Is the temperature-dependence of soil respiration Q10 similar during soil drying and rewetting?

Understanding how soil respiration responds to fluctuations in soil moisture and temperature is increasingly important as climate change intensifies drying and rewetting events and causes soil warming. In this study, we investigated whether the temperature sensitivity of soil respiration (Q 10 ) and its temperature dependence differ between drying and rewetting periods. We collated high-frequency field data on soil respiration, soil moisture, and soil temperature from the COSORE dataset (28 sites), and partitioned them into dry-down and rewetting periods. Next, random forest regressions and accumulated local effects plots were used to assess the main effect of temperature on soil respiration for both periods. This approach enables estimation of the temperature dependence of Q 10 without the confounding effect of soil moisture variations. Results showed that the temperature dependence of Q 10 differs between the drying and rewetting periods; Q 10 is lower during rewetting than during drying in soils with temperatures below 15 °C, but higher in soils with temperatures higher than 15 °C. No differences were found in the temperature dependences of Q 10 between rewetting events followed by large and small respiration pulses. We conclude that the effects of warming on soil respiration differ between dry-down and rewetting periods.