Friday, March 7, 2014

Understanding how bark beetles are changing our forests

When you visit the Snowy Range in the Medicine Bow National Forest, you notice something—brown trees. Since 2008, this high alpine forest west of Laramie by way of highway 130 has undergone a considerable transformation caused by a bark beetle epidemic. 

There are many species of bark beetles in the United States, and uncontrollable bark beetle outbreaks are occurring in forests throughout the country. In the high alpine forest surrounding the Glacier Lakes Ecosystems Experimental Site (GLEES) near the Snowy Range Mountains, the spruce beetle is the dominate species of bark beetle present and tree mortality is noticeable in this Wyoming Engelmann spruce-subalpine fir forest. 

These photos show the changes in the forest near GLEES from 2003 to 2013.  
Photo Credit: John Frank

Spruce beetles aid in killing trees by exposing them to blue stain fungi which colonize the xylem of the attacked trees; thus, not allowing water to travel through the tree.  Although spruce beetles can be a part of healthy forest cycle, under epidemic conditions spruce beetles drastically impact forests by attacking large populations of larger diameter trees.

At GLEES, University of Wyoming scientists, including members of the Wyoming Center for Environmental Hydrology and Geophysics (WyCEHG), have an ongoing partnership with the U.S. Forest Service to monitor spruce beetle impacts there and assess how this epidemic has changed forest conditions. 

Last Friday, UW doctoral student, John Frank, discussed findings from his research at GLEES on changes in the ecosystem due to tree mortality. John is not only working towards earning his Ph.D. within the Program in Ecology, but he is also an employee of the U.S. Forest Service Rocky Mountain Research Station. With support from his UW Ph.D. advisor, Dr. Brent Ewers, John discovered that to accurately model predictions of ecological conditions (ecosystem fluxes of carbon dioxide and water vapor) after disturbance from the spruce beetle epidemic, changes in tree physiology have to be accounted for in addition to the observed mortality of the trees.
To get to this conclusion, John evaluated six years of data which was collected during the progression of the spruce beetle epidemic. 

With WyCEHG scientists and partners examining impacts on forests from bark beetle disturbance, researchers and managers will be better able to understand how forest ecology is changing and how to predict ecological changes in the future. 

By: Elizabeth Nysson 
Sources used:
Interview with Dr. Brent Ewers by Elizabeth Nysson on March 4, 2014.

“How much does a spruce beetle epidemic alter ecosystem carbon and water processes?” Department of Botany Seminar; John Frank, Ph.D. Student, Botany Department, PiE; Friday, February 28, 2014.

“Ecosystem CO2/H2O fluxes are explained by hydraulically limited gas exchange during tree mortality from spruce beetles.” (IN REVIEW: Journal Geophysical Research-Biogeosciences) John M. Frank, William J. Massman, Brent E. Ewers, Laurie S. Huckaby, José F. Negrón; U.S. Forest Service, Rocky Mountain Research Station, 240 W. Prospect Road, Fort Collins, Colorado, 80526, USA; Department of Botany and Program in Ecology, University of Wyoming, 1000 E. University Avenue, Laramie, Wyoming, 82071, USA

“Western U.S. Bark Beetles and Climate Change.” Preparer: Barbara Bentz, FWE, Rocky Mountain Research Station, Western Bark Beetle Research Group (WBBRG). Accessed from:

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