Climatic warming enhances soil respiration resilience in an arid ecosystem

Precipitation plays a vital role in maintaining desert ecosystems in which rain events after drought cause soil respiration (R_s) pulses. However, this process and its underlying mechanism remain ambiguous, particularly under climatic warming conditions. This study aims to determine the magnitude and drivers of R_s resilience to rewetting. We conducted a warming experiment in situ in a desert steppe with three climatic warming scenarios-ambient temperature as the control, long-term and moderate warming treatment, and short-term and acute warming treatment. Our findings showed that the average R_s over the measurement period in the control, moderate and acute warming plots were 0.51, 0.30 and 0.30 μmol·CO₂·m^-2·s^-1, respectively, and significantly increased to 1.72, 1.41 and 1.72 μmol·CO₂·m^-2·s^-1, respectively, after rewetting. Both microbial and root respiration substantially increased by rewetting; microbial respiration contributed more than root respiration to total R_s. The R_s significantly increased with microbial biomass carbon and soil organic carbon (SOC) contents. The R_s increase by rewetting might be due to the greater microbial respiration relying heavily on microbial biomass and the larger amount of available SOC after rewetting. A trackable pattern of R_s resilience changes occurred during the daytime. The resilience of R_s in acute warming plots was significantly higher than those in both moderate warming and no warming plots, indicating that R_s resilience might be enhanced with drought severity induced by climatic warming. These results suggest that climatic warming treatment would enhance the drought resilience of soil carbon effluxes following rewatering in arid ecosystems, consequently accelerating the positive feedback of climate change. Therefore, this information should be included in carbon cycle models to accurately assess ecosystem carbon budgets with future climate change scenarios in terrestrial ecosystems, particularly in arid areas.