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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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ScienceShot: Fairy Circle Mystery Gets New Explanation
20 August 2013 1:45 pm
Every time a scientist thinks he’s solved the mystery of the fairy circles, someone else comes up with another answer. The bare, circular patches of land—some as wide as a helicopter landing pad and ringed by a border of tall grasses—freckle the landscape from Angola to South Africa. In 2012, a researcher claimed the circles were “alive,” finding that they appeared and disappeared at regular intervals; he saw no evidence that insects or lack of nutrients were causing the formations. But in March, another researcher blamed termites, citing termite tunnels and specimens that he found within the circles. Now, there’s a new hypothesis. In a paper published this month in PLOS ONE, researchers measured the size and density of fairy circles in Namibia and fed data on soil chemistry, moisture content, climate, and vegetation into a computer model. The model suggested that competition between plants is causing the bizarre formations. In the harsh desert environment, plants compete for resources belowground, and some don’t survive. When weaker grass dies, its absence facilitates growth of neighboring plants. The vegetation gap expands until it reaches a size that limits competition between grasses. The circles do not appear further west in Namibia, where it’s even drier, suggesting that they are dependent on a certain balance of not-too-much but not-too-little rainfall. Because the circles occur only over this narrow range of rainfall, short-term changes in precipitation may cause the circles to appear and disappear. Case closed? Not quite. To definitively prove the culprit, researchers will need to go into the field and tinker with fairy circle variables such as moisture and soil chemistry. For now, the mystery still endures.