They also are contributing to global warming, scientists say, by upsetting the carbon balance while they are burning and for years to come.
Trees breathe in carbon dioxide, but how long they hold onto it affects the amount of greenhouse gases in the atmosphere.
Charred logs, standing dead tree trunks and decaying branches mark the site of the 1996 Hochderffer Fire, a “crown fire” that burned hot through 16,000 acres west of the San Francisco Peaks north of Flagstaff.
Mike Stoddard, a forest ecologist with the Northern Arizona University Ecological Restoration Institute, has been looking for a sign, any sign, of ponderosa pine seedlings 15 years after the fire.
“These large fires are devastating our forests,” Stoddard said. “We’re concerned that ponderosa pine is not regenerating after these wildfire events.”
Crown fires burn into the canopies and treetops or crowns of the trees—massive, intense crown fires, such as the Wallow Fire in eastern Arizona, are not natural in the ponderosa pine forest. Naturally occurring ponderosa pine fires burn along the ground, or base, of the trees.
Scientists also are concerned about the invisible impacts of crown fires.
In a study conducted from 2001 to 2007, forest ecologist Matthew Hurteau with NAU’s School of Earth Sciences and Environmental Sustainability found that the nation’s wildfire emissions were the equivalent of 4 percent to 6 percent of all emissions from burning coal, oil and natural gas. The percentage of lingering emissions is even greater.
“We’re looking to forests to take in carbon, thereby lowering the greenhouse gases. But at a site like the Hochderffer Fire, the grassy vegetation that’s growing in is not making up for the amount of carbon that’s being released from the dead trees,” he said.
Across Arizona Highway 180, the story is much the same. NAU forestry professor Tom Kolb is calculating the amount of carbon dioxide moving between the land and the air at the site of the Horseshoe Fire. This 8,000-acre crown fire also burned in 1996.
“The fire has had a long-term legacy effect on the capacity of this site to take in and store carbon dioxide,” Kolb said. “This site has gone from being a carbon sink, where carbon was being stored, to a carbon source, where carbon is being released.”
With carbon making up about half the dry weight of a tree, researchers say overstocked ponderosa pine thickets can store a lot of carbon, at least for a while.
“Storing carbon in lots of little trees in a dense forest is like investing your retirement funds in junk bonds. It’s risky,” Hurteau said. “Our research has shown that if we reduce the amount of trees per acre and return ground fire to the system to manage those surface fuels, the carbon left in the live trees is much more stable because it’s less vulnerable to crown fire.”
Carbon flux research south of Flagstaff where excess small diameter ponderosas have been removed shows the remaining trees have become more vigorous.
“They photosynthesize at a much greater rate than the trees in the un-thinned situation,” Kolb said. “The thinned forest has an equal to or slighter greater rate of carbon sequestration than an un-thinned forest.”
Bonnie Stevens | Newswise Science News
International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
World Water Day 2017: It doesn’t Always Have to Be Drinking Water – Using Wastewater as a Resource
17.03.2017 | ISOE - Institut für sozial-ökologische Forschung
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
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Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
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In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
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