Elevational gradients do not significantly alter soil microbial respiration and temperature sensitivity in a subtropical forest

Soil carbon (C) cycling plays critical role in regulating global C budget and atmosphere CO2 concentration. The ongoing global warming potentially accelerates soil C loss induced by microbial respiration (MR) and makes soil a large C source to atmosphere. Quantifying the drivers of MR and its response to rising temperature (also called temperature sensitivity, Q10) is a high priority in order to improve the modelling and prediction of terrestrial C cycle under global warming. In this study, we applied a standardized soil sampling along 9 gradients from 400 m to 1100 m in a subtropical forest in South China, and conducted the incubation experiment at the same temperature ranges (from 10 °C to 25 °C) to measure MR and Q10, then the measured MR was adjusted by the field temperature of sampling site. Our objectives were to examine the response of MR and Q10 to the environmental change induced by elevational gradients in the subtropical forest, and then quantify their main drivers. We totally collected 54 abiotic and biotic factors relative to the MR and Q10. Our results showed that the incubated MR increased from low to high elevation. However, significantly elevational trend of the adjusted MR was not examined after adjusted by the field temperature of sampling sites, due to the tradeoff between increasing soil C concentration and declining temperature as elevation increased. We further found that the 9 elevational gradients did not cause significant change of Q10. The variation of Q10 was negatively dominated by soil C quality. Since climate warming is predicted faster at high elevation than that at low elevation, C loss from high elevation might be accelerated in the future and need more attentions in the further studies