Effect of soil moisture on the response of soil respiration to open-field experimental warming and precipitation manipulation

Soil respiration (R_S, Soil CO₂ efflux) is the second largest carbon (C) flux in global terrestrial ecosystems, and thus, plays an important role in global and regional C cycling; moreover, it acts as a feedback mechanism between C cycling and global climate change. R_S is highly responsive to temperature and moisture, factors that are closely related to climate warming and changes in precipitation regimes. Here, we examined the direct and interactive effects of climate change drivers on R_S of Pinus densiflora Sieb. et Zucc. seedlings in a multifactor climate change experiment involving atmospheric temperature warming (+3 °C) and precipitation manipulations (-30% and +30%). Our results indicated that atmospheric temperature warming induced significant changes in R_S (p < 0.05), enhancing R_S by an average of 54.6% and 59.7% in the control and elevated precipitation plots, respectively, whereas atmospheric temperature warming reduced R_S by 19.4% in plots subjected to lower rates of precipitation. However, the warming effect on R_S was influenced by soil moisture. On the basis of these findings, we suggest that atmospheric temperature warming significantly influenced R_S, but the warming effect on R_S may be weakened by warming-induced soil drying in water-limited environments.