摘要：Belowground root biomass plays an essential role in the mangrove ecosystem as potential carbon storage, nutrient gain, or sediment accumulation yet is still overlooked. Therefore, estimation of root biomass is necessary. The objective was to determine and compare the belowground root biomass at the natural and planted mangrove ecosystem. We also measured the forest structure and the aboveground biomass. This study was conducted at four stations in Pramuka Island, Pari Island, Rambut Island (2 stations), Seribu Islands, Jakarta. The first island represented planted mangroves, whereas the latter two as natural stems. Rhizophora stylosa was the dominant species in three stations except for Rambut Island 2 that dominated by Ceriops Tagal. Stand densities were 2730±5 stems ha-1, 1733±5 stems ha-1, 1311±2 stems ha-1, and 1300±2 stems ha-1 for Pramuka Island, Pari Island, Rambut Island 1 and 2. The highest pile density was counted in Rambut Island 2 for 1612±8 stems ha-1 and the lowest in Pramuka Island (780±5 stems ha-1). The aboveground biomass was estimated as follows 109.13±11.91 Mg ha-1 in Pari Island, 89.45±19.53 in Rambut Island 2, 68.41±17.12 Mg ha-1 in Rambut Island 1, and 14.05±5.74 Mg ha-1 in Pramuka Island. Belowground root biomass in planted mangrove Pramuka Island (3.63±0.82 Mg ha-1) and the other two natural mangroves Pari Island (6.56±0.47 Mg ha-1) and Rambut Island 1 (7.17±0.81 Mg ha-1), were similar except for Rambut Island 2 (49.23±6.77 Mg ha-1). The contribution of root biomass ranges from 6-24% of the total biomass of mangrove trees, whereas the fine roots (< 2 mm) biomass occurred 28-74% in the entire root biomass. The results confirm the high contribution of belowground root biomass to the total biomass pool and the importance of maintaining the planted mangrove as a part of ecosystem rehabilitation.
