Abstract:Based on the data of located observation in Jianfengling,Hainan Island,China, the following aspects were investigated: the carbon storage of the main tropical forest soils; the release of CO2 from the soils and litter layers under tropical mountain rain forest and tropical semi-deciduous monsoon forest; the effect of slash-and-burn agriculture on the content of soil carbon and the release of CO2 from soil; and the effect of clear-cutting on the soil carbon storage. The results show that the carbon storage of the main tropical forest soils in Jianfengling was from 97.10t·hm-2 to 119. 54t·’hm-2, and ,in average 102.60t·hm-2 ;in tropical mountain rain forest, the storage of carbon in litter layer was 2.98t·hm-2 ,and CO2 was released at a rate of 33.16t·hm-2·a-1 from the forest land, of which 29.89t·hm-2·a-1 from soil, 3.27 t·hm -2·a-1 from litter layer; in tropical semi-deciduous monsoon forest, CO2 is released with a rate of 10.50 t· hm-2·a-1 from the forest land. The effect of slash-and-burn agriculture on soil carbon was observed even at the depth of 60 cm below soil surface, the release of CO2 from the land under the activity of slash-and-burn agriculture was 37.9 % ,higher than that from the land covered with tropical semi-deciduous monsoon forest. The results also show that clear cutting-caused the decrease in the carbon storage of the forest soil and natural regeneration made the carbon storage recovered.