Carbon sequestration potential of mixed garden land use in the Gombong tropical Karst landscape of Central Java, Indonesia

Karst ecosystems can sequester carbon in both organic and inorganic forms through their vegetation and limestone. The carbon cycle in karst landscapes exhibits distinctive characteristics, including the recycling of carbon dioxide emissions by the landscape through karstification. This study was conducted in the Kalisirah Spring catchment area, which is geologically of the Neogene period, characterized by mixed garden land use in a tropical setting. This research aimed to quantify the organic carbon stock derived from biomass and the inorganic carbon stock contained in its limestone samples. The findings reveal that Aboveground biomass carbon averaged 2.55 ± 3.11 t C ha⁻¹ across 19 plots. Meanwhile, the inorganic carbon reserve within the limestone of the Gombong Karst, geologically belonging to the Kalipucang Formation (Tmk) of the Miocene epoch, with a total karst area of 48.47 km² and an average limestone thickness of 200 m, is estimated at 0.428 Gt C (SD = 0.123 Gt C equivalent).