Decade-Long Study Shows Warming World Helps, Then Stunts Vegetation Growth

Global warming may initially make the grass greener, but not for long, according to new research conducted at Northern Arizona University. The study, published this week in Nature Climate Change, shows that plants may thrive in the early stages of a warming environment but begin to deteriorate quickly.

“We were really surprised by the pattern, where the initial boost in growth just went away,” said Zhuoting Wu, NAU doctoral graduate in biology. “As the ecosystems adjust, the responses changed.”

Researchers subjected four grassland ecosystems to simulated climate change during the decade-long study. Plants grew more the first year in the global warming treatment, but this effect progressively diminished over the next nine years, and finally disappeared.

The research reports the long-term effects of global warming on plant growth, the plant species that make up the community, and the changes in how plants use or retain essential resources like nitrogen. The team transplanted four grassland ecosystems from higher to lower elevation to simulate a future warmer environment, and coupled the warming with the range of predicted changes in precipitation—more, the same, or less. The grasslands studied were typical of those found in northern Arizona along elevation gradients from the San Francisco Peaks down to the Great Basin Desert.

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http://www4.nau.edu/insidenau/bumps/2012/4_9_12/climate.html