‘Fairy Circles’ are a phenomena that occurs in the Namib Desert involving circular patches of bare ground forming striking patterns visible in satellite imagery. We have looked at a number of similar phenomenon around the world caused variously by ants, termites and worms. Last month, we had a look at some Fairy Circle-like patterns in the Northern Cape, South Africa, and on reading the post, my sister Clare, alerted us to similar patterns found in northern Zambia.
Fairy Circle-like patterns in northern Zambia.
Closer inspection reveals the clearings are for cultivation:
The reason for the interesting pattern is the method of agriculture being employed in the region. It is locally known as the Chitemene System. The soils of the region are nutrient-poor. Trees are coppiced and the branches brought to a central point and burnt. The ash is then spread over the field, which fertilises the soil, allowing crops to be grown for several years. The pattern is caused by the need for a larger area than the cultivated field to supply the necessary vegetation. Fields are moved after a number of years. In the above image we can see fields of various ages.
In this image we can actually see the burnt areas in the centres of some fields.
Commercial farmers can afford to buy fertiliser so are less restricted. We believe the spottiness in the field below is due to termite activity.
We also came across a vast region that had recently experienced bush fires. We can see what appear to be termite mounds and the path of the fire appears to flow like water across the landscape:
It would appear that in some places, fields have been made around termite mounds. This presumably means the termites make the soil a bit more fertile. Strangely, this seems to be the opposite of what we see in large commercial fields that tend to have bare patches where termite mounds used to be.
For the locations featured above, download this KML file.