CORVALLIS, Ore. -- The pattern of nitrogen release from decaying plant material is remarkably similar and predictable across the planet, researchers have concluded in a new study, which should make it easier to understand nutrient dynamics, vegetation growth, estimate carbon release and sequestration, and better predict the impacts of climate change.

The findings, to be published Friday in the journal Science, are the results of one of the largest and longest studies ever done on nitrogen release during plant decomposition, involving dozens of researchers working for 10 years in 27 sites, ranging from Arctic tundra to tropical forests of North and Central America.

"The availability of nitrogen is one of the key factors limiting vegetation growth around the world, but its release from plant litter can be very slow," said Mark Harmon, a professor of forest science at Oregon State University and the coordinator of the study. "For the first time, we studied this process at enough sites and over a long enough time period to really understand what's happening."

The surprise, researchers said, is that the basic pattern of nitrogen release is pretty much the same wherever it occurs, and is driven primarily by the initial concentration of nitrogen present in the decaying plant material. It has little to do with location, soil types, microbes present, or other factors. The speed of the process is affected by climate, particularly temperature and precipitation, the study concluded. But the overall pattern, or "trajectory" of nitrogen release remains much the same regardless of the site.

There is significant interest in the way that nitrogen recycles in the ecosystem, scientists say, because it plays such a critical role in the growth of almost all vegetation grasses, shrubs, trees and agricultural crops. The presence or absence of adequate amounts of nitrogen can often dictate what types of vegetation are able to survive in a certain area, and h
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Contact: Mark Harmon
mark.harmon@oregonstate.edu
541-737-8455
Oregon State University
18-Jan-2007