>This came from Roy Overton -


>Subject: Environment News Service U.S. Ecosystems Altered by Nitrogen 
>Pollution
>Date: Wed, 30 Jan 2002 12:01:00 -0600
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>Environment<http://ens-news.com/ens/jan2002/2002l-01-25-06.html../../aboute 
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>
>U.S. Ecosystems Altered by Nitrogen Pollution
>
>By Cat Lazaroff
>
>WASHINGTON, DC, January 25, 2002 (ENS) - Much of the nitrogen in 
>ecosystems throughout the United States comes not, as previously believed, 
>from natural sources, but from acid rain and agricultural fertilizers. A 
>study of ancient and unpolluted South American forests promises to upend 
>longstanding beliefs about ecosystems and the effects of pollution in the 
>Northern Hemisphere.
>
>
>
>Burning fossil fuels like coal produces nitrogen pollution (Photo courtesy 
>National Renewable Energy Lab)
>
>
>
>
>Ecologists previously thought that nitrogen containing minerals, referred 
>to collectively as inorganic nitrogen, have always been the dominant 
>nutrient in forests worldwide. The study of South American forests, 
>however, showed a sharply different picture: complex, organic compounds 
>are the main form of nitrogen in unpolluted ecosystems.
>
>"It's one of those things where everybody's intuition that they've gotten 
>from studying the world is wrong," said Stephen Pacala, professor of 
>ecology and evolutionary biology at Princeton University. "It's still not 
>clear what the consequences are, but as a pattern it's completely 
>different. You know there have to be lots of implications."
>
>The study, published in the January 24 issue of the journal "Nature," 
>focused on nitrogen, a plant nutrient that plays a critical role in 
>maintaining everything from the health of local waterways to the global 
>climate.
>
>The authors argue that the ecosystems of South America, with their 
>preponderance of organic nitrogen, are a window into the past, showing 
>that U.S. ecosystems were very different before the industrial revolution.
>
>
>
>Agricultural runoff contains large amounts of nitrogen laden fertilizer 
>(Photo by Jack Dykinga, courtesy Agricultural Research Service)
>
>
>
>
>
>"We traveled in time by traveling to South America," said Lars Hedin, a 
>coauthor of the study and a professor of ecology and evolutionary biology 
>at Princeton University.
>
>Conditions in North America are different from those in South America for 
>two reasons, the researchers said. First, burning fossil fuels produces 
>great quantities of nitrogen and oxygen compounds, which wash out of the 
>air as acid rain.
>
>Second, during World War I the chemist Fritz Haber invented a process for 
>extracting nitrogen from the atmosphere for use in making explosives. The 
>Haber process allowed the mass production of fertilizers, which has fueled 
>a boom in agricultural productivity.
>
>In the remote areas of Chile and Argentina that the researchers studied, 
>there is no fertilizer use and almost no influx of fossil fuel emissions.
>
>The information they uncovered could have far reaching impacts in many 
>areas of ecology, from predicting the pace of global climate change to 
>understanding the consequences of acid rain and agricultural runoff.
>
>"I think it is potentially very important research," said Nico van Breemen 
>of the University of Wageningen in the Netherlands. "It raises points that 
>are fundamental for our understanding of very big global environmental 
>issues."
>
>
>
>Many forested areas in the United States are populated with young trees, 
>because the old growth forests have been logged (Photo courtesy 
><http://www.americanlands.org>American Lands)
>
>
>
>
>The findings raise questions about science's understanding of global 
>warming, which is partly caused by fossil fuel burning and increasing 
>levels of heat trapping carbon dioxide in the atmosphere. When trees grow 
>and mature they remove carbon dioxide from the air.
>
>The ability of trees to grow and absorb more carbon is intimately related 
>to the availability of nitrogen.
>
>"Nitrogen is a sort of master variable," said Steve Perakis, the paper's 
>lead author and a research scientist with the U.S. Geological Survey. "If 
>we don't get the fundamental elements of the nitrogen cycle right, we 
>can't answer many other ecological questions."
>
>The scientists spent five years preparing experiments in remote Chilean 
>temperate forests and another five years conducting detailed analyses of 
>water in those forests. They also conducted one time tests in a dozen 
>other remote areas in Chile and Argentina to prove that the preponderance 
>of organic nitrogen they observed was not unique to the site they were 
>studying.
>
>At the same time, they repeated their measurements in three U.S. virgin 
>forests, two in the Smokey Mountains and one in Pennsylvania. All of the 
>areas studied contained unlogged primary forests, in ecosystems that have 
>developed in place for 4,000 years to over 20,000 years.
>
>
>
>By contrast, many Chilean forests, like this stand of araucaria trees, are 
>far more ancient (Photo courtesy 
><http://www.ancientforests.org/projects.html>Ancient Forests International)
>
>
>
>
>The results suggest that in North America the impact of nitrogen pollution 
>from acid rain and agriculture may be more dramatic in years to come than 
>previously thought.
>
>North American forests are mostly young, recovering from past logging and 
>agricultural clearcutting. Young trees use nitrogen from the soil for 
>growth, serving as a buffer that lessens the impact of nitrogen pollution.
>
>As trees mature, they sequester less nitrogen from the environment. When 
>that happens, more inorganic nitrogen will be available to run off into 
>rivers and groundwater, changing conditions even more from their natural 
>state.
>
>Another interesting finding, said Perakis, was that the nitrogen cycle - 
>the way nitrogen compounds are exchanged between plants, soil, waterways 
>and the atmosphere - in South America is more uniform than it is in the 
>United States.
>
>"We found that even though there were some noticeable variations in South 
>America, they were pretty small compared to the variations caused by air 
>pollution," Perakis explained. "We live in a transient world, a world 
>that's changing because of many human activities, so many systems are 
>responding in unique ways."
>
>
>
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