completely disappeared due to mining across the decades. By such impacts, there is
only concentrated considerable peatlands remained in the U Minh region, which
comprises some 0.345% of the area of Mekong River Delta, Vietnam (Quoi 2014b).
Although small areas of peatland scattered in the delta have been still exploited
for organic fertilizer production, peatland values and functions have been realized by
local governments, resulting in changes in the management in recent years. The
peatlands in the U Minh region (Kien Giang and Ca Mau Provinces) have been
protected as national parks, where conservation and restoration of peatland ecosystems and biodiversity have been carried out, with funds provided by central and local
authorities. One of the two peatlands is U Minh Thuong National Park recognized as
an ASEAN Heritage Parks (AHP) and the Ramsar site.
29.2 Peatland in Mekong River Delta
29.2.1 Formation of Peatlands
Peatland formation in Southeast Asia has functioned as a long-term C sink for
thousands of years, with most peatlands formation began during the mid-Holocene
around 6000–8000 years ago (Dommain et al. 2011). The MRD was formed by the
deposition of Holocene sediments starting from the late Pleistocene era about
8000 years ago (Ngo et al. 1991b; Nhan 1996; Oanh et al. 2005; Stattegger et al.
2013). The deltaic sediment deposition continued through periods of the Late
Pleistocene to Holocene, under the influence of water during periods of the low
and raised sea levels in the Holocene era (Tamura et al. 2009; Stattegger et al. 2013).
During the late Pleistocene era, sea levels fell over 60 m below its present level
(Biswas 1973; Takehiko 2001), sediments of the Mekong river covered all the delta
(Chiem 1993) and the shoreline was located several hundred kilometers to the east of
the modern delta (Ngo et al. 1991a, b).
During the Flandrian, a large part of the MRD was covered by the sea (Fontaine
1971; Stattegger et al. 2013). During its withdrawal, the sea left traces of ancient
shores and shell deposits. C-14 dates of shells ranged between 4150 and 5680 B.P.
(Fontaine 1971). In the mid-Holocene, sea levels lowered sharply after the rapid
early-Holocene rise (Chiem 1993; Takehiko 2001; Oanh et al. 2002; Stattegger et al.
2013). The embayment within which the modern delta is located was a river valley
shaped by fluvial erosion and some possible tectonic movements. This valley was
subsequently inundated by the sea due to the rapid sea-level rise following the glacial
(the Holocene transgression) to form a marine embayment. Several recorded deltaic
sediment types in which peatlands were formed in some regions in the MRD (Ngo
et al. 1991a, b; Chiem 1993; Nhan 1996; Tamura et al. 2009).
The peat formation period in the MRD began from the middle Holocene until
several hundred years ago. It can be divided into two main stages: (1) Mid-late
Holocene and (2) Late Holocene. The landscapes favorable for peat formation
included ancient coastal swamps/marshes and coastal plains. The sediment deposits
778
Q. P. Le and T. X. Le
only concentrated considerable peatlands remained in the U Minh region, which
comprises some 0.345% of the area of Mekong River Delta, Vietnam (Quoi 2014b).
Although small areas of peatland scattered in the delta have been still exploited
for organic fertilizer production, peatland values and functions have been realized by
local governments, resulting in changes in the management in recent years. The
peatlands in the U Minh region (Kien Giang and Ca Mau Provinces) have been
protected as national parks, where conservation and restoration of peatland ecosystems and biodiversity have been carried out, with funds provided by central and local
authorities. One of the two peatlands is U Minh Thuong National Park recognized as
an ASEAN Heritage Parks (AHP) and the Ramsar site.
29.2 Peatland in Mekong River Delta
29.2.1 Formation of Peatlands
Peatland formation in Southeast Asia has functioned as a long-term C sink for
thousands of years, with most peatlands formation began during the mid-Holocene
around 6000–8000 years ago (Dommain et al. 2011). The MRD was formed by the
deposition of Holocene sediments starting from the late Pleistocene era about
8000 years ago (Ngo et al. 1991b; Nhan 1996; Oanh et al. 2005; Stattegger et al.
2013). The deltaic sediment deposition continued through periods of the Late
Pleistocene to Holocene, under the influence of water during periods of the low
and raised sea levels in the Holocene era (Tamura et al. 2009; Stattegger et al. 2013).
During the late Pleistocene era, sea levels fell over 60 m below its present level
(Biswas 1973; Takehiko 2001), sediments of the Mekong river covered all the delta
(Chiem 1993) and the shoreline was located several hundred kilometers to the east of
the modern delta (Ngo et al. 1991a, b).
During the Flandrian, a large part of the MRD was covered by the sea (Fontaine
1971; Stattegger et al. 2013). During its withdrawal, the sea left traces of ancient
shores and shell deposits. C-14 dates of shells ranged between 4150 and 5680 B.P.
(Fontaine 1971). In the mid-Holocene, sea levels lowered sharply after the rapid
early-Holocene rise (Chiem 1993; Takehiko 2001; Oanh et al. 2002; Stattegger et al.
2013). The embayment within which the modern delta is located was a river valley
shaped by fluvial erosion and some possible tectonic movements. This valley was
subsequently inundated by the sea due to the rapid sea-level rise following the glacial
(the Holocene transgression) to form a marine embayment. Several recorded deltaic
sediment types in which peatlands were formed in some regions in the MRD (Ngo
et al. 1991a, b; Chiem 1993; Nhan 1996; Tamura et al. 2009).
The peat formation period in the MRD began from the middle Holocene until
several hundred years ago. It can be divided into two main stages: (1) Mid-late
Holocene and (2) Late Holocene. The landscapes favorable for peat formation
included ancient coastal swamps/marshes and coastal plains. The sediment deposits
778
Q. P. Le and T. X. Le