Page 8 - Tropical Peat Swamp Forests of Sarawak FA
P. 8
Introduction to tropical
peat swamp forests
Tropical peat swamps and “In their natural state, lowland
their forests tropical peats support an
Tropical peat basins can develop in regions
of the tropics where precipitation exceeds the abundant growth
evaporation for most of the year. This is the case
in tropical rainforest zones that do not experi- of peat swamp forest, with
ence a strong seasonality in rainfall, i.e. a long
dry season. Large areas of the Amazon and the a characteristic tree species
Congo Basin are therefore excluded from peat
formation. Tropical rainforests with conditions composition.”
that support peat formation are mostly found
in Southeast Asia, in particular in the coastal
regions of the islands of Sumatra and Borneo. Rivers leaving the peat swamp forest have dark
Peat consists of accumulated dead plant mate- brown, almost black water (‘tea’), because of
rial, formed under poorly bufered waterlogged the high content of humic acids, polyphenols,
conditions. When plants decay in these often tannins, and other degradation products of
anoxic circumstances, humic acids are formed, decaying vegetation. In spite of the dark colour,
and when these acids are not neutralised by the waters are very clear, because of the absence
bufering agents, acidity inhibits further decay of silt. The waterlogged peat swamp is an acidic
and organic material starts to accumulate. environment, with pH-values usually ranging
Contrary to boreal and temperate peat, most between 3.0 and 4.5. In periods of high rainfall,
tropical peat has been formed by the accumula- large parts of the peat swamp forests are perma-
tion of slightly or partially decomposed organic nently inundated.
material derived mostly from trees. The thick-
ness of tropical peats depends on their age and In their natural state, lowland tropical peats
the rate of peat accumulation, which may be support an abundant growth of peat swamp
over 2 mm per year. Most Southeast Asian peat forest, with a characteristic tree species com-
swamp forests grow on elevated peat domes, position. The forest often has distinct zones or
usually up to eight metres thick but occasionally ‘Phasic Communities’ (P.C.) arranged concentri-
reaching more than twenty metres, formed over cally from the outer to the inner part of the peat
the past 5,000 to 10,000 years. Surface water swamp, based primarily on topographic/edaphic
runof in peat swamp domes takes place from factors and successional stages.
the elevated centre.
Distribution of
peatlands (black)
in Southeast Asia
(After Rieley et al.
2008).
A young male pro-
boscis monkey in
the riparian zone
of peat swamp.
forest
8 8 9 9
peat swamp forests
Tropical peat swamps and “In their natural state, lowland
their forests tropical peats support an
Tropical peat basins can develop in regions
of the tropics where precipitation exceeds the abundant growth
evaporation for most of the year. This is the case
in tropical rainforest zones that do not experi- of peat swamp forest, with
ence a strong seasonality in rainfall, i.e. a long
dry season. Large areas of the Amazon and the a characteristic tree species
Congo Basin are therefore excluded from peat
formation. Tropical rainforests with conditions composition.”
that support peat formation are mostly found
in Southeast Asia, in particular in the coastal
regions of the islands of Sumatra and Borneo. Rivers leaving the peat swamp forest have dark
Peat consists of accumulated dead plant mate- brown, almost black water (‘tea’), because of
rial, formed under poorly bufered waterlogged the high content of humic acids, polyphenols,
conditions. When plants decay in these often tannins, and other degradation products of
anoxic circumstances, humic acids are formed, decaying vegetation. In spite of the dark colour,
and when these acids are not neutralised by the waters are very clear, because of the absence
bufering agents, acidity inhibits further decay of silt. The waterlogged peat swamp is an acidic
and organic material starts to accumulate. environment, with pH-values usually ranging
Contrary to boreal and temperate peat, most between 3.0 and 4.5. In periods of high rainfall,
tropical peat has been formed by the accumula- large parts of the peat swamp forests are perma-
tion of slightly or partially decomposed organic nently inundated.
material derived mostly from trees. The thick-
ness of tropical peats depends on their age and In their natural state, lowland tropical peats
the rate of peat accumulation, which may be support an abundant growth of peat swamp
over 2 mm per year. Most Southeast Asian peat forest, with a characteristic tree species com-
swamp forests grow on elevated peat domes, position. The forest often has distinct zones or
usually up to eight metres thick but occasionally ‘Phasic Communities’ (P.C.) arranged concentri-
reaching more than twenty metres, formed over cally from the outer to the inner part of the peat
the past 5,000 to 10,000 years. Surface water swamp, based primarily on topographic/edaphic
runof in peat swamp domes takes place from factors and successional stages.
the elevated centre.
Distribution of
peatlands (black)
in Southeast Asia
(After Rieley et al.
2008).
A young male pro-
boscis monkey in
the riparian zone
of peat swamp.
forest
8 8 9 9
