Research shows that fairy circles, which were previously only found in Namibia and Australia, have now been discovered in more than 250 locations in 15 countries on three continents. Fairy circles are one of the most fascinating and mysterious natural phenomena in arid regions of the world. These mysterious circles appear as exposed clods of earth surrounded by rings of vegetation and, until recently, were only recorded in Namibia and Australia.
Researchers used artificial intelligence to identify 263 locations around the world with fairy circle patterns, which were previously known only from Namibia and Australia. This study reveals some of the environmental factors associated with fairy circle formation and suggests that fairy circles may be indicators of ecosystem health and resilience to climate change.
Over the years, various hypotheses have been proposed to explain their formation, leading to much discussion about the mechanisms by which they form. However, until now, we did not know the global extent of such phenomena and the environmental factors that explain them.
So far, we have not analyzed the climate, soil and environmental factors that determine their global distribution, as we are only aware of the phenomenon in parts of Namibia and Australia.
"Analyzing their impact on ecosystem functioning and discovering the environmental factors that determine their distribution are crucial to better understand the causes of these vegetation patterns and their ecological importance," said lead researcher Emilio Guirado of the Laboratory of Arid Zone Ecology and Global Change at the University of Alicante (UA).
With the help of artificial intelligence-based models, the scientists classified satellite images and obtained 263 locations where similar patterns to the fairy circles described so far can be observed, namely those in Namibia and Western Australia, including the Sahel, Western Sahara, the Horn of Africa, Madagascar, Southwest Asia or central Australia.
Manuel Delgado Baquerizo, head of the Laboratory of Biological Interests at IRNAS-CSIC and co-author of this study, emphasizes: "Our study provides evidence that prickly pear is much more common than previously thought. It allows us to understand for the first time the factors that influence the distribution of prickly pear on a global scale."
The researchers found that certain soil and climate characteristics, such as low nitrogen levels and average annual rainfall of less than 200 millimeters, were associated with the presence of fairy circles.
"This study takes into account a variety of variables that have not been considered so far, such as albedo or aquifer conditions," says Jaime Martínez-Valderrama of EEZA-CSIC. "This is a particularly relevant factor because the heavy use of groundwater in arid areas around the world, including deserts, may disturb these formations."
The researchers also compared the stability of primary productivity of fairy circle vegetation with that of other ecosystems and found that its stability was higher when fairy circles existed.
"These results provide the first empirical evidence of increased stability of fairy circle productivity, a key attribute of ecosystems related to the stable provision of ecosystem services (such as feed volume)," said Fernando T. Maestre, professor at the University of California and director of the Arid Zone Ecology and Global Change Laboratory.
Study co-author Miguel Berdugo said: "These results also open the door to studying whether these spatial patterns can serve as indicators of ecosystem degradation due to climate change, as well as other spatial patterns in vegetation in arid areas."
This study provides a global fairy circle atlas and database that can help determine whether fairy circle vegetation patterns are more resilient to climate change and other disturbances.
"We hope these unpublished data will be helpful to those interested in comparing the dynamic behavior of these patterns with other patterns in arid regions around the world," Emilio-Girardot concluded.