Sensitivity of soil organic matter decomposition to temperature at different depths in permafrost regions on the northern Qinghai‐Tibet Plateau

The temperature sensitivity coefficient ( Q 10 ) of soil organic matter decomposition is an important variable for global climate models. Permafrost regions contain large organic carbon pools. A deep core was taken in permafrost from the northern Q inghai‐ T ibet P lateau ( QTP ) and exposed to increases in temperature below and above 0° C . The production of CO 2 was related to the soil organic carbon ( SOC ) contents and stable carbon isotopes. Smaller values of δ 13 C‐SOC and δ 13 C‐CO 2 showed that the release of CO 2 was primarily from soil with large SOC contents. The sensitivities of soil organic matter ( SOM ) decomposition to temperature near to the permafrost table and in some permafrost layers were larger than those in other layers. In some layers, a temperature increase below 0° C had a greater effect on the decomposition of SOM than one above 0° C . The values of Q 10 in active layers varied from 2.7 to 23.0, with a mean of 8.8. The values of Q 10 were larger in the deeper layers; they varied from 1.6 to 49.4, with a mean of 20.8. This is because the degradation of permafrost is usually associated with an increase in temperature even when the soil is in a frozen state. Our results suggest that the large values of Q 10 at depth under frozen conditions merit more consideration of the response of SOC to climate warming in future research. Highlights The sensitivity to temperature coefficient, Q 10 , is an important property for global climate models. The values of Q 10 for soil organic matter decomposition were also large in deep layers. A temperature increase below 0° C has large effects on Q 10 . The large values of Q 10 at depth under frozen conditions merit more consideration.