Environmental rehabilitation of tropical peat land

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Lowland-tropical peatlands are unique ecosystems. They are both peatlands and tropical swamp forest wich have co-existed for several thousands of years. We investigated both ecosystems of natural swamp forest and Sago palm cultivation at Naman forest reserve and Talau Peat Research Station, respectively, in Sarawak, East Malaysia.Tropical peat soils were classified into oligotrophic peat soils due to their low N,P,K and Ca contents and low pH.Most of Cu and Fe occured in strongly chelated and non-extractable forms. However, the concentrations of N,P,K and Ca in soil solution were not low. A large quantity of hardly decomposed logs and stumps are buried in peat soils. To clarify the distribution of them, ground proving radar was used and succeeded to identify.Amount of litterfall in mixed swamp forest was stable through the year. Nutrient deficiency was not detected for major nutrients. Nutrient cycling in mixed swamp forest is not different from other tropical forest. Decomposition of leaf litter was rapid on Convex of forest floor, which showed higher density of soil macro-fauna and microarthropods. Methane production and emission from soil were studied. Small amount of methane was released from the soil surface, though large amount was accumulated in deeper peat layrsDespite of low Cu and Zn concentration in peat soil and soil solution, Cu and Zn deficiency did not appear in Sago palm. Cu content was low in Sago palm growing on deep peat, which showed slow growth compared with those growing on shallow peat or alluvial soils. The input and output buget of Cu and Zn in eco-system showed that Cu tended to accumurate and Zn tended to be lost from peat land under Sago palm cultivation. Cultivation without appropriate plannings will not assure the sustainable land use in tropical peatlands.