Remeasurement of the Health of Whitebark Pine Stands in the Central Washington Cascades


Nancy Parra

Faculty Mentor(s)

Alison Scoville (Biological Sciences)


Whitebark pine (Pinus albicaulis) plays a vital role in colonizing newly disturbed area, providing shade for other tree species to colonize, and supplying food for a variety of birds and mammals, such as Clark’s nutcrackers (Nucifraga columbiana) and grizzly bears (Ursus arctos horribilis). Whitebark pine’s decline has been attributed to several factors such as white pine blister rust (Cronartium ribicola), mountain pine beetle (Dendroctonus ponderosae) outbreaks, and fire exclusion. In 2009, the U.S Forest Service began to install permanent plots in whitebark pine stands in Washington and Oregon as part of a Pacific Northwest restoration strategy to track blister rust and mountain pine beetle mortality. Forest Service crews conducted surveys on these plots that included standard tree inventory and measurements of blister rust, mountain pine beetle, and fire activity. Before summer 2020, only 12 of 47 plots located in the Okanogan-Wenatchee National Forest had been remeasured. To evaluate the changes that occurred in the whitebark population and provide updated data to the Forest Service, volunteer crews during summer 2020 remeasured eight of these plots located in three areas of the Okanogan-Wenatchee National Forest: Mission Ridge, Clover Springs, and Darland Mountain. Results indicate a significant increase in blister rust stem cankers (from 2% to 16%: t(5) =-5.6434, P = .0024) and low, unchanged mountain pine beetle activity, but more plot remeasurements are needed to understand the current status of the whitebark pine population, the changes that occurred since 2009, and the future status of whitebark pine.

Keywords: Whitebark pine, Monitoring, Conservation


5 thoughts on “Remeasurement of the Health of Whitebark Pine Stands in the Central Washington Cascades”

  1. Great poster! Very informative with regard to the importance of measuring tree health. Any reason to believe that the span of time between your remeasure and prior measurements was indicative of what will happen in the next 20 years or were there any major events that could have contributed to big changes between the timepoints?

    1. Hi Gabriel, thank you for watching my poster! Particularly for mountain pine beetles, where a sudden cold spell can kill the bark beetles and slow down their spread, there could be a major environmental event that contributed to changes in trends. A major event such as that could also alter expected trends in the next 20 years.

  2. Nice work Nancy! Is the information collected from these trees relevant towards other types of trees in the area or are the trends seen only applicable to this specific species?

    1. Hi Marc! Blister rust fungus infects all our North American white pines. Here in Washington, that means the western white pine is also affected. Mountain pine beetles will also attack our other pines like ponderosa and lodgepole. We would expect to see these trends in these other species where their ranges overlap, but of course we would need to collect data to be sure. We’ve seen this with past outbreaks of mountain pine beetles, where numerous acres of lodgepole and ponderosa pine were also destroyed in regions experiencing a very hot, dry summer and mild winter.

  3. Nice job introducing whitebark pine, its importance, and the factors affecting its survival. I’m curious that blister rust infections increased but this did not seem to cause more tree mortality. Was this an unexpected result?

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