Satellites show mysterious rings of vegetation in more parts of the world | ET REALITY


Fairy circles inspire awe in onlookers and fuel discord among experts. For decades, scientists have hotly debated the origin of the strange, polka-dot-shaped patterns of barren soil that have been found in the Namib Desert, which stretches from Angola to northern South Africa. Some researchers also say that they occur in the australian desert.

Now, there’s something new to discuss: To what extent do fairy circles exist all over the world?

Findings based on satellite images published Monday in the Proceedings of the National Academy of Sciences raise the possibility that fairy circles are significantly more widespreadoccurring at up to 263 sites in 15 countries on three continents.

“We discovered fairy circle locations in many other places that we didn’t know existed before, because most of the work on this topic has been carried out in just two countries, Namibia and Australia,” said Fernando Maestre, an ecologist at the University . from Alicante in Spain and author of the study.

Other researchers who have worked on fairy circles say that until field work is done, it remains to be seen whether any of the newly identified circular, bare patches are true fairy circles.

“In all arid regions of the world there are various types of bare patches, which are caused by different processes,” said Norbert Jürgens, an ecologist emeritus at the University of Hamburg, who was not involved in the research.

Until this study, Dr. Maestre and his colleagues were not part of the sometimes fractious fraternity of fairy circle researchers. They were swept up in the mystery when Emilio Guirado, a data scientist also at the University of Alicante and one of the authors of the study, detected something strange on Google Earth: patterns in Niger that appeared to be fairy circles. He wondered if they might exist in other dryland habitats.

To find out, the researchers trained a pattern recognition model with images of known fairy circles from Namibia and Australia. They applied the model using satellite images of 575,000 two-and-a-half-acre plots of dryland habitat around the world.

Although drylands cover 41 percent of Earth’s land surface, the researchers’ model identified only a small fraction that potentially contains fairy circles: about 193 square miles. The researchers consulted satellite images to manually confirm that fairy circle-like patterns occurred in almost every location identified by the model, from Kazakhstan to Madagascar.

Based on their findings, they created a profile of the types of habitats where fairy circle-like patterns are most likely to occur: hot, arid places with sandy soil that is low in nitrogen and that receive four to 12 inches of annual rainfall. . .

Statistical tests confirmed that “the patterns we have found are exactly the same as what people have found in Namibia and Australia,” Dr. Maestre said.

Dr. Maestre said he and his colleagues began their study well aware, however, that fairy circles were “a hotly debated topic.” Partly because of this, they chose to be conservative in describing their findings as “fairy circle patterns of vegetation.”

“We are not trying to fight with anyone,” Dr. Maestre said.

However, the new findings have inspired strong reactions.

“Unfortunately, the study dilutes the term ‘fairy circle’ and ignores the definition of fairy circles,” said Stephan Getzin, an ecologist at the University of Göttingen in Germany.

In 2021, Dr. Getzin and his colleagues argued that true fairy circles they occur in a grid-like pattern with “extremely strong” ordering.

None of the newly identified fairy circle-type gaps match this strict pattern, Dr. Getzin said.

Florida State University biologist Walter Tschinkel, who was also not involved in the research, agreed with Dr. Getzin. While the authors of the new paper “certainly found many round or rounded spaces located in areas with arid climates and sandy soil,” he said, the pattern does not “really meet the fairy circle criterion.”

Dr. Maestre responded that Dr. Getzin’s definition “was not supported by the entire scientific community working with fairy circles” and “does not undermine our findings in any way.”

Michael Cramer, an ecophysiologist at the University of Cape Town, who was not involved in the research, said the lack of a standard definition of a fairy circle was a problem for the entire field.

“Unfortunately, the only guardians of the term ‘fairy circle’ are the self-proclaimed ones,” Dr. Cramer said. “Reaching agreement on the naming of fairy circles would probably require establishing a Fairy Circle Naming Convention, which seems unlikely.”

Whatever the newly discovered gaps are, they give scientists a lot of work to do, said Hezi Yizhaq, an environmental physicist at Ben Gurion University in Israel, who was not involved in the research.

“We now have 263 new sites to investigate,” he said. “This is what is so interesting and exciting about science: solving natural puzzles.”

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