Landslides after clearcuts
dwheeler at teleport.com
dwheeler at teleport.com
Thu Feb 19 23:58:26 EST 1998
The following is an article which ran in The Oregonian on Friday, Jan. 30,
State study links clear-cuts to landslides
By JONATHAN BRINCKMAN, of The Oregonian staff
Preliminary results show forested land tends to be more stable, but steepness
and rain also are key factors.
The state of Oregon has calculated for the first time that clear-cutting
increases the chance of landslides, a finding that raises concern in a logging
industry already beset by government constraints.
The study follows massive rainstorms in 1996 that triggered tens of
thousands of landslides across the state, some of them lethal. Slides
emanating from clear-cuts killed five people and destroyed at least a dozen
Now state officials are considering tightening logging rules, to increase
the public's safety and to protect salmon that spawn in streams that can be
damaged by logging practices.
The study, outlined Thursday in Portland, was begun by the state
Department of Forestry after the February 1996 storms. It was expanded after a
November 1996 storm caused more damage.
Results of the $370,000 study, which will not be made final until late
this year, will be used by a special panel convened by Gov. John Kitzhaber to
recommend changes to Oregon logging rules.
The subject is fractious among loggers, those whose homes adjoin prime
land for tree harvest and the state officials who establish allowable logging
practice. Landowners who lease to loggers also are entwined in the debate.
Roughly 56 percent of Oregon's private timberland is owned by large timber
companies, with the remainder owned by small firms and individuals. Harvest
from private lands generated $1.25 billion in revenues in 1996.
The findings released Thursday, though confirming for the first time that
clear-cuts are twice as likely to slide as forest land, indicate that slides
are driven by variables such as the amount of rain and steepness of slope.
Moreover, the scientists conducting the study found that clear-cut areas
do not always slide more than uncut forests. In the Elk Creek region of
Southern Oregon, for example, land covered with forests 100 years or older
slid more frequently than clear-cut sections.
But timber inudstry officials were alarmed Thursday by the results thus
"There is a potential that this could be devastating for the industry,"
said Jim James, general manager of wester timber and logging for Willamette
Industries, which owns 610,000 acres of Oregon timber land.
James said that even if final results confirm that clear-cut areas are
slide-prone, harvesting prohibitions should not be required. More careful
logging practices, including construction of fewer roads, might be the answer,
"I do not foresee that the landslide issue will put us out of business,"
Jim Geisinger, executive director of the Northwest Forestry Association, a
timber trade group, called Thursday's preliminary findings alarming. "If the
ultimate outcome is to restrict timber management on steep slopes, it could
have a very serious impact on the industry," he said.
Environmentalists said the state's calculations set the stage for long-
needed overhauls of logging practices.
"The timber inudstry has had free reign over Oregon's forests for
decades," said Dougl Heiken, a field representative for the Oregon Natural
Resources Council. "It's about to be put in its place."
Federal scientists and others called Thursday's clear-cut-slide
"They've decided to face the music," said David Montgomery, a professor at
the University of Washington.
Gordon Grant, a research hydrologist with the U.S. Forest Service in
Corvallis, said the study seems to confirm previous findings. "It give us
confidence that this study and the studies that preceded are right," he said.
Department of Forestry officials said their study, which covered a
patchwork of 52 square miles in the state's coast range, was the most
exhaustive landslide study undertaken. Rather than rely on aerial photos to
identify landslides, crews walked 136 miles of stream channels, inspected 170
miles of road and documented about 600 landslides.
The scientists examined eight sites in Western Oregon. Three were chosen
to represent the most severe effects caused by the February storm, two
represented the effects of the November storm, and three were randomly chosen
to represent typical storm effects.
- Newer logging roads, which are better built and placed in less fragile
sites than older roads, trigger few landslides.
- Aerial surveys detect less than 25 percent of the landslides found by
researchers traveling streams and roads.
- Almost 80 percent of the total landslides that entered streams came from
very steep slopes.
Submitted by Daniel B. Wheeler
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