The fairy circles found in the arid grasslands of Africa's southern region may not be caused by termites, as what previous studies have claimed, but rather a simple phenomenon of dealing with competition for water.
This is according to a team of scientists at the Helmholtz Centre for Environmental Research (UFZ) after using a novel approach in studying these mysterious circles that confounded the scientific community for decades. By studying multiple aerial images, scientists have come to what they consider the most convincing reason: the vegetation undergo a "self-organizing" process of making the most of the resources in the area where they grow.
"The occurrence of such patterning in nature is rather unusual," said Stephan Getzin, one of the authors of the study. "There must be particularly strong regulating forces at work."
Fairy circles are barren patches of land about seven to 49 feet in diameter and are mainly outlined by plants belonging to the genus Stipagrostis. In Africa, they are teeming in Namibia but these patches can also be found in South Africa and Angola. When viewed from above, they appear like brown freckles enlivening a bleak landscape.
Several theories have sprouted on what exactly is causing these fairy circles to form. Some studies have shown that the mysterious "artists" behind the fairy circles are not literally fairies but termites. Just last year, biologist Norbert Juergens from the University of Hamburg presented evidence that a species of sand termite called Psammotermes allocerus were the ones responsible for the formation of the circles. He spotted termites in almost every fairy circle he investigated and came down to a conclusion that they were nibbling on the grass' roots. His findings were published in the journal Science.
Other biologists claim that the presence of hydrocarbons is causing the patches. As they surface the Earth from beneath its depths, it kills any vegetation in its way.
However, for Getzin, who has been studying these fairy circles for over 15 years now, the most likely reason would be the self-regulating grass growth of the plants that made the fairy circles. Together with his team, he analyzed several images shot from above to determine the spatial location of the fairy circles. As per their findings, which recently came out in the journal Ecography, the fairy circles are distributed very neatly and evenly.
This led the researchers to conclude that it could only be the "self-organizing" behavior of the vegetation that formed the circles. Getzin explained that the fairy circle phenomenon is similar to what happens among young plants in the forest. Ample space and nutrition is needed in a forest teeming with mature trees and in order for every plant life to survive, they have to "space out."
Getzin, with the help of his colleagues from Israel, further proved their case by generating a computer simulation of the plants' competition with water. Results showed that they formed a pattern similar to those in Namibia, hence convincing Getzin and the others to consider the plant behavior as a concrete explanation in the myriad of theories about fairy circles.