The mysterious ‘fairy circles’ now have an explanation

These circular plant formations are more widespread in the world than previously believed, according to research from the CSIC.

The mystery of fairy circles (circular plant formations that usually appear in African deserts) is one of the unsolved enigmas of global ecosystems. Until now, it was thought that they only existed in Africa and Australia, but Spanish scientists from the CSIC have just demonstrated, through a study that has applied new techniques, that they are actually distributed throughout the globe.

These enigmatic circular patterns are some of the most mysterious natural formations that can be observed in the arid areas of our planet. They are circles of bare soil surrounded by rings of vegetation, which until now had only been described in the desert regions of Namibia and Australia. Over the years, multiple hypotheses have been proposed to explain their formation, which have given rise to numerous discussions about the mechanisms that cause them. However, until this moment, the global dimension of this type of phenomenon and the environmental factors that explain them were unknown.

According to the magazine Proceedings of the National Academy of Sciences (PNAS), which collects the conclusions of the study, through satellite images and artificial intelligence It has been possible to identify these unique plant patterns in 263 desert regions of the world, spread across 15 countries on three continents. It is, therefore, a widespread phenomenon. Among the regions where they have been detected are places as different from each other as the Sahel, Western Sahara, Madagascar, the Horn of Africa or southwest Asia.

A form of biological self-organization

The research has made it possible to verify that these plant circles They are formed by a combination of specific characteristics of the soil and climate. This is what was deduced after analyzing climatic factors such as the average annual precipitation, the physical, chemical and biological characteristics of the soil, and also the nitrogen content of the land in which they are found.

That is, in these generally desert areas, the vegetation would be organized through these regular patterns, in the form of patches or spots, in order to optimize the scarce nutrients and water resources existing in those areas. It is, therefore, a survival strategy in a hostile environment. This explanation would not exclude additional ones, which could be complementary.

The first fairy circles were located in a desert area of ​​Namibia in 1971, but similar formations were later found in the Western Desert of Australia. Among the first hypotheses were the action of termites for the formation of these circles, among other possibilities. It has been now, with the study of CSIC, which has been shown that these circles are not exclusive to one or two parts of the planet, but to numerous deserts.

The researchers found that the combination of certain soil and climate characteristics, such as having a low nitrogen content and an average precipitation of less than 200 mm/year, can explain the presence of fairy circles. Both termites and ants were of low importance as responsible for these formations. However, On a regional scale, termites were a more important factor in Namibia than in regions such as the Sahel or Australia. “This study has taken into account multiple variables not considered to date, such as albedo or the state of the aquifers,” he points out. Jaime Martínez-Valderrama, scientist at the Arid Zones Experimental Station (EEZA-CSIC) and co-author of the study.

“These results also open the door to investigations into whether these spatial patterns can be indicators of the degradation of ecosystems with climate change, as is the case with other spatial patterns of vegetation in arid areas,” says Miguel Berdugo, another of the co-authors of the publication.

Reference study: https://www.pnas.org/doi/10.1073/pnas.2304032120

……………..

Contact of the Environment section: [email protected]