Mangrove Restoration for Coastal Protection

The world’s population continues to grow, and at the same time, the oceans are rising, posing challenges for those living near coastal areas. Almost two-thirds of the global population resides within 50 kilometers of the coast. Mangrove forests offer solutions to mitigate the potential for flooding and provide natural coastal protection. Traditionally, mangrove restoration has been approached from the seaward edge through large-scale planting, with limited success. This dissertation describes how mangrove restoration can be approached from both the seaward and landward edges along degraded coastlines to create functional mangrove forests. Chapter 2 examines how the natural factors drive mangrove dynamics along the landward and seaward edges of a mangrove greenbelt. This work reveals that landward mangrove expansion in old aquaculture ponds was slow because of long inundation times and soft sediment. In contrast, seaward mangrove expansion was associated with elevated mudflats and gentle slopes. Chapter 3 further investigates the effects of different foreshore morphologies on mangrove expansion. This work shows that cheniers, or elevated sand lenses atop muddy foreshores, significantly decrease waves that enter the mangrove fringe. A stable chenier can promote mangrove expansion, even in combination with a negligible small mudflat of 10 to 20 metres. Without a chenier, a 10 times wider mudflat was required to make mangrove expansion more likely than mangrove retreat. Chapter 4 compares traditional mangrove planting with ecological restoration measures for mangrove restoration (EMR). This work shows that EMR measures were more effective at creating connected forest expansion in a landward direction. EMR in the landward direction could be achieved through smart sluice gate management in the right season. This work shows how mangrove cover in associated mangrove aquaculture ponds significantly increased over the project lifetime. Along the seaward edge, field experiment