November 09, 2009
A new study in Science found that as deserts become hotter their soil releases nitrogen, a gas vital for life. Losses of nitrogen in these arid environments, scientists believe, will result in a loss of plant life, since nitrogen is second only to water in determining the amount of life in a desert.
"We're on a trajectory where plant life in arid ecosystems could cease to do well," says lead author Carmody McCalley, a graduate student at Cornell University. If plant life diminishes then animals and insects dependent on them for survival will also be negtaively impacted.
Using instruments sensitive enough to measure level of nitrogen in parts per trillion, the researchers discovered that abiotic (non-biological) factors played a bigger role in nitrogen loss than biological—where past researchers have placed their focus.
"At 40 to 50 degrees Celsius [about 100-120 F], we found rapid increases in gases coming out of the soil" regardless of the light, McCalley said. Midday ground temperatures average about 150 Farenheit and can reach almost 200 Farenheir in the Mojave Desert.
"This is a way that nitrogen is lost from an ecosystem that people have never accounted for before," said Jed Sparks, associate professor of ecology and evolutionary biology at Cornell and co-author of the study. "It allows us to finally understand the dynamics of nitrogen in arid systems"
The discovery that hotter temperatures lead to nitrogen loss requires changes in climate models, according to the researchers. Nitrogen in the lower atmosphere adds to air pollution and the greenhouse effect.
Citation: Carmody K. McCalley, Jed P. Sparks. Abiotic Gas Formation Drives Nitrogen Loss from a Desert Ecosystem. Science. Vol. 326. no. 5954, pp. 837 - 840. DOI: 10.1126/science.1178984.
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