Studying fairy circles,,,
Posted by Sane Spirit on Tuesday, August 21, 2012
Under: In the News
Small fairy circles stick around an average of 24 years, while larger ones can exist as long as 75 years, according to research detailed today (June 27) in the journal PLoS ONE. Still, the study sheds little light on why the circles form, persist and then vanish into the landscape after decades.<br><br>
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Tschinkel grew interested in fairy circles during a 2005 safari to NamibRand Nature Reserve in southwest Namibia, in the Namib Desert. It was his first experience with the round clearings, tens of thousands of which expose the red sandy soil in the area. A short time after the circles form, a tall ring of grass grows around the border, highlighting the bare area.<br><br>
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In fact, little was known even about the life cycle of the circles, Tschinkel said. With the help of the nature reserve's staff, satellite images and aerial photos, he set out to change that. By comparing satellite images from 2004 and 2008, he found that circles are quite stable, popping up at nearly their full size, or growing quickly to full size once they get started. The smallest are about 6.5 feet (2 meters) in diameter, while the largest can be almost 40 feet (12 m) across. Winds scour the bare areas of soil, turning them into slight depressions. Eventually plants move back in, recolonizing the circles and leaving only slightly indented "ghost circles" behind.<br><br>
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"There are some mathematical models that are based on the idea that plants can withdraw resources toward themselves, which has a positive feedback on plant growth where they're located, but it has a negative effect on plants at a greater distance," he said.<br><br>
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With few people studying the circles — and no funding for chasing down the mysteries of the landscape of southern Africa — Tschinkel said the fairy circles will likely remain an enigma.<br><br>
"I'm not too worried that this mystery is going to be solved anytime soon," he said. And the persistence of the mystery makes it ever more intriguing.<br><br>
Mysterious African 'Fairy Circles' Stump Scientists
[,,,]<br>
Tschinkel grew interested in fairy circles during a 2005 safari to NamibRand Nature Reserve in southwest Namibia, in the Namib Desert. It was his first experience with the round clearings, tens of thousands of which expose the red sandy soil in the area. A short time after the circles form, a tall ring of grass grows around the border, highlighting the bare area.<br><br>
[,,,]<br>
In fact, little was known even about the life cycle of the circles, Tschinkel said. With the help of the nature reserve's staff, satellite images and aerial photos, he set out to change that. By comparing satellite images from 2004 and 2008, he found that circles are quite stable, popping up at nearly their full size, or growing quickly to full size once they get started. The smallest are about 6.5 feet (2 meters) in diameter, while the largest can be almost 40 feet (12 m) across. Winds scour the bare areas of soil, turning them into slight depressions. Eventually plants move back in, recolonizing the circles and leaving only slightly indented "ghost circles" behind.<br><br>
[,,,]<br>
"There are some mathematical models that are based on the idea that plants can withdraw resources toward themselves, which has a positive feedback on plant growth where they're located, but it has a negative effect on plants at a greater distance," he said.<br><br>
[,,,]<br>
With few people studying the circles — and no funding for chasing down the mysteries of the landscape of southern Africa — Tschinkel said the fairy circles will likely remain an enigma.<br><br>
"I'm not too worried that this mystery is going to be solved anytime soon," he said. And the persistence of the mystery makes it ever more intriguing.<br><br>
Mysterious African 'Fairy Circles' Stump Scientists
In : In the News