Properties and carbon stocks of tropical tidal peat soils deposited on coral limestone in Numfor and Supiori Islands, Papua Province

Abstract

Tidal peatlands in Numfor and Supiori Island, Papua are unique because it accumulates above coral limestone on the tidal environment. The substratum layer is solid coral limestone (lithic contact). The objective of this study was to determine the characteristics and carbon stocks in these areas. The soil samples were collected from each horizon for chemical and physical analysis. Carbon stocks estimation was calculated by multiplying peat thickness, area, bulk density, and organic C content in each soil map unit. The results showed that tidal peat soil reaction was acid to neutral (pH H2O 4.9 to 7.3), while soil salinity was very high (8.32 to 22.3 dS m-1). The cation content is very high in the order of dominance of Na> Ca> Mg> K. Peat thickness varied from shallow to deep (50 to <300 cm). Soil organic C content ranged from 23.03 to 46.99% and bulk density ranged from 0.12 to 0.36 g cm-3. The average of carbon stock in each peat soil map unit was 1.151 to 1.314 t ha-1. Peat soils deposited on coral limestone in this region should be preserved as conservation areas due to its functions as a carbon sink and part of a tidal hydrological unit.