Electronic Supplemental Materials

SUPPLEMENTAL A

Table S1. Carbon substrates added to soils for the community-level physiological profile (CLPP) incubation. Guild is the functional group the molecule belongs to and MW is molecular weight.

Substrate / Molecular Formula / Abbrev. / Structure / Guild / MW / C:N /
ascorbic acid / C6H8O6 / ASCO /

/ carboxylic acid / 198.106
asparagine / C4H8N2O3 / ASPA / / amino acid / 132.12 / 2:1
citric acid / C6H807 / CITR / / carboxylic acid / 192.124
L-cysteine / C3H7NO2S / CYST / / amino acid / 121.16 / 3:1
D-glucose / C6H12O6 / GLUC / / carbohydrate / 180.16
glycine / C2H5NO2 / GLYC / / amino acid / 75.07 / 2:1
humic acid / ??? / HUMI / / polyaromatic hydrocarbon / ???
α-ketobutyric acid / C4H6O3 / KETO / / carboxylic acid / 102.089
lignin / ??? / LIGN / / polyaromatic hydrocarbon / ???
malic acid / C4H6O5 / MALI / / carboxylic acid / 134.09
N-acetyl glucosamine / C8H15NO6 / NAG / / amide / 221.21 / 8:1
oxalic acid / C2H2O4 / OXAL / / carboxylic acid / 90.03
pepsin / C33H61N5O9 / PEP / / protein / 671.866 / 33:5
tannin / C76H52O46 / TANN / / polyaromatic hydrocarbon / 1701.2
urea / CH4N2O / UREA / / carbamide / 60.06 / 1:2

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Table S2. Results from backward multiple linear regression with variables: β0-23 = coefficients 0 through 21, T = temperature (°C), θ = volumetric water content (m3 m-3), H = warmed treatment

W = wetted treatment. The full model was:

ln (R) = β0 + β1*T + β2*θ + β3*H + β4*W + β5*θ2 + β6*T*θ + β7*T*H + β8*θ*H + β9*T*W + β10*θ*W + β11*H*W + β12*T*θ2 + β13*H*θ2 + β14*W*θ2 + β15*T*θ*H + β16*T*θ*W + β17*T*H*W + β18*θ*H*W + β19*T*H*θ2 + β20*T*W*θ2 + β21*H*W*θ2 + β22*T*θ*H*W + β23*T*θ2*H*W

Coefficient / Estimate / Standard error / p value
β0 (Intercept) / 2.09 / 0.36 / <0.0001
β1 T / 0.16 / 0.02 / <0.0001
β2 θ / 9.13 / 2.12 / <0.0001
β3 H / 3.24 / 0.55 / <0.0001
β4 W / 1.61 / 0.53 / 0.0023
β5 θ2 / -15.48 / 2.98 / <0.0001
β6 T θ / -0.44 / 0.15 / 0.0027
β7 T H / -0.19 / 0.03 / <0.0001
β8 θ H / -14.64 / 3.29 / <0.0001
β9 T W / -0.08 / 0.03 / 0.0092
β10 θ W / -9.09 / 3.13 / 0.0039
β11 H W / -3.05 / 0.79 / 0.0001
β12 T θ2 / 0.95 / 0.25 / 0.0002
β13 H θ2 / 18.93 / 5.11 / 0.0002
β14 W θ2 / 13.82 / 4.40 / 0.0018
β15 T θ H / 1.00 / 0.23 / <0.0001
β16 T θW / 0.56 / 0.21 / 0.0085
β17 T H W / 0.18 / 0.05 / 0.0001
β18 θ H W / 15.04 / 4.75 / 0.0016
β19 T H θ2 / -1.50 / 0.41 / 0.0002
β20 T W θ2 / -0.93 / 0.35 / 0.0075
β21 H W θ2 / -22.13 / 7.09 / 0.0019
β22 T θ H W / -1.20 / 0.32 / 0.0002
β23 T θ2 H W / 2.11 / 0.55 / 0.0001

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Table S3. ANOVA and least-squared means (Tukey adjusted) results for the cumulative CO2 efflux and home-field advantage (HFA) index. Significant values (P < 0.05) are highlighted bold.

ANOVA Factor / Cumulative CO2 / HFA index
F ratio / P value / F ratio / P value
H / 0.77 / 0.40 / 24.61 / < 0.001
W / 0.52 / 0.52 / 01.55 / 0.24
H*W / 11.79 / 0.01 / 15.20 / < 0.010
Contrasts / t value / P value / t value / P value
A vs W / -1.96 / 0.07 / -1.88- / 0.09
A vs H / -3.05 / 0.01 / 0.75 / 0.47
A vs H+W / -0.15 / 0.88 / 4.39 / < 0.010
W vs H / -1.09 / 0.30 / 2.63 / 0.02
W vs H+W / -1.81 / 0.10 / 6.26 / <.0001
H vs H+W / -2.90 / 0.01 / 3.64 / < 0.01

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Table S4. Pearson correlation coefficients (r) between aboitic factors, soil C and N pools, and biotic factors (n = 16). Abbreviations are: GWC = gravimetric water content, WEOC = water-extractable organic carbon, cCO2 = cumulative CO2 over the 2.5 yr experiment (Fig. 1), Q10 = metabolic quotient or measure of temperature sensitivity, MBC = microbial biomass C, F:B = fungi-to-bacteria ratio, PC1 = scores from 1st principal component from Fig. 3a, PC2 = scores from 2nd principal component from Fig. 3a, CE = catabolic evenness (Fig. 3b), HFA = home-field advantage index (Fig. 4b).

GWC / pH / sand / clay / CTotal / NTotal / C:N / WEOC / NH4 / NO3 / cCO2 / Q10 / MBC / F:B / PC1 / PC2 / CE / HFA
GWC / -- / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / 0.6*_
pH / -- / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns
Sand / -- / ns / ns / ns / ns / ns / ns / ns / ns / ns / -0.58* / ns / ns / ns / ns / ns
Clay / -- / ns / ns / ns / ns / ns / -0.6* / ns / 0.5*_ / ns / -0.59* / ns / ns / -0.63* / ns
CTotal / -- / ns / ns / ns / 0.56* / ns / ns / 0.51* / ns / ns / ns / ns / ns / ns
NTotal / -- / ns / ns / 0.6*_ / ns / ns / ns / ns / ns / 0.63** / ns / ns / ns
C:N / -- / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns
WEOC / -- / ns / ns / ns / ns / ns / ns / ns / ns / ns / ns
NH4 / -- / ns / ns / ns / ns / ns / 0.51** / ns / ns / ns
NO3 / -- / ns / ns / ns / 0.52* / ns / ns / ns / ns
cCO2 / -- / ns / ns / ns / ns / ns / ns / ns
Q10 / -- / ns / ns / -0.75* / ns / ns / ns
MBC / -- / ns / ns / ns / ns / ns
F:B / -- / ns / ns / 0.68** / ns
PC1 / -- / ns / ns / -0.55*
PC2 / -- / ns / ns
CE / -- / ns
HFA / --

P values at * < 0.05, ** < 0.01, *** < 0.001, ns = non-significant

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SUPPLEMENTAL B

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Figure S1. Soil respiration sensitivity to temperature (as measured by modified van’t Hoff equation: Q10 = RT2 / RT1 [10 / (T2 - T1)]) over the modeled moisture gradient from θ = 0.005 to 0.5 m3 m-3 for each treatment.

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Figure S2. Soil respiration rates shown for the reciprocal transplant incubation (RTI) experiment over two weeks. Treatment means are shown with error bars representing ± 1 standard error (n = 4).

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