Results of a new study show that episodes of reduced precipitation in the Southern Rocky Mountains, especially during the 2001-2002 drought, greatly accelerated a rise in numbers of mountain pine beetles. The overabundance is a threat to regional forests.
The research is the first to chart the evolution of the current pine beetle epidemic in the southern Rocky Mountains.
It compared patterns of beetle outbreaks in the two primary host species, the ponderosa pine and lodgepole pine, said University of Colorado at Boulder (CU-Boulder) researcher Teresa Chapman.
A paper on the subject is published in the current issue of the journal Ecology. Chapman is lead author of the paper; co-authors include CU-Boulder scientists Thomas Veblen and Tania Schoennagel.
The National Science Foundation (NSF) funded the research.
"This study confirms that warming temperatures and drought are likely triggers of the widespread bark beetle outbreaks that have devastated forests over vast areas of the West," said Richard Inouye, program director in NSF's Division of Environmental Biology.
"It also suggests why bark beetle outbreaks may vary for two different tree species," he said, "and how different forests may be more or less susceptible to these insects that are transforming mountain landscapes."
The current mountain pine beetle outbreak in the Southern Rockies--which ranges from southern Wyoming through Colorado and into northern New Mexico--is estimated to have affected almost 3,000 square miles of forests.
While the 2001-2002 drought in the West played a key role in pushing the pine beetle outbreak into a true regional epidemic, the outbreak continued to gain ground even after temperature and precipitation levels returned to levels nearer the long-term averages.
The beetles decimated lodgepole pine forests by moving into wetter and higher elevations and into less susceptible tree stands--th
|Contact: Cheryl Dybas|
National Science Foundation