Abstract:

The importance of the decomposition of soil organic carbon (SOC) and its temperature sensitivity (Q₁₀) in terrestrial ecosystem carbon (C) cycling have been widely recognized, especially under climate change. A small change in the Q₁₀ of SOC decomposition may result in a large effect on the global C cycle. Therefore, the identification of critical driving factors of Q₁₀ is needed for accurately predicting soil CO₂ efflux and its feedback to climate change under a continuously warming scenario. By reviewing the published literatures, we explored how different incubation approaches, substrate quality, physicochemical protection and microbial properties affect Q₁₀. We found that: (1) Varying temperature incubation largely overcomes the issues of substrate depletion and microbial adaption that occur using constant temperature incubation, and provides a more accurate and rapid estimation of Q₁₀. (2) While the results of some studies have shown that the Q₁₀ value of recalcitrant C is higher than that of labile organic C, others have also found that the Q₁₀ of recalcitrant C is not necessarily higher than that of labile C, which is mainly due to the heterogeneity of SOC pool. (3) The protection of soil aggregates and minerals on organic matter can affect Q₁₀ by changing the substrate availability or concentration at reaction microsites. (4) Physiological characteristics and community composition and structure of microorganisms also influence the Q₁₀. Microbial communities and physiological characteristics in warmed soils possess a varying relative abundance of key functional genes involved in the degradation of SOC. the SOC decomposition and its Q₁₀ are the essential aspects of the global C cycle. A better understanding of Q₁₀ could contribute to the development of the global change models and accurate projection of future climate.

Key words: soil organic carbon decomposition, temperature sensitivity, incubation approaches, substrate quality, physicochemical protection, microbial property