Effect of Soil Moisture on the Response of Soil Respiration to Open-Field Experimental Warming and Precipitation Manipulation

Soil respiration (RS, 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. RS 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 RS 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 RS (p < 0.05), enhancing RS by an average of 54.6% and 59.7% in the control and elevated precipitation plots, respectively, whereas atmospheric temperature warming reduced RS by 19.4% in plots subjected to lower rates of precipitation. However, the warming effect on RS was influenced by soil moisture. On the basis of these findings, we suggest that atmospheric temperature warming significantly influenced RS, but the warming effect on RS may be weakened by warming-induced soil drying in water-limited environments