The grasslands in Namibia are home to so-called "fairy circles" - circular bare spots, usually surrounded by a ring of taller grass of unknown origin. These circles are described and characterized in a report published June 27 in the open access journal PLoS ONE.
The author, Walter Tschinkel of Florida State University, showed that the circles are not permanent, and go through a birth, maturation, and death process. The life spans appear to range from 24 to 75 years, and smaller circles were generally shorter-lived than larger ones. The ultimate cause, however, remains unknown.
"The fact that fairy circles are born, mature and die, brings the dynamic nature of this mysterious ecological phenomenon into focus." Tschinkel explains. "Until now, their long life spans made it hard to detect that they are not permanent features."
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More information: Tschinkel WR (2012) The Life Cycle and Life Span of Namibian Fairy Circles. PLoS ONE 7(6): e38056. doi:10.1371/journal.pone.0038056