Consistent temperature sensitivity of labile soil organic carbon mineralization along an elevation gradient in the Wuyi Mountains, China

Labile soil organic carbon (LOC) is an essential component in the global carbon (C) cycling due to its fast turnover and sensitivity to environmental changes. However, responses of the mineralization of LOC to current global warming are still not fully understood. In this study, we investigated LOC mineralization at 5, 15, 25 and 35 °C incubation temperatures through laboratory incubation of soil samples and estimated the temperature sensitivity of LOC mineralization at various temperature ranges (i.e. 5–15, 15–25, and 25–35 °C) in an evergreen broad-leaf forest (EBF), a coniferous forest (CF), a sub-alpine dwarf forest (SDF), and an alpine meadow (AM) along an elevation gradient in the Wuyi Mountains in southeastern China. Our results showed that mineralization of LOC significantly increased along the elevation gradient and with increasing incubation temperatures. The interaction of elevation and incubation temperatures was additive on LOC mineralization. Moreover, the temperature sensitivity (Q₁₀) of LOC mineralization significantly decreased with increasing incubation temperature ranges. However, elevation gradient had no statistically significant impact on Q₁₀ within each incubation temperature range. Our results suggest that soil organic C (SOC) at high elevations is more vulnerable to global warming. Moreover, consistent Q₁₀ of LOC mineralization along the elevation gradient indicates that locally, C quality maybe a minor factor in affecting LOC mineralization and it may be adequate to use a constant Q₁₀ value to represent the response of LOC mineralization to warming in regional climate-C cycling models.