Soil respiration, CO₂ efflux from soil surface to air, accounts for 40-95 % of total ecosystem respiration. Therefore, small changes in this component could have considerable impacts on the ecosystem C budget. Our recent studies found that hot spots of soil respiration, which is extremely high emission of CO₂ from soil surface. Each of the CO₂ hot spots occurred sporadically at different times and locations.

The nesting and feeding activity of termites and ants is one likely cause of the CO₂ hot spots. In tropical rainforests, ants and termites are astonishingly abundant, accounting for nearly 30 % of the entire animal biomass and 80 % of the entire biomass of insects. They could contribute on soil CO₂ efflux directly by their respiration and indirectly by changing the chemical, physical and biological condition of the soil. In this study, we hypothesize that the sudden and considerable increase in soil respiration could be caused by the colony formation of termites and ants.

In order to verify the hypothesis, our project aims to solve three questions; 1) Do hot spots of soil respiration appear in tropical seasonal forest in Thailand? 2) What are the sources of soil respiration? 3) Whether ants and termites relate to the dynamics and formation of hot spots of soil respiration? In this symposium, I introduce outline of the project and our preliminary results.