Climate forces fires, salvage logging makes ’em worse
Lance Olsen

Proceedings of the National Academy of Sciences (US)
PNAS | *June 19, 2007* | vol. 104 | no. 25 | *10743-10748*

* Reburn severity in managed and unmanaged vegetation in a large wildfire*

* Jonathan R. Thompson^* ^,{dagger} , Thomas A. Spies^{ddagger} , and
Lisa M. Ganio^* *

*Department of Forest Science, Oregon State University, Corvallis, OR
97331; and ^{ddagger} Pacific Northwest Research Station, U.S.
Department of Agriculture Forest Service, Corvallis, OR 97331

Edited by Ruth S. DeFries, University of Maryland, College Park, MD,
and approved April 26, 2007 (received for review January 10, 2007)

Debate over the influence of post-wildfire management on future fire
severity is occurring in the absence of empirical studies. We used
satellite data, government agency records, and aerial photography to
examine a forest landscape in southwest Oregon that burned in 1987
and then was subject, in part, to salvage-logging and conifer
planting before it reburned during the 2002 Biscuit Fire. Areas that
burned severely in 1987 tended to reburn at high severity in 2002,
after controlling for the influence of several topographical and
biophysical covariates. Areas unaffected by the initial fire tended
to burn at the lowest severities in 2002. Areas that were
salvage-logged and planted after the initial fire burned more
severely than comparable unmanaged areas, suggesting that fuel
conditions in conifer plantations can increase fire severity despite
removal of large woody fuels.


“We got records going back to 1960 of the acres
burned in America. So, that’s 47 fire seasons.
Seven of the 10 busiest fire seasons have been
since 1999,” he tells Pelley.

Expert: Warming Climate Fuels Mega-Fires
Scott Pelley Reports On The Rising Number Of Mega-Fires

(CBS) Global warming will result in more than
rising oceans and melting icecaps. According to
one of the world’s leading fire ecologists, the
warming trend is also increasing the intensity
and number of forest fires so much that the
American West could lose half its forests by the
end of the century.

60 Minutes correspondent Scott Pelley speaks to
Tom Swetnam, a fire ecologist at the University
of Arizona, for a report on mega-fires to be
broadcast this Sunday, Oct. 21, at 7 p.m. ET/PT.

“As fires continue to burn — these mega-fires
continue to burn — we may see, ultimately, maybe
more than half the forest land converting to
other types of ecosystems,” says Tom Swetnam.
“(It will happen) within some decades, to a
century, as warming continues and we continue to
get large-scale fires,” he tells Pelley.

Last year was the worst fire season in recorded
history and this season is already second, with
eight million acres burned. Average temperatures
are up a degree, causing earlier springs and
longer fire seasons and quadruple the number of
fires. “The fire season in the last 15 years has
increased more than two months over the whole
Western U.S.,” says Swetnam. “So actually 78 days
of average longer fire season in the last 15
years compared to the previous 15 or 20.”

Tom Boatner, chief of fire operations for the
federal government, says he has seen the results
up close on the fire line and in the statistics.
“We got records going back to 1960 of the acres
burned in America. So, that’s 47 fire seasons.
Seven of the 10 busiest fire seasons have been
since 1999,” he tells Pelley. The fires are
bigger and more frequent. “Ten years ago, if you
had a 100,000-acre fire, you were talking about a
huge fire … Now we talk about 200,000-acre
fires like it’s just another day at the office,”
says Boatner, who says he and his firefighters
have battled two fires this year that were over
500,000 acres.

Part of the blame for the fires is a strategic
mistake made by the forest service. Throughout
most of the 20th century, all forest fires
sighted, big and small, were extinguished. This
vigilance led to an increase in the amount of
fuel in forests. “So now, when the fires get
going, there’s a lot more to burn than
historically you would have seen,” Boatner tells

With more to burn, the fires are more intense and
all consuming, leaving very little to grow back
and scant soil from which it can take
nourishment. On a fire-ravished landscape,
Swetnam points to the ground. “We used to have
forest soil here that might have been this deep,”
he says, indicating about a foot of depth, “but
now we’re just down to rock … sort of armored
soil and that is not a good habitat for trees to
re-establish,” he tells Pelley.

Produced By David Gelber and Joel Bach
© MMVII, CBS Interactive Inc. All Rights Reserved.


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