ECOSYSTEM CARBON STORAGE OF TROPICAL FORESTS OVER LIMESTONE IN XISHUANGBANNA, SW CHINA

Tropical forests are recognised for their high biodiversity and the roles they play in carbon (C) storage and their influence on climate. Tropical forests over limestone take up 40% of the total area of tropical Asia. Nevertheless, C cycling in tropical forests over limestone is poorly quantified. There is a need for robust measurement of ecosystem carbon storage in tropical forests over limestone. We assessed the ecosystem C stocks, not only aboveground biomass but also belowground biomass, forest floor and mineral soil (to 1 m depth) in a tropical forest over limestone on the northern edge of tropical Asia. Mean total ecosystem C stock was estimated as 214 ± 28 t C ha-1 (± SE). The contribution of plant biomass in storing C was substantial, accounting for 80% of the total ecosystem C storage. The mean C stock of tree layer was 155 ± 24 t C ha-1. Soil C stocks in tropical forests over limestone in this area (50 ± 10 t C ha-1) were much lower than those in tropical forests from South-East Asia. Higher percentage of C stock in plant biomass while lower percentage in mineral soil indicated that C stocks of the tropical forests over limestone would be more vulnerable to vegetation destruction than other tropical forests on non-limestone substrate. This study gave an accurate estimation of C stocks of different components in tropical forests over limestone in Xishuangbanna and highlighted the important role they play in C sequestration.