The relative influences of the three predictor variables that were retained in the simplified BRT model for fairy circle (FC) presence/absence.

The variables are mean annual precipitation (MAP), the 1st principal component of the enhanced vegetation index (1st PC of EVI) and temperature seasonality (Fig. S3). The relative interaction sizes (in parentheses) for two-way interactions between these variables were calculated using BRT analyses. The ranges are between the 5 and 95 percentiles of sites sampled either with or without fairy circles (Fig. S1).