Growth release of subcanopy trees following Mountain Pine Beetle induced overstory mortality in Rocky Mountain National Park

Christopher DeaderickDr. Daniel Tinker

Department of BotanyPROPOSED RESEARCH PROJECT

For the past decade, mountain pine beetles (MPB) have invaded millions of hectares of forest in Colorado and Wyoming, causing extensive conifer mortality. While it is commonly believed that growth rates of subcanopy trees increase following removal of overstory trees, limited empirical data exist to confirm this. Tree ring data can provide insights into such growth releases, as well as chronological occurrence of past climate and disturbance events and the severity and frequency of these events.

Dr. Daniel Tinker

Gregory Pappas

McNair Scholars Program

This study will examine the magnitude of growth release of subcanopy trees following MPB-induced overstory mortality, and will estimate the differences in growth release among cohorts (vertical canopy layers) and among tree species.

Purpose StatementThe study area is located in Rocky Mountain National Park (RMNP) west of the Continental Divide in Lodgepole pine dominated forest severely impacted by MPB. In 2008 the MPB epidemic appeared to be subsiding during field surveys.

Thirty-eight sites will be resampled, each containing two 20 m x 20 m square plots randomly positioned 90 m apart, for a total of 76 plots. In each plot tree core samples and tree diameter (DBH) will be collected for 5 trees of each canopy cohort and species type. Collecting densiometer measurements will estimate tree canopy cover.

Tree core preparation and analysis will follow standard dendrochronological methods (Stokes and Smiley 1996). Tree ring crossdating matches the growth patterns of narrow and wide rings across the sampled trees to show past regional environmental factors that produce common year-to-year radial growth variations. This study will identify the timing and magnitude of growth release events detected from tree ring widths.

Hypothesis

Methods

Importance of Study

Acknowledgements

Introduction

I hypothesize that there will be an increase in subcanopy growth as a result of decreased overstory cover and reduced competition for water, light and nutrients as a result of extensive mortality among mature trees.

By elucidating the growth response of subcanopy trees, this study will enhance understanding of important alterations in stand structure and composition following severe MPB forest mortality.

Relationship between wildfire synchrony, precipitation anomaly, and seedling establishment in the Black Hills, South Dakota (Brown 2006).

The Mummy Range from Moraine Park, Rocky Mountain National Park

Range of the mountain pine beetle in North America