Table S1:Linear relationships between different metrics of C quality parameters.

X\Y / SEC / CWEC / HWEC / SR-15°C / SUVA-15°C / β-TDOC
SEC / 1
CWEC / y= 16.3 + 0.4*x (R2=0.94**) / 1
HWEC / y= 995.8 + 2.6*x (R2=0.47**) / y = 414.98 + 7.87*x (R2=0.42**) / 1
SR-15°C / y = -0.3 + 0.0*x (R2=0.97**) / y = -0.31 + 0.003*x (R2=0.89*) / y = -0.36 + 9.2e-5*x (R2=0.44*) / 1
SUVA-15°C / y = 6.0 - 0.0*x (R2=0.92***) / y = 6.09 - 0.007*x (R2=0.98***) / y = 4.7 - 0.000*x (R2=0.54**) / y = 5.2 - 2.27*x (R2=0.94**) / 1
β-TDOC / y = 29.4 + 0.1*x (R2=0.94**) / y = 32.18 + 0.18*x (R2=0.96**) / y = 2.65 + 0.01*x (R2=0.47**) / y = -8.25 + 56.34*x (R2=0.86**) / y = 123.8 - 25.62*x (R2=0.97***) / 1

* p<0.1, ** p<0.05, *** p<0.01

SR-15°C and SUVA-15°C represent SR and SUVA254 values at 15°C. β-TDOC represents β values of TDOC fraction.

Table S2:CO2-C, CH4-C, and DOC production rates (µg g-1 soil day-1) as determined from

microcosm experiment (n=3, mean±SE).

C fractions Temperature (°C) / Surface soil / Subsurface soil
High P site / Low P site / High P site / Low P site
CO2-C / 15°C / 72(9.6) / 60(8.5) / 42(8.7) / 16(4.5)
20°C / 97(15.3) / 85(14.5) / 55(4.6) / 23(7.3)
25°C / 149(19.2) / 131(17.2) / 87(11.8) / 37(5.3)
30°C / 245(30.4) / 210(38.9) / 152(10.7) / 90(11.5)
CH4-C / 15°C / 0.48(0.08) / 0.16(0.01) / 0.04(0.00) / 0.04 (0.00)
20°C / 1.96(0.18) / 0.90(0.25) / 0.20(0.01) / 0.17(0.08)
25°C / 7.01(1.1) / 2.82(1.27) / 0.73(0.16) / 0.59(0.21)
30°C / 22.35(6.8) / 7.78(2.29) / 3.07(1.18) / 2.25(0.37)
DOC / 15°C / 89(16.2) / 75(10.9) / 64(12.8) / 34(23.7)
20°C / 97(15.9) / 92(12.4) / 74(10.6) / 41(6.8)
25°C / 126(28.4) / 128(36.7) / 90(28.2) / 54(13.9)
30°C / 179(35.1) / 167(28.4) / 155(39.6) / 85(17.4)