Up until recently, scientists had two major theories for the appearance of these mysterious circles. The first theory claimed that the circles were caused by termites, while another suggested that grasses self-organized to maximize water availability. Then, some researches suggested that both termites and self-organization may be behind the "fairy circles."
However, the mystery became even more confusing after similar circles were discovered in Australia in 2016, where the connection with termites was not traced.
The Göttingen University researchers, who among others, studied potential root damage caused by termites, pointed to plant self-organization as the cause, finding no connection with termites.
According to the scientists, plant water stress is the reason behind the mysterious circles.
The researchers' soil-moisture measurements show that the grasses around the circles significantly depleted the water within the circles, likely causing the grasses inside the circles to die.
“By forming strongly patterned landscapes of evenly spaced fairy circles, the grasses act as ecosystem engineers and benefit directly from the water resource provided by the vegetation gaps. In fact, we know related self-organized vegetation structures from various other harsh drylands in the world, in all those cases the plants have no other chance to survive except by growing exactly in such geometrical formations,” explained Dr. Stephan Getzin, Department of Ecosystem Modelling at the University of Göttingen.
There are millions of "fairy circles" around 80-140 kilometers from the coast in the Namib.