Forest soil is the largest carbon sink in terrestrial ecosystems. Soil carbon dynamics determines amount of carbon uptake and sequestration in the forest. It is complex because various biological processes control the dynamics. Roots and rhizosphere processes are especially important because significant amount of carbon fixed by photosynthesis are used. These processes vary between different forest ecosystems, which characterize the soil carbon dynamics of each ecosystem. In boreal region, for example, soil fungal biomass and respiration changes by forest fire, which explain the changes of carbon stock and turnover during forest recovering. In tropics, root development of giant trees can be a controller of spatial variation of soil carbon flux, suggesting the importance of stand structure on soil carbon dynamics in this area. Studies about the root and rhizosphere processes in ecosystem scale are crucial to increase our understanding of ecological role of forest soil. In this session, we invite the scientists who try to explain the mechanisms of soil carbon dynamics using roots and rhizosphere processes. We would like to synthesize our understanding, exchange useful information of methodologies and clarifying our future works for this challenging topic.