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Thinning leaves owner's mark

Careful tending allows forest to thrive despite pressure from fire, disease


Capital Press

RAVENSDALE, Wash. -- Small forestland owners cite several reasons for owning trees, but turning a profit is far down the list.

Andy Perleberg, head of the Washington State University Extension forestry program, said privacy is the main reason. Behind that come pride of ownership, wildlife and a family legacy. "Periodic income is about third from the last in a list of 15 reasons," he said.

Perleberg was speaking at a family forest field day July 31 near the Cascade foothills east of Tacoma.

Whatever the intent, he said, "Every forest owner wants a healthy forest ... and every one loves tools. Harvesting and managing are compatible with all intentions."

Several sessions in the daylong workshop addressed the practice of thinning.

"It's like carrots," Perleberg said. "You can have a whole bunch of tiny carrots, or a few really big ones. Once they start competing for resources, ... you start thinning. Trees are competing when their branches are touching."

Arno Bergstrom, director of WSU Extension in Kitsap County, illustrated what happens when a forest is not thinned.

Holding a wedge of wood from a downed Douglas fir, he pointed to tree rings showing 15 years of healthy growth in the young tree, followed by a sudden slowing of growth the past 10 years.

"It should have been thinned 10 years ago," he said. "You see these trees crowding each other? In this sample plot, I calculated 180 trees per acre with an average diameter of 12.8 inches. If you take out 100 of the smallest trees, you leave those most capable of responding to the additional moisture, sunlight and nutrients in the soil."

The dominant trees, those with greater height and bigger crowns, get plenty of sunlight, he said. But he pointed to many of the tallest surrounding firs that had about 20 percent of their height in crowns. In unstressed trees, the crowns would make up 40 percent or more, he said.

Bergstrom said the hormones in Douglas fir keep it from recovering from a stunted stage of development, as opposed to Western hemlock or cedar, which when released "will take off."

Some reasons for thinning -- besides yielding better growth and disease resistance -- include better access for equipment, more open ground for wildlife, better understory health, diversity of age and species -- and income, Bergstrom said.

"Even these smaller, 10-inch trees are merchantable," he said. "Talk to a consultant. They're worth more than you pay them. You could net something."

Kristi McClelland, forester with King County, told the family forestland owners that they have the right and privilege of choosing what to do with their piece of forest.

For example, variable-density thinning -- "skips and gaps" -- can introduce many microclimates into the landscape, providing food and shelter for wildlife. Creating or protecting snags invites birds. Introducing new species of trees helps conifers and hardwoods resist disease.

"Diversity should be the goal of sustainability," she said. "But keep the best trees. This is one place where bigger butts are OK."

Bill Loeber, also a King County forester, suggested planting hazelnuts in opened-up areas. "With more light, they'll put on nuts and attract wildlife."

A thinning project can also change the entire makeup of a stand, Bergstrom said. The owner can underplant with shade-tolerant species, he said. "Eventually, within two or three generations, those trees will be dominant." Suggested shade-tolerant species include Western hemlock and red cedar.

Perleberg said an owner can thin a stand multiple times, each time keeping the biggest and the best. "Harvesting timber is not about what you take, it's about what you leave. Like a farmer keeping the best cows."

Upcoming event

WSU forestry will sponsor another field day for Oregon and Washington family forestland owners on Aug. 28. Information: ext.wsu.edu/forestry


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