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From January 29, 2002

Fertilizers Contribute to Altering U.S. Ecosystems

A recent study published in the journal Nature dispels the theory that much of the nitrogen in U.S. ecosystems comes from natural sources. Scientists now argue that nitrogen pollution from acid rain and agricultural fertilizers is altering U.S. ecosystems. Previously, ecologists believed that inorganic nitrogen has always been the dominant nutrient in all forests.

The authors of the January 24th article in Nature compared the unpolluted ecosystems of South America to those of the United States, and found that South American forests have a preponderance of organic nitrogen. Lars Hedin, a coauthor of the study and a professor of ecology and evolutionary biology at Princeton University said, "We traveled in time by traveling to South America."

The study shows that U.S. ecosystems were much different prior to the industrial revolution. The two reasons the U.S. has nitrogen pollution are because of burning fossil fuels and the mass production of fertilizers.

Nitrogen is a plant nutrient that determines the health of ecosystems, from local waterways to global climate. The findings of this study raises questions about our understanding of global warming: When trees mature they remove carbon dioxide from the air. Yet, the ability of trees to grow and absorb more carbon depends on the availability of nitrogen. "If we don't get the fundamental elements of the nitrogen cycle right, we can't answer many other ecological questions," said Steve Perakis, the paper's lead author.

For the full article about this study, see www.ens.lycos.com/ens/jan2002/2002L-01-25-06.html. The study was published in the January 24, 2002 issue of Nature.