In October 2022, we published in PPEES the first thorough test of the plant self-organization hypothesis and the sand termite hypothesis. Based on examining 500 excavated grasses in the southern, central and northern Namib we showed that grasses within fairy circles died due to plant water stress but not due to root herbivory by termites. Jürgens & Gröngröft (2023) were allowed to write a rebuttal in PPEES, claiming that “Sand termite herbivory causes Namibia´s fairy circles”. The statements of that paper have caused some confusion about the topic. Therefore, we have now examined the claims of that paper in detail and published a response paper in PPEES, which presents the current state of knowledge. Below you will find a list of fairy circle facts that briefly summarize the content of our new paper “Desiccation of undamaged grasses in the topsoil causes Namibia’s fairy circles – Response to Jürgens & Gröngröft (2023)”.

Plants in arid environments often form spatially periodic vegetation patterns in order to respond to water stress. This patterned type of a population-level response to resource stress happens mainly in species-poor communities where only very few herbaceous or woody species dominate. The simple structure of the plant community thus allows for the emergence of strongly geometric patterns, composed of plants and bare soil, because there are no other niche-adapted species that would occupy the space. Usually, there is a pattern sequence between the two stable states of uniform vegetation cover under higher precipitation regimes on the one hand and bare soil at very low mean annual precipitation on the other.

In September 2023 appeared a new study in PNAS by Guirado et al. which showed that the global occurrence of circular vegetation gaps is associated with soil and climatic conditions. The authors used modern methodology such as deep learning algorithms and remote sensing to search for fairy-circle related vegetation gap patterns worldwide. They found these vegetation gaps at 263 sites in 15 countries across the three continents Africa, Asia and Australia.