Namibia's legendary fairy circles are mysterious, circular, bald patches in the dry grasslands on the edge of the Namib Desert.
Namibia's legendary fairy circles are mysterious, circular, bald patches in the dry grasslands on the edge of the Namib Desert. Their formation has been researched for decades and has recently been the subject of much debate. With extensive fieldwork, researchers from the University of Göttingen in Germany and Ben Gurion University in Israel investigated how freshly germinated grass dies inside the fairy circle. Their results show that the grass withers due to a lack of water inside the fairy circle. The topsoil, comprised of the top 10 to 12 centimetres of the soil, acts as a kind of "death zone" in which fresh grass cannot survive for long. The new grass dies between 10 and 20 days after the rain. According to the researchers, the fact that it shows no signs of termite damage disproves a competing theory. The results were published in the journal Perspectives in Plant Ecology, Evolution and Systematics.
For the study, the scientists analysed 500 individual grass plants in four regions of the Namib by taking measurements of root and leaf lengths, carrying out statistical analyses, as well as collecting and comparing photographic evidence. They also took several hundred measurements of soil moisture during or after the 2023 and 2024 rainy seasons.
This showed that the topsoil is very susceptible to drying out. During and after the rainy season, the soil moisture here is three to four times lower than the soil at a depth of around 20 centimetres. In addition, the topsoil is significantly drier within the fairy circle than outside during the period of grass growth after ample rainfall. Under these conditions, freshly germinated grasses cannot survive in the fairy circle: they dry out because they cannot reach the deeper, more moist layers of soil with their roots, which are on average 10 centimetres long.
Read more at University of Göttingen
Image: A typical fairy circle on the Kamberg, which the researchers investigated during the 2024 rainy season: The clumps of grass – up to 80 cm high – can be seen at the edge of the fairy circle. These clumps use the fallen rain first and have an immense competitive advantage due to their size. With their established roots at a depth of 20 cm to 30 cm, they are able to suck up the soil water in the fairy circle, leaving it dry and then bare of fresh grass. (Photo Credit: Stephan Getzin)
