These grasses, which grow in remote areas of the Namib Desert and rely on the region’s low rainfall for their livelihood, are thriving.
It’s amazing, but also intriguing to see how so much grass can grow in such a harsh environment. Millions of odd circles are scattered across the grassland, all without any grass or vegetation. Together, they form an eerie, polka-dot pattern called “Polka-dot”.Fairy circles“Across the landscape.
The area is 80 to 140 km (50 to 87 mi) inland from Namibia’s coast. According to the study’s researchers, it displays “an extraordinary degree spatial ordering.”
A typical fairy-tale circle Measures anywhereFrom 2-10 meters in diameter, separated by up to 10 metres from the rest.
Scientists are making steady progress in demystifying Namibia’s fairy circle, with the most popular theories falling into two camps.
One theory suggests that the circles are caused due to termites eating roots. The other theory suggests that the grasses self-organise to maximize water supply.
Each theory has been supported by studies, while some research supports both. Self-organization and termitesThis could be the reason for the fairy circles. This explanation was made more difficult when similar circles were found. Australia:In 2016, there was no clear link to termites.
Recent research suggests that self-organization is more likely, with the grasses creating fairy circles. Make the most out of the limited rainfallBut, it is not necessary to rule out termites.
Stephan Getzin from the Department of Ecosystem Modeling, University of Goettingen, Germany added support for the water-scarcity scenario in 2020. Getzin and his collaborators described it as an “analogous” scenario. Example of a Turing Pattern.
Getzin and a team returned to Namibia with the hope of uncovering more evidence. The researchers explored fairy circles in 10 areas of the Namib Desert.
This area experiences very little rain. Researchers note that grasses between the fairy circles can sometimes grow within them after rains. However, they usually die soon after.
Getzin and his associates tracked the sporadic rainfall in the 10 regions. They examined the roots, shoots and grasses and any potential termite damage.
They investigated the conditions of dying grass after rain and built soil-moisture sensors to monitor data at half an hour intervals. The sensors were placed in and around fairy circles and recorded data starting in the dry season in 2020 and continuing through the end of the rainy season in 2022.
The study revealed that the fairy circles’ interior had little new growth ten days after the rains. Even the new grass was already dead. Any grass within the circles died twenty days after rain, while the surrounding grass was green and soft.
Roots from dead grass inside the circles were as long – or even longer than – roots from outside the circles, suggesting the plants were investing heavily in root growth to search for water. According to the researchers, there was no evidence that termites were eating roots.
Getzin: “The sudden absence in grass in most of the circles cannot possibly be explained by termites’ activity because there wasn’t enough biomass for them to eat.” Says. “But, what’s more important is that we can prove that termites aren’t responsible for the death of the grasses immediately after rain without any signs of creatures eating on the root.”
Researchers found that the soil sensors detected a gradual decrease in soil moisture within and outside of the circles following an initial rainfall. This was despite the fact that grasses hadn’t yet been established.
Once the surrounding grasses were robust, however, soil moisture vanished quickly everywhere — including inside the fairy circles, despite the lack of grass there to take up the water.
“Grasses lose water and transpire constantly under the heat of the Namib. “They create soil-moisture vacuums surrounding their roots and water is drawn to them,” Getzin Says.
“Our results are in line with the findings of researchers who found that soil water diffuses horizontally and quickly in these sands, even at distances exceeding seven meters.”
The researchers describe this amazing example of “ecohydrological Feedback” in which the barren areas are transformed into reservoirs that provide water for grasses near the edges.
This research could also have implications elsewhere, Getzin points out, as this kind of self-organization seems to buffer plants against rising aridity – a problem that’s already worsening in some places due to Climate change.
Getzin Says.
“In reality, we know of similar self-organized vegetative structures from other harsh drylands around world. And in all those cases, plants have no other way to survive than by growing in precisely such geometrical configurations.”
The study was published by Perspectives in Plant Ecology and Evolution..
