Similar to the giant crop circles that sporadically appear in different parts of the world, strange grass circles that mysteriously emerge in South Africa's Namib Desert have dumbfounded both locals and scientists for many years. Measuring between 6 - 40 feet across, each 'fairy circle' is outlined by a ring of vegetation taller, than the surrounding grassland.
What has puzzled observers most is the perfect size and spacing of the circles, leading some to speculate that they may be a supernatural phenomenon. Now there are finally two two plausible theories - both rooted in science of course - that may help explain this mystery.
The first report was published by Norbert Jürgens of the University of Hamburg on March 29th, 2013. After studying the fairy circles for eight years from 2004 to 2012, he found that they all had one common thread - sand termites! This led the researcher to conclude that the insects eat the plant roots before they emerge through the desert soil, which results in creating a water trap, similar to how beavers create dams.
Because there is no grass, the water is not lost through transpiration, but instead remains below the surface of the soil. This enables the termites to survive even during the dry season but allows the grasses to grow only along the edge in areas where the termites have not managed to get to the roots. As time goes by, the insects feed on the plant roots of the grasses that are growing, which means the next batch of green grows out even further, thereby making the circles increasingly bigger.
While the theory resonated with some people, others were not so sure. Among them were Michael Cramer from the University of Cape Town and Nichole Barger from the University of Boulder who both argued that Norbet's theory did not explain the regular spacing of the circles and their almost perfect shapes.
In early September, the two researchers published a new report with what they think is a more logical explanation. They believe that the competition for water and nutrients among different types of grass in the arid region could be the reason behind the phenomenon. To conduct their research they studied the area on Google Earth and then using sophisticated modeling software analyzed the competition for resources among these grasses.
Their conclusion? The stronger grasses take advantage of the scarce water and nutrients in the soil, leaving their weaker counterparts with nothing to feed on. As a result, they die out in the center, leaving behind the signature 'fairy circle' that is outlined by the dominant grasses.
Whether the fairy circles are caused by either or a combination of the two theories or maybe something totally different is anybody's guess. What is certain though is that they look quite magical in the middle of the otherwise barren desert!
Resources: Dailymail.co.uk,livescience.com, newscientist.com