Nitrogen loss threatens desert plant life, study shows

Kristina Ramanujan in Cornell University Chroncile Online: As the climate gets warmer, arid soils lose nitrogen as gas, reports a new Cornell study. That could lead to deserts with even less plant life than they sustain today, say the researchers. "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 and co-author of the study, published in the Nov. 6 issue of Science. "It allows us to finally understand the dynamics of nitrogen in arid systems"

Available nitrogen is second only to water as the biggest constraint to biological activity in arid ecosystems, but before now, ecologists struggled to understand how the inputs and outputs of nitrogen in deserts balance. By showing that the higher temperatures cause nitrogen to escape as gas from desert soils, the Cornell researchers have balanced the nitrogen budget in deserts. They stress that most climate change models need to be altered to consider these findings.

Sparks and lead author Carmody McCalley, a graduate student, warn that temperature increases and shifting precipitation patterns due to climate change may lead to further nitrogen losses in arid ecosystems. That would make arid soils even more infertile and unable to support most plant life, McCalley warned. Although, some climate models predict more summer rainfall for desert areas, the water, when combined with heat, would greatly increase nitrogen losses, she added. "We're on a trajectory where plant life in arid ecosystems could cease to do well," she said.

…In addition, the researchers note, more nitrogen oxides in the lower atmosphere creates ozone near the ground, which contributes to air pollution and increases the greenhouse effect that warms the planet….

The Amboy Crater in the Mojave Desert, shot by Jeff T. Alu, Wikimedia Commons, under the Creative Commons Attribution ShareAlike 3.0 License