Silent Invaders

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Colorado State Forest Service

I live in the mountains of southern Colorado, close to the border with New Mexico. Farther up the canyon from my home, there’s a deadly invader attacking countless victims. It’s a silent battle, but I can almost hear their screams.

The victims are spruce trees.

The invader is the spruce bark beetle: tiny, viciously hungry, and about the size of a grain of rice.

As I stand at the top of the pass on the road to Chama, I can see the results: thousands of acres of dead, brown trees on mountain after mountain as far as my eyes can see. It’s a total transformation of what was once a beautiful green landscape, creating a dangerous fire hazard for the years ahead.

The beetles kill spruce trees by boring through the bark and feeding and breeding in the cambium, the layer of living tissue right underneath the bark. The beetles usually attack fallen trees, but sometimes they will attack standing ones and kill them.

Spruce bark beetles have always been a natural feature of the forest environment, and their infestations are nothing new. But this one is especially catastrophic. According to Michael Tooley, a timber specialist with the Forest Service in the Rio Grande National Forest, “an epidemic like this one is rare and only comes up once every 500 to 600 years.”

Usually, live spruce trees are able to defend themselves by attempting to “pitch out” the beetle. It fills the holes the beetles make with resin and pushes the beetles out of them. However, because of rising temperatures and drought, spruce trees can’t make enough pitch for their defense, giving the advantage to the beetles.

Tooley says that the drought of 2002 to 2003 drove the event that we’re seeing right now. Fire suppression is also to blame. Small wildfires are actually good for forests, clearing space and encouraging new growth. But because we have been preventing wildfires for so long, the forests have become congested. The trees are too dense for sunlight to pass through and for anything to grow underneath them. And in a congested forest, the beetles can spread very quickly.

The epidemic is spreading across Colorado and beyond. In our district alone, according to Tooley, about 126,000 acres have been affected by the beetle – 85 percent of our spruce forests to date. Millions of trees have already died. “With an epidemic like this,” Tooley says, “there’s nothing we can do to stop the beetles.”

During my lifetime, I will never see the spruces as they were a few years ago. It will take our spruce forests hundreds of years to recover from this epidemic.

There are a lot of spruce trees where I live, but none of them have yet been affected by the beetles; you have to go farther up into the higher mountains to see the effects. I’m still worried that the beetles will reach the forest around my home and all our spruce trees will be killed. Meanwhile, I can still almost hear those silent screams up in the mountains.