Aerial images
We used an unmanned aerial vehicle (DJI Phantom 3 advanced) to capture aerial images of the main part of the high cluster (Fig. 1A). Images were captured in similar lightning conditions, at 45 m above ground, with ISO speed 100, F-stop 4.5, auto-shutter and white balance set as cloudy. The images were processed using Agisoft Metashape Professional v.1.5.5 and converted into an orthophotomosaic with a 4-cm pixel size. During image acquisition, it became clear that not all vegetation can be seen on images, even if captured from low heights. Most plant species grow only in-between polygons shaped by frost (Kabala et al., 2021), mainly as single individuals and their colour is greyish-green. In turn, patches of cushion plants (Acantholimon sp., Androsace sp. and Oxytropis sp.) were clearly visible. Therefore, we decided to use cushion plants as a proxy for all vegetation. Due to long periods of strong wind, we did not manage to take photographs of the low cluster.