Fairy circles found in Australian outback

March 15, 2016 by Bob Yirka report
A fairy circle in the Western Australian outback. Credit: Stephan Getzin.

(Phys.org)—A small team of researchers from Germany, Israel and Australia has confirmed that fairy circles exist in a part of the Australian outback. In their paper published in Proceedings of the National Academy of Sciences, the researchers describe not only evidence for fairy circles in Australia, but evidence of why they form.

Prior to this , have only ever been seen in Namibia, Africa, where they have elicited explanations for their existence from various people for hundreds, if not thousands of years. More recently, scientists have been split between two explanations—that termites are responsible for their formation or that they are self forming due to the way grasses pull moisture from the soil.

Fairy circles are bald patches in fields of grass and are evenly spaced over a large area in a . Each patch is typically circular with a diameter of several feet. Because the ground is red, the patches stand out against the green and brown grass, particularly when seen from an airplane. In this new effort, one of the members of the research team, Stephan Getzin was part of another team that published a paper supporting the self-forming theory—that paper came to the attention of Bronwyn Bell, an environmental manager for a mining company who noticed a resemblance between pictures in the paper and patches in areas near the mines where she worked. She contacted Getzin, who promptly organized a team to investigate.

The researchers studied the circles both on the ground and from the air, and determined that despite drastic differences in soil makeup, the circles appeared to be nearly identical to those in Africa. The finding has led credence to the natural formation theory because termites are sparse in the area where the circles exist in Australia.

An aerial view on the Australian fairy circles which spread homogeneously over the landscape. Credit: Kevin Sanders

The researchers suggest the circles form due to competition for water in the arid area—dominant pull more water from the soil than less dominant plants eventually leading to the death of weaker plants and leaving bare earth behind. When it does rain, the water on the surface drains to plants around the rim. In Africa, where the soil is sandier, the water is pulled from the circle underneath by strong rooted grass plants.

Explore further: Life cycles of mysterious Namibian grassland 'fairy circles' characterized

More information: Stephan Getzin et al. Discovery of fairy circles in Australia supports self-organization theory, Proceedings of the National Academy of Sciences (2016). DOI: 10.1073/pnas.1522130113

Abstract
Vegetation gap patterns in arid grasslands, such as the "fairy circles" of Namibia, are one of nature's greatest mysteries and subject to a lively debate on their origin. They are characterized by small-scale hexagonal ordering of circular bare-soil gaps that persists uniformly in the landscape scale to form a homogeneous distribution. Pattern-formation theory predicts that such highly ordered gap patterns should be found also in other water-limited systems across the globe, even if the mechanisms of their formation are different. Here we report that so far unknown fairy circles with the same spatial structure exist 10,000 km away from Namibia in the remote outback of Australia. Combining fieldwork, remote sensing, spatial pattern analysis, and process-based mathematical modeling, we demonstrate that these patterns emerge by self-organization, with no correlation with termite activity; the driving mechanism is a positive biomass–water feedback associated with water runoff and biomass-dependent infiltration rates. The remarkable match between the patterns of Australian and Namibian fairy circles and model results indicate that both patterns emerge from a nonuniform stationary instability, supporting a central universality principle of pattern-formation theory. Applied to the context of dryland vegetation, this principle predicts that different systems that go through the same instability type will show similar vegetation patterns even if the feedback mechanisms and resulting soil–water distributions are different, as we indeed found by comparing the Australian and the Namibian fairy-circle ecosystems. These results suggest that biomass–water feedbacks and resultant vegetation gap patterns are likely more common in remote drylands than is currently known.

Related Stories

Fairy circles apparently not created by termites after all

May 20, 2014

For several decades scientists have been trying to come up with an explanation for the formation of the enigmatic, vegetation-free circles frequently found in certain African grassland regions. Now researchers have tested ...

Mysterious desert fairy circles share pattern with skin cells

April 7, 2015

Patterns appearing on both the very large and very small scale are extremely rare, but researchers at Okinawa Institute of Science and Technology Graduate University (OIST) in Japan have found a similar pattern in two apparently ...

Soil frost affects greenhouse gas emissions in the Arctic

January 14, 2016

Soil frost is a nearly universal process in the Arctic. In a recent dissertation by doctoral student Marina Becher at Umeå University, it is shown that the frequency and extent of soil frost is important for the release ...

Recommended for you

Herbicides can't stop invasive plants. Can bugs?

August 31, 2016

Over the past 35 years, state and federal agencies have spent millions of dollars and dumped untold quantities of herbicides into waterways trying to control the invasive water chestnut plant, but the intruder just keeps ...

Smarter brains are blood-thirsty brains

August 30, 2016

A University of Adelaide-led project has overturned the theory that the evolution of human intelligence was simply related to the size of the brain—but rather linked more closely to the supply of blood to the brain.

4 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

JB85
3 / 5 (4) Mar 15, 2016
The circular bare patches remind me of the way some species of fungus grow in circular areas and some even generate rings of mushrooms or spore sacks. I suspect the bare patches are fungus that happens to interfere with other plants. The fungus may be hard to see from a few feet away or may be under the surface. If (when) the fungus generates spores it might generate a pattern of circles. The fungus could have inadvertently been brought from one land to another as a side effect of human activity.
antigoracle
1 / 5 (2) Mar 16, 2016
I'm saying, ant colonies.
soldiers
2 / 5 (1) Mar 16, 2016
Would like to add that I have observed similar circles in the Western US deserts (They are often visible in Google Earth). When I encounter these "circles" they are always appearing to be associated with harvester ant colonies (especially when the circles are less than 10 meters in diameter).
compose
Mar 16, 2016
This comment has been removed by a moderator.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.