the survival of whitebark pine.

Whitebark pines may need our help to survive the assault of these enemies. They are an important member of the alpine ecosystem, providing food for nutcrackers and shelter to other birds and mammals, and contributing to the beauty of the high mountain environment. We can help them survive by supporting efforts to combat blister rust, and by reducing greenhouse gas emissions.

If you want to see some whitebark pines, here are some locations that are easy to get to: Above Timberline Lodge on Mount Hood, on the rim above Crater Lake, and at the top of the Mount Howard tram at Wallowa Lake.

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More info

Northwest Conifers: Whitebark Pine  

Gymnosperm Database: Pinus albicaulis 

Our Threatened Timberlines: The Plight of Whitebark Pine Ecosystems