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A 20-year reassessment of the health and status of whitebark pine forests in the Bob Marshall Wilderness Complex, Montana

Author(s): Signe B. Leirfallom, Robert E. Keane, Molly L. Retzlaff
Year Published: 2016
Description:

Whitebark pine plays a prominent role in high elevation ecosystems of the northern Rocky Mountains. It is an important food source for many birds and mammals as well as an essential component of watershed stabilization. Whitebark pine is vanishing from the landscape due to three main factors: white pine blister rust, mountain pine beetle outbreaks, and successional replacement by more shade-tolerant species. Between 1990 and 1994, 116 research plots were established to determine the health and status of whitebark pine populations in the Bob Marshall Wilderness Complex in Montana, USA. In the summers of 2013 and 2014, we assisted volunteers or "citizen scientists" from the Bob Marshall Wilderness Foundation in remeasuring 25 of these 116 plots to assess changes in the health and status of whitebark pine over the past 20 years. Methods from the original study were simplified to accommodate volunteer crews' inexperience. Results of this remeasurement effort show that mortality of mature whitebark pine trees in the Bob Marshall Wilderness Complex has more than doubled in the last two decades (to 80 percent from 35 percent) with white pine blister rust now present in all surveyed stands. Most tree deaths were from white pine blister rust (>60 percent), but a large increase in mountain pine beetle attacks was also noted. As blister rust kills more stands dominated by whitebark pine, the trees will be replaced with the more shade-tolerant subalpine fir and Engelmann spruce, further inhibiting regeneration of the shade-intolerant species.

Citation: Retzlaff, Molly L.; Leirfallom, Signe B.; Keane, Robert E. 2016. A 20-year reassessment of the health and status of whitebark pine forests in the Bob Marshall Wilderness Complex, Montana. Res. Note RMRS-RN-73. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 10 p.
Topic(s): Fire Ecology, Insects & Disease
Ecosystem(s): Alpine forest/krummholz, Subalpine wet spruce-fir forest, Subalpine dry spruce-fir forest
Document Type: Technical Report or White Paper
NRFSN number: 14676
Record updated: Oct 24, 2016