The findings create a more complex view of the carbon cycle in forests, where it was already known that logging or other stand-replacement events – whether natural or not – create periods of 5-20 years when there is a net release of carbon dioxide from forests to the atmosphere, instead of sequestration as they do later on.
The end result is a highly variable forest carbon cycle that appears to be heavily influenced by the footprint of humans, one way or another. It’s a complicated process with powerful driving forces that were poorly understood, said scientists from 10 institutions in the U.S., Canada and Europe.
Until this report, researchers had never quantified the effect of continuous low levels of nitrogen deposition – about 5-10 percent of the amount used by a farmer each year - to spur net carbon uptake by forests and actually offset a significant amount of greenhouse gases into the atmosphere.
This broad study analyzed the carbon balance across a network of forest sites that represent nitrogen deposition in most of Western Europe and the continental United States. Until now, it has been difficult to separate the effects of nitrogen deposition on forests from the many other variables that affect their carbon release or sequestration – things like forest age, logging, wildfires, disease or insect epidemics, or other causes. This study attempted to do that, and found that the net carbon sequestration by temperate and boreal forests was overwhelmingly determined by nitrogen inputs.
“What is surprising is that the net sequestration is quite large for a relatively low level of nitrogen addition,” said Beverly Law, a professor of forest science at Oregon State University, co-author of the study and director of the AmeriFlux monitoring network in North and South America.
“Through our forests, fertilization by nitrogen deposition is to some degree offsetting our carbon dioxide emissions – at least right now,” she said.
It was first recognized in the 1980s that human activities, by releasing unprecedented amounts of active nitrogen into the atmosphere, were not just altering the global nitrogen cycle but also causing the eutrophication of large parts of the biosphere, the researchers said in their report. Nitrogen – produced by automobile engines, factories, and intensive agriculture – is often a key, limiting nutrient in forests and other ecosystems.
Early forest growth puts a severe nitrogen stress on the ecosystem initially, and then the forest continues to grow and remove carbon from the atmosphere for the rest of the management or life cycle, accumulating wood at a high rate on the small additional nitrogen inputs.
This growth and sequestration is achieved without applications of fertilizer that would likely result in nitrous oxide emissions, another greenhouse gas, that would offset the benefits to the atmosphere of carbon removal.
However, it’s known that large additions of nitrogen to ecosystems can also be damaging above a certain threshold, researchers say, and it’s unclear how long this process will continue.
“The results demonstrate that mankind is ultimately controlling the carbon balance of temperate and boreal forests, either directly through forest management or indirectly through nitrogen deposition,” the study authors said.
Ultimately, mature forests, at least in northern latitudes, absorb and sequester substantial amounts of carbon from the atmosphere. Forest protection and management options have been viewed as one mechanism to absorb carbon dioxide from the atmosphere and reduce concerns about the greenhouse effect and global warming.
Beverly Law | EurekAlert!
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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