Year of Award

2017

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Forestry

Department or School/College

College of Forestry and Conservation

Committee Chair

Dr. David Affleck

Commitee Members

Dr. John Goodburn, Dr. Sharon Hood

Keywords

Whitebark pine, regeneration, release treatments, restoration

Subject Categories

Forest Management

Abstract

Whitebark pine (Pinus albicaulis Engelm.) plays a prominent role throughout high-elevation ecosystems in the northern Rocky Mountains. It is an important food source for many birds and mammals, as well as a major player in high-elevation watershed maintenance, both slowing snowmelt and stabilizing soils. Whitebark pine is vanishing from the landscape due to three main factors – white pine blister rust (Cronartium ribicola) invasions, mountain pine beetle (Dendroctonus ponderosae) outbreaks, and successional replacement by more shade-tolerant tree species historically controlled by wildfire. In the past century, human activity such as fire suppression has altered these systems, potentially causing dramatic changes to the landscape. Managers now are implementing a variety of treatments across the landscape to encourage whitebark pine regeneration and survival. The objective of this study was to determine how whitebark pine regeneration (less than 9 inches diameter at breast height) responds to selective thinning and prescribed burn treatments, otherwise known as release treatments, intended to cause an increase in annual growth. I examined the growth ratio (GR) obtained from tree cores and destructive sampling at four sites in Montana and Idaho treated in the late 1990s. Overall, the average annual radial growth rates of the trees in treated areas was greater than that of trees in control areas. Specifically, there were significant increases in the GR in the two sites that were both thinned and later burned. All sites showed high variability in the GR of individual trees; however, there was greater variability in the annual growth rates of trees in treated areas than in trees from the control areas. I also mapped the height to age relationship of a subsample of the trees to examine how the vertical growth profile changed after treatment. Results suggest that whitebark pine regeneration can respond to thin and burn release treatments and that managers may see positive results in other areas that are treated similarly.

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© Copyright 2017 Molly L. McClintock Retzlaff