Fig.1 Soil microbial PLFAs under cyanobacteria-lichen and moss crusts in revegetated areas in the Tengger Desert［25］

Fig.2 Diazotrophic community compositions in the topsoil of sampling sites at the family level （A） and the genus level （B）， respectively［38］

Fig.3 Unrooted neighbor-joining phylogenetic tree based on the representative sequences of the 20 most abundant OTUs at the DNA level and the 13 most abundant OTUs at the cDNA level in our four sampling sites and their closest sequence match determined from GenBank BLASTp. Bootstrap values of relevant nodes are shown based on 1 000 tree replicates. nifH sequences retrieved both at the DNA and cDNA level are indicated with solid circle symbols. nifH sequences retrieved specifically at the cDNA level are indicated with hollow circle symbols

Fig.4 Microstructure of common algae （including cyanobacteria） in biological soil crusts communities

Fig.5 Canonical correspondence analysis （CCA） of microbial functional structure and environmental variables （A）， and variation partitioning analysis （VPA） of microbial community function diversity among three groups of variables （B）［46］

Fig.6 Normalized average signal intensity of bacterial genes involved in the N cycle of differently-aged biological soil crusts. Gray-colored genes represent those that were not detected by GeoChip 5.0.［48］