In the southwestern corner of Namibia is the Namib Desert, which covers an area of approximately 50,000 square kilometres.
The desert landscape is home to some of the largest sand dunes on Earth and is believed to be at least 80 million years old. But the grains of sand also hide an enigma that has eluded scientists for nearly half a century.
Some 80-140 kilometers off the Atlantic coast is a special terrain covered in millions of circles, each a few meters in diameter, which together form a distinctive pattern.
Now researchers from, among others, the German University of Göttingen believe that they may have found the cause of the circles.
Various theories out there
The two strongest theories behind the formations so far have been that the circles are either created by termites or that plants arrange themselves this way to make the most of the scarce amount of water in the area.
But in 2016, researchers discovered similar circles in Australia and found no link to termites there.
The grass is dead
In the new study, two good rainy seasons allowed landscape grass and riverbanks to be examined both before and after rain.
With the help of special sensors, the researchers were able to measure the humidity and thus also the differences in the movement of the water in and out of the circles.
The results showed that the grass inside the circles began to die about ten days after the rain. After 20 days it was completely dead, while the grass bloomed again outside.
Pure survival
The measurements are in line with previous studies which have shown that water moves quickly and horizontally in the sand – even over distances of more than seven meters – creating a sort of reservoir that helps keep the grass at its edges.
In this way the plants become a kind of engineers of their own ecosystem, which allows them to survive in the arid zone. According to the researchers, the tactic is particularly interesting in light of climate change, as it could become a survival weapon in times of increasing droughts.
VIDEO: Follow the researchers in the desert sand:
