The study site has been strongly impacted by coastal erosion
and mangrove loss in recent years. Hydrological modeling
undertaken by ADB (2011) indicates medium erosion along the
coast in this area in both NE and SW monsoons. Hoa et al. (2013)
have recently estimated the loss rate of coastlines recently is up to
2.7% year1 or 24 m year1 which has been exposing earth sea
dykes to strong sea wave and wind action. This directly threatens
high productivity agricultural land behind the dykes.
Kien Giang Department of Agriculture and Rural Development
(Kien Giang DARD) had previously undertaken planting attempts
at this site to protect the sea dyke. The
first planting in 2004 of
normal small seedlings that have often been used for planting in
depositional areas failed after several months because of deep tidal
inundation and strong wave action. In 2005, a second attempt
using saplings that had been raised in a nursery and then protected
from the wave action by anchoring with 3–4 small sticks
surrounding, the trees also failed because the strings attaching
the seedling to the supporting sticks ring-barked the seedlings as a
result of wind and wave action. These failures led to the dyke being
broken in 2006 and 2007 (Fig. 2) causing significant damage to the
local properties, crops, fruit trees and fresh water
fish ponds (GIZ
Kien Giang Project, 2012). Kien Giang DARD rebuilt the dyke late
2008 to prevent further sea water incursion.
Transect surveys to identify plant species and seed sources in
the remained mangrove patches nearby the restoration site found
16 species of 11 families distributed in the areas. Nine of the plants
species identified in the survey are true mangroves, dominated by
Avicennia alba. This area had previously been at a higher elevation
where survey data suggests that the mangrove forests were in a
late successional stage (Hong and San, 1993).