Fairy circles are circular vegetation-free patches with diameters of a few meters that occur in arid regions of Africa, particularly in Namibia. There has been a great deal of discussion about their origin, with hypothesis ranging from termites over modification of the environment by certain plants to purely geological / physical mechanism such as wind turbulences or geological activity. A new paper by Norbert Juergens in Science suggests that the sand termite, Psammotermes allocerus, generates the pattern
through removal of short-lived vegetation that appears after rain, leaving circular barren patches. Because of rapid percolation and lack of evapotranspiration, water is retained within the circles. This process results in the formation of rings of perennial vegetation that facilitate termite survival and locally increase biodiversity. This termite-generated ecosystem persists through prolonged droughts lasting many decades.
Is that the last word spoken on the origin of fairy circles? Looking at the history of this problem, I somehow suspect not, but if so, yet another great conference dinner discussion topic is gone – will we end up having to discuss about the latitudinal gradient all the time? 😉