Observations of Natural Recruitment and Human Attempts at Mangrove Rehabilitation After Seismic (Tsunami and Earthquake) Events in Simeulue Island and Singkil Lagoon, Aceh, Indonesia - Post-Tsunami Hazard: Reconstruction and Restoration - page 307

Fig. 19.4 Mangrove forest at Singkil Lagoon before and after subsidence. The original zonation
was shifted “inland” after subsidence; the most upland species of mangroves A. ilicifolius and A.
aureum ran out of room to shift inland as the beach/chenier occurred in relatively the same original
geographical position before and after subsidence (Source: Blue Forests/author)

￿ Zone 4: Ceriops tagal

￿ Zone 5: Acrostichum aureum and Acanthus ilicifolius

After the seismic events and tectonic subsidence, a clear shift took place, with
the die off of adult trees, and the establishment of seedlings precisely one zone
“upwards.”
Adult Rhizophora apiculata die off in Zone 1, with adult Brugueira gymnorrhiza
die off in Zone 2 and establishment of young R. apiculata in zone 2 under the dead
B. gymnorrhiza . This pattern is depicted in Fig. 19.4 .
At the highest intertidal elevation, adjacent to the chénier formation that sepa-
rates the lagoon from oceanic coast, Acrostichum aureum and Acanthus ilicifolius
were forced to retreat onto the submerged sands of the former chénier - which is
only a very narrow zone as the chénier itself continues to build due to the action of
winds, currents and waves depositing sand. Therefore, these two species were
reduced in relative abundance, as their habitat was effectively squeezed.