The U.S. Forest Service has made forest thinning one of its top priorities, particularly in fire-prone and unhealthy dry forests. But environmental groups say dense Douglas fir plantations on the wet side of the Cascades need to be thinned too. And that could help increase the lumber supply.
On a steep slope in the Siuslaw National Forest, Douglas fir trees are packed in like matchsticks. Dan Segotta, the U.S. Forest Service’s timber operations manager in the Siuslaw, says these woods were clear-cut in 1965, and then densely replanted. 20 years ago, forest managers in the Siuslaw began a thinning experiment on the site. They left this stand alone to serve as an experimental control.
Although a winter wren’s song can be heard, Segotta says this stand is poor habitat for most bird species. Too much competition has weakened the firs, leaving them spindly and unable to grow real branches.
“The green crowns are very small up in the trees. They’re only green up there where they can get the sunlight,” he says.
This is what looks like when 220 trees are all trying to grow on one acre of land.
Segotta drives a few miles down the road, to another part of the experiment: a stand that was thinned 20 years ago. About 80 percent of the young firs were cut down and sold. That may sound drastic. But the trees that were left behind have enough room and light to grow limbs.
“You’re seeing large green canopies in the trees that extend from just a few feet off the ground up into the tops.”
This kind of forest thinning and restoration isn’t a new idea. But environmental groups are pointing to the Siuslaw as an example of just how many Doug fir logs restoration thinning could produce. Randi Spivak is a policy analyst with the Geos Institute.
“This is exactly the kind of work we want to see much more widespread because it will yield a significant increase in timber volume,” she says.
The Geos Institute and three other environmental non-profits have published a report that it inventories how much lumber could be produced by thinning younger stands in about two dozen federal forests in the Northwest.
Spivak says thinning could generate 774 million board feet a year for twenty years. That’s roughly 150 million two-by-fours each year.
“That is stability, predictability, um, a good wood supply for jobs in the woods, all while protecting water salmon and wildlife,” she says.
There’s a caveat to Spivak’s numbers though; the groups found the greatest potential for new thinning projects in Washington and California, and less in Oregon.
Gordon Culbertson is an industry analyst with the company Forest2Market. He agrees thinning is a good tool.
“It can produce valuable small logs that can be used in the production of Douglas fir lumber and veneer,” Culbertson says.
But Culbertson does not think thinning on federal land will support a healthy timber industry for the long haul. It’s just less profitable. He says traditional clear-cut harvesting might give you eight loads of logs a day.
“Thinning is more difficult to do and complicated. And you only get two loads of logs a day. It costs the same amount of money but you produce less,” Culbertson says.
Eventually, Culbertson says, the Forest Service will run out of younger stands that need thinning. He thinks that will happen sooner than the conservation groups predict. And, he worries, once those thinned forests have matured, their value as wildlife habitat will arm environmental groups in the battle to restrict logging on public lands.
“The problem with the way that thinning is being promoted today is that it’s not growing that will be harvested at a later date, it’s simply to thin to grow trees to produce habitat in older forests,” he says. “When that’s completed, there won’t be any commercial opportunities for timber harvest on federal lands.”
Back in the Siuslaw National Forest, Forester Dan Segotta isn’t worried about running out of plantations to thin.
“In 28 years, we will have been through and looked at initially thinning of all the plantations on the forest,” he says.
And in 28 years, Segotta says, it will be up to the next generation to decide how much to cut.
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