Effects of Litter Input on Temperature Sensitivity of Soil Organic Carbon Mineralization along a Forest Elevation Gradient

Abstract

The mineralization of soil organic carbon (SOC) is generally stimulated under global warming, known as temperature sensitivity (Q10), which is critical for predicting terrestrial C-climate feedback. However, how Q10 varies in different elevations, particularly with litter input, constraining the establishment of accurate models remains poorly understood. Here, the soil samples of three elevations (750, 950, and 1150 m) were collected from the transition zone of subtropical and warm temperate forests in China for incubation. Soils were incubated with and without 13C-labeled Cunninghamia lanceolata litter at 15 °C and 17.4 °C for 97 days. Incubation process was divided into two stages (0–37 days and 38–97 days) according to the dynamics of CO2 emission. The results showed that Q10 did not change significantly with elevation in the first stage, but Q10 at 950 m was significantly higher than that at 1150 m in the second stage. The variations in Q10 with elevation were regulated by pH in the first stage, while soil C/N was the primary factors that regulated Q10 in the second stage. Q10 showed no response to litter input at 750 m, while it decreased at 950 m in both stages. Following litter input, Q10 at 1150 m increased in the first stage but kept stable in the second stage. The change in Q10 with litter input was mainly affected by the restriction of soil P availability. Overall, our findings emphasized the importance of vertical spatial heterogeneity of Q10 of SOC mineralization in order to improve the prediction accuracy of C dynamics in terrestrial ecosystems.