Daily and seasonal dynamics of CO2 fluxes from soils under different stands of monsoon tropical forest

The analysis of daily, seasonal, and annual dynamics of CO2 emission from soils under different stands of monsoon tropical tall-tree forest was performed on the basis of field observations conducted at the Russian-Vietnamese Tropical Research and Technology Center of the Russian Academy of Sciences. Under a tropical climate, the main factors responsible for the rate of carbon dioxide emission from the soils are shown to be the soil type and the topographic position of the area studied along with the type of vegetation. Depending on these factors, the rate of CO2 emission from the soils was 65–178 mg C/(m2 h) during the dry season and 123–259 mg C/(m2 h) during the wet season. The daily dynamics of CO2 emissions from the soils of the tropical zone was weakly pronounced in both the wet and the dry season owing to the insignificant diurnal fluctuations of soil temperature. The investigations carried out allowed making an expert evaluation of the annual CO2 fluxes from the soils under different stands of monsoon tropical tall-tree forest in southern Vietnam. They amounted to 900–2000 g C/(m2 yr) depending on the forest type.