Fire Study: Trees Return on Their Own
By Michael Milstein, The Oregonian
April 4, 2007

Forests torched by wildfires in southern Oregon and northern California in almost all cases are coming back on their own some 10 to 20 years later -- one of several new findings that may help land managers decide whether to log and replant or just let things be.

Oregon State University researchers reported the results in a study published today, the latest to examine forests in the wake of wildfires increasingly sweeping the West. While sawmills push to make use of the burned trees and plant seedlings to jump-start recovery, others argue forests are better left alone.

Planting seedlings may bring big trees back faster, the new research suggests. But if time is not crucial, and funding is limited, nature does just fine on its own.

That key finding counters arguments that fast-growing brush will crowd out young trees after a fire, blocking the return of forests for decades or even centuries.

Logging took place on a small amount of the 500,000 acres burned by the giant 2002 Biscuit fire in southwest Oregon. But lawsuits and controversy in the aftermath of the blaze turned salvage logging of burned trees into a national issue.

Oregon State's College of Forestry took a leading role. One group of professors and others argued in a report that rapid logging and replanting would best bring trees back quickly. Without it, they said, brush could take over the burned lands and choke out new trees.

The U.S. Forest Service expanded its logging plans based on the findings.

Then OSU graduate student Daniel Donato published research concluding that many seedlings sprouted on their own after fires only to be destroyed in the course of logging, which also littered the ground with extra tinder. Donato's research gained wider attention after some OSU professors tried to derail its publication in the journal Science.

The new research, published today in the Journal of Forestry by OSU researcher Jeff Shatford and others, offers some support for both positions.

While Donato's team examined seedlings only a few years after the fire, Shatford examined 35 pieces of land that burned anywhere from nine to 19 years ago. The parcels were not logged or replanted after they burned, and there was no effort to control competing brush.

Shatford and his team found lots of fir and pine seedlings growing, although the number and type depended on elevation and other factors. That suggests the seedlings Donato counted a few years after a fire will hang on for years afterward, even amid competing shrubs.

Seeds easily found their way into burned areas as far as three football fields away from the nearest seed tree.

There was no evidence the shrubs were killing off young seedlings, Shatford found.

At many sites, he found, the more shrubs were growing, the more seedlings were growing too, suggesting that both can flourish where conditions are good.

Competition and shade from the shrubs clearly slowed down the tree seedlings, Shatford found. But eventually they will rise above the brush, into the sunlight, and their growth will take off, he predicted. He found more than enough trees to grow into mature stand.

In some cases so many seedlings sprouted they would grow into overly dense thickets. But they had the hardest time on hot and exposed southern slopes.

That's an indication that left to its own devices, nature, while providing lots of opportunities for trees to grow back, remains unpredictable and varied -- which may not suit foresters trying to grow trees for logging.

"If you want to depend on natural regeneration, you have to be patient and put up with a great deal of variation," Shatford said. "That's tough for management agencies to do when they have specific goals in mind."

Action after forest fires must depend on the goals for the land involved, said Michael Newton, professor emeritus at Oregon State who also studied forest recovery in southwest Oregon. If the goal is to grow big trees fast, for logging or to help species such as spotted owls that need them, then planting and controlling brush is the way to go, he said.

Although planting costs more, it gives trees a critical head start.

"It makes a huge difference," he said. "It's like where you are in the Army chow line when there's limited food."

Natural regrowth after the Biscuit fire was so strong that the Forest Service scaled back its plans to plant trees in some places, said Rob Shull of the Rogue River-Siskiyou National Forest. Elsewhere, planting efforts focused on speeding up the return of large, old trees.

In accordance with Title 17 U.S.C. Section 107, and as defined under the provisions of "fair use", any copyrighted material herein is distributed without profit or payment for non-profit research and for educational use by our membership.