Impacts of elevated CO2 and temperature on soil respiration in warm temperate evergreen Quercus glauca stands: an open-top chamber experiment

Abstract

We conducted an open-top chamber experiment for 3 years to examine the effect of elevated CO2 and temperature on soil respiration in experimental stands of Quercus glauca, an evergreen tree species common in the warm temperate zone of Japan. Seedlings of Q. glauca were planted in open-top chambers and treated with factorial combinations of ambient and elevated (ambient × 1.4, ambient × 1.8) CO2 concentrations and ambient and elevated (+3°C) air temperatures. Elevated CO2 significantly increased the total soil respiration rate (P < 0.001) and the soil respiration rate at 15°C (R 15) (P < 0.05) but had no significant effect on the temperature coefficient Q 10. Although temperature significantly affected total soil respiration rate (P < 0.05), neither the R 15 nor the Q 10 of total soil respiration was affected significantly by the air temperature increase. Annual soil respiration rate, estimated from R 15, Q 10, and soil temperature data, tended to increase with elevated CO2 concentration. These results suggest that soil respiration rate in Japanese warm temperate broad-leaved forests dominated by Q. glauca is sensitive to elevated CO2 and is likely to increase under future climatic conditions.