Over the past few years the origin of the so-called “fairy circles” has caught the attention of many scientists and tourists visiting Namibia. These fascinating phenomena occur in a broken belt in the pro-Namib zone of the West Coast of Southern Africa, extending from southern Angola through Namibia to just south of the Orange River in the Richterveld in South Africa. Dr Willie Jankowitz, Dean of the School of Natural Resources & Tourism of the Polytechnic of Namibia, looks at some of the theories surrounding these mysterious and intriguing occurrences.
Most of the sites where “fairy circles” occur lie between the 50-mm and 100-mm rainfall isohyet, at sites found roughly between 60 km – 120 km inland. Fog may be a source of moisture at some sites, since fog is still frequent up to 80 km inland. Some of the major sites are in the Marienfluss, Hartmann Valley and Giribes Plains in the Kunene Region. Further south they are especially conspicuous in the region on the western side of the dune belt between the Kuiseb and Koichab rivers. The other localities are just to the north and the south of the Orange River. They vary in diameter from 2 m – 20 m (averaging from 6 m – 8 m), and occur in densities of up 20 circles per ha. However, a specific pattern in their distribution and size is yet to be determined.
The well-known ecologist, Ken Tinley, was apparently one of the first scientists to report on this phenomenon. He proposed that the circles were fossil termitaria. Prof GK Theron from the University of Pretoria started to work on the circles back in 1978, and suggested that the poisonous latex of Euphorbia damarana, which occurs abundantly in those areas, could be responsible for the formation of the barren patches. Since then several scientists have developed hypotheses on the origin of the circles, most of which are related to the activities of termites.
Under the leadership of Prof Gretel van Rooyen from the Department of Botany, University of Pretoria, a group of scientists including the author, started to follow up on the many different theories. They started in April 2000 by visiting the sites selected and marked by Prof Theron in 1978 on the Giribes Plain. These patches were still easily recognised after 22 years. The decomposition in this arid region was so slow that the remains of the dead E. damarana plants were still present, but there was no evidence that new circles had started where the dead plants had been marked. The hypothesis that the poisonous latex is responsible for the circles therefore seems unlikely.
Taking into account that most of the theories refer to termite activity, special attention was given to the presence of termites/ants or any other biotic life form such as fungi on all the other sites visited in the last two years. All types of termites were collected and deep trenches were dug to look for underground nests or activity.
On the basis of actual observation in and around the circles from the Kunene area all the way down to the Orange River, no clear evidence was found to substantiate any of the existing hypotheses related to termites. This includes activities of any other organisms, such as small mammals. Previous microbiological work done by Prof Eicker from the University of Pretoria also clearly illustrates that there is no evidence that fungi or bacteria are responsible for the circles.
In an article published in Conservation 2001, the possibility of radioactivity was mentioned as a possible factor. However, tests done by the CSIR for radioactivity on soil samples collected from within the circles were all negative. Analysis of soils collected from the circles demonstrate an inhibitory or toxic effect on plant growth, while samples collected at the edge of the circle where the grass is normally taller, indicate a stimulatory action on plant growth.
In conclusion, all the present stories, theories and hypotheses fail to explain the origin of these mysterious circles. In fact, current research only deepens the secret and increases the curiosity of both scientist and layman about these curious phenomena.
This article appeared in the 2003/4 edition of Conservation and the Environment in Namibia.