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Africa’s Mysterious “Fairy Circles” Explained

Fairy circles—circular patches of bare soil surrounded by a ring of grass—have long mystified scientists.

Found mainly in the grasslands of southern Africa, the oddly shaped formations can grow to more than 65 feet (20 meters) wide, but no one knew what caused them. Now, perhaps dashing the hopes of those who thought actual fairies were involved, a new study has found a possible explanation: termites. (See videos of ants and termites.)

It seems the culprit—or landscape artist if you prefer—is a particular species of sand termite, Psammotermes allocerus, that was found at all of the hundreds of sites studied along a 1,240-mile-long (2,000-kilometer-long) belt of desert from central Angola to northern South Africa.

fairy circles picture
Zebras run across plains dotted with fairly circles in Namibia’s Namib Rand Nature Reserve. Photograph by George Steinmetz, National Geographic

 

It works like this: Termites munch away at grass roots, making the soil less dense and more porous and creating a sandy donut hole cleared of plant life. Since plants transpire—or evaporate water into the atmosphere—these vegetation-free sandy centers are able to absorb and retain water more efficiently than if plants were present. (Related pictures: “Nature’s Perfect Circles.”)

The resulting reservoir of water that builds up under the fairy circle allows the surrounding ring of vegetation to flourish in the form of perennial grasses, which in turn provide the termites with food, according to the study, to be published tomorrow in the journal Science.

Termites Farm “Plantations”

By circling the wagons in such a manner, the ecosystem is often able to persist for decades. The question is: how do the termites know to stop eating once they’ve cleared the center? According to study leader Norbert Juergens, of the University of Hamburg, what’s going on is a form of “ecosystem engineering.”

“I believe that the termites stop their grass-destroying activity at the margin of the bare patch based on evolved behavior,” Juergens said by email.

“Thereby, they allow the formation of the perennial grass belt that could be interpreted as a grass ‘plantation.’ Functionally that grass is not touched, but left as an insurance for a series of extreme drought years.” (See a map of Earth’s grassland hot spots.)

These termite farmers also create opportunities for other species, which then establish themselves in the newly created ecosystem.

For instance, the study found that fairy circles attract a variety of organisms, including several species of ants, bees, wasps, plants, and small mammals.

Indeed, by creating these circular oases, the termites turn “wide desert regions of predominantly ephemeral life into landscapes dominated by species-rich perennial grassland, supporting uninterrupted perennial life even during dry seasons and drought years,” according to the study.

Which, you might say, makes the humble termite a fairy godmother of sorts indeed.

Comments

  1. NamibRand Nature Reserve
    Namibia
    April 16, 2013, 9:15 am

    Scientist Norbert Juergens believes he has unlocked the mystery behind Fairy Circles. We are not convinced as the termites he is referring to have never been found on NamibRand (Several scientists have intensively looked for them and others over a period of more than 20 years.). Other prominent scientists such as Dr Walter Tschinkel (Florida State University) and Michael Cramer (University of Cape Town), who have been working on Fairy Circles on NamibRand, are also not convinced. Read more about their opinion at:

    http://www.businessinsider.com/mystery-of-fairy-circles-solved-2013-3?op=1#ixzz2PO2Cmtbh

    http://news.sciencemag.org/sciencenow/2013/03/fairy-circle-mystery-solved.html

    There are quite a few articles on Fairy Circles in past issues of our newsletter. Feel free to read these at http://www.namibrand.org/Newsletter.htm

    We are actually quite pleased that there is something out there in Nature that can’t yet be fully explained.

    Kind regards,
    Nils Odendaal
    CEO – NamibRaned Nature Reserve

  2. bill torbitt
    windhoek
    April 4, 2013, 4:51 am

    and there is no evidence whatever that there is a ‘reservoir of water’ under the fairy circle

  3. bill torbitt
    windhoek
    April 4, 2013, 4:49 am

    But how would this explain the usually almost perfect circular symmetry of the rings?

  4. Nagaraj
    Mysore
    April 1, 2013, 9:55 pm

    Incredible Africa! It is an amazing country full of discoveries yet to come! Nat Geo should be thanked for the extensive coverage on such facts and makes me thrill to look forward to see this wonderful world!

  5. Margaret Ayad
    Bay Roberts, NL, Canada
    March 29, 2013, 5:26 pm

    Our neighbouring community of Harbour Grace has a Fairy Ring, but this is made of trees.
    http://www.flickr.com/photos/baccalieu/sets/72157627823183506/with/6213579853/

  6. GRAND-PITTMAN Steve
    FRENCH POLYNESIA
    March 29, 2013, 1:42 pm

    It seems awsome that such animals are providing life by adopting respect for what they have so as to survive, while we, so called human beings, are destroying ourselves by destroying wild life for MONEY. Today with the sea level rising, WE ARE and have all the technology to built huge pumps so as to get water out the Ocean, we rather dry our rivers and killed all of the endemics plants and life inside at the same time so as to water huge fields . When are we going to understand that what GOD has given us knowledge, but not to destroy but to create and give LIFE !!

  7. Max Huskins
    Vancouver,WA. USA.
    March 29, 2013, 12:41 pm

    There is a typo in the caption, it says “Photograph by” two times.

  8. Vickie
    March 29, 2013, 12:13 pm

    @Julia

    Nat Geo did a cover story on the sailing stones back in 2007. Here’s the link to the article:

    http://ngm.nationalgeographic.com/2007/11/death-valley/cahill-text/1

    It’s a really cool phenomenon!

  9. Khalil
    iran sistanbalochistan chabahar
    March 29, 2013, 11:18 am

    wow that’s so beautiful place

  10. Julia
    March 28, 2013, 9:28 pm

    That is so cool!!!!! In California we have sailing stones which are actually a little scary…. Maybe NatGeo could have an article about how those work?????

  11. Andrew Howley
    March 28, 2013, 3:50 pm

    That is beautiful. Life loves giving life.