ABSTRACT
The tropical rainforest (TRF) ecosystems consist of approximately one-sixth of the deciduous forests of the world and occur between 6 to 10° north and south of the equator in South America, Africa, Southeast Asia, and the Pacific. By virtue of their size and the biomass contained in them, tropical ecosystems are important to the global C cycle. Combination of the soil and rainfall regime governs the existence of principal biomes or ecoregions of the tropics. Two principal biomes of the tropics are tropical rainforest and tropical savannas (TS). The types of vegetation in three ecoregions of Asia, Africa and tropical America are quite different from one another, highly variable or diverse, and are characterized with a large quantity of above- and below-ground biomass. The Soil Organic Carbon pool under undisturbed soils of TRF and TS ecosystems may be larger and highly variable depending on rainfall regime and soil conditions.
