natural wetlands (excluding lakes, ponds, and rivers) for 2008–2017 were approximately 30–50 (mg CH 4 /m
2 /day) in Amazonia and the Congo Basin and approximately 20–30 (mg CH 4 /m
2
/day) in Indonesia, and these wetlands are overlain by
peatland.
In an undrained secondary peat swamp forest in Central Kalimantan, Indonesia,
the ecosystem-scale CH 4 flux estimated using the eddy covariance method was a
CH 4 sink during the dry season (as low as À8.9 mg C m
À2 day
À1 )
[À11.9 mg CH 4 m
À2 day
À1 ] and a source of CH 4 during the wet season (up to
10.7 mg C m
À2 day
À1 ) [14.2 mg CH 4 m
À2 day
À1 ], depending on the groundwater
level (Sakabe et al. 2018).
In Alan Batu Forest (non-trenched plots) in Maludam National Park in Sarawak,
Malaysia, the annual CH 4 emissions measured by continuous measurement using an
automated chamber system was 4.32 Æ 3.95 g C m
À2
year
À1
[15.7 Æ 14.4 mg CH 4 m
À2 day
À1 ] for the mean annual gap-filled (without the
outlier) value (Ishikura et al. 2019).
In conclusion, CH 4 emissions are lower in dome-type peatlands in the maritime
continent likely because nutrients, especially the clay supply, are very limited than
CH 4 emissions in the cuvette-type peatlands in the Amazon and Congo basins.
The digital elevation model (DEM) shows clearly different topography between
dome-type peatlands on the maritime continent and cuvette-type peatlands in the
Amazon Basin and Congo Basin (Fig. 1.8).
• In dome-type peatlands, the rivers are short and have small catchment areas. As
the river slope is steep, the dikes are relatively high on both sides. Thus, rivers in
dome-type peatlands do not flood often. Thus, the peat water is supplied mainly
by rain, indicating the lack of a nutrient supply.
• In cuvette-type peatlands, the rivers are long and have large catchment areas. As
the river slope is low, the dikes are relatively low on both sides. Thus, rivers in
cuvette-type peatlands flood often. Thus, the water is likely supplied by rain and
flood water, providing a supply of nutrients and clay.
• In conclusion, large-scale topography is important in (1) peatland formation,
(2) peatland water and nutrient supply systems, (3) GHG emissions-related
redox potential, and (4) vegetation, i.e., trees are dominant at redox potentials
greater than approximately 0 mV and palms or grasses are dominant at redox
potentials less than approximately 0 mV.
Thus, as dome-type (dome formation) and cuvette-type (Cuvette Centrale depression) peatlands are different, they should also be managed differently. This book is
focused on dome-type peatlands because this type of peatland is the climax phase of
peatlands that are specifically supplied only by rain with no nutrients. Thus, the final
nutrient-poor ecosystem will provide new ideas and new concepts for optimal peat
and soil management.
16
M. Osaki et al.
2 /day) in Amazonia and the Congo Basin and approximately 20–30 (mg CH 4 /m
2
/day) in Indonesia, and these wetlands are overlain by
peatland.
In an undrained secondary peat swamp forest in Central Kalimantan, Indonesia,
the ecosystem-scale CH 4 flux estimated using the eddy covariance method was a
CH 4 sink during the dry season (as low as À8.9 mg C m
À2 day
À1 )
[À11.9 mg CH 4 m
À2 day
À1 ] and a source of CH 4 during the wet season (up to
10.7 mg C m
À2 day
À1 ) [14.2 mg CH 4 m
À2 day
À1 ], depending on the groundwater
level (Sakabe et al. 2018).
In Alan Batu Forest (non-trenched plots) in Maludam National Park in Sarawak,
Malaysia, the annual CH 4 emissions measured by continuous measurement using an
automated chamber system was 4.32 Æ 3.95 g C m
À2
year
À1
[15.7 Æ 14.4 mg CH 4 m
À2 day
À1 ] for the mean annual gap-filled (without the
outlier) value (Ishikura et al. 2019).
In conclusion, CH 4 emissions are lower in dome-type peatlands in the maritime
continent likely because nutrients, especially the clay supply, are very limited than
CH 4 emissions in the cuvette-type peatlands in the Amazon and Congo basins.
The digital elevation model (DEM) shows clearly different topography between
dome-type peatlands on the maritime continent and cuvette-type peatlands in the
Amazon Basin and Congo Basin (Fig. 1.8).
• In dome-type peatlands, the rivers are short and have small catchment areas. As
the river slope is steep, the dikes are relatively high on both sides. Thus, rivers in
dome-type peatlands do not flood often. Thus, the peat water is supplied mainly
by rain, indicating the lack of a nutrient supply.
• In cuvette-type peatlands, the rivers are long and have large catchment areas. As
the river slope is low, the dikes are relatively low on both sides. Thus, rivers in
cuvette-type peatlands flood often. Thus, the water is likely supplied by rain and
flood water, providing a supply of nutrients and clay.
• In conclusion, large-scale topography is important in (1) peatland formation,
(2) peatland water and nutrient supply systems, (3) GHG emissions-related
redox potential, and (4) vegetation, i.e., trees are dominant at redox potentials
greater than approximately 0 mV and palms or grasses are dominant at redox
potentials less than approximately 0 mV.
Thus, as dome-type (dome formation) and cuvette-type (Cuvette Centrale depression) peatlands are different, they should also be managed differently. This book is
focused on dome-type peatlands because this type of peatland is the climax phase of
peatlands that are specifically supplied only by rain with no nutrients. Thus, the final
nutrient-poor ecosystem will provide new ideas and new concepts for optimal peat
and soil management.
16
M. Osaki et al.