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 (R_S) 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 R_H and R_A. 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 R_S and its two components (heterotrophic [R_H] and autotrophic [R_A]) 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 R_H were also negatively correlated with soil microbial biomass carbon. Positive relationships were found between the temperature dependency of R_H and soil organic carbon and C:N only in birch forest, and the seasonal dynamics for Q₁₀ of R_A 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 R_H and R_A; and a single apparent Q₁₀ should be used with caution in estimating soil CO₂ emission under global warming.