For the past two decades, a mountain pine beetle epidemic has ravaged the lodgepole pines in Colorado’s forests. But now, as most of the vulnerable trees are dead or dying off, the epidemic is finally coming to an end. While this may sound like good news, Colorado is bracing itself for a second bug epidemic that is currently attacking spruce trees and is spreading rapidly.
Every year, the U.S. Forest Service and Colorado State Forest Service conduct an aerial survey of the state’s trees. On Thursday, the 2015 survey was released and revealed that Colorado’s aspen trees are “generally faring well” after suffering from drought die-offs in previous years. Additionally, the mountain pine beetle incidences have returned to “pre-epidemic levels,” after affecting more than 5,300 square miles of forest since 1996.
Meanwhile, the spruce beetle, a relative to the mountain pine beetle, attacked another 285 square miles of spruce trees last year. Since 1996, the spruce beetle has attacked 2,500 square miles.
According to Bob Cain, an insect expert with the U.S. Forest Service, spruce trees are apt to recover more slowly than lodgepoles do. While most species of trees do not thrive unless they are grown in areas that are exposed to 50% or more of sunlight, spruce trees are found in wetter areas with higher elevation, and they thrive in the shade as opposed to direct sunlight.
According to Cain, persistent droughts in the early 2000s helped to contribute to both beetle epidemics by making the trees weaker and more susceptible to illness.
“The lesson we can take away from the extensive insect and disease damage we’ve seen in Colorado over the past two decades is the need for proactively taking care of our forests,” said Mike Lester, state forester and director of the Colorado State Forest Service. “The best time to take actions to address long-term forest health is before a major outbreak starts, and not after.”