Supplementary materials

Cryptogams signify key transition of bacteria and fungi in Arctic sand dune succession Heli Juottonen1*, Minna Männistö2, Marja Tiirola1 & Minna-Maarit Kytöviita1 1Department of Biological and Environmental Science, University of Jyväskylä, Finland 2 Natural Resources Institute Finland (Luke), Rovaniemi, Finland

Table S1 Table S2 Figure S1 Figure S2 Figure S3 Figure S4 Figure S5 Table S1. Vegetation, soil chemistry, environmental parameters and microbial characteristics of successional stages in sand dune deflation basins. Data are mean values ± SD of six deflation basins (vegetation, soil temperature) or four deflation basins (chemistry, microbial data) and three replicates per deflation basin.

successional stage sand grass moss lichen heath forest vegetation - Deschampsia Polytrichum Stereocaulon Empetrum E. nigrum, flexuosa piliferum sp., nigrum Vaccinium vitis- Racomitrium idaea, ericoides, P. Pleurozium piliferum, schreberi, D. Cladonia sp. flexuosa, Linnea borealis sand cover (%) 100 ± 0 95 ± 3 92 ± 8 52 ± 36 39 ± 48 0 ± 0 organic matter (%) 0.4 ± 0.2 0.3 ± 0.1 0.5 ± 0.2 0.9 ± 0.3 1.8 ± 1.0 4.5 ± 1.7 pH 5.6 ± 0.2 5.8 ± 0.2 5.3 ± 0.2 5.2 ± 0.1 5.2 ± 0.2 4.7 ± 0.1 snow cover (cm)a 95±6 86±6 80±4 85±3 46±5 84±5 moisture (%) 0.16±0.02 0.17±0.04 0.17±0.02 0.25±0.05 0.36±0.11 0.51±0.14 N (%) 0.021 ± 0.022 ± 0.001 0.025 ± 0.003 0.036 ± 0.005 0.047 ± 0.088 ± 0.024 0.002 0.014 P (mg/kg) 2.4 ± 0.6 1.9 ± 0.7 3.1 ± 1.3 4.3 ± 1.2 6.7 ± 2.8 14.1 ± 3.2 Al (mg/kg) 118 ± 42 64 ± 28 91 ± 32 128 ± 42 94 ± 19 70 ± 27 Ca (mg/kg) 42 ± 64 84 ± 57 40 ± 33 50 ± 59 132 ± 90 269 ± 104 Mg (mg/kg) 9 ± 15 19 ± 16 8 ± 6 9 ± 9 27 ± 20 103 ± 30 Fe (mg/kg) 6.1 ± 1.6 6.7 ± 1.0 6.9 ± 1.5 9.8 ± 3.0 6.1 ± 1.8 24.9 ± 15.1 S (mg/kg) 2.4 ± 0.5 1.8 ± 0.6 2.8 ± 0.7 4.0 ± 0.8 4.8 ± 1.5 8.8 ± 3.3 microbial biomass 1.69±0.8 2.18±1.5 9.16±5.9 17.9±5.2 43.7±25.7 98.7±33.9 (nmol/g soil dw)b fungal:bacterial 0.04±0.02 0.04±0.04 0.24±0.13 0.18±0.07 0.48±0.14 0.29±0.10 biomassb minimum soil -3.8 ± 0.6 -3.9 ± 0.6 -3.5 ± 0.3 -2.8 ± 0.5 -6.2 ± 1.5 -2.2 ± 1.1 temperature (°C)c maximum soil 15.3 ± 1.1 15.3 ± 0.3 15.3 ± 0.2 15.0 ± 0.8 14.6 ± 0.2 10.7 ± 0.8 temperature (°C)d bacterial diversity 5.0 ± 0.3 5.3 ± 0.3 5.4 ± 0.1 5.5 ± 0.2 5.8 ± 0.1 5.3 ± 0.2 (Shannon) e fungal diversity 3.6 ± 0.7 2.8 ± 0.8 2.7 ± 0.6 2.4 ± 0.2 2.8 ± 0.8 2.9 ± 0.5 (Shannon)f a maximum snow depth (cm) measured in late March-early April, mean values ± SE in years 2016, 2017, 2018 b based on phospholipid fatty acid (PLFA) analysis c average temperature in January-February d average temperature in July e based on bacterial 16S rRNA gene sequencing f based on fungal ITS2 region sequencing Table S2. Bacterial and fungal generalist OTUs based on indicator species analysis.

number of kingdom OTUs taxonomic classification bacteria 1 Proteobacteria, Alphaproteobacteria, Rhizobiales, unclassified 4 Proteobacteria, Alphaproteobacteria, Rhizobiales, Xanthobacteraceae 3 Proteobacteria, Alphaproteobacteria, Rhodospirillales, Acetobacteraceae 1 Proteobacteria, Betaproteobacteria, Burkholderiales, unclassified 1 Proteobacteria, Betaproteobacteria, Burkholderiales, Comamonadaceae 1 Proteobacteria, Gammaproteobacteria, Xanthomonadales, Incertae Sedis 1 Actinobacteria, Thermoleophilia, Solirubrobacterales, unclassified 2 Acidobacteria, Acidobacteriales, Acidobacteriaceae 1 Acidobacteria, Subgroup 2 fungi 1 , , Leotiales, (Pezoloma ericae) 1 Ascomycota, Leotiomycetes, , Hyaloscyphaceae 1 Ascomycota, Leotiomycetes, Helotiales, unclassified 1 Ascomycota, Dothideomycetes, Venturiales, Venturiaceae 1 Ascomycota, Lecanoromycetes, unclassified 1 Ascomycota, Pezizomycetes, Pezizales, Sarcosomataceae (Pseudoplectania nigrella) 1 Ascomycota, unclassified Figure S1 Deflation basin in an Arctic inland sand dune area and the six successional stages defined in this study. Figure S2 Non-metric multidimensional scaling (NMDS) plot of phospholipid fatty acid (PLFA) data of sand dune successional stages (stress= 0.11). Shapes of the symbols refer to four different deflation basins. Figure S3 Phylum level (class level for Proteobacteria) community composition of bacteria based on 16S rRNA gene sequencing of six sand dune successional stages. B1-B4 indicate four deflation basins, and three columns within a deflation basin are replicate soil samples. ‘Other’ includes Armatimonadetes, Verrucomicrobia, Planctomycetes, Saccharibacteria, unclassified Proteobacteria, Gracilibacteria, TM6, Firmicutes, Nitrospirae, Elusimicrobia, Parcubacteria, WCHB1-60, and Hydrogenedentes. Figure S4 Class-level community composition of fungi based on ITS2 region sequencing of six sand dune successional stages. B1-B4 indicate four deflation basins, and three columns within a deflation basin are replicate soil samples. ‘Other’ includes Microbotryomycetes, Mucoromycotina (Incertae sedis), Taphrinomycetes, Pucciniomycetes, Ustilaginomycotina (Incertae sedis), Chytridiomycetes, Exobasidiomycetes, Ascomycota Incertae sedis, Glomeromycetes, Cystobasidiomycetes, Saccharomycetes, Orbiliomycetes, Wallemiomycetes, and Ustilaginomycetes. Inc. sedis, Incertae sedis. Figure S5 Unclassified (A) bacterial phylum level groups (75% 16S rRNA gene sequence similarity) and (B) fungal class level groups (75% ITS2 sequence similarity) as percentage of total sequence reads per sand dune successional stage (four deflation basins and three replicate samples combined per stage). Groups with relative abundance of >0.15% of total reads are included.