21.2 Rewetting Programs in the Forest with Specific
Purposes Tumbang Nusa
Proper water management is the key for the success of restoration, which minimizes
carbon loss and fire occurrences, and enhances the possibility of the vegetation to
regrow (Ritzema and Wösten 2002; Ritzema et al. 2014). Although the capacity of
carbon absorption from vegetation components is lower than the loss of carbon from
peat decomposition in open degraded peatlands, a high groundwater level (GWL) is
an important factor to reduce the fire risk and create favorable conditions for
vegetation to grow well (Jauhiainen et al. 2008; Page et al. 2009).
One of the strategies for the water management improvement in a peatland
ecosystem is establishing canal blockings. These canal blockings are expected to
bring back and improve the peatland hydrological condition. The objectives of the
canal blocking establishment are to raise the water level in the canals and peatlands,
reduce the waterflow out of the canals and peatlands, and also maintain or stabilize
the water level differences between the upstream and downstream section of the
canal blockings <50 cm (Ritzema et al. 2014), and, thus, it will decrease the drying
and help to maintain the carbon absorption capacity (Suzuki et al. 1999; Hirano et al.
2007).
Started in 2017, through the BRG program, 15 canal blockings were built in the
Forest with Specific Purposes Tumbang Nusa (hereinafter referred to as Kawasan
Hutan dengan Tujuan Khusus/KHDTK). The canal blockings were established in
three locations. In 2018, the water level monitoring was carried out to determine the
effectivity of canal blockings (Fig. 21.1). The canal blocking location #1 is positioned at 114
o 3’22.0
00 east and 2
o 19’09.2
00 south; the location #2 is positioned at
114
o 3’35.4
00 east and 2
o 19’51.2 south; and the location #3 is positioned at
114
o 4’29.63
00 east and 2
o 20’20.32
00 south.
The canal blockings were made with V and U shapes (Fig. 21.2). The V-shape
was designed to give access for small boats in the rainy season (Limin et al. 2008).
Fire occurred in the canal blocking location #1 (see Fig. 21.1) almost during each
dry season in 1997, 2002, 2009, 2014, and 2015. This location was utilized by the
local people for oil palm and sengon (Albizia chinensis) plantations. In several parts,
the area was dominated by ferns (Stenochlaena sp., Lygodium sp., Polypodium sp.,
and Pteris sp.) and fast-growing tree species such as tumih (Combretocarpus
rotundatus) and gerunggang (Cratoxylum glaucum) (Fig. 21.3). In this location,
six canal blockings were built. At the beginning, these canals were functioning well
to prevent the water from flowing out of the peatland. Unfortunately, the farmers
living in the surrounding area destroyed the spillway and dug the canals bigger and
deeper to flow the water out of the area (Fig. 21.4). In accordance with their
knowledge on plantations, the farmers believe that the rise of water level in this
area will cause the slow growth of the planted sengon and oil palms.
21 Peatland Restoration in Central Kalimantan by Rewetting and Rehabilitation with. . .
597
Purposes Tumbang Nusa
Proper water management is the key for the success of restoration, which minimizes
carbon loss and fire occurrences, and enhances the possibility of the vegetation to
regrow (Ritzema and Wösten 2002; Ritzema et al. 2014). Although the capacity of
carbon absorption from vegetation components is lower than the loss of carbon from
peat decomposition in open degraded peatlands, a high groundwater level (GWL) is
an important factor to reduce the fire risk and create favorable conditions for
vegetation to grow well (Jauhiainen et al. 2008; Page et al. 2009).
One of the strategies for the water management improvement in a peatland
ecosystem is establishing canal blockings. These canal blockings are expected to
bring back and improve the peatland hydrological condition. The objectives of the
canal blocking establishment are to raise the water level in the canals and peatlands,
reduce the waterflow out of the canals and peatlands, and also maintain or stabilize
the water level differences between the upstream and downstream section of the
canal blockings <50 cm (Ritzema et al. 2014), and, thus, it will decrease the drying
and help to maintain the carbon absorption capacity (Suzuki et al. 1999; Hirano et al.
2007).
Started in 2017, through the BRG program, 15 canal blockings were built in the
Forest with Specific Purposes Tumbang Nusa (hereinafter referred to as Kawasan
Hutan dengan Tujuan Khusus/KHDTK). The canal blockings were established in
three locations. In 2018, the water level monitoring was carried out to determine the
effectivity of canal blockings (Fig. 21.1). The canal blocking location #1 is positioned at 114
o 3’22.0
00 east and 2
o 19’09.2
00 south; the location #2 is positioned at
114
o 3’35.4
00 east and 2
o 19’51.2 south; and the location #3 is positioned at
114
o 4’29.63
00 east and 2
o 20’20.32
00 south.
The canal blockings were made with V and U shapes (Fig. 21.2). The V-shape
was designed to give access for small boats in the rainy season (Limin et al. 2008).
Fire occurred in the canal blocking location #1 (see Fig. 21.1) almost during each
dry season in 1997, 2002, 2009, 2014, and 2015. This location was utilized by the
local people for oil palm and sengon (Albizia chinensis) plantations. In several parts,
the area was dominated by ferns (Stenochlaena sp., Lygodium sp., Polypodium sp.,
and Pteris sp.) and fast-growing tree species such as tumih (Combretocarpus
rotundatus) and gerunggang (Cratoxylum glaucum) (Fig. 21.3). In this location,
six canal blockings were built. At the beginning, these canals were functioning well
to prevent the water from flowing out of the peatland. Unfortunately, the farmers
living in the surrounding area destroyed the spillway and dug the canals bigger and
deeper to flow the water out of the area (Fig. 21.4). In accordance with their
knowledge on plantations, the farmers believe that the rise of water level in this
area will cause the slow growth of the planted sengon and oil palms.
21 Peatland Restoration in Central Kalimantan by Rewetting and Rehabilitation with. . .
597