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SUMMARY This review article collates and synthesizes the available information on the potential of agroforestry and tropical plantations on soil carbon (C) sequestration to mitigate the greenhouse effect. Tropical forest ecosystems (TFEs) occupy 1.8 billion hectares (Bha) of the total area of 4.2 Bha in forest biomes. The terrestrial C pool in TFEs comprises 120 Mg/ha (tons) in vegetation and 123 Mg/ha in soil to 1 -m depth. Soil: vegetation C pool ratio ranges from 0.9 to 1.2 and increases with increase in latitude. Total C pool is 212 petagrams (Pg = 1 × 1015 g = 1 gigaton) in vegetation and 216 Pg in soil. The soil C pool of TFEs represents about 14% of the global soil organic C (SOC) pool of 1550 Pg. Deforestation and conversion of natural to agricultural ecosystems depletes the C pool. Thus, the SOC pool can be enhanced by restoration of degraded soils, and conversion to planted fallows, agroforestry, plantations, improved pastures, and mulch farming. The rate of SOC sequestration in soils is 100-1000 kg C/ha/yr, and total potential of SOC sequestration in TFEs is 200-500 Tg C/yr (1 Teragram = 112 g) for two to five decades. There is a vast potential of converting degraded ecosystems and agriculturally marginal soils to agroforestry and forest plantations to restore ecosystems, sequester carbon, and mitigate the greenhouse effect.
R. Lai (Sat,) studied this question.