Document Type

Thesis

Date of Degree Completion

Spring 2013

Degree Name

Master of Science (MS)

Department

Resource Management

Committee Chair

Megan Walsh

Second Committee Member

Patrick McCutcheon

Third Committee Member

Steve Hackenberger

Abstract

With the creation of Mount Rainier National Park (MORA) in 1899 came the active management of the park's landscapes and a heavy emphasis on fire suppression. Today managers at MORA have made returning fire to the park's landscapes a top priority. In order to achieve this goal, and to make more informed decisions in regard to the application of fire, land managers at MORA need to better understand past fire occurrences and the drivers of fire activity on the mountain. To address this problem, analysis of macroscopic charcoal preserved in lake sediments was used to reconstruct the fire history for Shadow, Sunrise, and Little Sunrise Lakes along the Sunrise Ridge of MORA. Reconstructions for these sites show that during the late Pleistocene fire activity on the Sunrise Ridge was low. Transitioning into the early Holocene, fire activity increased and remained high from the start of the mid-Holocene through ca. 6,000 cal yr BP and then declined through ca. 4,500 cal yr BP. From the start of the late Holocene, fire activity increased substantially through ca. 2,000 cal yr BP, decreased through ca. 1,000 cal yr BP, and then increased to present. The similarity between the Sunrise Ridge records and other sites in the Pacific Northwest suggests that broad-scale climatic variability, such as changes in annual insolation and the El Nino-Southern Oscillation, were likely the primary driver of fire activity on Mount Rainier during the Holocene. While it is possible that human-set fires also influenced the fire reconstructions, results from the lakes along the Sunrise Ridge do not show clear evidence of anthropogenic burning. In terms of future fire activity, projected increases in summer temperature and decreases in summer precipitation will most likely lead to a higher occurrence of drought and subsequent fire at MORA.

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