Trends in whitebark pine health in the Greater Yellowstone Ecosystem
Shanahan, Erin Kathleen
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Whitebark pine (Pinus albicaulis) occurs at high elevations and in subalpine communities in the Pacific Northwest and Northern Rocky Mountains. It is a key component in the upper ranges of these ecosystems where it provides a variety of ecological roles, including regulating snowpack and providing high-energy food sources to birds and mammals. As a stone pine species, it produces indehiscent cones and relies primarily on birds for seed dispersal. In mixed and dominant stands, whitebark pine occurs in over two million acres within the six national forests and two national parks that comprise the Greater Yellowstone Ecosystem (GYE). Currently, whitebark pine is impacted by multiple ecological disturbances. White pine blister rust (Cronartium ribicola), mountain pine beetle (Dendroctonus ponderosae), wildfires, and warming temperature all pose significant threats to the persistence of healthy whitebark pine populations on the landscape. Substantial declines in whitebark pine populations have been documented throughout its range. In 2004, an interagency whitebark pine long-term monitoring program was established. The objectives of the whitebark pine monitoring program are to detect and monitor changes in the health and status of whitebark pine populations across the GYE due to infection by white pine blister rust, attack by mountain pine beetle, and damage by other environmental and anthropogenic agents. Here we present work done in three areas of whitebark pine ecology; trends in white pine blister rust infection and overall health status, infection and infection transition probability, and methods for monitoring understory (< or = 1.4-m tall) populations of whitebark pine.