By building “fairy circles,” termites engineer their own ecosystem

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The Namib Desert is dotted with thousands of mysterious “fairy circles,” which are near-perfect circles of barren soil two to fifteen meters wide, rimmed by tall grass. They are unmistakable and stretch for miles, giving the landscape an ethereal and otherworldly feel. Many possible explanations have been proposed, including toxic substances in the soil, meteorites, termites, UFOs, and the ghosts of dead natives. But the circles are extremely remote—more than 110 miles from the nearest village—and have been difficult to study scientifically. Despite decades of research, the cause of these bizarre circles has remained elusive.


But now, after a six-year study and more than 40 trips to the Namib Desert, Dr. Norbert Juergens believes he has come to understand the biological underpinnings of this strange phenomenon. According to Juergens, a single species of termites is responsible for creating and maintaining the circles. But the barren circles aren't just a byproduct of these tiny insects living below the sandy desert surface; they are part of a carefully cultivated landscape that helps the termites—and many other organisms—thrive in an otherwise inhospitable climate.

Juergens hypothesized that if the fairy circles’ cause was biological, the organism would need to co-occur with the circles and would probably not be found elsewhere. Only one species fit the bill:Psammotermes allocerus, the sand termite. Not only was the sand termite the only insect species that lived across the entire range of the fairy circles, but these termites were found to be living beneath nearly every circle sampled. And the harder the termites worked – foraging, burrowing, and dumping their refuse – the more grass died, leading Juergens to conclude that the termites keep the circles barren by burrowing underground and foraging on the roots of germinating grasses.

But the story doesn’t end there. The particular structure of the fairy circles—bare soil edged by tall grass— isn't just a side effect of the insects’ hard work. Instead, this characteristic architecture is vital to the termites' success, and even plays a role in structuring the rest of the ecosystem.

Written By: Kate Shaw
continue to source article at arstechnica.com

9 COMMENTS

    • In reply to #2 by ANTIcarrot:

      Not sure if April’s fool or not.
      Though quite certain RD.net delayed story publication until this date for entirely this reason.

      The article comes from a serious publication and makes perfect sense. Seems legit to me. Incidentally, this region of Africa, the Kalahari, is the theme of the first episode of the excellent BBC series “Africa” with David Attenborough.

  1. Juergens found that the water content of the soil inside the circles was surprisingly high, even at the driest times of the year. Soil humidity between the circles, meanwhile, was much lower. It turns out that the barren ground within the circles allows water to percolate down through the sandy soil and accumulate underground, rather than being taken up by plants and lost via transpiration. The termites living below the circles benefit from this store of water in an otherwise parched desert that receives less than 4 inches of rain annually. Furthermore, perennial grasses also flourish around the circles, thanks to the underground water. The termites then feed on this surrounding grass, expanding their circles ever so slowly.

    In a desert environment, many perennial plants, either widely spread their roots just below the surface to quickly collect any passing rain showers before the water evaporates, or have deep tap roots seeking a water table at depth.

    In essence, the termites are cultivating their own constant sources of water and food by creating and maintaining these circles.

    By clearing surface vegetation, these termites, are allowing rain to soak deeper without being intercepted by plants, and therefore providing a more durable reservoir than would otherwise exist.

    Termites and their harvesting activities provide the base of the food chain, in many ecosystems, in various ways.

  2. It’s a complicated phenomenon, and, more than likely, there’s no actual consciousness or planning involved on the part of the termites; they are just instinctually performing tasks that have been etched into their DNA over millions of years. However, the end result of the insects’ behavior is a massive change in their habitat, a process that scientists call “ecosystem engineering.

    Finally, an article that almost points out what isn’t that obvious to most people. Should have read, there is absolutely no consciousness…

  3. Actually, Juergens only found the Termites in most of the “Circles” (wich are mostly ovals and some irregular forms). But he did not observe the Termites in the process of making the Circles. So, he just guessed that the Termites build the Circles, but he has no proof. Also there is no proof for the Story with the Water reservoir.
    At the Moment, the Termites are the best guess for building the Circles, but it is still a guess.

  4. It is interesting that in dry windswept climates, humans use a similar technique to collect the limited rain or dew in sheltered circular or semi circular pits, which build a moisture reservoir in the centre, that is protected from evaporation by a gritty top dressing of volcanic ash.

    Alt Text (Right click and selct “view image”)

    The vineyards of La Gería (a sub-zone of the Lanzarote Denominación de Origen wine region), with their traditional methods of cultivation, are a protected area. Single vines are planted in pits 4–5 m wide and 2–3 m deep, with small stone walls around each pit. This agricultural technique is designed to harvest rainfall and overnight dew and to protect the plants from the winds. The vineyards are part of the World Heritage Site as well as other sites on the island. http://en.wikipedia.org/wiki/Lanzarote

    It has a unique landscape and is exhilarating to witness due to its vast expanse of volcanic ash from the eruption of Timanfaya during 1730-1736; the whole scenery is bathed in its remains. Surprisingly this area of land cultivates vines by simply digging a pit into the volcanic ash and then to cleverly create a small semi -circular stone wall around it to help protect it from the wind. In fact this is the largest vine growing area in Lanzarote. In land so dry that benefits from the contrasting temperatures ensures year after year the production of the best grapes resulting in the best Malvasia wine in Lanzarote. http://ociolanzarote.com/en/touring-the-island/la-geria-wine-route/

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