Red sand dunes in NamibRand Nature Reserve, near Sossusvlei, Namibia
Our first evening sunset drive from &Beyond Sossusvlei Desert Lodge, Namibia, was south and then west from the lodge to catch sunset at the Petrified Dunes in NamibRand Nature Reserve. We were fortunate on the drive to see many of the local animals that have managed to survive in the arid desert. Just before sunset we arrived at a region of petrified dunes – sand dunes that have solidified into rock and are believed to be the oldest dunes in the Namib Desert. The petrified dunes are noticeable because of their much darker “burnt” red color, compared with the red sand dunes.
All along our drive, we were surprised to find circular patches of ground on the dunes that were barren of grass, and many at what appeared to be regular intervals – so called Namibian “fairy circles” (see photograph below). Of course, being Americans, we suggested that they were drawn by Aliens. The actual explanation only came to light a year ago through computer simulations at Princeton University – explained at the end of this blog post.
An ostrich in NamibRand Nature Reserve, near Sossusvlei, Namibia
The red of the sand dunes contrasts with the darker soil of the mountains, behind, NamibRand Nature Reserve, near Sossusvlei, Namibia
An Oryx watched us warily as we drove up, stopped for some photographs, and drove on, NamibRand Nature Reserve, near Sossusvlei, Namibia
This “table top” reminded us of the namesake mountain in Cape Town [see our previous blog post, “Cape Town, South Africa (2018)”], NamibRand Nature Reserve, near Sossusvlei, Namibia
Fairy circles in the Namib Desert are circular patches of land barren of plants, varying between 2-15 meters (7-49 feet) in diameter, often encircled by a ring of stimulated growth of grass, NamibRand Nature Reserve, near Sossusvlei, Namibia; see the article at the bottom of this blog post from The Guardian (2017) that details the scientific research at Princeton University that finally explains the secret
The road to the petrified dunes in NamibRand Nature Reserve, near Sossusvlei, Namibia
When we arrived at the darker red petrified dunes, we were greeted by an Oryx on the slope of a dune, NamibRand Nature Reserve, near Sossusvlei, Namibia
Dune grass, NamibRand Nature Reserve, near Sossusvlei, Namibia
A panorama of some petrified dunes in front of the mountains in NamibRand Nature Reserve, near Sossusvlei, Namibia
Grasses alight at sunset on a petrified dune, NamibRand Nature Reserve, near Sossusvlei, Namibia
Your blogger/photographer’s shadow at sunset on at the petrified dunes in NamibRand Nature Reserve, near Sossusvlei, Namibia
“The secret of Namibia’s ‘fairy circles’ may be explained at last” The marks on the ground in the Namib desert resemble a vast sheet of polka dots, or to the less romantic observer, perhaps a bad case of chickenpox. In local myths, the bare, red circles fringed with grass are footprints of the gods, or patches of land once poisoned by the breath of a subterranean dragon. But even among scientists, who strive for more convincing theories, the curious, repetitive patterns have proved hard to explain. Since “fairy circles” became the focus of scientific study, researchers have proposed a host of ways by which the bare discs of soil may form. One idea points the finger at underground termites that engineer the landscape above their heads. Another proposal claims the patterns, which can grow to 25 metres [82 feet] wide, arise from natural competition between desert grasses. In the latest effort to nail the answer, ecologists at Princeton University turned to computer models. To start with, they ran simulations to mimic the impact on desert grasses of termites building colonies underground. Sand termites in the Namib desert eat the roots of low-lying vegetation, meaning more moisture for them, and dead patches on the ground above. In the simulations, the dead zones were confined to patches created when neighbouring colonies of a similar size came up against one another, and settled on a border between their territories.
“‘The termites start with their own mound and go out and forage,’ said Corina Tarnita at Princeton. ‘If they find a smaller colony, they simply kill it and expand their own territory. But if they run into a colony that is about the same size, they cannot do that, and end up with a boundary where there’s permanent conflict, but not a full-blown war.’ But the termites did not explain the patterns completely. Tarnita next built a computer model that simulated the warring underground termites as well as the natural competition that arises between desert greenery. If a plant takes root in the desert, it can provide moisture and shade for others nearby, and so give them a helping hand. But as the plant grows, its roots spread out to draw in more water, making it harder for more distant plants to find water themselves.
“When Tarnita ran the new simulation, fairy circle-like patches appeared as the digital termites went about their business. But the conflict between plants in the simulated desert gave rise to their own fresh patterns – small clumps of vegetation in the spaces between the fairy circles.
“‘You find a much smaller scale pattern that’s driven by the plants self-organising in response to water,’ Tarnita said. To check whether the patterns might occur in the wild, the scientists went to Namibia and took photographs of the landscape. ‘We found an exact agreement, as you zoom in you see these very striking patterns,’ Tarnita said. The researchers, who report their findings in Nature, do not claim to have an explanation for how every fairy circle forms. But when they combine the two theories, the patterns that arise more closely match those seen in the desert, Tarnita said. ‘We get a much more complete description of the patterns,’ she said.
“‘One of the most striking things about nature is that despite the complexity of all of its interactions and the many processes that act simultaneously, sometimes, and more often than we expected, you find these amazing regularities,’she added. ‘We wanted to know how can these messy things results in so much beauty and order on such enormous scales?’” — http://www.theguardian.com/science/2017/jan/18/
Legal Notices: All photographs copyright © 2018 by Richard C. Edwards. All Rights Reserved Worldwide. Permission to link to this blog post is granted for educational and non-commercial purposes only.