Undergraduate Honors Theses

Thesis Defended

Spring 2013

Document Type



Environmental Studies

First Advisor

Dale Miller

Second Advisor

Mark Williams, Ph.D.

Third Advisor

Thomas Veblen, Ph.D


This research examines relationships between annual radial growth and the status of spruce beetle (Dendroctonus rufipennis) outbreak in Engelmann spruce (Picea engelmannii). Spruce beetle has affected over 392,000 hectares from 1998-2011 in Colorado and Wyoming’s subalpine forests, as well as extensive areas in other western states. This research aims to help forest managers, academic researchers, and policy makers determine better management techniques for our national forests. I examined ecological data from tree samples in 18 forest stands in Western Colorado. After analyzing data from tree samples, the radial growth rates between unaffected and affected trees were compared. Results of this study show that affected trees are more likely to have faster overall radial growth rates than unaffected trees. However, radial growth rates from the 5 or 10 years of outermost rings representing growth rates immediately prior to death or attack by spruce beetle did not significantly differ. More research is needed to evaluate whether faster growing spruce invest less in tree defense mechanisms and are therefore more likely to get attacked.