The temperature sensitivity of soil organic carbon decomposition is not related to labile and recalcitrant carbon

The response of resistant soil organic matter to temperature change is crucial for predicting climate change impacts on C cycling in terrestrial ecosystems. However, the response of the decomposition of different soil organic carbon (SOC) fractions to temperature is still under debate. To investigate whether the labile and resistant SOC components have different temperature sensitivities, soil samples were collected from three forest and two grass land sites, along with a gradient of latitude from 18 degrees 40'to 43 degrees 17'N and elevation from 600 to 3510 m across China, and were incubated under changing temperature (from 12 to 32 degrees C) for at least 260 days. Soil respiration rates were positively related to the content of soil organic carbon and soil microbial carbon. The temperature sensitivity of soil respiration, presented as Q(10) value, varies from 1.93 +/- 0.15 to 2.60 +/- 0.21. During the incubation, there were no significant differences between the Q(10) values of soil samples from different layers of the same site, nor a clear pattern of Q(10) values along with the gradient of latitude. The result of this study does not support current opinion that resistant soil carbon decomposition is more sensitive to temperature change than labile soil carbon.