Tropical and subtropical ecosystems contain about quarter of the global SOC, and play crucial role in the global C cycle. It is still under debates, at what extent tropical ecosystems are sensitive to climate warming and land us change. This session will address the experimental studies and modelling approaches on microbial processes of SOM decomposition, C sequestration, and nutrients turnover in tropical and subtropical ecosystems as major elements of global C cycle for control the SOC stabilization in tropical ecosystems.