By Damon Arthur
The Record Searchlight
REDDING, Calif. — Wildfires in the north state have been getting bigger during the past several decades, but they have not been getting more severe, according to a recent U.S. Forest Service study.
Scientists studied fires in four national forests in Northern California from 1910 to 2008 and concluded that blazes decades ago burned more severely than they do these days.
“We were kind of surprised as to what the results turned out to be,” said Carl Skinner, one of the study’s authors.
The report also found:
• Most fires since 1987 have been low to moderate in severity.
• From 1987 through 2008, 87 percent of the fires on the four national forests were caused by lightning.
• The more acreage burned in a year the less severely fires burned.
• Humans caused most of the fires in the first half of the 20th century, while lightning has caused most of the blazes in recent decades.
Steve Fitch, of Cottonwood, a former superintendent of the Shasta-Trinity National Forest, said the finding that fires were not burning as severely seemed to buck conventional knowledge.
“It does go against the common opinion. That’s a real surprise,” Fitch said.
In the summer of 2008, lightning-caused fires charred hundreds of thousands of acres of forestland. But less than 15 percent of the acreage burned caused severe damage, the report says.
“‘High’ severity patches within fires are areas where greater than 95 percent of the forest canopy was killed,” according to a news release that was issued on the report.
Scientists with the forest service and the University of California at Davis looked at fires on the Shasta- Trinity, Klamath, Mendocino and Six Rivers national forests. But Skinner said the report’s findings are unique to those forests, which Skinner said generally comprise the Klamath Mountains.
Fires in the Sierra Nevada have been getting larger and causing more damage, according to a 2009 study written by scientists with the forest service, UC Davis and officials with the University of Arizona and Northern Arizona University.
Skinner, a geographer with the Pacific Southwest Research Station in Redding, said differences in the Klamath and Sierra topography and climate led to differences in fire behavior. Fitch said fires are getting larger, in part, because in the past decade or so, firefighters have changed the way they manage blazes. If fires are in an area where they don’t threaten homes or lives, fires aren’t attacked as aggressively, he said.
He said fire managers can use information from the report to better manage fires and use fires to manage forests.
“By understanding these patterns, managers could potentially think about how to use fire to achieve some other objectives,” Skinner said.
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