Fairy circles: The puzzle solved?
23 February 2021 | Environment
In Angola, Namibia and South Africa there are large tracts that resemble a landscape full of freckles or craters. The cause of these so-called fairy circles has fascinated countless researchers and scientists for decades.
Now researchers from the University of Pretoria (South Africa) and the ITMO University in Saint Petersburg (Russia) say they have finally gotten to the bottom of the matter.
In a study published in the journal BMC Ecology, the researchers come to the conclusion that two types of euphorbia, the Euphorbia damarana and Euphorbia gummifera, as well as other species belonging to the milkweed family, are the cause. When the plants die, they release a water-repellent sap that inhibits the growth of other grasses, forming the barren, strange circles.
In addition, rising temperatures - as a result of global climate change - could exacerbate the formation of these fairy circles.
The research was undertaken by Professor Marion Meyer of the University of Pretoria of the Department of Plant and Soil Sciences in 2015 after she said there was a lack of scientific evidence in previous theories. “I worked with four PhD students for several years, focusing on soil chemistry, biological toxicity and geographical considerations,” Meyer told Daily Mail. “We are convinced that the Euphorbia milk bushes caused the fairy circles and continue to do so today.”
The fairy circles are not permanent, because over the course of decades, the toxicity decreases with occasional rain, she said.
The fairy circles are found along on a narrow strip, about 50 to 100km inland from the Atlantic, which stretches from south-west Angola through Namibia to north-west South Africa. The circles are two to 15 meters in diameter and have fascinated researchers for years.
There have been several theories about the cause thereof: In 2017, their existence was ascribed to the activity of termites, ants or rodents. In 2014, researchers from the Helmholtz Centre for Environmental Research (UFZ) supported the theory of a natural cause. They came to the conclusion that the fairy circles can be explained by the competition of plants for water.