Rugged grasses eke out a living from the region's meager rain.
In a harsh environment, the growth of so much grass is impressive. The grassland is dotted by millions of strange circles, each devoid of grass or other vegetation, that together form an eerie polka-dot pattern of " fairy circles".
The study's authors note that the zone of circular gaps in the grassland is visible from miles around.
A fairy circle is usually 2 to 10 meters across and separated from the rest by a distance of up to 10 meters.
Scientists have made steady progress on demystifying the fairy circles.
One theory suggests that the circles are caused by pests, while the other suggests that the grasses organize to maximize water availability.
Some research has shown that both self-organization and termites may be behind the fairies. It was difficult to explain after circles were reported in Australia without a link to the pests.
Recent research has pointed to self-organization in which the grasses form fairy circles to make the most of little rain.
The water-scarcity scenario, which Getzin and his colleagues described as an example of a Turing pattern, was supported by research in 2020.
In their latest study, Getzin and a team of researchers went back to Namibia to investigate fairy circles in 10 regions.
There is not a lot of rain in this area. Grasses can sometimes appear within the fairy circles right after it rains, but they die quickly and the grass between the circles is still alive.
The grasses, their roots and shoots, and any potential root damage were examined by Getzin and his colleagues.
They set up soil-moisture sensors in and around fairy circles to record data for half an hour at a time, beginning in the dry season of 2020 and continuing until the end of the rainy season.
The study found that the interior of the fairy circles had very little new growth after the rain. The grass in the circles was dead twenty days after the rain.
The roots from dead grass inside the circles were as long as the roots from outside the circles, suggesting that the plants were growing to find water. The researchers did not find evidence of the pests.
The sudden absence of grass for most areas within the circles can't be explained by the activity of termites because there wasn't enough food for them to eat. We can show that the termites are not to blame because the grasses die immediately after rain.
When grasses weren't well-established after an initial rain, the soil sensors showed a decline in soil hydration.
Despite the lack of grass there to take up the water, soil moistness vanished quickly everywhere once the surrounding grasses were strong.
The grasses lose water under the strong heat in theNamib. Getzin says that they created soil-moisture vacuums around their roots.
Water diffuses quickly and horizontally in these sands even over distances greater than seven meters, according to the results of our study.
This is an amazing example of ecohydrological feedback, in which the barren circles become a source of water for the grass at the edges.
This kind of self-organization seems to buffer plants against rising aridity, which is a problem that is already worsening in some places due to climate change.
Getzin says that by forming strongly patterned landscapes of evenly spacing fairy circles the grasses act as ecosystems engineers and benefit from the water resource provided by the vegetation gaps.
Plants have no other chance to survive except by growing in such geometric formations, which is what we know about related self-organized vegetation structures from various other harsh drylands.
Perspectives in plant ecology, evolution and systematics published the study.
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