Plant-derived C input regulates the temperature sensitivity of soil organic carbon by changes in bacterial community composition in an alpine tundra

Tundra ecosystems are vast reservoirs of organic carbon and sensitive areas to climate change. The plant community and soil properties in tundra are changing significantly due to climate warming, which may further affect the temperature sensitivity of soil organic carbon (SOC) decomposition. However, the microbial mechanism by which plant-derived C input affects the temperature sensitivity of SOC decomposition remains unclear. Here we used quantitative stable isotope probing of DNA to examine how bacterial taxa affect the temperature sensitivity of SOC decomposition in an alpine tundra following the addition of glucose. Our results showed that the glucose addition caused significant changes in microbial community composition, with microorganisms transitioning from the sensitive taxa at lower temperatures (5-15℃) to the sensitive taxa at higher temperatures (15-25℃), which may explain why the Q10 of native SOC decomposition increased in 15-25 ℃, compared with no glucose addition. The study suggests many bacterial taxa change with temperature and plant-derived C input, and community-assembled traits of microbial taxa may better predict SOC dynamics in the alpine tundra.