Mysterious natural features are a great source for turf wars between scientists trying to figure out what is going on.
One of the best examples are the circular patches of barren earth dotting the landscape of the Namib desert. Last year the mystery got renewed attention when researchers announced the discovery of similar circles in the Australian outback, the first time this honeycomb landscape pattern had been spotted outside Namibia.
For nearly a century scientists have been trying to work out the cause of these strange formations, affectionately dubbed ‘fairy circles’. Conspiracies and folklore aside, there are several ideas floating around, with fierce proponents for each.
Some researchers believe the barren patches of land are water catchments for underground termites. The insects destroy the root systems of plants to gain access to rainfall that would otherwise be soaked up by grass.
This activity forms circular patches because termite colonies live in competition with each other—where the edges of similar-sized colonies meet, they establish a border underneath the grass.
Fairy circles seen in the western Australian desert.
PHOTO BY KEVIN SANDERS
But there’s another hypothesis which doesn’t involve any critters. Other scientists have vehemently argued that the patterns arise due to plant self-organisation which happens when they compete for limited water.
Stephan Getzin from Helmholtz Centre for Environmental Research in Germany has been studying fairy circles for 16 years and is a proponent of the latter idea. His team discovered the circles in Australia, and to Getzin that was a strong argument against termites being at play.
“There we found in the majority of cases no nests in the circles and unlike in Namibia, cryptic sand termites do not exist in Australia," he said.
A close-up view of one of the fairy circles in Namibia.
PHOTO BY JEN GUYTON.
Now the long-standing dispute has been compromised by a new study published in Nature today. Researchers led by ecologist Corina Tarnita at Princeton University ran a series of computer models and found that it could actually be an interaction of both termites and plants.
The scientists ran simulations of what termite colony impact would look like based on the concept of warring colonies with established borders. The outcome of their computer model did indeed correspond to the circular patterns seen in the Namib desert.
Wondering what the scene would look like if they also incorporated plant self-organisation, they ran more models and found something they claim was previously unnoticed—not only are there large-scale termite circles, but in the spaces between them you can also find smaller circles formed by plants as they compete for water in the scarce landscape.
“The fairy circles have drawn so much attention, people haven’t paid attention to how the vegetation looks between the circles,” Tarnita told New Scientist.
A visit to Namibia confirmed what they had seen in the simulations. The researchers argue that taking both theories into account actually forms a more comprehensive understanding of the fairy circles.
However, it looks like the debate is not over yet.
For now, the findings only apply to the circles in Namibia, not the ones found in Western Australia. And, according to New Scientist, Stephan Getzin remains unconvinced, maintaining that termites are not always found in areas where we see fairy circles.
Header image: Aerial view of fairy circles in the Namib-Naukluft National Park of Namibia. PHOTO BY FELIX LIPOV/SHUTTERSTOCK