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. 2016 Oct 14;82(21):6303–6316. doi: 10.1128/AEM.01170-16

TABLE 2.

Effect of environmental parameters on soil bacterial community structure

Environmental parametera Autocorrelation group no.b R2c P value FDR-corrected P valued
pH 1 34.27 0.001 0.003
CaO 1 15.04 0.001 0.003
Mineral carbon 1 13.64 0.001 0.003
SiO2 1 12.68 0.001 0.003
Annual avg site water balance accounting for soil properties (0.1 mm · yr-−1) 1 11.07 0.001 0.003
Calcite (%) 1 9.62 0.001 0.003
Bulk C:N ratio 1 7.41 0.001 0.003
Nitrogen stable isotope ratio (per ml vs air-N2) 1 6.43 0.001 0.003
Organic matter content via loss of ignition 1 3.96 0.002 0.004
Quartz (%) 1 3.28 0.013 0.021
Ankerite (%) 1 2.20 0.052 0.073
Bulk carbon content 1 1.52 0.156 0.182
Hydrogen index (mg hydrocarbons · g−1 TOC) 2 15.48 0.001 0.003
Bulk soil gravimetric water content (dried at 40°C) (%) 2 8.40 0.001 0.003
Soluble phosphorus content (mg · kg [DW]−1) 2 6.53 0.002 0.004
Sieved soil gravimetric water content (dried at 105°C) (%) 2 5.15 0.002 0.004
Bulk hydrogen content 2 4.37 0.006 0.012
Bulk nitrogen content 2 3.67 0.013 0.021
Oxygen index (mg CO2 · g−1 TOC) 2 3.43 0.008 0.014
Total organic carbon content 2 3.12 0.012 0.021
Annual avg no. of frost days during the growing season (days × 100) 3 15.23 0.001 0.003
No. of precipitation days per growing season (day) 3 11.24 0.001 0.003
Elevation (m) 3 10.51 0.001 0.003
Monthly avg temp (°C × 100) 3 9.81 0.001 0.003
Carbon stable isotope ratio (per ml vs VPDB) 3 9.73 0.001 0.003
Monthly mean precipitation sum (mm) 3 9.60 0.001 0.003
Monthly moisture index (0.1 mm · mo−1) 3 9.32 0.001 0.003
Final latitude 3 9.14 0.001 0.003
Annual degree days (day × °) 3 8.76 0.001 0.003
Soil temp (−5 cm) (°C) 3 6.14 0.001 0.003
Topographic position 3 2.90 0.022 0.034
NiO 4 9.91 0.001 0.003
MgO 4 6.17 0.002 0.004
Phyllosilicates (%) 4 5.07 0.003 0.006
Na2O 4 4.23 0.003 0.006
TiO2 4 2.06 0.067 0.092
Al2O3 4 1.65 0.132 0.161
Fe2O3 4 0.80 0.574 0.618
K2O 4 0.74 0.619 0.642
Cr2O3 4 0.59 0.728 0.728
Electrical conductivity (1:1 μS · cm−1) 5 6.67 0.001 0.003
MnO 6 3.51 0.007 0.013
Plagioclase-Na (%) 7 3.05 0.017 0.027
Daily avg global potential shortwave radiation per mo (kJ · day−1) 8 2.67 0.037 0.055
Sine-transformed direction that a slope faces (° · %−1) 8 2.50 0.026 0.039
Terrain slope (°) 9 2.34 0.04 0.057
Direction that a slope faces (° · %−1) 10 2.00 0.078 0.104
Final longitude 11 1.90 0.082 0.107
Goethite (%) 12 1.85 0.105 0.134
Total phosphorus content (mg · g−1) 13 1.66 0.123 0.153
P2O5 13 1.59 0.152 0.181
Topographic wetness index 14 1.31 0.238 0.272
Indoses (%) 15 0.97 0.41 0.459
Dolomite (%) 16 0.81 0.598 0.632
Temp of maximal pyrolytic yield (°C) 17 0.77 0.548 0.602
Feldspath-K (%) 18 0.68 0.669 0.681
a

Data are presented as the % (wt), unless otherwise indicated. For a full list of environmental parameters and their abbreviations, see Table S2 in the supplemental material. VPDB, Vienna Pee Dee Belemnite.

b

The numbers represent the different modules (groups) of autocorrelated environmental parameters derived from the Spearman's rank correlation network (coefficients >±0.5) shown in Fig. S4 in the supplemental material. The modules were calculated using the modularity statistics in Gephi 0.8.2.

c

Proportion of variability in the bacterial community structure explained by each environmental parameter using adonis() and the weighted UniFrac matrix as the input dissimilarity matrix.

d

Nonsignificant P values after FDR correction are italicized.