Forest fire enables unique research

Forest fire enables unique research

28 July 2013

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USA — Shortly after their funding was renewed for another five years in June, University of Arizona researchers lost one of their critical-zone research sites to the 24,000-acre Thompson Ridge Fire in the Valles Caldera National Preserve near Jemez Springs in northern New Mexico.

The grant renewal was good news, said Jon Chorover, co-investigator for the National Science Foundation grant that underwrites research of the Critical Zone Observatory on mountain slopes in Arizona and New Mexico, including sites on nearby Mount Lemmon.

Chorover was reluctant to characterize the fire as “bad” news, instead calling it “interesting.”

The fire destroyed some of the group’s instruments but could provide an opportunity for significant research during the five-year, $4.9 million grant period, said Chorover, a professor of environmental chemistry and interim head of the UA Department of Soil, Water and Environmental Science.

“A heroic effort” by seven researchers in New Mexico managed to save about $250,000 worth of equipment two days before fire burned across the heavily instrumented Redondo Peak site, he said.

The fire was close enough to rain ash on the rescue crew, said Mark Losleben, field manager for the Valles Caldera site. “The smoke was dense enough to make the sun a very dark red.”

The group was given a few hours to “cut and grab as much as we could.”

Recently, Chorover and researchers from Arizona and New Mexico spent three days assessing damage and reinstalling sensors to record what comes after the fire.

They had to wear protective fire gear and were escorted by a U.S. Forest Service fire safety officer.

The fire was declared 100 percent contained on July 1, but parts of it continue to smolder, and burned trees are prone to fall on windy days. The researchers had to retreat to their trucks when thunderstorms blew through.

Also, the group detoured two hours after a debris flow blocked the road they had come in on, Losleben said.

The intense monsoon storms gave them an opportunity to observe the burned crust of “hydrophobic” soil repelling water rather than absorbing it, cutting new paths down the slopes, Chorover said.

Chorover is excited to be able to compare four years of data from an unburned mountain watershed with whatever comes next.

“All indications are that it will change drastically,” he said.

Hydrologists have recorded drastic changes in streamflow and topography after fires, he said, but seldom have pre-fire data for comparison. The Critical Zone Observatory also takes a much deeper look at the geochemical and biological processes that occur when mountain rock weathers into soil.

The original plan for the Jemez site was to compare changes on burned and unburned landscapes.

The mid-elevation site on the eastern rim of the Valles Caldera was chosen in 2011 after it had partially burned in the July 2011 Las Conchas Fire. Now both sites are burned, and the group plans to establish a pristine site.

The renewal of the NSF grant, which brought $4.35 million to the project in its first five years, came as the fire burned toward the site.

NSF reviewers knew the destruction was a possibility, Chorover said, and renewed the grant anyhow. “We have a unique opportunity to do something nobody’s ever done before.”

It will take an additional $250,000 to restore all the equipment at the site, Chorover estimates. A 100-foot-tall “eddy flux” tower that takes continuous atmospheric measurements will have to be replaced after its metal was compromised by the extreme heat of the fire.

The Catalina/Jemez Critical Zone Observatory is part of a network of highly instrumented sites in a variety of watersheds across the country, where researchers are trying to gain a deeper understanding of the water, carbon and energy cycles at the critical zone, the area between the tops of the trees and the underground aquifers where the physical, chemical and biological exchanges that create life all take place.

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