[Characteristics of soil organic carbon mineralization in low altitude and high altitude forests in Wuyi Mountains, southeastern China]. / 武夷山低海拔和高海拔森林土壤有机碳的矿化特征.

Examining the variations of soil organic carbon mineralization at different altitudes is crucial for better understanding of soil organic carbon (SOC) dynamics. We selected the low altitude and high altitude broad-leaved forest soils in Wuyi Mountains as the research object, and incubated them under particular annual average temperature (17 and 9 ℃, respectively) in laboratory to investigate the difference of SOC mineralization characteristics. The results showed that the cumulative SOC mineralization had no significant difference between forest soils at low and high altitude in a 126-day incubation period under ambient temperature. Soil organic carbon content of high altitude soil was significantly higher than that from low altitude. The dynamics of SOC mineralization could fitted by the first-order kinetics. Both mineralization potential (CP) and mineralization rate constant (K) values of two soils had no significant difference, but CP/SOC value and mineralization ratio were significantly higher at low altitude, indicating that the carbon sequestration capacity of low altitude soil was relatively lower than that of high altitude under ambient temperature. Soil microbial biomass carbon and microbial quotients were significantly higher than that of low altitude with the increase of incubation time, indicating that the ability of microbial carbon assimilation was greater at high altitude. On the other hand, the activities of ß-1,4-glucosidase and cellobiohydrolase in high altitude soil were higher, suggesting that more labile carbon would be decomposed by soil microbes. The carbon sequestration capacity and microbial carbon utilization efficiency in high altitude soil would be reduced and thus result in a decline of soil organic carbon storage under the scenarios of climate warming.