Success in Fire Suppression Threatens Quaking Aspens : Southwest: Species relies on blazes, insects or disease to clear other trees, giving them room to thrive.

Quaking aspens, which primp each fall in their finery of gold, are falling victim in Southwestern forests to a century of ardent fire suppression.

“It’s really important for us to understand that the beauty that we see in these aspen stands isn’t going to be there forever unless something is done to maintain it,” said Reggie Fletcher, a U.S. Forest Service ecologist in Albuquerque.

A U.S. Forest Service report in July, 1993, said New Mexico and Arizona had 263,000 forested acres dominated by aspen in 1986, compared with 486,000 acres in 1962--a 46% decrease.

Quaking aspens grow as far north as Alaska and as far south as Mexico on mountain slopes at elevations of 6,500 to 10,500 feet.

In the Southwest, aspens rarely, if ever, grow from seed. The aspen, Populus tremuloides in scientific terminology, requires plenty of sunlight to grow--sunlight often blocked by competing conifers such as fir and spruce, which live longer and eventually crowd out aspens.

So, aspens rely on fire--and in some instances insects, disease or windstorms--to clear other trees from the landscape. Aspen suckers then sprout from their parents’ undamaged roots.

The genetically identical youngsters flourish in the unhindered sunlight, their leaves once again trembling in the breeze and casting shadows that dance against the trees’ white trunks.

Young stands of aspen, full of moisture, are almost fireproof. Fires raze older aspen stands mixed with conifers, making way for the young progeny, starting the cycle anew.

But the lives of aspens have been thrown out of kilter by human intervention in the natural forest cycle.

“It’s certainly true that . . . over the last century or so the natural fire regime, the natural process and ecosystems have been strikingly altered by human activity,” said Timothy Fahey, an associate professor of forest science at Cornell University in Ithaca, N.Y.

Aspens, which grow as high as 120 feet and live as long as 200 years, are a nursery for conifers and home to 221 animal species, including chipmunks, deer, hares, weasels, foxes, bears, grouse, turkey and hummingbirds.

As aspens decrease, “then the ability of those animals to provide viable populations is decreased,” Fletcher said.

But aspens also are important to people, he said.

“Being a selfish human being myself, it’s hard to get around the primary importance of how aspens feel to us as the wind rustles through the leaves,” Fletcher said.

The Forest Service must grapple either with attempting to mimic the natural scheme to spur aspen growth or let nature work it out.

Fahey says enough is now known about how forests work to “make some good judgments on how we should alter how nature should take its course. . . . “

“The Forest Service is not only charged with preserving ecosystems, but with providing commodity values such as higher-value wildlife habitat, domestic grazing habitat and higher-value recreation and timber,” he said.

All that places the Forest Service in an almost impossible management situation, he said.

Naturally occurring fires can be allowed to burn themselves out, but to let dangerous fires burn uncontrolled also endangers people who are part of the landscape, Fahey said.

Fletcher says aspen stands could be rejuvenated with controlled burns or harvesting for fuel wood, while the conifers could be thinned for Christmas trees.

“But regardless of how important it is to the diversity of the ecosystem, we can’t discount or minimize the importance of the aspen to us purely through an aesthetic standpoint,” Fletcher said.