Temperature Sensitivity (Q10) of Soil Basal Respiration as a Function of Available Carbon Substrate, Temperature, and Moisture

Basal respiration is one of the key indicators of soil C mineralization. Temperature sensitivity (Q10) of basal respiration is important for predicting changes in C mineralization due to warming. A modified methodology of Q10 determination is proposed. Soil samples were incubated at 25°C with periodic short-term (2 h) decline of temperature to 15°C and high-frequency measurements of CO2 production rates. The temperature sensitivity is estimated as the average rate of CO2 production at 25°C (before and after temperature decline) divided by the rate of CO2 production at 15°C. With this method we demonstrated that glucose addition most strongly affects the Q10 values at low temperature ranges (20–10°C), while temperature range affects Q10 stronger than the glucose additions. The negative effect of soil moisture on Q10 of basal respiration was demonstrated: the Q10 values decreased with increasing soil moisture.