What are known as fairy circles are circular patterns that appear naturally in arid areas. 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. There are several hypotheses for the reasons behind these formations: the action of insects or self-regulated growth have until now explained this strange phenomenon. Now, Spanish scientists have created an atlas and found more than 250 areas around the world that present these enigmatic circles, demonstrating that they are much more common than thought. The results have just been published in the journal 'Proceedings of the National Academy of Sciences' (PNAS). The study, in which the Higher Council for Scientific Research (CSIC) participates through the Biodiversity and Ecosystem Functioning Laboratory (BioFunLab) of the Institute of Natural Resources and Agrobiology (IRNAS-CSIC), includes novel factors to explain why these patterns on the ground. Specifically, it analyzes the climatic, edaphic and environmental factors that determine its distribution on a global scale thanks to the fact that the catalog of places that have these formations has been expanded. "Analyzing their effects on the functioning of ecosystems and discovering the environmental factors that determine their distribution is essential to better understand the causes of the formation of these vegetation patterns and their ecological importance," indicates Emilio Guirado, the principal investigator of this study. , which is part of the Multidisciplinary Institute for the Study of the Environment of the University of Alicante (UA). With the help of models based on artificial intelligence, scientists classified satellite images and obtained 263 sites where patterns similar to the fairy circles described to date can be observed, those of Namibia and Western Australia, including the Sahel, Western Sahara, the Horn of Africa, Madagascar, southwest Asia or Central Australia. "Our study provides evidence that fairy circle vegetation formations are much more common than previously thought, which has allowed us, for the first time, to globally understand the factors that affect their distribution," highlights Manuel Delgado Baquerizo, leader of the IRNAS-CSIC BioFunLab and co-author of this research. The conditions for fairy circles to emerge 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, were related to the presence of fairy circles. fairies Both termites and ants had low importance as predictors on a global scale. However, on a regional scale, termites were a more important predictor 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 the albedo or the state of the aquifers," says Jaime Martínez-Valderrama, scientist at the Arid Zones Experimental Station (EEZA-CSIC) and co-author of the study. The study authors also compared the stability of primary vegetation productivity of fairy circles with that of other ecosystems and found greater invariance when fairy circles were present. "These results provide the first empirical evidence of greater stability in the productivity of fairy circles, a key property of ecosystems that is related to the stable provision of ecosystem services such as the amount of forage," details Fernando T. Maestre, professor at the UA. "These results also open the door to research 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, co-author of the publication. MORE INFORMATION news No An artificial intelligence capable of detecting life, a new weapon to search for extraterrestrials news No 'Pangea Ultima', the next supercontinent, will no longer be habitable for humans Scientists also make a global atlas of the fairy circles and a database that could be useful in determining whether fairy circle vegetation patterns are more resilient to climate change and other disturbances. "We hope that these unpublished data will be useful for those interested in comparing the dynamic behavior of these patterns with others present in arid areas around the world," concludes Guirado.
