Global synthesis of temperature sensitivity of soil organic carbon decomposition: Latitudinal patterns and mechanisms

The response of soil organic carbon (SOC) decomposition to global warming is a potentially major source of uncertainty in climate prediction. However, the magnitude and direction of SOC cycle feedbacks under climate warming remain uncertain because of the knowledge gap about the global‐scale spatial pattern and temperature sensitivity ( Q 10 ) mechanism of SOC decomposition. Here, we collected data of Q 10 and corresponding soil variables from 81 peer‐reviewed papers using laboratory incubation to explore how Q 10 varied among different ecosystems at the global scale and whether labile and recalcitrant SOC pools had equal Q 10 values. Q 10 with a global average of 2.41 substantially varied among different ecosystems, ranging from the highest in cropland soils (2.76) and the lowest in wetland soils (1.84). Hump‐shaped correlations of Q 10 values with the maximum at SOC = 190 g/kg and the minimum at clay = 37% were observed. However, the main influencing factors of Q 10 differed among various ecosystems. Q 10 values showed a clear decrease with increasing incubation temperature but no significant decrease above 25°C. In general, labile SOC was less sensitive than recalcitrant SOC to warming. Structural equation model analyses showed that total N and SOC accounted for 53% and 46%, respectively, of the variation in Q 10 of labile SOC and recalcitrant SOC. This finding suggested that Q 10 values of labile and recalcitrant SOC pools had different controlling factors. Our findings highlighted the importance of Q 10 ’s variations in ecosystem types and the response of recalcitrant SOC to warming in predicting the soil C cycling and its feedback to climate change. Therefore, ecosystem type and difference in Q 10 of labile and recalcitrant SOC should be considered to precisely predict the soil C dynamics under global warming. A plain language summary is available for this article.