funded the subsequent land use change, and invariably the new form of land use was
drainage-based, with canals lowering groundwater levels to prevent waterlogging of
dryland crops (Hooijer et al. 2006; Giesen and Sari 2018). Drainage in plantations is
often 0.6–1.2 m below the surface, while in natural forests this is at or near the
surface in much of the year, falling to 30–40 cm below in dry seasons (Giesen and
Sari 2018).
By 2015 more than 95% of western Indonesia’s formerly forested peatlands
(13 Mha) was logged and drained, and about half of which (6.3 Mha) was converted,
with oil palm (kelapa sawit/Elaeis guineensis) and Acacia crassicarpa pulpwood
being the main drivers. Many other dryland crops are also cultivated on drained peat,
including cocoa (Theobroma cacao), Liberica coffee (Coffea liberica), Hevea rubber
(Hevea brasiliensis), dragonfruit (Hylocereus undatus), pineapple (Ananas
comosus), Aloe vera, papaya (Carica papaya), and betel nut (pinang/Areca catechu). While large-scale plantation companies play an important role in the conversion (3.2 Mha in 2015), smallholders have been involved in conversion of a similar
area (3.1 Mha in 2015), mainly for oil palm (Miettinen et al. 2016).
These land use changes have brought prosperity and, in the short term, have
benefitted the country’s economy. However, the use of drained peatland has led to
many issues, including fires and haze, losses relevant to the economy and human
health (esp. respiratory illness), land subsidence, and significant carbon emissions.
Peat wildfires during the last major El Niño event in 2015 alone extended over
around 2 Mha and led to an economic loss of an estimated USD16–47 billion, along
with widespread human suffering (World Bank 2016). Efforts to curb fires may have
had effect—the years 2016–2018 were relatively wet, but 2019 witnessed a long dry
season and in spite of this, fires burnt “only” 330,000 ha from January to
15 September (Normile 2019), which is markedly less than that in 2015. The
Government of Indonesia (GOI) responded with a raft of measures over the past
decade, especially since 2015, including the establishment of the National Peatland
Restoration Agency (Badan Restorasi Gambut or BRG) in January 2016, with the
mandate to coordinate and facilitate the restoration of 2.0 Mha of degraded peatland
in a period of 5 years (2016–2021). Soon after its establishment BRG launched a
three-step program of peatland restoration based on rewetting, revegetation, and
revitalization of degraded peatland (the 3-R program).
Rewetting of degraded peatland is the first and most important step in peatland
restoration, as only by restoring the hydrology can carbon emissions and peat loss be
curbed, and any compromises on rewetting (e.g., partial rewetting) are unsustainable
in the long-term, although it may serve a purpose as a step towards full rewetting
(Deltares 2015; Evers et al. 2017; Giesen and Sari 2018). Revegetation or
establishing a tree cover on rewetted peatland is an important next step, as this
will lower peat desiccation, increase humidity, and lower the risk of peat fires.
Revegetation can occur via natural regeneration, especially if the remnant forest
and/or scattered trees still exist (Giesen and van der Meer 2009; Graham et al. 2016;
Giesen and Sari 2018). However, seed banks are poor in tropical lowland forests and
are virtually absent in lowland peatlands, so when trees are absent in degraded
peatland, recovery of a woody cover will require replanting (Graham and Page
412
W. Giesen
drainage-based, with canals lowering groundwater levels to prevent waterlogging of
dryland crops (Hooijer et al. 2006; Giesen and Sari 2018). Drainage in plantations is
often 0.6–1.2 m below the surface, while in natural forests this is at or near the
surface in much of the year, falling to 30–40 cm below in dry seasons (Giesen and
Sari 2018).
By 2015 more than 95% of western Indonesia’s formerly forested peatlands
(13 Mha) was logged and drained, and about half of which (6.3 Mha) was converted,
with oil palm (kelapa sawit/Elaeis guineensis) and Acacia crassicarpa pulpwood
being the main drivers. Many other dryland crops are also cultivated on drained peat,
including cocoa (Theobroma cacao), Liberica coffee (Coffea liberica), Hevea rubber
(Hevea brasiliensis), dragonfruit (Hylocereus undatus), pineapple (Ananas
comosus), Aloe vera, papaya (Carica papaya), and betel nut (pinang/Areca catechu). While large-scale plantation companies play an important role in the conversion (3.2 Mha in 2015), smallholders have been involved in conversion of a similar
area (3.1 Mha in 2015), mainly for oil palm (Miettinen et al. 2016).
These land use changes have brought prosperity and, in the short term, have
benefitted the country’s economy. However, the use of drained peatland has led to
many issues, including fires and haze, losses relevant to the economy and human
health (esp. respiratory illness), land subsidence, and significant carbon emissions.
Peat wildfires during the last major El Niño event in 2015 alone extended over
around 2 Mha and led to an economic loss of an estimated USD16–47 billion, along
with widespread human suffering (World Bank 2016). Efforts to curb fires may have
had effect—the years 2016–2018 were relatively wet, but 2019 witnessed a long dry
season and in spite of this, fires burnt “only” 330,000 ha from January to
15 September (Normile 2019), which is markedly less than that in 2015. The
Government of Indonesia (GOI) responded with a raft of measures over the past
decade, especially since 2015, including the establishment of the National Peatland
Restoration Agency (Badan Restorasi Gambut or BRG) in January 2016, with the
mandate to coordinate and facilitate the restoration of 2.0 Mha of degraded peatland
in a period of 5 years (2016–2021). Soon after its establishment BRG launched a
three-step program of peatland restoration based on rewetting, revegetation, and
revitalization of degraded peatland (the 3-R program).
Rewetting of degraded peatland is the first and most important step in peatland
restoration, as only by restoring the hydrology can carbon emissions and peat loss be
curbed, and any compromises on rewetting (e.g., partial rewetting) are unsustainable
in the long-term, although it may serve a purpose as a step towards full rewetting
(Deltares 2015; Evers et al. 2017; Giesen and Sari 2018). Revegetation or
establishing a tree cover on rewetted peatland is an important next step, as this
will lower peat desiccation, increase humidity, and lower the risk of peat fires.
Revegetation can occur via natural regeneration, especially if the remnant forest
and/or scattered trees still exist (Giesen and van der Meer 2009; Graham et al. 2016;
Giesen and Sari 2018). However, seed banks are poor in tropical lowland forests and
are virtually absent in lowland peatlands, so when trees are absent in degraded
peatland, recovery of a woody cover will require replanting (Graham and Page
412
W. Giesen