The African and Australian continents are both known to be the homes of some of the richest and most diverse species in the world. However, it seems that the two may also share similar problems with the sudden appearance of barren patches of land on their grasslands.
For years, scientists have been trying to find out the cause of arid grass formations known as fairy circles. These barren spots of land were first mentioned in technical literature during the 1920s, but have since become widespread in the western region of Africa, particularly in Namibia.
Possible reasons for the appearance of fairy circles include an unbalanced distribution of nutrients in the soil, deposits of toxic underground gases and even termite or ant infestations. Some researchers have also suggested that the pattern of the patches seen in Namibia had some similarities with the pattern typically observed in the organization of skin cells.
However, with similar fairy circles appearing in some parts of the Australian Outback as well, researchers say they may have discovered new information that could help them understand the cause of these strange land formations.
In a new study featured in the Proceedings of the National Academy of Sciences, Stephan Getzin, an ecological modeler from the Helmholtz Center for Environmental Research in Leipzig, Germany, led a team of scientists in examining the fairy circles in Australia.
They found that the arid grass formations seem to appear in a self-perpetuating pattern that is likely influenced by the scarcity of water in the region.
The area in Pilbara, Australia where the fairy circles were discovered is known to be a flat, sunbaked terrain that is regularly exposed to temperatures of up to 167 degrees Fahrenheit.
Getzin and his colleagues believe that this harsh environment is what likely produced the conditions that allowed the barren patches of land to appear and not the presence of termite or ant colonies as suggested in the formation of the circles in Africa.
The research team also analyzed soil samples taken from the area of the fairy circles. They also looked at how water in these places is able to penetrate the soil.
The fairy circles in Australia were formed on top of sandy soil that is covered in a hard layer of clay, which prevents water from being able to penetrate the crust. The water would instead run off to where the plants were able to take root around the clay spot.
The soil inside the fairy circles tends to remain barren because it is too hot and too difficult to penetrate to allow any plant life to grow there.
Getzin explained that this may also be the case in fairy circles in Africa, although with a few differences.
While the runoff of water that led to the formation of the circles in Pilbara tended to occur above ground, the one in Namibia may occur below ground. Getzin said this is because the water in that area is able to drain more efficiently than in Pilbara.
The researchers said that more fairy circles may also be found in drylands in other parts of the world. They are likely confined to narrow climatic envelopes where there may not be enough rainfall.