Comprehensive literature and World Wide Web searches were performed identifying 90 sites around the world where R/R actions have been implemented. We analyzed current best practices and recommendations used in the implementation of mangrove rehabilitation and restoration (R/R) projects in the Atlantic-East Pacific (AEP) and the Indo-West Pacific biogeographic regions during the last 20 years. This paper makes the case that observation and monitoring of natural regeneration, and calculation of rates of recruitment after a major disturbance event is equally or more important than mangrove planting, from not only ecological but also social and economic points of view.
When comparing the “success” of natural recovery versus planted sites, we see that practitioners are still faced with signifi cant challenges. Near to total mortality was observed in 6 out of 7 planting sites in the two districts, while recruitment rates, stem densities and species diversity in nearby intertidal zones indicated that natural recovery was well underway. All the while, mangroves were naturally recruiting seismically repositioned intertidal surfaces, and growing well. (Brown and Yuniati 2008 ) Despite a great deal of commitment from such organizations to bringing back mangroves in the affected areas, the majority of the rehabilitation attempts, which mainly relied on hand planting methods, failed to restore mangrove forests.
After the seismic events, at least 163 separate institutions (government agencies, local and international non- governmental organizations) planned and implemented mangrove rehabilitation activities in Aceh, including over a dozen in Simeulue and Singkil districts. Simeulue and Singkil effectively straddle the Sunda Megathrust, yet experienced the cumulative effects of the tsunami and earthquakes differently, with Simeulue Island undergoing seismic uplift while coastal mainland Singkil subsided. The effects of this rapid change in coastal geomorphology are well expressed in a pair of locations, the remote Island of Simeulue, relatively unknown even in Indonesia before the tsunami, and the district of Singkil, which includes a mainland section as well as the Banyak (Many) Islands. The December, 2004 tsunami and March 2005 earthquake along the Sunda Megathrust off the Western Coast of Aceh, Sumatra, Indonesia not only resulted in catastrophic losses of life and livelihood, but also changed the very shape of the land and coast. Tree communities are more equilibrated in the eastern lagoon which points to a more stable and less disturbed mangrove forest. The high sedimentation rates and deforestation are likely to prevent the formation of a mature forest there. Compared to former studies, seedling density and tree diameter in the central lagoon has declined considerably and tree species dominance has changed. By contrast, understorey species and the pioneer species (Avicennia alba, Aegiceras corniculatum and Sonneratia caseolaris) dominate the central lagoon where several rivers discharge. There, the dominant tree species are Aegiceras corniculatum, Nypa fruticans and Rhizophora apiculata, of which the two latter are characteristic for mature forests.
Tree density and diversity are high in the eastern part of the lagoon, located near the city of Cilacap. Average tree density is 0.80 ± 0.99 Ind./m² with 48.71% seedlings and an average basal area of 9.86 ± 10.54 cm²/m². In the Segara Anakan lagoon, Java, 21 tree species and 5 understorey genera have been identified.