Additional file 1 of Revisiting Theron’s hypothesis on the origin of fairy circles after four decades: Euphorbias are not the cause
Creators: name: Getzin, Stephan
name: Nambwandja, Ailly
name: Holch, Sönke
name: Wiegand, Kerstin
Publisher: name: figshare
Year: 2021
Subjects: subject: 59999 Environmental Sciences not elsewhere classified
subject: FOS: Earth and related environmental sciences
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: Ecology
subject: FOS: Biological sciences
subject: Developmental Biology
subject: Plant Biology

description: Additional file 1. Google satellite image showing the three study regions Giribes and Brandberg (with Euphorbia damarana) and Garub (with E. gummifera). Fig. S2. Google satellite image from 2016 of the plot Gir-1, where Theron [6] marked the Euphorbias, fairy circles and control locations in the matrix. The white square shows the 500 m × 500 m extent of the drone-mapped plot. Fig. S3. The large-scale spatial distributions of fairy circles and Euphorbias, assessed with the L-function. The pattern is regular or aggregated at circular neighborhood distances if the red line of the L-function is below the lower or above the upper grey lines of the simulation envelopes, respectively. Fig. S4. Formation of new FCs in the Theron-Plot Gir-1. The four Google-Earth satellite images from 2004 to 2016 show how FCs emerge at places where there was no Euphorbia before (a-d). Fig. S5. This drone image shows the “C1-plot”, as used for spatial analysis of FCs by Meyer et al. [14]. This plot, however, is not representative for the spatially periodic ordering of FCs that can be seen in vast parts of the Giribes Plains further north under more homogeneous habitat conditions. Fig. S6. Several examples of typical sand piles, accumulating around decaying Euphorbia gummifera at the two sites Gar-1 and Gar-2 near Garub (a-d). These circular sand piles with reduced vegetation cover may look similar to fairy circles in aerial or satellite imagery. However, these piles of sand cannot be called fairy circles. Fig. S7. Evidence for clustered patterns of E. damarana and E. gummifera. Euphorbia damarana in the Theron-plot Gir-1 of the southern Giribes (a) and in the plot Bra-2 near Brandberg (b) showed statistically significant clustering because regeneration of the shrubs often happens in a clumped distribution where individual shrubs are tightly packed together (arrows). Also, Euphorbia gummifera in the plot Gar-1 near Garub showed strongly clustered patterns (c) while in the plot Gar-2 the Euphorbias showed a mixed pattern of clustered and random distributions (d). Oblique drone images with overviews over the plots Gar-1 (e) and Gar-2 (f) near Garub clearly show how the individual shrubs with their humped growth form are tightly clustering but they do not have a regularly spaced pattern. Fig. S8. In the north-eastern part of the Giribes Plains, the species Parkinsonia africana co-occurs in various densities with fairy circles over an area of several square kilometers. Two examples have been photographed in March 2020 with a drone (a, b). Parkinsonia africana is a shrub species or small tree, which may grow on its own (c) or it may be occupied by Salvadora persica which scrambles into it (d)