Future atmospheric levels of the notorious heat-trapping gas, carbon dioxide, remain a controversial topic among environmental scientists. Many researchers believe that increasing amounts of CO2, belched into the atmosphere by human fossil fuel use, will be captured through nature's ability to lock up the carbon in soil organic matter and faster growing trees. But it's not so simple. A new report, published in the November 28 Science, shows that the availability of nitrogen, in forms usable by plants, will probably be too low for large increases in carbon storage.
Ecosystems on land can store carbon, through bigger trees and more organic matter in soils, but shortages of mineral nutrients, especially nitrogen, curb potential future carbon storage. Several approaches to calculating ecosystem carbon storage, including some featured in the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) assume that nitrogen available to plants is abundant, even though current nitrogen limitation is widespread. "Realistic scenarios for future changes in nitrogen availability limit ecosystem carbon storage to the low end of the range presented in the recent IPCC report," says Field.
"In a garden limited by water, a gardener would not expect a big increase in growth from adding potassium. Similarly, plants in natural ecosystems limited by nitrogen may not grow much faster when they are exposed to increased levels of carbon dioxide," explained co-author Jeffrey Dukes. "Plants will need more nitrogen if they're going to lock up more carbon. The mo
Contact: Dr. Christopher Field
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