There's a silver lining to the brown trees in the Rocky Mountains.
While almost a million acres of evergreens across the state are dying from an unparalleled outbreak of bark beetles, experts say the infestation is creating hidden benefits.
Among them are increased water runoff to streams, opportunities for new vegetation and more varied wildlife habitat.
"Some people think of the beetles as destroying our forests. That's not really the case," said Jim Maxwell, a hydrologist with the U.S. Forest Service.
"What they're doing is they're killing off the mature lodgepole pine, but the forest is already renewing itself," he said.
The beetle, a native species that burrows into the bark of the tree to lay its eggs, has hit the Rockies hard in the past five years, spreading through the pines like a slow-moving wildfire.
Biologists say the trees, already weakened by drought, are particularly susceptible because almost a century of wildfire control and logging restrictions has left entire forests that are uniformly 80 to 100 years old.
Among the most important changes expected is an increase of as much as 30 percent or more in water yield, depending on the number of trees lost and variables such as snowfall, said Lee MacDonald, a professor with the Colorado State University watershed-science program.
The roots of dead trees no longer absorb water, and their denuded branches no longer serve as a platform for snow that never reaches the ground before evaporating, MacDonald said.
The additional water may, however, be of limited benefit because it will flow into streams during the wettest times of the year, MacDonald said.
"You'd have to capture that additional melt that you get early in the spring, and that means building reservoirs," he said.
The increase in water also would be relatively short-lived, typically lasting only 20 to 30 years, until new plants and trees replace the dying pines.
As the new vegetation grows it will also compete for that extra water, said Kelly Elder, a research hydrologist at the Fraser Experimental Forest.
"These younger trees are very efficient at using that water," Elder said.
That natural succession of plants and trees is likely to be a benefit, too, by creating a more-diversified forest that will be less prone to catastrophic wildfires, disease and insect infestation, experts say.
"Even though it's a dramatic and painful change for people, I think that decades down the road we may be better off," said Greg Aplet, a senior forest scientist at The Wilderness Society.
Meanwhile, the dead trees will provide both benefits and drawbacks for wildlife, according to a 2006 analysis by Ann C. Allaye Chan-McLeod in the British Columbia Journal of Ecosystems and Management.
Woodpeckers feast on the beetle larvae, and once the trees fall and begin to rot, they provide shelter for animals such as voles and snowshoe hares, she wrote.
Foresters suspect that all of the mature lodgepole pines have been killed in some places and 90 percent may die statewide, but the epidemic won't claim every tree, said the Forest Service's Maxwell.
Aspen roots, some of which have lain dormant for two or three centuries, already are sending up shoots in places where pines have died, he said.
"The forest is still a forest," Maxwell said. "It's just in that death-and-rebirth phase."The Denver Post
