months and cost millions of Dollars. Peatland fires result in harmful health effects,
loss of economic benefits and high emissions GHGs as well as loss of biodiversity
and ecosystem services. The government has recognised the importance of focusing
on fire prevention rather than just fire suppression. State governments such as
Selangor State that have invested significantly in fire prevention measures by
government, private sector and community have seen a significant reduction in the
area and severity of peatland fires.
26.3.6 Subsidence and Flood Risk
Subsidence is a process of lowering of the soil surface as the result of physical
compression of the peat and loss of carbon due to oxidation and erosion. Peat soils
comprise only 10% of accumulated organic material and 90% of water. When
drained, most of the water is immediately lost and the remaining organic matter
oxidises such that all peat above the drainage level will eventually be lost. Subsidence and the related flood risk is a well-known and inevitable phenomenon in all
places in the world where lowland peatlands have been converted to drainagedependent land uses. In Malaysia, many of the PSFs have been drained for development, mainly for oil palm plantations. Research results show that in the first
5 years after drainage, peatland subsidence is typically 1–2 m. In subsequent
years, this stabilises to a constant 3–5 cm/year, resulting in a subsidence of 2–3 m
in 25 years and 4–5 m within 100 years (Hooijer et al. 2012a, b; Jauhiainen et al.
2012). According to Wosten et al. (1997), after drainage of 40 years, Johor has total
subsidence of 3 m of which annual subsidence of up to 75 mm has been recorded
(Hooijer et al. 2012a, b). Widespread over-drainage in Southwest Johor State in the
1970s led to peat subsidence of over 4 m, collapse of infrastructure, disruption of
water supply and serious flooding.
26.3.7 Encroachment/Unsustainable Extraction of Timber
and NTFP (Non-Timber Forest Products)
Typically, infrastructure and access to a peatland area may be improved due to land
preparation for plantation development. The need to ensure good transport (whether
ground or water) for the palm oil crop means that access for migrants or local people
to the edges of remaining PSF increases significantly, if the plantation is located next
to the PSF. This presents an opportunity for either opportunistic or externally driven
illegal actions including logging (which further increases the risk of fires), poaching,
extraction of forest products without due permission (deforestation and trespassing
to forest reserve) and encroachment. The presence of communities adjacent or within
plantations often adds complexity to ensuring sustainable and fair use of the forest
26 National Strategies on Responsible Management of Tropical Peatland in Malaysia
687
loss of economic benefits and high emissions GHGs as well as loss of biodiversity
and ecosystem services. The government has recognised the importance of focusing
on fire prevention rather than just fire suppression. State governments such as
Selangor State that have invested significantly in fire prevention measures by
government, private sector and community have seen a significant reduction in the
area and severity of peatland fires.
26.3.6 Subsidence and Flood Risk
Subsidence is a process of lowering of the soil surface as the result of physical
compression of the peat and loss of carbon due to oxidation and erosion. Peat soils
comprise only 10% of accumulated organic material and 90% of water. When
drained, most of the water is immediately lost and the remaining organic matter
oxidises such that all peat above the drainage level will eventually be lost. Subsidence and the related flood risk is a well-known and inevitable phenomenon in all
places in the world where lowland peatlands have been converted to drainagedependent land uses. In Malaysia, many of the PSFs have been drained for development, mainly for oil palm plantations. Research results show that in the first
5 years after drainage, peatland subsidence is typically 1–2 m. In subsequent
years, this stabilises to a constant 3–5 cm/year, resulting in a subsidence of 2–3 m
in 25 years and 4–5 m within 100 years (Hooijer et al. 2012a, b; Jauhiainen et al.
2012). According to Wosten et al. (1997), after drainage of 40 years, Johor has total
subsidence of 3 m of which annual subsidence of up to 75 mm has been recorded
(Hooijer et al. 2012a, b). Widespread over-drainage in Southwest Johor State in the
1970s led to peat subsidence of over 4 m, collapse of infrastructure, disruption of
water supply and serious flooding.
26.3.7 Encroachment/Unsustainable Extraction of Timber
and NTFP (Non-Timber Forest Products)
Typically, infrastructure and access to a peatland area may be improved due to land
preparation for plantation development. The need to ensure good transport (whether
ground or water) for the palm oil crop means that access for migrants or local people
to the edges of remaining PSF increases significantly, if the plantation is located next
to the PSF. This presents an opportunity for either opportunistic or externally driven
illegal actions including logging (which further increases the risk of fires), poaching,
extraction of forest products without due permission (deforestation and trespassing
to forest reserve) and encroachment. The presence of communities adjacent or within
plantations often adds complexity to ensuring sustainable and fair use of the forest
26 National Strategies on Responsible Management of Tropical Peatland in Malaysia
687