Desert Fairy Circles

Neat, seeing the advance of science in action

http://www.huffingtonpost.com/2012/06/27/fairy-circles-namibia-grasslands-mystery-scientists_n_1632571.html

By: Stephanie Pappas, LiveScience Senior Writer
Published: 06/27/2012

In the sandy desert grasslands of Namibia in southern Africa, mysterious bare spots known as "fairy circles" will form and then disappear years later for no reason anyone can determine. A new look at these strange patterns doesn't solve the wistful mystery but at least reveals that the largest of the circles can linger for a lifetime.

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.

"The why question is very difficult," said study researcher Walter Tschinkel, a biologist at Florida State University. "There are a number of hypotheses on the table, and the evidence for none of them is convincing."

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http://www.universityherald.com/articles/4453/20130906/mystery-fairy-circles-namib-desert-revealed-research.htm

Michael Cramer at the University of Cape Town in South Africa has resolved the mystery behind the formation of millions of strange round patches of barren land called 'fairy circles' that are found across the Namib Desert in southern Africa.

Cramer found that due to scanty rainfall and nutrient deficiencies in the soil, there is an intense competition between the grasses underground. Strong grasses absorb all of the water and nutrients from the soil, leaving nothing for their weaker counterparts. They ultimately die, leaving barren gaps in the landscape, which later forms a reservoir for nutrients and water.

With the help of other resources, larger grass species grow on the border of the gap, forming a steady fairy circle, approximately measuring 2-12m in diameter.

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Prior to this revelation, several researchers believed that the patches were formed due to ants, termites, grass-killing gas and some of them even claimed that a fire-breathing dragon lived underneath which burnt the plants.

In April, Norbert Jürgens from the University of Hamburg claimed that a species of sand termite was to blame for the bizarre patterns. Jürgens arrived at the conclusion, after studying hundreds of fairy circles across 1,200 miles of the desert and found that the Psammotermes allocerus, or sand termite, was the only species constantly present in the region.