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Nitrogen Weakens Marshes’ Ability to Hold Back Climate Change

Wednesday, June 30th, 2010

Scientists Find Excess Nitrogen Favors Plants That Respond Poorly to Rising CO2

A photo of a marsh with a boardwalk and plastic chambers surrounding various patches of plants.

The Smithsonian's Global Change Research Wetland. Photo: SERC

As atmospheric carbon dioxide levels rise, so does the pressure on the plant kingdom. The hope among policymakers, scientists and concerned citizens is that plants will absorb some of the extra CO2 and mitigate the impacts of climate change. For a few decades now, researchers have hypothesized about one major roadblock: nitrogen.

Plants build their tissue primarily with the CO2 they take up from the atmosphere. The more they get, the faster they tend to grow—a phenomenon known as the “CO2 fertilization effect.” However, plants that photosynthesize greater amounts of CO2 will also need higher doses of other key building blocks, especially nitrogen. The general consensus has been that if plants get more nitrogen, there will be a larger CO2 fertilization effect. Not necessarily so, says a new paper published in the July 1 issue of Nature.
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