Fairy Circles Of The Namib - Ecosystem Modeller Contradicts Himself

20 Feb 2023


In October 2022, he had still spread it on thick in his media release: The mystery of the fairy circles in the Namib had finally been solved. It was not termites that produced the bald circles, he claimed, but the grasses themselves. This was confirmed by his most recent research, said Dr Stephan Getzin at the time (see publication "Plant water stress, not termite herbivory, causes Namibia’s fairy circles"). Getzin works in the Department of Ecosystem Modelling at the University of Göttingen.

At his lecture in Windhoek last Thursday, however, the ecosystem modeller was not even able to explain how a fairy circle is actually created and how it grows. He concealed findings from fairy circle research that support the competing termite theory. He also did not mention the preliminary publication of two experts that scientifically refute his conclusions of October 2022.

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Ecosystem modeller Dr Stephan Getzin gives his talk on the fairy circles of the Namib to an audience of about 45 in the Namibia Scientific Society hall. 
Photo: Sven-Eric Stender


Getzin offered a review of more than two decades of research on the bare circles in the grasslands on the eastern edge of the Namib. He elaborated on three explanations, two of which he described as refuted: the euphorbia theory and the termite theory.

Residues of poisonous euphorbias have actually been ruled out by the research as a possible cause years ago. For there are fairy-circle areas, as Getzin also noted, in which euphorbias do not occur and did not occur.

Fake facts about termites

In his "refutation" of the termite theory, Getzin resorted to arguments that had already been proven wrong in the research debate. Termites would only eat dead plant material, Getzin said, quoting Namib expert Mary Seely from 1994. On the other hand, he concealed the laboratory experiment by biologist Kelly Vlieghe (see publication "Herbivory by subterranean termite colonies and the development of fairy circles in SW Namibia" of 2014). This had proven that the sand termite Psammotermes allocerus eats parts of living grasses.

Getzin also showed photos of young grass plants that had died in the circles and claimed that the roots showed no traces of eating. He brushed off objections that a microscope might be needed to rule out possible fatal damage with certainty as "new excuses from termite theorists".

As in his October 2022 paper, the ecosystem modeller stressed, no termites had been found in any of the circles he studied (see recording of the Namibia Scientific Society on YouTube). Confronted with a termite nest that a visitor had brought back fresh from a fairy circle in the Namib, he suddenly admitted, when asked, that also he had indeed found sand termites (see recording at 1:11:28).

But "correlation is not causation", he now claimed. Which is a perfectly justified objection: The fact that sand termites are found in fairy circles does not mean that they actually cause them. However, the ecosystem modeller did not address the indications and evidence that termite theorists have collected in the meantime.

Fake facts about grasses

In the third part of his lecture, Getzin presented his attempt at an explanation, according to which the bare patches develop through self-organisation of the grasses in response to a lack of water. He based this on a model by the British mathematician Alan Turing, with which the patterns of the fairy circles and their circular shape can be reproduced.

The basic assumption for applying this model to the fairy circles of the Namib, however, is met with considerable doubt even by the layman: The grasses outside the circles, according to the ecosystem modeller, would develop a suction force with their roots that would draw water away from the young grasses inside the circle.

Has this horizontal "flow" of moisture over several metres been proven? After all, there are fairy circles with a diameter of more than ten metres. When asked by Namibian.org News, Getzin refers - as he did in November (see report "Latest solution to the fairy circle riddle does not hold water") - to the biologist Michael Cramer of the University of Cape Town. Cramer, who, by the way, is not a soil science specialist, had proven this in an experiment.

Experts, on the other hand, shake their heads: this contradicts all theory and knowledge of soil science (see "Sand termite herbivory, not plant water stress, causes Namibia's fairy circles" von Januar 2023, S. 4 - 6). "Facts are facts", the ecosystem modeller insists.

Getzin cannot give a concrete answer to the first question from the audience about how the process of creating a fairy circle is taking place. Instead, he tries to answer abstractly (see recording at 1:01:54). The ecosystem modeller also cannot explain that a circle grows in that STRONG grasses at the edge die, but not the WEAK grasses further out, which on the contrary grow stronger (see recording at 1:23:52). For the general lack of water he cites would naturally cause the weaker grasses to die first and the stronger grasses to die last. Which is ultimately the basis of his explanation of the fairy circles.

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Speaks for the termite theory and against the explanation of self-organisation of grasses: Grown fairy circle with clumps of dead grasses of the former "luxury belt". With a general lack of water, they would have had to survive longer than the grasses further out in the matrix, which now form the new "luxury belt", due to their strength and lack of competition on one side. 
Photo: Norbert Jürgens


Self-organisation explanation scientifically refuted

In January, the science journal PPEES, where Getzin's study had appeared, published in advance a scientific response by fairy circle expert Prof. Norbert Jürgens and soil science specialist Dr. Alexander Gröngröft from the University of Hamburg (see "Sand termite herbivory, not plant water stress, causes Namibia's fairy circles" of January 2023). It removes the theoretical and factual basis for his explanation of self-organisation.

It also exposes a contradiction between his measurements and his conclusions that should not have escaped him, his co-authors and the reviewers of the science journal PPEES. One of the co-authors is Getzin's boss, Prof. Kerstin Wiegand. Incidentally, she is also a member of the journal's core editorial team ("Editors in charge") and a specialist reviewer for ecology at the German Research Foundation which funded Getzin's study (Grant No. 433057155).

Here is a short version of the points that Jürgens and Gröngröft justify in detail:

1 - Getzin refutes himself. His measurements show that the soil in the fairy circle is always similarly moist or wetter than outside, in the matrix. Therefore, lack of water cannot be the cause of young grasses dying in the circle.

Incidentally, Getzin's measurements (2020 to 2022, at a depth of 20 cm) do not provide any new findings, but confirm Jürgens' measurements (2008 to 2013, at four soil depths), without stating this in the text. This is a clear violation of the basic rules of scientific work.

2 - Getzin's basic assumption that grasses outside the bare areas would suck the moisture out of the soil of the circles contradicts theory and collected data of soil hydrology. Moisture does not "flow" several metres in a horizontal direction within a few days - let alone five metres, as would be necessary in fairy circles of ten metres in diameter.

3 - As Getzin describes, confirming Jürgens' observations, the young grasses in the circle die very early, although even the layer near the surface is still moist then. A lack of water cannot therefore be the cause of their death.

4 - The assumption that the grasses outside the circle suck out the moisture would also mean that grass death in the circle takes place from the outside inwards. However, it takes place from the centre of the circle outwards.

5 - Even where Getzin claims not to have found sand termites, they do exist, as several studies carried out independently of Jürgens and even PhD projects at the University of Cape Town have shown. The corresponding publications are not cited by Getzin in his publication.

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Fairy circles with distinct "luxury belt" in the grasslands of Gondwana Namib Park on the eastern edge of the Namib Desert. 
Photo: Norbert Jürgens


Sven-Eric Stender

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