Fig. 4: Regulation of microbial carbon use efficiency on soil carbon-climate feedback.

Warm forests had a mean annual temperature greater than 10°C with the positive temperature sensitivity of microbial carbon (C) use efficiency (CUE) (red lines are the fitting values across all warm forests), while cold forests had a mean annual temperature lower than 10°C with the negative temperature sensitivity of microbial CUE (blue lines are the fitting values across all cold forests). Microbial C uptake is the sum of growth and respiration. The red and blue boxes (Centerline, median. Box limits, upper and lower quartiles. Whiskers, 1.5 times interquartile range) are microbial CUE and soil organic C (SOC)-specific C uptake, growth, and respiration in warm and cold forests, respectively. The green dashed, and orange points show the ecological process in current conditions, warming conditions without altering microbial physiology, and warming conditions altering microbial physiology, respectively, modifying from Singh et al. 2010 (Singh et al., 2010. Nature Reviews Microbiology, 8, 779–790). If there is no adaption of microbial physiology to warming, we could predict the ecological process using the blue line, i.e., the ecological process would shift from the green point (control) to the dashed point (warming). The current study indicates the adaption of microbial physiology, i.e., shifting from green point to orange point. The intersection point of two fitting curves for the relationships between C emission and measuring temperature in warm and cold forests with a measuring temperature of ~24 °C. Source data are provided as a Source Data file.