Seasonal variations of Q(10) soil respiration and its components in the temperate forest ecosystems, northeastern China
Understanding the temperature sensitivity (Q10) of soil respiration (RS) and corresponding controlling factors is crucial for estimating the feedback of soil carbon pool to future climatic changes. In this study, trenching method was used to separate RH and RA. Simultaneous measurements of soil respiration and soil microclimate were conducted within two temperate forests (a birch forest and a spruce fir forest). We aimed to analyze the seasonal variations of the Q10 of RS and its two components (heterotrophic [RH] and autotrophic [RA]) and to find relevant influencing factors. The Q10 values ranged from 0.3 to 5.4, and exhibited strong seasonal variation. The regression analysis showed a negative relationship between Q10 and soil temperature in the two forests. Additionally, the Q10 values of RH were also negatively correlated with soil microbial biomass carbon. Positive relationships were found between the temperature dependency of RH and soil organic carbon and C:N only in birch forest, and the seasonal dynamics for Q10 of RA was more dependent on fine root biomass compared to soil temperature in this forest. Soil moisture had no effects on the seasonal changes of Q10 due to its slight fluctuation throughout the growing season. The Q10 value of long-term was a little higher compared to that of short-term. These results emphasize the importance of independently exploring the short-term Q10 of RH and RA; and a single apparent Q10 should be used with caution in estimating soil CO2 emission under global warming.