Abstract:Lingnan Duoji Fruit Forest Wetland is a semi-natural managed wetland in Pearl River Delta, which plays an important role in soil carbon sequestration. The soil organic carbon (SOC) components in surface layer (0-20 cm) under five planting types in Duoji Fruit Forest Wetland in Guangzhou were studied, including Clausena lansium (HP), Dimocarpus longan (LY), Averrhoa carambola (YT), D. longan and C. lansium interplanting (LH), A. carambola, D. longan and C. lansium interplanting (YLH). The results showed that the fruit-forest types significantly affected the contents of SOC, dissolved organic carbon (DOC), microbial biomass carbon (MBC), readily oxidizable carbon (ROC) and non-liable carbon (NLC). The SOC content of LY was the highest (22.6 g/kg), which was significantly higher than that of YLH (P < 0.05), and the NLC content was also significant higher than LH and YLH. The NLC was positively related with soil N and P, negatively related with soil bulk density. The content of MBC in YT was higher than that in LY, HP and LH, while the MBC/SOC was higher than that in HP and LY. The DOC content and DOC/SOC in YLH were significantly higher than that of other types (P < 0.05). The ROC/SOC of LH were significantly higher than that of HP and LY, while the NL/SOC were significantly lower than that of HP and LY (P < 0.05). Therefore, it was suggested that the stability of soil organic carbon was improved by planting C. lansium and D. longan alone, while the activity of soil organic carbon was the highest under mixed planting mode.
