FIG 1.

Location of and sampling at the long-term ecological research (LTER) site in the Negev Desert, Israel. (A) Location of the Avdat LTER site. The map was generated with GeoMapApp and Global Multi-Resolution Topography data (http://www.geomapapp.org)/CC BY/CC BY (Ryan et al., 2009 [130]). (B) Landscape at the LTER site. Crust was sampled from shrub-free patches with a homogeneous surface appearance. (C) Close-up of soil crust pieces. The crusts were light in color and largely free of lichens or mosses. Coherent pieces of soil crust of ca. 5 mm thickness were collected and transported in petri dishes. (D) Surface of dry crust as seen through a stereoscope. (E) Surface of a rehydrated crust piece after 24 h as seen through a stereoscope. Large bundles of Cyanobacteria could be observed on the surface of soil crusts starting at around 2 h and reaching the largest extent by 12 h. (F) Areal distribution of sampling plots. From each plot of ca. 0.5 by 0.5 m, 20 petri dishes of crust pieces were sampled. For 16S rRNA amplicon sequencing, crust pieces were randomly chosen from three petri dishes per plot, as is exemplified for plot F.