Change of dissolved inorganic carbon (DIC) in karst peak cluster during natural restoration: A case study in Yaji Station

Plant evolution at the Yaji station during the recent twenty years gives a chance for comparing the change of dissolved inorganic carbon in a typical peak cluster karst drainage system. In 1980s, plants on the peak clusters in the station were cut and used for fire wood. Most shrubs were cut regularly only grasses being remain. From 1990s people use electric and gas instead of wood. By now plants are dominated by shrub and arbor. The CO2 concentration of soil air increased during the ecological rehabilitation because of increase of soil respiration. This process enhances the DIC in spring by more intensity of karstification. By means of the hydrochemical model, the flux of spring DIC was separated. One part means that the DIC is brought by original water and the other DIC flux comes with the newly fallen rain water. The flux of original water in the spring accounts for 65 %～83 % in a typical storm event, but the carbon from the newly fallen rain water only accounts for small parts that can not reflect the environmental changes. So, it is proposed here that only the carbon flux from original water can represent the impact of plant evolution. The DIC concentration in original water increased 27 % affected by plant evolution, and the proportion of the original water accounts for 72 %～84 % of the spring’s annual flux. So the increased amount of carbon flux led by plant evolution is revised to 19 %～23 %.