Beetle Kill 2009: How far has the beetle spread beyond Grand County?
May 8, 2009
The aerial survey results released in January for northern Colorado and southeastern Wyoming revealed that about 900,000 new acres were impacted by mountain pine beetle in 2008. Approximately 400,000 of these new acres were in northern Colorado. These acres had not previously been affected by the MPB epidemic. This catastrophic event has affected almost 2.5 million acres from the first signs of outbreak in 1996.
Fourteen counties in Colorado are now experiencing the outbreak in varying levels. Larimer and Boulder counties have experienced the most severe increases, seeing an approximate doubling of total acreage of beetle kill in lodgepole pine between 2007 and 2008.
Since the outbreak began larger diameter lodgepole, ponderosa, limber and bristlecone pines have been attacked and killed by mountain pine beetles.
The current epidemic is primarily in lodgepole pines where their trunks are greater than five inches in diameter. However, the epidemic has now expanded to the ponderosa pine-dominated forests of the northern Front Range, where there is greater variability in age, size, density and species diversity. How the epidemic will proceed in these areas as well as the severity of losses is difficult to predict. Tree mortality in Ponderosa pines is expected to be more variable than the losses observed in lodgepole pine forests that are west of the Continental Divide. However, the beetle has been attacking a wider variety of trees, and has been found in limber and scotch pine at higher elevations and in Fort Collins where the beetle caught a ride with the wind and has made a minor attack within city limits.
Visitors to Colorado’s National Forests, particularly in northwest and north central Colorado, won’t have to look far to see the effects of the spread. As of 2008, approximately 20 percent of all the trails on the Medicine Bow, Routt, White River, Arapaho and Roosevelt National Forests have been affected by the beetle, while 40 percent of all the roads have been affected. Nineteen percent of all of the acres of campgrounds and picnic areas on the three National Forests could be closed or use could be limited while hazards are removed. The beetles’ growth patterns indicate that visitors and Coloradans alike will continue to see increases in red, brown and needle-less trees. Between 2007 and 2008, the Medicine Bow-Routt National Forest saw an approximate increase of 340,000 acres of beetle-impacted areas, particularly in lodgepole, Ponderosa and limber pine. During the same time period, the beetles spread by approximately 118,000 acres in the Roosevelt National Forest. The Arapaho National Forest, which includes Grand County, saw an increase of about 32,000 acres.