These insects were the only organism found regularly in the early stages of the formation of the fairy circles. The grass root-eating sand termites reduced the grass growth in the vegetationless flats, according to jurgens. Other experts vehemently contradict the biologist.
Fairy circles occur in hundreds of thousands in the arid land near the southwestern coast of africa. Each of the points, drawn as if with a compass, is surrounded by a wreath of tall grass at a closer look. From the bird's perspective the red spots are almost priceless. With diameters up to about 20 meters, they give the impression that the earth had freckles.
In his study, he has raised research on this phenomenon to a solid level of data, jurgens told the news agency dpa. His results were distinguished from earlier scientific assumptions that the bald spots were caused by rising natural gas or ants.
During his study between 2006 and 2012, the biologist investigated a 2000-kilometer stretch of desert from central angola to northwestern south africa. At the bare spots he measured the proportion of soil moisture. His finding: when he stumbled on fairy circles, he also found populations of psammotermes termites in the bare spots and surrounding vegetation. Jurgens found that the insects destroyed all the grasses – which are grounded for a short period of time during rainfall – by killing the roots. All that remained were the empty eaten and circular flat.
According to the study, due to the lack of vegetation, rainwater cannot evaporate at fairy circles. The precipitates seep into the sandy soil and are deposited. This reservoir allows termites to survive in the dry season. At the same time, the subterranean water also provides plants with sufficient moisture, causing a lush ring of vegetation to grow on the edges of the bare spots.
"The termites thus provide a masterpiece of ecosystem design," jurgens emphasized. It is an impressive example of the sustainable use of scarce resources.
However, according to a report in "spiegel online," other researchers consider this explanation to be less than plausible. "I am not convinced that psammotermes allocerus plays a causal role in the formation of the circles," the magazine quotes termite researcher vivienne uys from the plant protection research institute in queenswood, south africa. "In the fairy circles i examined, termites were rather rare," said michael cramer of the university of cape town in south africa.
Walter tschinkel of florida state university in the u.S. Said the report lacked observations that termites were actually destroying the grass. It is also unclear why the patches mostly formed circles, when termites often created long tunnel networks in the ground. "The tunnels, however, do not show any relationship to the circles," tschinkel said, according to "spiegel online".