Arizona Daily Star TUCSON, Ariz.—It took more than a century to create the conditions that killed the spruce-fir forest on Mount Graham.
A plan to begin restoring it to its "pre-settlement" condition — complicated by the need to protect an array of telescopes and preserve habitat for a threatened squirrel — will take a decade and cost $7 million.
The damage to the Pinaleno Mountains — usually identified by the name of their highest peak, Mount Graham — began when man arrived.
In the early 1900s, sheep and cattle began to graze the grasslands, eradicating much of the fuel that would carry widespread but low-intensity fires into the higher reaches of the mountains at least once each decade.
In the 1930s and 1940s, many of the mountain's big trees, which had evolved by shrugging off fire and creating a canopy that kept the forest floor free of smaller, sun-loving trees and shrubs, were cut down for timber. Those logged Douglas firs and ponderosa pines gave way to species less adapted to fire.
Settlers built summer cabins to escape from the valley heat, making it necessary to protect them from fire.
The Arizona Game and Fish Department introduced the Abert's squirrel in the 1940s for hunters, and it now competes for resources with the Mount Graham red squirrel, a distinct subspecies that biologists call the most endangered mammal in North America.
Drought and higher temperatures, traced to man's warming of the globe, made it a cozier place for insects that attack the trees.
The Engelmann spruce forest atop Mount Graham was invaded by waves of killer insects in the last two decades.
Entomologist Ann Lynch, who has studied insect outbreaks atop Mount Graham for eight years, estimates that 80 percent of the mature Engelmann spruce trees have died.
Lynch traces the plague of insects to an ice storm in the winter of 1992-93 that allowed the spruce beetle and the Western balsam bark beetle to establish populations. Then came a leaf-eating moth in 1996 that weakened trees in the spruce-fir forest and triggered an eruption of those beetles. An exotic species of spruce aphid took over the defoliation of the Engelmann spruce.
Stands of those spruce then burned in the Clark Peak and Nuttall-Gibson fires in 1996 and 2004.
The severity of those burns might have been heightened by the presence of University of Arizona telescopes, built in red-squirrel habitat after a protracted battle with environmentalists.
As a result, the forest atop Mount Graham is considerably different from the one that existed in "pre-settlement" times.
How can that be corrected?
"It's not that simple."
That's Craig Wilcox's answer to just about every question about the complex ecological puzzle.
Even if forest managers knew exactly what to do, Wilcox said, they still would have to juggle the need to protect the endangered red squirrels and the telescopes.
Wilcox, a U.S. Forest Service silviculturist (tree expert), said the key to the Pinalenos' restoration is the mixed conifer forest beneath the higher-elevation spruce and fir. Creating a checkerboard of open forest canopy and denser stands there would reduce the severity of fires that burn through.
It's important to leave some dense growth as you thin, Wilcox said, providing places for the endangered Mount Graham red squirrel to hide its cones in caches, called "middens," and to escape avian predators. Known middens will be given a wide berth when thinning begins, he said.
Thinning is essential, but it's just the first step in restoring the ecosystem, said Don Falk, a professor of natural resources at the University of Arizona and part of a team of scientists working to determine what the mountain looked like before man and how it might resemble that state again.
"If you thin, you increase the resilience of individual trees, increase the light and the nutrients," Falk said. "It improves survival rates. You're more likely to have low- to medium-density fires. It reduces the probability of certain insect activity if it is used as a way to let fire back in."