Fairy circles are circular patches of land barren of plants, varying between 2 and 15 meter in diameter, often encircled by a ring of stimulated growth of grass. Until 2014, the phenomenon was only known to occur in the arid grasslands of the Namib desert. In that year, ecologists were alerted to similar rings of vegetation outside of Africa, in a part of the Pilbara in Western Australia.
The cause of fairy circles has long been a puzzle and the investigation has proved challenging. One favored theory is that the distinct vegetation patterns are a population-level consequence of competition for scarce water, as the plants “organise” themselves to maximise access to scarce resources. The circular barren patches capture water which then flows to the outer edges of the ring. More water available increases biomass and roots which leads to the soil becoming looser. The less dense soil allows more water to penetrate and feed the vegetation, creating a feedback loop supporting the plants at the edge of the circle.