USA — Should forests be thinned to reduce fires, or should they be tended to store the maximum amount of carbon in their trees to prevent global warming?
It is not a simple question, as researchers at Oregon State University explain in a new study in Ecological Applications, a professional journal.
Stephen R. Mitchell, an OSU researcher now at Duke University, and other scientists studied the Coast Range and the west side of the Cascade Mountains and found that salvage logging, understory removal, prescribed fire and other techniques can reduce fire severity. But these same techniques will almost always reduce carbon storage even if the woody products that are removed are then used to produce electricity or make cellulosic ethanol, they found.
“It had been thought for some time that if you used biofuel treatments to produce energy, you could offset the carbon emissions from this process,” said Mark Harmon, an OSU professor of forest ecosystems and society and a co-author of the study. “But when you actually go through the data, it doesn’t work.” Harmon said that policymakers should consider using forests on the west side of the Cascades, the wetter side, for carbon sequestration, and focus fuel-reduction efforts near people, towns and infrastructure.
However, the Oregon State findings may not be applicable to other forests. “It is a fertile debate,” said Andrea Tuttle, former head of the California Department of Forestry and an authority on forest carbon regulation. “But be careful what forest type you are talking about.” Studies of other forests have produced different results, she explained, citing a UC Berkeley study of warmer, drier Sierran forests that found that measures to increase fire resistance were also applicable to long-term carbon sequestration.
The study comes at a time when state governments and the U.S. Congress, as well as other nations, are looking to forests to offset emissions from automobiles, power plants and other sources of carbon dioxide, which, scientists say, is heating the planet to dangerous levels. Trees suck carbon out of the atmosphere and store it for long periods. California recently enactedstrict rules to govern the use of offsets for carbon sequestration in forests.