Aerial Survey Shows Spruce Beetle Activity Escalating, Mountain Pine Beetle Declining in Colorado

The U.S. Forest Service and Colorado State Forest Service (CSFS) have released the results of the annual aerial forest health survey in Colorado. Each year the agencies work together to aerially monitor insect and disease-caused tree mortality or damage across 28 million acres of Colorado forests. Results for 2014 indicate that the spruce beetle epidemic continues to escalate, while the mountain pine beetle epidemic has slowed dramatically.

The spruce beetle outbreak was detected on 485,000 acres in 2014, compared to 398,000 acres across the state in 2013. The epidemic expanded to 253,000 new acres, as compared to 216,000 new acres in 2013. The spruce beetle epidemic is expanding most rapidly in southwestern Colorado’s forests, and the total area affected by this beetle since 1996 has increased to almost 1.4 million acres statewide. Windthrow events, combined with drought stress, warmer temperatures and extensive amounts of older, dense spruce, have contributed to this epidemic.

The mountain pine beetle epidemic declined further in 2014, with surveyors recording the lowest acreage of active infestation observed in 17 years. Statewide, mountain pine beetle was active on 15,000 acres in 2014, compared to 98,000 acres in 2013. Only 3,000 acres of new infestation were detected in 2014, versus 9,000 acres of new infestation in 2013. Active acres are those that may be impacted over multiple years, while new acres are those not previously impacted in the current epidemic. Approximately 3.4 million acres in Colorado have been affected by mountain pine beetle since the first signs of the outbreak in 1996. Reduced beetle activity in many areas is due to extensive mortality of the larger host trees necessary for beetle populations to maintain epidemic levels.

Additionally, aspen defoliators, such as the western tent caterpillar, were detected on 78,000 acres in Colorado in 2014. This caterpillar defoliates aspens and can lead to tree mortality if present over several consecutive years. Affected aspens typically regrow new leaves during the summer; however, drought conditions can increase mortality.

The USFS Rocky Mountain Region is focused on increasing the pace and scale of active forest management across Colorado. Each National Forest is stepping up forest treatments, and many are working collaboratively to strategically plan and apply work to the areas that need it most. In addition to dozens of shorter-term stewardship contacts, the USDA Forest Service has four 10-year stewardship contracts to remove dead trees to restore forests and increase their resiliency. The agency also has awarded several short-term stewardship contracts aimed at improving forest health and contributing to local economies.

Forestry agencies have a key role in sustaining forest ecosystems, which provide many benefits to the people of Colorado and surrounding states. Whether progress is measured by the reduction of large-scale wildfires, timber harvested or number of forest acres treated, the outcome is the same: healthy and resilient forests, and the protection of forested watersheds.

For further information on forest health conditions in the USFS Rocky Mountain Region, click here.



Jeff
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