Mountain Pine Beetle

Photo credit: USFS

Small Beetles May Pose Large Problems for the CDT

From the Continental Divide Trail just north of Marshall Pass near Steamboat Springs in Colorado, the views of the surrounding valleys are now increasingly filled with large stands of red and brown dying lodgepole pines.

In the next few years, it is expected that the Trail states will lose millions of acres to the mountain pine beetle. How will this affect the CDT and what is being done to mitigate the damage?

The mountain pine beetle (MPB), or Dendroctonus ponderosae, is native to the forests of western North America. Only a ¼ inch long, during epidemic outbreaks these beetles can kill millions of trees over the span of a few years.

The enormity of the beetle outbreak has overwhelmed the natural controls on beetle population such as woodpeckers and other insects like clerid beetles. The heavy density and relatively homogeneous age of many Western forests have made this infestation particularly devastating.

These insects have been rapidly spreading and multiplying due to the hot dry conditions of recent years. The beetle population prefers dense stands of large diameter trees. Older trees weakened by drought are most likely to become infested, but as the outbreak progresses, all large trees in the area may be affected.

As the beetles have spread, views from the Trail have been impacted. The dead trees will present challenges for many years to come for CDT maintenance as trail-blocking blow downs will steadily increase. The Forest Service has already experienced some of these effects with other trails, with one crew working for three weeks to reopen a two mile stretch of trail in one particularly hard hit area. Hiker safety may also be an issue as it is may be difficult to find a campsite not threatened by dead trees in a heavily infected region.

More images: The same area of Willow Creek Pass in 2005 and 2007. (Photo credit: USFS)

How to Mitigate the Damage?

The Forest Service is implementing solutions to the problems the MPB poses to outdoor recreation, including spraying trees in campgrounds, removing hazard trees, clearing trails and roads, re-planting campgrounds and utilizing volunteers.

Working with the Forest Service, future CDTA volunteer projects may include clearing fallen timber from the Trail and hazard tree removal.

Managing the forest by creating diversity in age and structure will result in a healthy forest that will be more resilient and less vulnerable to MPB. Most mature Rocky Mountain forests have about twice as many trees per acre as those forests which are more resistant to MPB. Contact your local forester for more information on forest management practices.

Some of the information in this article was compiled from Colorado State University and U.S. Forest Service materials.

Click on the images below to see the extent of the beetle kill area in 1996 and 2006 along the CDT in Colorado.