Environmental Engineering Reference
In-Depth Information
Fig. 19.1
Pretsunami mangroves distribution in Simeulue island (Source: Blue Forests)
formed, in essence, further out to sea. In order for mangrove forests to continue to exist in
Eastern and Western Simeulue, their propagules (mangrove fruits and seeds) needed to
colonize the new intertidal zone, establish themselves and grow. In NE and NW
Simeulue, this process was arduous at fi rst, as the majority of adult trees had been uplifted
and began to die. They died both due to desiccation and also due to intense competition
with terrestrial vegetation more suited to this new uplifted environment (Fig.
19.3
). Only
a relatively small number of adult mangrove survived, those which occurred either very
low in the tidal profi le, near MSL, or those situated directly adjacent to river mouths and
tidal creeks. This differed from the North Central coast of Simeulue, in the area known as
Teluk Dalam (deep bay). Here a signifi cant number of adult mangroves persisted, as the
amount of seismic uplift was less than the tidal range (Fig.
19.3
). These adult tress contin-
ued to produce and disperse propagules, and, initially, the newly uplifted intertidal
zone was colonized at a much higher rate than NE or NW Simeulue.
19.1.2
Singkil District
Whereas Simeulue Island was uplifted between 25 and 150 cm, mainland Singkil
experienced seismic subsidence of between 25 and 50 cm. When mangroves are
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