Year of Award

2017

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Forestry

Department or School/College

Forest Management

Committee Chair

Edwin Burke

Commitee Members

John Goodburn, Jim Reardon

Publisher

University of Montana

Subject Categories

Forest Management | Other Forestry and Forest Sciences | Wood Science and Pulp, Paper Technology

Abstract

In an era of accelerated climate change, with persistent and increasing disturbance on our landscapes it is important to increase our knowledge of how these natural disturbances effect our lands. This study investigated the changes that take place in ponderosa pine (Pinus ponderosa) stems after death when killed by mountain pine beetle (Dendroctonus ponderosae) and by fire. Trees killed by mountain pine beetle as well as trees killed by fire were sampled and separated into two age classes, those dead 0-4 years and those dead 4+ years. Data was gathered on the modulus of rupture, modulus of elasticity, specific gravity, holocellulose to lignin ratio, and volumetric heat content for each age class and disturbance type. Analysis was conducted looking not only through time but also vertically through the stem profile. Looking vertically through the stem showed similar trends between beetle killed and fire killed trees in a lowering of the modulus of rupture, modulus of elasticity and specific gravity as height up the tree increases. Over all structural integrity of the stem in terms of modulus of rupture and modulus of elasticity is shown to be significantly different between disturbance types in the “young” age class (0-4 years dead) but not in the “old” age class (4+ years dead). This indicates an initial difference in the post disturbance environment influencing the decay of the stems, and suggests that this difference becomes mitigated as time since disturbance increases. Future studies in this area are needed to fully understand the driving factors behind these findings and the greater implications that mortality vector and disturbance have on the structural and physical properties of the trees left on the landscape.

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© Copyright 2017 Edward J. O'Donnell