A study of the mangrove community in the coastal area of Dodinga Bay, South Jailolo District, West Halmahera Regency, North Maluku Province

Abstract

The coastal area of Dodinga Bay possesses a 125 ha mangrove forest. Mangroves have essential ecological roles besides being exploited for firewood, building construction, lift net construction and fish pond. This study was carried out to obtain the following information: (1) mangrove species composition, (2) structural formation of the vegetation and habitat conditions and (3) growth rate of mangrove community. Results showed that mangrove vegetation in the study site consisted of 10 species belonging to six families, Avicennia alba, Bruguiera gymnorrhiza, Bruguiera parviflora, Ceriops decandra, Lumnitzera littorea, Rhizophora apiculata, Rhizophora mucronata, Scyphiphora hydrophyllacea, Sonneratia alba and Xylocarpus granatum. The dominant and subdominant plant compositions in the mangrove ecosystem of Dodinga Bay could be classified into six association types: (1) A. alba/R. apiculata association with closed forest formation and substrate salinity between 5-10‰, sandy sediment texture, muddy sand, mud and total biomass of 153.7 tons/ha; (2) R. apiculata association with closed low forest formation, substrate salinity of 10‰ and ashy sand sediment texture, mud and total biomass of 84.5 tons/ha; (3) A. alba/C. decandra association with open forest formation and open low forest, with substrate salinity between 5-10‰, muddy sand sediment texture, ashy sand and total biomass of 91.8 tons/ha; (4) R. apiculata/C. decandra association with closed forest formation, substrate salinity between 10-12‰, muddy sand sediment texture, mud and total biomass of 209.6 tons/ha; (5) R. mucronata/R. apiculata association with closed forest formation, substrate salinity between 9-12‰ and sandy clay mud sediment texture, muddy sand and total biomass of 266.8 tons/ha; and (6) B. parviflora/R. mucronata association with forest formation, salinity of 12‰ and muddy sand sediment texture, ashy mud and total biomass of 274.2 tons/ha.