Footprints of the Gods, to some, fairy tale to others? Yet, Fairy Circles in Sub-Saharan Africa are 'alive' - Biologist finds! Circles have a lifespan of about 6 decades, and dynamically change, satellite images prove!
'So Tschinkel turned to satellite images. By comparing photos taken over a 4-year period, he confirmed something other scientists had suspected: The circles were alive — or at least they were dynamic. A number of circles appeared and disappeared over this time period. Extrapolating from the data, Tschinkel calculated that most smaller circles arise and vanish every 24 years, whereas larger circles last up to 75 years. Overall, the lifespan averaged 41 years.
To confirm his results, Tschinkel crunched data collected from the NamibRand Nature Reserve. Over the past 10 years, the park has sold fairy circles to ecotourists for about $50 each. The buyers don’t actually get the land; they just adopt it—kind of like people who “purchase” stars. Each circle the reserve sells is marked with the date of sale, and new owners are given the latitude and longitude so they can check up on their purchase on Google Earth.
Tschinkel’s friends at the reserve revisited the sold fairy rings and took photos to estimate the amount of regrowth that had occurred over the years. From the number of fairy circles that had died or started to die over the past 2 to 9 years, Tschinkel calculated that the fairy circles had an average age of about 6 decades. “It gives me some confidence that we really are talking about a lifespan of about 30 to 60 years,” he says.'
Wired Magazine | 'Mysterious Fairy Circles Are ‘Alive’' by ScienceNow at June 28, 2012 at 12:00 pm USA
http://www.wired.com/wiredscience/2012/06/fairy-circles-grass/