Africa

The fairy circle mystery

Published 5:19 AM ET, Tue January 31, 2017
Share
Namibia fairy circlesNamibia fairy circles
1 of 13
Strange barren dots -- rimmed with tall grasses -- sprinkle a 1,100-mile stretch of Namibia's desert. Courtesy NamibRand Nature Reserve
Known as fairy circles, these dots have long posed a mystery to scientists. Courtesy NamibRand Nature Reserve
Over the years, several theories have been batted around. The main hypotheses have pointed to gasses, poisons and social insects as the cause -- though none have been proven. Courtesy NamibRand Nature Reserve
Last year, a paper was published in Science by professor Norbert Juergens claiming that fairy circles were the work of a species of sand termite, psammotermes allocerus. Juergens argued termites created an underground oasis for themselves by eating the grass roots and killing it, thereby causing a subterranean water trap (without vegetation, water doesn't evaporate and remains underground). Courtesy NamibRand Nature Reserve
Though many experts found his findings interesting, many remain unconvinced. Stephan Getzin, a scientist from the Helmholtz Centre for Environmental Research in Leipzig, Germany, recently put forth another theory with colleagues from Israel. Getzin argues the circles are formed by a process known as "self-organization." Courtesy NamibRand Nature Reserve
In arid climates, where water is scarce and soil nutrient-poor, plants face stiffer competition for resources. As a result, they 'organize' themselves at a distance to maximize what limited resources are available --ultimately forming strongly ordered patterns on the landscape. Courtesy NamibRand Nature Reserve
On January 19 a team led by Princeton University researchers released a study detailing findings which unified both theories. Potentially, they say, the "termite theory" and the "self-organization theory" are not only both true, but rely upon one another. Courtesy NamibRand Nature Reserve
Sand termites kill vegetation creating bare patches, which are evenly spaced in a hexagonal formation reflecting territorial battles with neighboring colonies. In doing so the earth accumulates more water. Courtesy NamibRand Nature Reserve
Plants surrounding the termites' territory are able to utilize the extra moisture through extensive root growth, growing taller vegetation than their neighbors in drier soil. Courtesy NamibRand Nature Reserve
The team's computer models were able to map the fairy circles' hexagonal layout and visualize their life cycle, which can span from a few years to more than 200. Courtesy NamibRand Nature Reserve
In the Namib Desert it takes approximately 20 years for a fairy circle to close up after the death of a termite colony, the study found. Courtesy NamibRand Nature Reserve
The team behind the paper say marrying the two theories could have wide-ranging implications. Courtesy NamibRand Nature Reserve
A combination of insect colonies, regular formations and benefiting vegetation have been identified all over the world. Courtesy NamibRand Nature Reserve