Whitebark Pine

Whitebark pine (Pinus albicaulis) can be found at high elevation in the Rocky Mountains from central British Columbia to western Wyoming. It occurs in the timberline zone of the Cascades and coastal ranges from British Columbia to the Sierra Nevada, as well as most high ranges between the Rockies and Cascades, such as the Blue Mountains. It is also populous in subalpine forests of Montana and Idaho.

The whitebark pine is an important source of food for many granivorous birds and small mammals, including most importantly the Clark's nutcracker (Nucifraga columbiana), the major seed disperser of the pine. Clark's nutcrackers each cache about 30,000 to 100,000 seeds each year in small, widely scattered caches, usually under 2 to 3 cm (3⁄4 to 1+1⁄4 in) of soil or gravelly substrate. Nutcrackers retrieve these seed caches during times of food scarcity and to feed their young. Cache sites selected by nutcrackers are often favorable for germination of seeds and survival of seedlings. Those caches not retrieved by the time the snow melts contribute to forest regeneration. Consequently, whitebark pine often grows in clumps of several trees, originating from a single cache of two to 15 or more seeds. Other animals also depend upon the whitebark pine. Douglas squirrels cut down and store whitebark pine cones in their middens. Grizzly bears and American black bears often raid squirrel middens for whitebark pine seeds, an important pre-hibernation food. Squirrels, northern flickers, and mountain bluebirds often nest in whitebark pines, and elk and blue grouse use whitebark pine communities as summer habitat. Fallen needles under these trees serve as beds that are used by deer and wild sheep seeking shelter during stormy weather.

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Interior Salish peoples harvested seeds from this tree's cones for food. They were roasted, made into porridge, and mixed with dry berries. Whitebark pine plays a key hydrological role in the ecosystem by regulating runoff, enhancing and retaining snowpack, and reducing soil erosion. Habitat loss due to climate change could lead to downstream flooding and increased soil erosion, impacting agriculture, ranching, and drinking water supply.