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.