Tucked among the pine and juniper, often along rivers or streams in the Deschutes and Ochoco national forests, stands of white-barked aspens provide a unique habitat for elk, deer, turkeys, migratory songbirds and more.
But in Central Oregon and across the West, conifer trees are overshadowing the aging aspens, which aren't being replaced by young trees. The stands are shrinking and aspens are disappearing from the landscape.
"They're just a mere shadow of the extent they used to be," said Dave Zalunardo, forest wildlife biologist with the Ochoco National Forest.
On the Malheur National Forest in Eastern Oregon, studies suggest that aspens currently occupy only about one-twentieth of the acres they used to cover, he said. That number is probably similar to the extent of aspen decline in the Ochoco and Maury mountains as well, he said. There are probably a couple thousand acres of aspens left in about 250 stands on the 850,000-acre Ochoco National Forest, he estimated.
To help reverse the decline of the aspen stands scattered across the Ochoco National Forest, the U.S. Forest Service and the Rocky Mountain Elk Foundation recently agreed to a 10-year restoration partnership. By removing conifer trees and using other management tools, the agency and the organization hope to restore aspens' natural life cycle, which was disrupted a century ago when people started suppressing wildfires.
"We've changed a lot of things, and since they're not a long-lived tree, it only takes 100 years to markedly change the aspen composition in our forests," Zalunardo said.
An aspen's life
Aspen trees live an average of 80 years, he said, and regenerate by sending up "suckers," or little saplings, from their huge root system.
But mature trees produce a hormone that suppresses the formation of these suckers, Zalunardo said. With this hormone in play, only a few sprouts pop through the ground - and grazing deer, elk and cattle munch on those.
Fire sparks new aspen growth, however. The natural fire cycle, in which fires burn through the area every 15 to 25 years, allowed enough sprouts to escape the mouths of grazers and repopulate the stands.
That's because when a fire comes through and kills the mature aspen trees, they stop producing the hormone, he said. Without the hormone, aspen roots can produce a lot of sprouts.
"The fire came in and basically killed everything, but the roots were still alive," he said. "So the next spring, boom, then you get this profusion of suckers."
But when people began using fire suppression as a management tool about a century ago, the lack of fire resulted in fewer suckers being produced and aging stands that lacked young aspens.
After fire sweeps through an area, aspens are one of the first plants that return, said Bob Lightley, wildlife biologist with the Ochoco National Forest. Conifers like pines and junipers will come in later, if they aren't killed off by subsequent fires. The needled trees will take over the stands, shading the deciduous aspens and, especially with juniper, sucking up the water.
"Conifers will come into the stands again, and over time aspens will disappear," Lightley said. The aspens are also susceptible to a number of diseases, many of which might not kill the tree but could make them weaker.
But without regular fires in the ecosystem, what few suckers come up are being eaten, and the conifers are encroaching on the older aspens that remain.
"I have seen at least one stand totally disappear, and quite a few that are almost gone," said Lightley, who has worked for the Ochoco National Forest since 1989.
The stands, many of which are in the Maury Mountains south of the Ochocos, are often less than 5 acres in size, and some only contain a few trees.
"Most of them are in one stage of decline or another," he said.
But restoration efforts, including conifer thinnings and fencing projects to keep out the grazers, have helped some of the stands start to recover. A few stands are recovering on their own, he said, and in the last five or so years he's seen more sprout growth than in previous years.
On the Sisters Ranger District of the Deschutes National Forest, big fires in the last few years have spurred aspen regeneration, said Monty Gregg, the district's wildlife biologist.
While shrubs dominated the landscape for the first year and a half, in many areas the aspen have started come back as well, he said.
Aspens generally grow near water, along rivers or in areas with water just below the ground, he said, but will also pop up in odd places like lava rocks in the Bend-Fort Rock District.
Aspen stands draw a diversity of wildlife and multiple songbirds, he said.
Their soft wood is also home to woodpeckers and migrating birds, Lightley said, but beyond the wildlife value, aspens are one of those trees that people just like seeing in the forest.
Restoration agreement
Aspens also provide key habitat for elk, said Al Christophersen, director of habitat stewardship services with the Rocky Mountain Elk Foundation. There's about 10 times more forage available for the animals in an aspen stand compared to a typical pine stand, he said.
To help get these stands healthy again, the foundation entered into an agreement with the Ochoco National Forest. The two organizations will collaborate on developing annual plans for what work needs to be done, Christophersen.
"Before, there never was enough money to go out and deal with aspen," he said.
But under stewardship agreements, the Rocky Mountain Elk Foundation will act kind of as contractors in projects to thin out conifers. It's sort of a trade, Zalunardo said. The Forest Service gives the foundation permission to log encroaching conifers. In return, the foundation agrees to contract out the necessary work to restore habitat
The projects could include not only removing commercially viable conifers which are under 21 inches in diameter, but also conducting prescribed burns or seeding projects, Christophersen said. The organization has similar long-term agreements with a national forest in Montana and a Bureau of Land Management district in Wyoming.
In the Paulina Ranger District of the Ochoco National Forest, the National Wild Turkey Federation has worked with the Forest Service on a shorter stewardship project. Young turkeys thrive on insects, and aspen stands are a prime place for bugs, said John Thiebes, regional wildlife biologist with the group.
On a 4-acre and a 5-acre parcel, the organization hired a timber company to remove the conifers between 6 and 21 inches in diameter, he said. The value of the timber was just enough to cover the cost of removing the trees, and then a band of volunteers came in and cut the conifers that didn't have commercial value.
"It took out enough trees to open up the forest floor to sun and is allowing new aspen seedlings to sprout," Thiebes said. "If we can keep a combination of elk, deer and cattle from grazing them too much, they'll be producing new aspen stands throughout those two areas."The Bend Bulletin
