USA — Scientists looking at the aftermath of wildfires in the forests of southwestern Oregon and Northern California found that after five to ten years even the most severely burned areas had sprouted plentiful seedlings without any help from man.
Though natural regeneration generally took longer to produce pines and firs, it created a more varied forest, even after brush had become established, which is likely to benefit wildlife, concluded to the study by scientists from Oregon State University appearing in Wednesday’s issue of the Journal of Forestry.
“When time is not a factor in achieving the goals, then natural regeneration appears to be a very good approach to reforestation,” said David Hibbs, a professor of ecology and silviculture at Oregon State University who took part in the study.
The study is the latest to address the contentious issue of whether to harvest trees killed by wildfires on national forests and replant, or let them regenerate on their own.
Fire serves as both an agent of destruction and renewal in the Klamath and Siskiyou mountains where the study took place, wrote lead author Jeff Shatford, a research assistant in Oregon State’s Department of Forest Science.
The study looked at 35 plots in eight areas that had burned between 1987 and 1996. Most were located in the Klamath River drainage of Northern California. Some were in the Umpqua River drainage of Southern Oregon. All had burned severely, Hibbs said.
Over 19 years, the study found hundreds of trees per acre in various types of forests, equal to or greater than the density of forests that are 60 to 100 years old. Seedlings were still sprouting 19 years after the fire, even in areas covered by brush.
Hibbs said they saw plentiful seedlings on sites located a quarter mile from surviving trees that provided seeds, leaving them to wonder how the seeds could have traveled so far.
The scientific and political debate erupted after the 2002 Biscuit fire, which burned 500,000 acres in southwestern Oregon. Conservation groups lost court battles to stop salvage logging and replanting in roadless areas not normally considered for timber harvest.
It continued last year as conservation groups battled the timber industry over legislation to speed up the logging of dead trees on national forests and replanting after wildfires.
A congressional hearing was called over research by OSU graduate student Dan Donato that found most of the seedlings that sprouted on their own after the Biscuit fire were destroyed by salvage logging, which also left more fuel on the ground for future fires.
The bill passed the Republican-controlled House, but not the Senate. It is considered a longshot in the Democratic-controlled Congress.
When timber production is the primary goal, planting seedlings and controlling competing brush is still a good way to speed forest regeneration, said Hal Salwasser, dean of the OSU College of Forestry, who did not take part in the study. However, he added, letting areas managed for fish and wildlife or wilderness regenerate on their own is probably OK, ecologically.
David Perry, an OSU professor emeritus of forest ecology who did not take part in the study, said it makes sense to embrace natural regeneration, given declining budgets to deal with the millions of acres of national forests that burn every year, the likelihood that even more will burn as global warming progresses, and the need to devote scarce resources to reducing fire danger.
“The forest will do it on its own and do it just fine,” he said.
The findings seem obvious, given the fact that forests have survived millions of years with wildfires, said Jerry Franklin, professor of forest ecology at the University of Washington and one of the nation’s leading experts on old growth forests.
“I did a masters degree at Oregon State in 1959 on natural regeneration of Douglas fir,” said Franklin, who did not take part in the new study. “And I was told by the head of timber management for the Forest Service in the region at the time that it was totally irrelevant. We were never, ever, going to depend on natural regeneration again. Gee whiz, it’s fun to see it back.”