however, the impact on water of the so-called Progressive management forestry in
the tropics, which involves draining peatlands and applying fertilizer, has not been
fully revealed in terms of global climate change.
Fires and smoke damage are concerns at the regional level, but when considered
on a global scale, they could result in a severe food shortage or natural disaster due to
flooding or drought brought about by irregular precipitation patterns.
The total peatland carbon pool is greater than that of the world’s forests and is
comparable to the total carbon pool of the atmosphere (Joosten and Clarke 2002).
Tropical peatlands are one of the largest near-surface pools of terrestrial organic
carbon, with a total peat carbon pool of 82–92 Gt (Page et al. 2011). Therefore,
tropical peatland conversion, drainage, and cultivation play important roles in the
global carbon cycle by changing soil conditions and altering the global carbon
balance (Swails et al. 2017). Indonesian peatlands contribute one-third of the carbon
stocks in tropical peat soils (Gumbricht et al. 2017), so they could be a major source
of greenhouse gas (GHG) emissions due to increasing pressures from agricultural
and forestry uses, particularly the expansion of oil palm plantations. If there are
disturbances that reduce the groundwater level (GWL) in peatlands, oxygen enters
the peat soil and disturbs the balance between peat accumulation and decay. This
results in the decomposition of the peat by oxidative microorganisms, and the
accumulated carbon is released into the atmosphere (Page and Baird 2016). At low
levels of intensity, the human use of peatland resources is likely to be sustainable as
long as the hydrological functions of the peatlands remain more or less natural and
the net carbon accumulation is maintained. Intensive use of drainage on a large scale
can result in the loss of carbon storage in peatlands (Swails et al. 2017), releasing
GHGs into the atmosphere and contributing to global warming.
When tropical peatlands were cleared and drained, and dry weather persists,
burning for land preparation caused fires to spread not only to the vegetation but
also to the below-ground peat. As a result, the fires smolder in the peat and release
large amounts of GHGs into the atmosphere.
The drainage of Indonesian peatlands for agriculture and timber extraction over
the past few decades has increased the likelihood of peatland subsidence and the fire
risk during the dry season, particularly in years of El Niño drought. High emissions
from biomass burning in Indonesia, often associated with drained peatlands, contributed significantly to the largest increase in global annual CO 2 emissions observed
during the strong El Niño of 2015 (Liu et al. 2017). However, such fires are not
limited to years with El Niño events; currently, large burns and CO 2 emissions occur
even in non-drought years (Harrison et al. 2019).
The addition of fertilizer to promote palm productivity may accelerate peat
mineralization and stimulate soil CO 2 and N 2 O emissions (Hergoualc’h and Verchot
2014; Comeau et al. 2016). In West Malaysia, nitrogen fertilization rates for oil palm
grown in deep peatlands have been reported to be 50–100 kg N ha
À1 year
À1 during
the immature stage and 120–160 kg N ha
À1 year
À1 at maturity (Mutert et al. 1999).
In Indonesia, the average fertilization rates for plantations in years 3–8, 9–13, and
14–25 are 136, 170, and 102 kg N ha
À1 year
À1 (Darmosarkoro et al. 2003). The oil
palm is generally said to have a cycle of approximately 25 years, with high-volume
66
T. Kato et al.
the tropics, which involves draining peatlands and applying fertilizer, has not been
fully revealed in terms of global climate change.
Fires and smoke damage are concerns at the regional level, but when considered
on a global scale, they could result in a severe food shortage or natural disaster due to
flooding or drought brought about by irregular precipitation patterns.
The total peatland carbon pool is greater than that of the world’s forests and is
comparable to the total carbon pool of the atmosphere (Joosten and Clarke 2002).
Tropical peatlands are one of the largest near-surface pools of terrestrial organic
carbon, with a total peat carbon pool of 82–92 Gt (Page et al. 2011). Therefore,
tropical peatland conversion, drainage, and cultivation play important roles in the
global carbon cycle by changing soil conditions and altering the global carbon
balance (Swails et al. 2017). Indonesian peatlands contribute one-third of the carbon
stocks in tropical peat soils (Gumbricht et al. 2017), so they could be a major source
of greenhouse gas (GHG) emissions due to increasing pressures from agricultural
and forestry uses, particularly the expansion of oil palm plantations. If there are
disturbances that reduce the groundwater level (GWL) in peatlands, oxygen enters
the peat soil and disturbs the balance between peat accumulation and decay. This
results in the decomposition of the peat by oxidative microorganisms, and the
accumulated carbon is released into the atmosphere (Page and Baird 2016). At low
levels of intensity, the human use of peatland resources is likely to be sustainable as
long as the hydrological functions of the peatlands remain more or less natural and
the net carbon accumulation is maintained. Intensive use of drainage on a large scale
can result in the loss of carbon storage in peatlands (Swails et al. 2017), releasing
GHGs into the atmosphere and contributing to global warming.
When tropical peatlands were cleared and drained, and dry weather persists,
burning for land preparation caused fires to spread not only to the vegetation but
also to the below-ground peat. As a result, the fires smolder in the peat and release
large amounts of GHGs into the atmosphere.
The drainage of Indonesian peatlands for agriculture and timber extraction over
the past few decades has increased the likelihood of peatland subsidence and the fire
risk during the dry season, particularly in years of El Niño drought. High emissions
from biomass burning in Indonesia, often associated with drained peatlands, contributed significantly to the largest increase in global annual CO 2 emissions observed
during the strong El Niño of 2015 (Liu et al. 2017). However, such fires are not
limited to years with El Niño events; currently, large burns and CO 2 emissions occur
even in non-drought years (Harrison et al. 2019).
The addition of fertilizer to promote palm productivity may accelerate peat
mineralization and stimulate soil CO 2 and N 2 O emissions (Hergoualc’h and Verchot
2014; Comeau et al. 2016). In West Malaysia, nitrogen fertilization rates for oil palm
grown in deep peatlands have been reported to be 50–100 kg N ha
À1 year
À1 during
the immature stage and 120–160 kg N ha
À1 year
À1 at maturity (Mutert et al. 1999).
In Indonesia, the average fertilization rates for plantations in years 3–8, 9–13, and
14–25 are 136, 170, and 102 kg N ha
À1 year
À1 (Darmosarkoro et al. 2003). The oil
palm is generally said to have a cycle of approximately 25 years, with high-volume
66
T. Kato et al.