The Namib Desert is located in the western part of Namibia in Africa. It is considered to be the world’s oldest. At least 80 million years old. As part of this desert, a bit remote, you will find a very special terrain. Here, grass grows, which more or less clings to the sand with the help of the little rainfall the area has to offer. But it is not the grass itself that creates wonder – it is rather the shape of the landscape. Small and large circles are found too close together in the sand. And together these form a completely distinctive pattern. Mysterious Circles Just the growth of grass in such an area is impressive. And quite mysterious. The landscape is marked by millions of strange circles. Each and every one of them devoid of grass or other vegetation. The diameter varies from 2–10 metres, and the circles are approximately 10 meters apart. Why is it like that? The question has preoccupied researchers for close to half a century. Among other things, researchers have examined dead grass from places around the mysterious circles in the Namib Desert. Photo: Dr Stephan Getzin Two known theories For a long time, researchers have tried to demystify Namibia’s circles. And so far, two different theories have been considered: One is that the rings are formed by termites. While the other theory is that the grass organizes itself in this way, in order to make the best possible use of the water that is available. Previous studies have given both these theories a leg to stand on. But in 2016 something changed. Then similar circles were discovered in Australia. But here scientists could not find a link to termites. Now a new study, published in October this year, has provided further answers. The grass died after ten days In the new study, researchers have examined the grass and the ground in the Namib Desert both before and after periods of rainfall. They installed sensors to measure moisture. The researchers then analyzed differences in the infiltration of water between the inside and outside of the circles. They did this in several places. The results showed that about ten days after a period of rainfall, the grass inside the circles began to die. There must have been little growth in there at all. 20 days later everything was dead. But the grass outside was both green and lush. Researcher and co-author of the new study, Sönke Holch, downloads grass data from the desert in February 2021. Photo: Dr Stephan Getzin One important discovery To understand what happened, the researchers examined, among other things, the roots of the grass. And then they discovered one important thing. Dr. Stephan Getzin and his colleagues found that termites were ruled out. He explains why: – The absence of grass in the circles cannot be explained by termites. There is no biomass that the insects can eat. We can prove that the insects are not responsible, as the grass inside the circles dies immediately after rain. He says so in a press release. Less than ten millimeters of rain falls per year in the Namib Desert, which means that there is very little life in the area. – An incredible example Furthermore, the German researcher explains that the results agree with previous studies: Water in the soil diffuses quickly and horizontally in the sand, even over greater distances. – This is an incredible example of “ecohydrological feedback”. The barren circles become reservoirs that help maintain grass in the edges. The findings may also have a wider significance. They can contribute to a better understanding of similar ecosystems. – This type of self-organization seems to protect plants from drought. And it is a growing problem, explains Stephan Getzin.
ttn-69
These mysterious circles in Namibia have made scientists wonder for half a century – news Trøndelag
