TABLE 2.

Correlations between unweighted UniFrac distances and environmental parameters (Spearman rank correlations estimated using Mantel tests)a

Phylum (no. of soils)Correlation
Soil pHSoil moisture deficitC/N ratio% OCMAT (°C)Potential C mineralization rate (μg C-CO2 g soil−1 day−1)% Silt plus clay
Full community (88)0.790.500.260.230.160.100.08
Acidobacteria (69)0.720.300.050.050.110.060.20
Actinobacteria (66)0.630.400.180.160.150.130.07
Alphaproteobacteria (69)0.700.370.100.170.120.030.11
Beta/Gammaproteobacteria (69)0.530.340.060.190.210.110.09
Bacteroidetes (57)0.370.450.290.120.240.060.11
  • a Significant correlations are indicated in bold (P < 0.01). Other soil and site characteristics that were tested but were not included in this table because there were no significant correlations (P > 0.15 in all cases) include mean annual precipitation, extractable NH4+ and NO3 levels, total microbial biomass, potential evapotranspiration, and latitude. Multivariate correlations did not increase the correlation coefficients.