Labile soil organic carbon and microbial activity in three subtropical plantations

Abstract

The effects of tree species on soil properties have been attracted much attention, but the specific responses of labile soil organic carbon (SOC) and microbial activity to changes in tree species of subtropical forest ecosystems remain unknown. In this study, we investigated the labile fractions of SOC from three different single species plantations, namely Pinus massoniana (PM), Cinnamomum camphora (CC) and Schima superba (SS) in subtropical China. Specifically, we analysed the soil microbial biomass C (MBC), dissolved organic C (DOC) and permanganate-oxidizable C (POC), soil respiration, and activities of six enzymes in surface mineral soil (0–20 cm). The MBC, POC and soil respiration, as well as the activities of urease, acid phosphatase and polyphenol oxidase significantly differed among the three plantations in the study. In contrast, changes in the DOC as well as the activities of invertase, catalase and cellulase were not significant. The CC soil exhibited the highest POC, DOC and urease activity. PM soil had the highest MBC, soil respiration and polyphenol oxidase activity, but also had the lowest POC, qCO2, urease activity and acid phosphatase activity. DOC and MBC were significantly correlated with the soil respiration. Urease activity was significantly related to the SOC fractions, except for MBC. Invertase and polyphenol oxidase activities were correlated with MBC. The results suggested that the tree species had different effects on the labile SOC and microbial activity and the observed differences seemed not to be explained by the differences in the litter quality.