Despite environmentalists’ recommendations for the conservation of remaining
peatlands, Vietnam continues planning peat exploitation throughout the country
until 2030 (MOIT 2015). Many areas of peatland in Kien Giang Province (Giang
Thanh, Hon Dat, and Kien Luong Districts) are still included mining of peats for
organic fertilizer production. Most of the peat mining activities involve cooperation
between local government agencies and private companies (Kien Giang 2011;
Humans and Nature 2011). To justify their plans, local authorities launched socioeconomic arguments that the exploitation of peatland resources was to support local
livelihoods and broader economic development (Mizuno et al. 2016).
Clearly peat mining in the interest of economic gain is mainly due to a lack of
knowledge about peatlands and their ecological values, which could also be deliberately ignored due to group interests. As a result of peat mining many peatlands
have lost almost completely.
29.3.2.4 Subsidence of Peatlands
Roots of most plants also require oxygen for respiration. Full saturation of the soil
pores leads to restricted root growth for non-aquatic plants (Majumdar 2000). Some
physical properties of peat, including high porosity, high water holding capacity, and
soft, are not suitable for crop cultivation due to peatlands in natural conditions are
usually saturated with water.
Most of the crops grown in reclaimed peats need a minimum nonsaturated depth
of 1 m for healthy rood growth. Greater depths of drainage may be needed for
building ridges/beds to grow vegetables (Osman 2018). In order to cultivate crops on
peatlands, therefore, in addition to canals, many internal ditches for drainage were
constructed by local farmers in buffer zones of peatlands national parks. On a
drained peatland, a certain quantity of water in the peatland is diverted directly to
the drainage ditches instead of holding within peatland (David and Ledger 1988;
Holden et al. 2006), drying out the upper peat layers. This changes their hydraulic
structure by, among others, decreasing the size of the pores, resulting in subsidence
in peatlands (Landry and Line 2012). The subsidence rate is positively related to
increased depth of the water table below the peat surface (Couwenberg and Hooijer
2013; Hooijer et al. 2012). The subsidence process resulted in reducing the peat
thickness and increasing bulk density over time. These have been recognized in the
U Minh peatlands (Minh and Guong 2008; Quoi 2014a, b; Khanh and Hong Ngoc
2019). These processes are irreversible and result in the degradation of peatlands
(Egglesmann et al. 1993).
790
Q. P. Le and T. X. Le
peatlands, Vietnam continues planning peat exploitation throughout the country
until 2030 (MOIT 2015). Many areas of peatland in Kien Giang Province (Giang
Thanh, Hon Dat, and Kien Luong Districts) are still included mining of peats for
organic fertilizer production. Most of the peat mining activities involve cooperation
between local government agencies and private companies (Kien Giang 2011;
Humans and Nature 2011). To justify their plans, local authorities launched socioeconomic arguments that the exploitation of peatland resources was to support local
livelihoods and broader economic development (Mizuno et al. 2016).
Clearly peat mining in the interest of economic gain is mainly due to a lack of
knowledge about peatlands and their ecological values, which could also be deliberately ignored due to group interests. As a result of peat mining many peatlands
have lost almost completely.
29.3.2.4 Subsidence of Peatlands
Roots of most plants also require oxygen for respiration. Full saturation of the soil
pores leads to restricted root growth for non-aquatic plants (Majumdar 2000). Some
physical properties of peat, including high porosity, high water holding capacity, and
soft, are not suitable for crop cultivation due to peatlands in natural conditions are
usually saturated with water.
Most of the crops grown in reclaimed peats need a minimum nonsaturated depth
of 1 m for healthy rood growth. Greater depths of drainage may be needed for
building ridges/beds to grow vegetables (Osman 2018). In order to cultivate crops on
peatlands, therefore, in addition to canals, many internal ditches for drainage were
constructed by local farmers in buffer zones of peatlands national parks. On a
drained peatland, a certain quantity of water in the peatland is diverted directly to
the drainage ditches instead of holding within peatland (David and Ledger 1988;
Holden et al. 2006), drying out the upper peat layers. This changes their hydraulic
structure by, among others, decreasing the size of the pores, resulting in subsidence
in peatlands (Landry and Line 2012). The subsidence rate is positively related to
increased depth of the water table below the peat surface (Couwenberg and Hooijer
2013; Hooijer et al. 2012). The subsidence process resulted in reducing the peat
thickness and increasing bulk density over time. These have been recognized in the
U Minh peatlands (Minh and Guong 2008; Quoi 2014a, b; Khanh and Hong Ngoc
2019). These processes are irreversible and result in the degradation of peatlands
(Egglesmann et al. 1993).
790
Q. P. Le and T. X. Le