12 Days of Conifers: Whitebark at Risk

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It’s Day 8 of 12 Days Of Conifers, and our featured species today is the whitebark pine (Pinus albucaulis), a high elevation species that often forms the upper treeline in the Sierra Nevada, Cascade, Warner, and Klamath ranges.

Small bird sits at the top of a pine tree

Clark's nutcracker in a whitebark pine

(Credit: Robert Klinger, USGS Western Ecological Research Station. Public domain.)

Whitebark pines are long-lived and slow-growing. They have relatively short needles that grow in clusters of five.

Whitebark pine is a keystone species of western subalpine environments, providing food and habitat to mammals and birds, like the Clark’s nutcracker featured in the photo and coloring sheet below. In turn, Clark’s nutcrackers disperse the seeds of the whitebark pine.

Whitebark pine was in the news earlier this month when the U.S. Fish and Wildlife Service proposed to list it as a threatened species under the federal Endangered Species Act. Though whitebark pine is not uncommon in California today, it is vulnerable to a variety of stressors, including altered fire regimes, white pine blister rust, mountain pine beetle, and changing climate.

Closed cone of a whitebark pine

Closed cone of a whitebark pine

(Credit: Robert Klinger, USGS Western Ecological Research Center. Public domain.)

USGS scientists and partners are studying how these stressors affect the tree in to help guide management decisions.

For example, a study published earlier this year by scientists from Humboldt State University, the National Park Service, and USGS examined the current status of mountain pine beetle and white pine blister rust infection in whitebark pine for seven western National Parks and projected how the trees in these parks may fare over the next century.

Among the parks studied, Sequoia & Kings Canyon and Yosemite appeared to be the least impacted by white pine blister rust and mountain pine beetle, but Lassen and more northern parks had high rates of infection and dead trees, and these pathogens are expected to spread in the future.

The data will serve as a baseline for monitoring these threats to whitebark pine in the years to come, helping inform its management in National Parks and across the western United States.

To learn more about whitebark pine, we suggest checking out the article “Subalpine sentinels: understanding and managing whitebark pine in California” by authors from USGS, the US Forest Service, the National Park Service, and UC Berkeley, in the May 2019 issue of Fremontia (Volume 47), which can be downloaded for free here.

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Mountain meadow scene with a lake and conifers

Whitebark stands at Evelyn Lake

(Credit: Robert Klinger, USGS Western Ecological Research Center. Public domain.)