Natural regeneration and rehabilitation of Aceh mangrove forests five years after the 2004 Indian Ocean Tsunami
1,2Onrizal and 2Mashhor Mansor
1Forestry Sciences Department, Faculty of Agriculture, Universitas Sumatera Utara
2School of Biological Sciences, Universiti Sains Malaysia
The Indian Ocean tsunami on 26 December 2004 caused catastrophic destruction to coastal communities. Disturbance is an important factor in structuring ecological communities, exerting its influence through changes to the physical environment and to the trajectories of succession processes. We conducted survey in Aceh to look at plant species that are resilient to the onslaught of 30-meter tidal waves which devastated the Aceh coastal zones killing more than 150,000 people in Aceh alone. The surveys was conducted during April to December 2009 or around five years after the 2004 tsunami in order to observe and record the emergence of several existing plant species as well as new ones that were caused by the tsunami. We also studied the survival of the rehabilitated mangrove forests after the tsunami disaster. Our result show that the disturbance habitat of mangrove forest in Northern Sumatra due to earthquake and tsunami disaster caused change in plant community. In our research site, mangrove tree Rhizophora apiculata and mangrove palm Nypa fruticans was found to migrate land-wand via seedling recruitment, naturally. Some mangrove plants species such as Avicennia marina, Bruguiera gymnorrhiza, Bruguiera sexangula, Ceriops tagal, Rhizophora apiculata, Rhizophora mucronata, Sonneratia alba, Sonneratia caseolaris, Nypa fruticans and Acrostichum aureum (mangrove fern) seemed to thrive well in the natural stands. However along the intertidal coastal zone, new species such as Typha latifolia are widely colonizing the zone. Most of the disturbed habitats are occupied with weedy species such as Calotropis gigantea and the noxious weedy species Mimosa pigra. Mangrove fern Acrostichum aureum population occupy the open areas left by mangrove plant communities or unmanaged aquaculture pond. The true mangrove species such as Rhizophora apiculata and Rhizophora mucronata are most popular selected in mangrove rehabilitation after tsunami disaster. The successful degree of mangrove rehabilitation are varied from low to middle survival due to some reason such as mistakes in the selection of planting sites, unsuitable choice of plants, insufficient preparation, inadequate guidance, no tending of the plants, and the low capacity of human resources. It should be noted that before 26th December 2004, most of the mangrove coastal zones had been destroyed to make way for aquaculture ponds. Since the mangroves provide a natural barrier, more human lives could probably be saved during the tsunami. Unfortunately, due to high demand of aquaculture products such as shrimps, prawns and fish, the widespread destruction of these mangrove forests was unmanaged. Therefore, mangrove forests should be rehabilitated and conserved very well in the future.
Keywords: mangroves, natural regeneration, rehabilitation, resilient, tsunami, Aceh
Paper presented at “An International Workshop for Conservation Genetics of Mangroves will be held on 11-12 Feb. 2009 at the Iriomote Station of the Tropical Biosphere Research Center, the University of Ryukyus” as part of the as part of the JSPS Exchange Program for East Asian Young Researchers, Feb. 9 – 25, 2010 at the Graduate School of Science, Chiba University, Japan