Supporting Information

Fig.S1 Monthly average rain precipitation, evaporation and relative humidity in Hopq Desert based on the records of 28 years. (Rao et al., 2009)

Fig.S2 Four typical crust types along the succession of BSCs communities according to the morphologic characteristics, which are under a gradient of environmental stresses. LA: light-algae crust; DA: dark-algae crust; MA: moss-algae crust; M: moss crust.

Fig.S3 The optimized priori theoretical model of the structure between matrices (species interaction, community properties and ecosystem functions). The one-way straight arrow indicates a direct effect of single causality, and two-way arrow indicates the co-variation of Species interaction and Community properties

Fig. S4 Neighbor-joining (NJ) phylogenetic tree of 16S rDNA sequences including five phototroph taxa, indicated by bars. The GenBank accession numbers are shown in parentheses. The clade stability of the phylogenetic trees was assessed using bootstrap analysis with 1000 replicate data sets; bootstrap confidence levels that are >50% are indicated in the NJ tree.

Table S1.
Species modeling matrix of identified OTUs in DGGE fingerprint gel of various BSCs. (Grey bar=1, presence; Blank=0, absence)
BSCs Types
OTUs / LA1 / LA2 / LA3 / DA1 / DA2 / DA3 / MA1 / MA2 / MA3 / MC1 / MC2 / MC3
1st
2nd
3rd
4th
5th
6th
7th
8th
9th
10th
11th
12th
13th
14th
15th
16th
17th
18th
19th
20th
21st
22nd
23rd
24th
C-score / 0.086 / 0.187 / 0.044 / 0.055
LA: light algae crusts; DA: dark algae crusts; MA: moss-algae crusts; MC: moss crusts.
Table S2.
Crust type / Soil Moisture / Crust Coverage
Value / Average±SD / Value / Average±SD
s1 / 0.01 / 0.01±0.00 / 0% / ND
Sand / s2 / 0.01 / 0%
s3 / 0.01 / 0%
s1 / 0.69 / 0.59±0.10 / 77% / 76±1%
LA / s2 / 0.59 / 76%
s3 / 0.49 / 75%
s1 / 0.49 / 0.82±0.36 / 95% / 97±2%
DA / s2 / 0.85 / 97%
s3 / 1.21 / 99%
s1 / 0.82 / 0.85±0.07 / 95% / 94±3%
MA / s2 / 0.75 / 90%
s3 / 0.89 / 96%
s1 / 1.41 / 1.27±0.14 / 95% / 97±2%
M / s2 / 1.27 / 99%
s3 / 1.13 / 97%
ND: indicates no BSCs formation; LA: light-algae crusts; DA: dark-algae crusts; MA: moss-algae crusts; M: moss crusts.

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