This dataset comprises the microbial community composition of biological soil crusts in north-German sand dunes. For this we obtained enrichment cultures of phototrophic microorganisms, by placing fragments of biocrusts of the same Petri dishes as used for sequencing, in Petri dishes with Bold Basal (1N BBM) agarized medium (Bischoff and Bold 1963). Cultures were grown under standard laboratory conditions: with a 12-hour alteration of light and dark phases and irradiation of 25 μmol photons m-2 s-1 at a temperature 20 ± 5 ºС. Microscopic study of these raw cultures began in the third week of cultivation. Morphological examinations were performed using Olympus BX53 light microscope with Nomarski DIC optics (Olympus Ltd, Hamburg, Germany). Micrographs were taken with a digital camera (Olympus LC30) attached to the microscope, and processed by the Olympus software cellSens Entry. Direct microscopy of rewetted samples was performed in parallel with cultivation for evaluation of dominating species of algae and cyanobacteria in the original samples. Morphological identification of the biocrust organisms was based mainly on Ettl and Gärtner (2014) for green microalgae, and on Komárek (2013) for cyanobacteria, as well as on some monographs and papers devoted to taxonomic revisions of the taxa of interest (Darienko and Pröschold 2019). Moss and lichens samples were air-dried after collection. For determination, a microscope with a maximum magnification of 400x was used. Morphological identification of mosses followed Frahm and Frey (2004) with taxonomical reference to (Hodgetts et al. 2020). Lichens were determined according to Wirth et al. (2013). Morphologically critical species of the genus Cladonia where additionally analyzed by thin-layer chromatography according to (Culberson and Ammann 1979) in solvent system A.

Encoding for species composition: presence = 1, absence = 0