Comparison of calorific values and ash content for different woody biomass components of six mangrove species of Bangladesh Sundarbans

The study of calorific values of mangrove plants is valuable indices for reflecting the energy conversion and material flow of the forest ecosystem. In this study, the calorific value and ash content of different biomass components, i.e. leaf, bark, sapwood and heartwood of six important mangrove species, namely goran (Ceriops decandra Griff. W. Theob.), keora (Sonneratia apetala Buch.-Ham.), passur (Xylocarpus mekongensis Pierre), sundri (Heritiera fomes Buch.-Ham.), gewa (Excoecaria agallocha L.) and jhana garjan (Rhizophora mucronata Lam.) of Bangladesh were evaluated. The gross calorific values (GCVs) and ash-free calorific values (AFCVs) of different biomass components of six species were in the range of 14.15–19.18 MJ/kg and 14.90–19.37 MJ/kg, respectively. Heartwood of H. fomes showed the highest GCV and AFCV among all of the mangrove species. The highest ash content (AC) was found for the bark of X. mekongensis (6.7%), while S. apetala sapwood and H. fomes bark showed the lowest AC (0.5%). The GCVs, AFCVs and ACs of different woody biomass components of six mangrove species were significantly different. The fuel value index (FVI) of heartwood and sapwood of six mangrove species was ranged between 1.34 for E. agallocha heartwood and 7.15 for H. fomes heartwood. The findings of this study are important for selecting the suitable fuelwood species for higher fuel value from and around the biggest single tract mangrove forest, the Sundarbans.