In Namibia, Africa, countless fairy circles (also called fairy rings) dot the Namib desert landscape from southern Angola to northern South Africa. The circles are barren rings enclosed by a loop of native brownish-green grasses called Stipagrostis. The circles range in diameter from 7 to 32 feet (2 to 10 meters) and are regularly spaced 16 to 32 feet (5 to 10 meters) apart. From above, they look like the speckled coat of a cheetah spanning the length of the reddish-orange sands of the Namib.
The indigenous Himba peoples of Namibia believe fairy circles (or fairy rings) are the work of spirits or gods. Some even say the formations are the footprints of the Himba god Mukuru. Outside of Indigenous folklore, explanations for the circles range from termites eating the grass to poisonous gases to plant-killing fungi or plant competition for water. Even UFOs.
But now, Dr. Stephan Getzin, an ecologist at the University of Göttingen in Germany and an author of a new study on fairy circles, has found strong evidence that plant water stress is the cause of the mysterious fairy circle formations. His research was published in Perspectives in Plant Ecology, Evolution and Systematics in October 2022.
How Plant Water Stress Creates Fairy Circles
Between 2020 and 2022, Getzin and his research team collected soil and plant samples in 10 regions of the Namib Desert where fairy circles are found. In the study, Getzin noted that the key to their research was collecting data from plants and soil before and after rainfall, which can be difficult to predict in the desert. Thankfully, 2021 and 2022 were particularly rainy years.
Getzin's team found that within a few weeks after rainfall, grasses that formed the ring around the circle depleted the water in the top 8 inches (2 meters) of soil on the inside of the circle. Plants inside the circle died within three weeks, giving plants on the edge of the circle the best chances of survival.
"Under the strong heat in the Namib, the grasses are permanently transpiring and losing water. Hence, they create soil-moisture vacuums around their roots and water is drawn towards them. Our results strongly agree with those of researchers who have shown that water in soil diffuses quickly and horizontally in these sands even over distances greater than 7 meters," said Getzin , in a press statement.
Here's how that works: When hot, dry locations experience rare rainfall, it's not just animals that compete for water. Plants have also come up with ways to survive in these environments. As plants lose water from their leaves, they need to take water up from their roots. In the case of the Namib fairy circles, established grasses draw water from the center of the ring, soaking up the available resources and leaving the newly germinated grass to die in the center.
Vegetation that grows in striking patterns is not unique to Africa. Australia, America and Asia have also revealed incredible formations of what scientists call self-organizing vegetation, in which plant life creates grids, gaps, stripes, and labyrinth patterns across different landscapes, including peat bogs and mussel beds. These patterns are often called "Turing patterns," named after scientist Alan Turing, credited with first introducing the concept.
Scientists aren't exactly sure why the vegetation in Namib grows in circles, but some researchers say it has to do with the amount of rain and the landscape's slope that contribute to an area's formation. No matter the shape, the study strongly suggests that plant water stress is at the root of the Namib Desert's fairy circles. Perhaps fairies don't live in the desert after all.
Now That's Interesting
Although some scientists think there is still room to investigate other theories, Getzin is so sure he has solved the mystery of the fairy circles that he is ending his research on the topic after 20 years, according to the New York Times.
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