Underlying microbial mechanisms driving temperature sensitivity of soil respiration vary by season

The intensity of soil respiration increases with temperature on a global scale. Temperature sensitivity of soil respiration, usually termed as Q₁₀, is defined as the increase in CO₂ efflux for a 10°C increase in temperature. In many traditional ecosystem models, Q₁₀ was regarded as a constant. But more and more studies have shown that the observed Q₁₀ values varied greatly in time and space, and that it is of great value to quantify the temporal-spatial pattern of Q₁₀, which involves in the accurate prediction of ecosystem carbon emissions.

Prof. Li Hui and her colleagues from the Institute of Applied Ecology of the Chinese Academy of Sciences recently revealed latitudinal and seasonal variations in temperature sensitivity of soil respiration (Q₁₀) by cultivating the soil samples collected from northern, central and southern regions of the broad-leaved Korean pine mixed forest (BKPF) in China.

The researchers found that the latitudinal pattern of Q₁₀ was season-dependent. In spring, the Q₁₀ values got higher along the north-to-south gradient, driven by the increasing temperature and the decreasing carbon availability. In summer, Q₁₀ remained relatively stable across the latitudinal gradient. In autumn, Q₁₀ values were still higher in the warmer regions of BKPF, as is the case in spring. And there was a positive linkage between Q₁₀ and the activity of microbial K-strategists in the late growing season.

They discovered a uniform seasonality pattern of Q₁₀ in both southern and central regions of BKPF, with higher Q₁₀ values observed in spring and autumn and lower values recorded in summer. However, the seasonality pattern of Q₁₀ was not found in the northern regions of BKPF and this could be attributed to "the dominance of conifers" there, according to the researchers.

This study expands our understanding of the temporal-spatial variation of Q₁₀ and of its driving mechanisms (e.g., carbon quality, carbon availability and microbial ecological functions), providing new theories and data for subsequent research about climate warming and ecosystem carbon balance.

This study was published in Soil Biology & Biochemistry, titled "Linkages between the temperature sensitivity of soil respiration and microbial life strategy are dependent on sampling season."