Insects continue to threaten forests across Colorado

(PhysOrg.com) -- Although the mountain pine beetle epidemic has largely run its course in north-central Colorado, insect and disease activity continued to stress the state’s forests in 2010.

“From dying walnut trees in cities along the Front Range to spruce beetles attacking high-elevation forests in southwest Colorado, we continue to have concerns about forests throughout the state,” said Jeff Jahnke, state forester and director of the Colorado State Forest Service.

The “2010 Report on the Health of Colorado’s Forests,” released by the Colorado State Forest Service today at the annual Joint Ag and Natural Resources Committee Hearing at the State Capitol, provides a comprehensive overview of insect and disease problems in the state.

The 10th annual CSFS report highlights forest health concerns and documents the status of established forest pests, such as spruce beetle, as well as emerging threats, such as thousand cankers disease in black walnut. Thousand cankers disease was the primary concern in Colorado’s urban forests in 2010, killing walnut trees in 16 counties, mostly along the Front Range and in eastern Colorado.

Less visible and farther from population centers, spruce beetle infestations impacted a total of 208,000 high-elevation acres of spruce forest in 2010 – almost twice the area affected in 2009. The outbreak already has impacted most of the mature spruce forests in the upper Rio Grande Basin in southwest Colorado.

This year’s forest health report also indicates that attacks on lower-elevation ponderosa pine by mountain pine beetle on the northern Front Range have intensified, with a tenfold increase in affected acreage for this pine species. The heaviest mountain pine beetle activity occurred in a swath running through Larimer, Boulder, Clear Creek and Gilpin counties. The beetles have impacted approximately 3.2 million cumulative acres in Colorado since 1996, mostly in lodgepole pine forests.

The forest health report and two additional sources of information – the “Colorado Statewide Forest Resource Assessment and Colorado Statewide Forest Resource Strategy” – will help guide forest management decisions and programs for the next several years.

“The forest health report and the statewide assessment and strategy provide a basis from which to engage in public discussion about our future forests,” said Joe Duda, Forest Management Division supervisor for the CSFS. “This dialogue will allow us to manage these forests while meeting the needs and interests of our stakeholders.”