195

Hydrogenetic Aspects of Peatland Restoration in
Tibet and Kalimantan
Hans JOOSTEN* and Martin SCHUMANN
Institute of Botany and Landscape Ecology
Grimmer Strasse 8, D-17487 Greifwald, Germany
e-mail: joosten@uni-greifswald.de*corresponding author

Abstract
Living peatlands are often intricate systems with important self-regulation mechanisms to maintain thebalance between ‘vegetation,’ ‘water’ and ‘peat.’ An important part of this self-regulation is directly associated with vegetation, which is generally ignored or insufficiently acknowledged in hydrological approaches
to peatland restoration. This paper illustrates the ecohydrological complications of restoration of recently
degraded peatlands in Tibet (China) and Kalimantan (Indonesia).
On the Ruoergai Plateau (China), long-term grazing has changed many original percolation mires into
more vulnerable surface-flow mires that since the 1950s have become subject to overgrazing and drainage.
In Kalimantan, especially since the 1990s, peat swamp forests have been disturbed by drainage and deforestation. For both areas, different peatland degradation stages are distinguished with their own restoration
perspectives and approaches. Because restoration of severely degraded peatlands is extremely difficult toachieve, the highest priority is the identification and protection of undisturbed mires and the prevention offurther degradation. In both areas the restoration of the water retaining and storing role of vegetation isindispensable to prevent the peat body from further erosion and to provide adequate conditions for theregeneration of living mires. As the vegetation in both peatland areas is the main object of human
exploitation (overgrazing, deforestation), peatland restoration is not only a matter of technical management,
but has an important social dimension.
Key words: degradation, ecohydrology, mires, self-regulation, vegetation

1. Introduction
Although the majority of the mires of the world isstill in pristine condition (Joosten & Clarke, 2002), insome regions the degradation of peatlands has – in addition to affecting the livelihoods of local communities –
effects of global dimensions. The Ruoergai peatlands on
the Tibetan Plateau constitute the headwaters of the
Yellow River and are vital for regulating water supply tomany millions of people in its extensive downstream
areas. Peat oxidation by drainage and peatland fires inSoutheast Asia is currently responsible for CO2 emissions of over 2 Gigatonnes per year (Hooijer et al.,2006) which constitutes a substantial part of global
anthropogenic CO2 emissions. Restoring these peatlands
and their regulation functions is therefore a task ofhighest urgency.
Peat is sequestered and conserved as a result of
permanent waterlogging. Consequently restoration must
pay much attention to hydrological aspects. In praxis,
however, hydrology often focuses on rather static
Global Environmental Research
11: 195-204 (2007)
printed in Japan

geohydrological aspects and insufficiently acknowledges the hydrological role of vegetation and the
dynamic hydraulic properties of vegetation and peat. In
this paper we illustrate the hydrological complicationsof peatland restoration from two case studies from Asia
(Fig. 1): the Ruoergai Plateau, Tibet, and the Ex-Mega

800 kmFig. 1 The location of the Ruoergai Plateau and the
Ex-Mega Rice Project (Central Kalimantan).
©2007 AIRIES196

H. JOOSTEN and M. SCHUMANN

Rice Project Kalimantan, Indonesia (Schumann &Joosten, 2007; Joosten et al., 2008; Joosten, 2008;
where also extensive references can be found).

2. Mire Ecology and Peatland Degradation
Crucial for understanding peatlands and especiallymires (actively peat accumulating peatlands) is theawareness that ‘plants,’ ‘water,’ and ‘peat’ are very
closely connected and mutually interdependent (Fig. 2).
The plants determine what type of peat will be formed
and what its hydraulic properties will be. The hydrological conditions determine which plants will grow,whether peat will be stored, and how decomposed thepeat will be. The peat structure determines how thewater will flow and fluctuate. The close interrelations
imply that when any one of these components changes,
the others will change too. Not necessarily at once, but
in the longer run inevitably.
Not all components react with the same speed.
Generally the vegetation is affected more easily than thehydraulic properties and those again react much fasterthan the composition of the peat. Indeed peat, unlike
Water

Mire

Peat

PlantsFig. 2 The interrelations between plants, water,
and peat in a mire.

sand, is alterable: as an organic substance it changes its
properties and can even totally disappear as a result of
decomposition and oxidation. When it is not protectedby vegetation, peat easily erodes, because it is muchlighter than sand. However, peat is a ‘slower’ component than plants: it is more difficult to change, but when
it has changed, it is more difficult to reverse the change.
Therefore we can distinguish peatland degradation
stages according to the ‘inertia’ of the components
affected (Table 1). As a general rule, components thatare more difficult to affect are also more difficult torestore.

3. Peatland Degradation and Restoration on
the Ruoergai Plateau (Tibet)
In contrast to the drier western and central parts of
the Tibetan Plateau, the Rouergai Plateau in North east
Tibet (32.20° - 34.10° N / 102.15° - 103.50° E, 3,400
to 3,900 m asl) has a cold and wet climate with long
winters and rather short summers. Since the end of thelast Ice Age this humid climate facilitated the development of the world’s largest extent of high altitude
peatlands.
The slightly humified radicel (sedge) peats in the
deepest layers of many peatlands suggest that during thefirst part of the Holocene ‘sloping percolation mires’
were the predominant mire type, whereas palynological,
soil, and recent vegetation records indicate that mosthills and mountains of the Plateau were at that timecovered by trees. ‘Sloping mires’ impede water flow,
enable their own continuous upward growth, and cause
a rise of the groundwater table in their catchment area.
‘Percolation mires’ develop in areas where groundwatersupply is large and evenly distributed over the year.
Their little decomposed peat is highly permeable, which

Table 1 Peatland degradation stages.

> 0 (≤ 0)> 0 (≤ 0)

≤0

≤0->0

≤ 0 - << 0<< 0 - <<< 0Hydrogenetic Aspects of Peatland Restoration in Tibet and Kalimantan

leads to water flowing through the peat body, andflexible, which enables them to respond to changing
water supply by shrinking and swelling of their peatbody. In this way percolation mires reduce downstream
flooding and guarantee stable base flow. Their ability tooscillate allows for stable relative water levels, constantvegetation productivity, high peat accumulation rates,
and makes percolation mires to the most stable peatlands in existence.
3.1 Change of peatland character
It was the domestication of the yak (Bos grunniens)that made permanent occupation of the harsh environment possible. Initially the percolation mires will havebeen only marginally used as grazing ground because
their load-bearing capacity is too low to support yaks.
Since about 5,000 years ago grazing has led to deforestation of the mineral uplands. Whether this deforestation
was solely attributable to human impact or also caused
by a changing climate is still a matter of debate. In any
case the recurrent traces of charcoal in the upper horizons of the peat profiles reveal that fires became more
frequent.
The deforestation resulted in increased erosion ofmineral substances from the uplands. Precipitation waterthat was previously absorbed by upland forests and soils
rushed more rapidly into the valleys. In most peatlands
an increase in clastic materials is visible in the upper
peat horizons, sometimes even as obvious sand or silt
layers. Highly compacted radicel peats below layerswith a higher clastic component illustrate that the increased load caused compaction of the hitherto accumulated peat. This improved the load-carrying capacity ofthe peatlands, enabling the cattle to switch from the(then overgrazed?) upland meadows to the peatlands forforage. The new peat became much stronger decomposed (because of regular animal tread and stronger
water level fluctuations) and less permeable for water.
This prevented water from further percolating throughthe peat body and forced it to flow over the peatland. As
a result the ‘surface-flow mires’ originated that currently
dominate many valleys of the Ruoergai Plateau.
In contrast to percolation mires, surface-flow mires
hardly shrink and swell with fluctuating water supply.
They show stronger peak discharge and less base flow.
The only way to store substantial amounts of water isabove the surface among the vegetation. The strongly
humified peats of the surface flow mires are susceptible
to erosion because of their higher degree of decomposition.
On the Ruoergai Plateau the water regulation function of the peatlands thus has become less effective fortwo reasons:
1. The upland water supply to the mires has becomeless regular due to deforestation and increased runoff.
2. The water regulation capacity of the mires has decreased through the change of percolation mires tosurface-flow mires.

197

As the incoming water now has to be transported‘over’ the peatland surface, the importance of vegetation
for water regulation has strongly increased. This has
made the system more fragile and vulnerable to climatechange and overgrazing.
3.2 Peatland erosion
With the construction of roads in the 1950s the
Ruoergai Plateau was opened to settlers. To enhancemeat and milk production, traditional husbandry was
replaced by a more market-oriented economy. Life stocknumbers on the Ruoergai Plateau increased dramaticallyas a result of population growth and a lack of regulation.
Increased overgrazing and the resulting decrease in pasture quality fuelled the demand for new rangeland.
Since the 1970s, almost 50 % of the Ruoergai peatlands
have been drained with severe consequences. Oxidationand mineralization of the uppermost peat layers lead tolarger emissions of carbon dioxide and nitrogen. The
increased water level fluctuations cause the formation of
cracks that impede capillary water flow and lead tomore frequent drying out of the soil. Through increased
activity of soil organisms, drained peat becomes loose
and fine-grained, and may eventually become hydrophobic and very easily erodable because of its low weight.
Small burrowing mammals like pikas (Ochotona
curzoniae, O. daurica, O. pallasi) and zokors (Myospalax
fontanierii) colonized the dry areas and - with up to 300
animals per ha - boost peat erosion and oxidation by
digging holes and burrows (Fig. 3).
Recognising the severity of the situation, the Chinese
authorities introduced a ban on draining wetlands andstopped forestry activities in the region in 1999. In addition, they have started to fill in drainage ditches andhave designated five nature reserves covering about
0.5 million ha.
3.3 Restoration perspectives
As a result of these developments, the majority of the
Ruoergai peatlands is currently showing moderate to
major degradation (cf. Table 1, Schumann et al., 2008).
Next to flora, fauna and vegetation, also hydrology, peat
properties and peat hydraulic conditions have changed
substantially and in most cases irreversibly.
Thousands of years of grazing have created a newlandscape of surface-flow mires that is recognized as abeautiful natural and cultural heritage. Although the origin of surface-flow mires from the original percolation
mires must be considered to be degradation in itself (atransition of minimal to moderate degradation), it cannot
be the aim to restore the former percolation mires overlarge extents. Firstly this would require the removal of
most animals and herders and would fundamentallychange the physical and social character of the Plateau.
But also, and more importantly, large scale restorationof percolation mires has become impossible because
over large areas the peat hydraulic properties havechanged irreversibly and it will take many hundreds
years of peatland development to get them back.

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H. JOOSTEN and M. SCHUMANN

Fig. 3 Relation between various peatland degradation processes on the Rouergai Plateau.
The change of percolation (green) to surface-flow mires (red) as a result of
long-term grazing has made the mires available as rangeland and vulnerable toovergrazing. Drainage and overgrazing in the 20th century then put a whole series
of interconnected degradation processes (purple box) into operation. The two entries
for restoration are indicated with a blue arrow.

3.4 Percolation mires
Many peatlands of the Ruoergai Plateau currently aresurface-flow mires. Percolation mires of minor or modest degradation have, however, survived or regenerated
locally. This is probably due to exceptional hydrologic
conditions (strong seepage) and to a low intensity ofgrazing at these sites. It is of utmost importance to rapidly locate, protect, and restore the mires that are still ina good condition (Schumann et al., 2008).
Grazing should be restricted as trampling compacts
the loose structure of the peat and may rapidly lead todegradation and erosion. New drainage must be strictly
forbidden. Existing drainage ditches must be closed. In
mires that have only recently been drained or that aresituated in an area with abundant groundwater supply,
soil hydraulics and relief may not have been severely
affected yet (degradation stage ‘modest,’ Table 1). They
can easily be restored fully by closing the drainage constructions. To disperse the water and reduce its volume,
damming should proceed starting from the highest part ofthe peatland. By guiding the water over the largest
possible area, flow velocity and erosive power are reduced, vegetation can more easily re-establish in theditches (‘self-recovery’ by terrestrialization), and pressure on downstream dams decreases. Concentration ofwater in preferential pathways has to be prevented because its force may lead to erosion. It is crucial to raise
the water table above the surface, so that as much area
as possible is optimally rewetted. Therefore, dams haveto be constructed at such distances from one another thatthe water level difference between adjacent dams does
not exceed 5-10 cm in the wet season.
The ditches may be dammed/filled with peat, woodor bales of hay or straw. It is not necessary to make theconstructions fully impermeable. It is sufficient to substantially hamper water flow: percolation mires arecharacterized by water slowly percolating through andover the peat. Sand, clay or stone should not be used,because they are too heavy and will eventually sink in
the loose, watery peat. Care has to be taken that thevegetation close to the dam is not damaged, as it plays
an important protective role to prevent the water fromeroding the peat.
3.5 Surface-flow mires
Many peatlands of the Rouergai Plateau are currently
surface-flow mires. These mires are a degradation stageof the original percolation mires (degradation stage‘moderate,’ Table 1): the peat hydraulic properties(porosity, storage coefficient, hydraulic conductivity andcapillarity) have substantially and largely irreversibly
changed. As a consequence the peatland’s capacity forwater storage and regulation has decreased. But as peat
accumulation has continued for some thousands of years,
they can be considered as a new type of mire. Surfaceflow mires belong currently to the most importantgrazing lands on the plateau.
Most important for the management of surface-flow
mires is to avoid peat erosion by water cutting into thepeat body. For that purpose it is necessary to slow downwater flow and to disperse the water so that it flows off
diffusely over the surface. This implies:• retaining the water upstream,• no construction of new and closure of existing drainage gullies, and• conducting the water diffusely over the surface. It is
crucial that no preferential flow pathways of water
develop. This can be brought about by○ maintaining dense vegetation in the wet season to
hold back and spread the water and to protect thepeat body and○ diffuse herding to prevent the origin of incising orbare tracks.
The maintenance of sufficiently dense and highHydrogenetic Aspects of Peatland Restoration in Tibet and Kalimantan

199

vegetation cover will normally imply an adjustment ofgrazing strategies (e.g. distribution of summer and winter pastures), a local and/or temporal reduction of animal numbers, or the use of the mires as hayfields for
winter fodder instead of as rangeland.
In contrast to percolation mires, dams in ditches andgullies should be completely closed to force the water toflow diffusely over the surface and to prevent the origin
of further preferential water pathways. To prevent thedevelopment of erosive flow paths next to the dam,
overflow provisions (e.g. pipes or incisions) are often
constructed in the middle of the dam/weir. Overflow
provisions, however, have as a drawback that water flow
is concentrated and that the drainage base remains too
low to sufficiently rewet the adjacent peatland area.

Table 2 Management objectives for peatlands on the Ruoergai
Plateau.

3.6 Eroding peatlands
Increasing areas of peatland on the Ruoergai Plateau
can not be considered ‘mire’ anymore because they havelost their capacity to accumulate peat. Such eroding
peatlands suffer from:• too little water: the water level is periodically too
low to enable peat accumulation; instead peatoxidation occurs.
• too much water: the available water comes with toomuch force, washing the peat away and creatinggullies.
These problems are interrelated because peat erosion
and gully formation lead to rapid drainage and consequently periodically low water levels.
Even stronger than with surface-flow mires (seeabove) the problem can not only be solved by damming
single ditches or gullies, because the abundant and concentrated water anyhow has to leave the peatland. Whenthe gully is obstructed by a single dam, the water willfind the next weak spot and erode the peat away there.
Restoration of eroding peatlands therefore is not a matter of thinking in single dams, but of thinking in coherent hydrological systems in whole catchment areas.
Even more than with percolation and surface-flow mires
it is necessary to hold back the water starting from thehighest part of the peatland and to disperse the water by
guiding it over the largest possible area.
Restoration of eroding peatlands to peat accumulating systems (surface flow mires) can only be done byraising the water level above the peatland surface. Thisrequires damming all drainage structures and allowing/stimulating a dense vegetation to develop. Whendegradation has progressed so far that it involves severe

3.7 Perspectives
Whereas with respect to percolation mires and surface-flow mires, the objectives of restoration are clear
and consistent (Table 2), it is more difficult to defineachievable aims for eroding peatlands. This is not only
attributable to the fact that the latter may comprise various stages of degradation (Table 1: stage ‘moderate’ to‘maximal’) but first and for all to the difficulty to restore
eroding peatlands to new peat accumulating mires.
Because restoration is extremely difficult to achieve,
the highest priority is to prevent further degradation andto keep good things good. This implies:• strict protection and where possible restoration of therare and vulnerable percolation and spring mires,• no further degradation of the ‘normal’ surface-flow(and similar water-rise) mires, and• restoration of the heavily eroding peatlands at least
to the extent that erosion is brought under control.

Percolation mire
Surface-flow mire

Main restoration objectivehydrology
rangeland

Eroding peatland

limit damage

Peatland type

4. Peat Swamp Forests in Kalimantan
Peat swamp forests in south-east Asia are domeshape peatlands between lower-lying rivers (Fig. 4).
Few people realize how special such peat domes are.
The dome is able to shape the improbable paradox ‘highand wet.’ And this wetness has to be almost permanent,
because the dome consists of organic material (peat) that
rapidly breaks down when not saturated with water. This
paradoxical situation is the result of close interactions
between vegetation, peat, and water that lead to ‘selfregulation’–mechanisms that enable the continued existenceof such peat domes under varying environmental conditions(Joosten, 1993).

Streams
StreamPEATPEAT

Batang Ballngan

6000

7000

Mineral Subsoil

1000

2000

3000

biodiversity
biodiversity, hydrologyhydrology, rangeland,biodiversity, climate

gully erosion, it is difficult to fully stop further erosion
as the slopes of the gullies are too steep to allow for peat
growth (Evans & Warburton, 2007). The primary aim
will then be to limit further erosion, which next tohydrological measurements may also include active
revegetation.

South China Sea

Drain

Additional objectives

4000

5000

Fig. 4 Cross-section of peat domes in Borneo. (PS Konsultant, 1998)

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H. JOOSTEN and M. SCHUMANN

The condition of being at the same time ‘high’ and‘permanently wet’ can only be achieved by continuous
input of water from above. A close relationship exists
between the height of the water bulge, the hydraulic conductivity of the soil, the amount of water input into the soil
(rainfall), and the diameter of the dome, following the formula (for a circular peat dome):
U
2h 2
=
2
k R − r2

in which
U = the amount of water input into the dome (m)k = the conductivity of the peat (md-1)
h = the height of the dome at point r (m)R = the radius of the domer = the distance of any point to the dome centre(Bakker, 1992).
The formula shows that to keep a peat dome with adiameter of 6 km and a height of 5 m permanently wet,a water input of U = 5.6 10-6 k (md-1) is required. When
we apply a rather high conductivity value of 10 md-1 toour entire model dome, we find something astonishing:
the dome only needs 5.6 10-5 md-1 of water input, or inmore normal terms only 0.06 mm per day or 20 mm per
year. Wider domes need even less water: a 5 m highdome with a radius of 6 km and a conductivity of
30 md-1, for example, only 15 mm per year. In a climate
with several thousands of millimetres of annual precipitation, a peat dome thus needs only a miniscule fractionof that amount to maintain itself. One might wonder
why peat domes are not much more common in the tropics.
The reason is simple: this small amount of – in our
example – 20 mm per year must be absolutely evenly
distributed over the year. Every moment that the peat
dome is not fed with water, the water level will immediately drop below the surface because of continued
gravity drainage. This leads to the surface peat layer
becoming oxidized. If a constant supply of water ofevery day 0.06 mm or every minute 0.0004 mm is notguaranteed, the dome can not be maintained and will
eventually disappear. This effect is aggravated byevapotranspiration, which may lead to additional water
losses of several mm per day.
Even in the humid tropical climate of Southeast Asia,
most of the time it is not raining. To persist, a peat dome
thus needs a ‘device’ to guarantee the necessary, extremely small but constant water supply. It needs an
AC/DC converter to transform the ‘alternating current’of precipitation and evapotranspiration into a ‘direct
current’ continuously feeding into the peat dome.
4.1 The AC/DC converter
The only way to guarantee a constant supply is byfeeding the dome from some sort of water reservoir on
top of the dome. Such ‘device’ must have the following
properties:
1) It must – after rain showers – retain part of the water,that otherwise would flow away over the water-satu-

rated surface. It must thus offer resistance against
water flow, i.e. have a limited horizontal hydraulicconductivity.
2) It must have sufficient water in store to compensate– in times without precipitation – for all water losses
from the dome by gravity drainage and evapotranspiration. It must thus have a large storage capacity
3) It must supply the entire dome because water saturation is required for every part of the dome (Fig. 5).
Actually all material lying and standing on the dome
will function as an AC/DC converter to some extent, as
it will delay surface run-off and retain some water oversome part of the dome surface for some time. Because
the dome-inimical periods are frequent and prolonged,
however, we need substantial material to create sufficient resistance and storage.
When this material is organic (and what else could itbe?), the inevitable water level fluctuations will result in
rapid aerobic decomposition. The proportion of coarse
pores will decrease and that of small pores increase.
This may look at first sight a positive development, because it might reduce lateral drainage by decreasing
hydraulic conductivity. The collapse and the decreasing
pore size, however, also imply a decrease in storage
capacity (reservoir depth) and storage coefficient (storage per volume) and will – with the same volumes ofwater losses – lead to larger fluctuations of the waterlevel. This enhances oxidation, a further collapse of thestructure, and results in a positive feedback that willrapidly make the device useless (Couwenberg & Joosten,1999). The only way to escape this dead-end development is the continuous renewal of the porous layers over
our dome, i.e. by continuously adding new coarse plantmaterial.
Such continual addition of new material to the surface leads to the development and maintenance of an
explicit vertical gradient in hydraulic conductivity: alayer that is very coarse in pores in the uppermost partand that going downward becomes increasingly lessporous. Such vertical gradient in pore space and hydraulic conductivity (cf. V-notch weir, Clymo, 1991) leads tomore water flowing through the open structure of trunks,
branches, and aerial roots at the surface in times ofwater surplus and high water levels. And it leads to lesswater flowing through the deeper, smaller pores of moredecomposed material in times of low water levels andimminent water shortage (Bragg, 1997). Such structure

Fig. 5 The model peat dome with the necessary AC/DC
converter.

Hydrogenetic Aspects of Peatland Restoration in Tibet and Kalimantan

thus provides – by negative feedback – a self-regulation
mechanism that reduces water level fluctuations undervarying meteorological conditions.
The structure depicted here is the ‘active layer,’ asdescribed by Ivanov (1953; 1981) and renamed ‘acrotelm’by Ingram (1978). In tropical peat swamp forests, thevegetation constitutes an important part of the acrotelm.
In fact, the sparsely available data indicate that in tropical swamps, in contrast to Sphagnum peatlands in the
Northern Hemisphere, the effective V-notch structure islargely situated above the ground surface (Fig. 6) andencompasses also the litter layer and the vegetation
mass up to the height that is reached by the highest annual water level. In the wet season the above groundmaterial retards the run-off of water leading to a temporary storage of water over the surface, especially in the
flatter centres of the dome (Hoekman, 2006).
This V-notch acrotelm structure of the lowermost
vegetation layer was already exemplarily pictured in thefirst illustration of a tropical peat swamp, which theDutch botanist Sijfert Koorders made during the
Ijzerman expedition through Sumatra in 1891 (Ijzerman
et al., 1895, Fig. 7).
4.2 Acrotelm building vegetation
In the temperate and boreal zones only five, six moss
species of the genus Sphagnum are able to shape acontinuously renewing acrotelm with the ‘criticalcompromise’ between a small hydraulic conductivity
and a large storage coefficient (Joosten, 1993). The
effectivity of these Sphagnum species is illustrated by
the distribution of Sphagnum raised bogs over a very
wide climatic range. The much richer diversity of species and life forms in tropical peat swamps and theirdifferent flora in different regions might suggest thatspecies composition is not that critical for the maintenance of domed peatlands in the humid tropics and thatthe huge amounts of rainfall would enable the formation

Depth of G.W.L (cm)Ground water level: Wt (cm)

Seepage rate (mm day-1)

201

of peat domes with less regulation than in Sphagnum
acrotelm bogs. However, ombrogenous domed peatlands
have only a limited distribution in the tropics. Of the
12.5 million km2 of humid tropics in the world (Schultz,
2005), less than an estimated 1% is covered by peatswamp domes. And although an estimated area of
150,000 km2 of forested peatlands exists in tropical
Africa and South-America, similar thick ombrogenous
peat domes are not described from these continents(IMCG Global Peatland Database, cf. Sieffermann,
1988) in spite of seemingly suitable climatic, geologic,
and geomorphic conditions.
These observations could indicate that in Southeast
Asia special biogeographic conditions occur and thatsome species and life-forms are more important for bog
dome formation and maintenance than others.
4.3 Forms of degradation
The challenges to restore severely disturbed peatswamp forest to living mire are enormous. Deforestationand fire not only destroy the vegetation, but with that
also the major regulation device to maintain adequatehydrologic conditions for sustaining the peat body.
Drainage not only facilitates the discharge of surficial
water needed to feed the peat body in the dry season. By
subsidence it creates flatter domes and a more explicit
microrelief (deep lying canals and ditches and adjacent
deeply subsided areas). Whereas the former can makehydrologic regulation simpler, the latter leads to extra problems for restoration. The relief is furthermore being alteredby deep fires that remove large parts of the peat body. As aconsequence parts of the dome become too steep and too
dry to support the ‘right’ vegetation, whereas in other areas
the surplus of water and prolonged flooding in newly originated depressions hampers revegetation.
4.4 Minor degradation
Domes with ‘minor’ degradation (Table 1) include
areas where the flora has been changed by selective forestry and that are not or only slightly drained by narrowand shallow logging extraction canals. Water outflow
from the latter should be annulled or reduced. Change in
species composition and the bottom-near vegetation

1998

1997

Runoff: R (mm/day)Fig. 6 Relation between ground water level (Wt, W.L.) andrunoff (R, seepage rate) in a peat swamp forest in theupper catchment of the Sebangau River, Central
Kalimantan during days without rainfall from March 1998
to February 1999 (left; Kayama et al., 2000) and in June October 1997 and March - October 1998 (right; Takahashi
et al., 2000).

Fig. 7 Vegetation types in the peatland near Biwak (Sumatra), as
seen by Koorders during the 1891 Ijzerman expedition(Ijzerman et al., 1895; Potoniè, 1907) with an explicit
V-notch-structure over the surface.

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H. JOOSTEN and M. SCHUMANN

structure by selective harvesting may change the quantity and quality of organic matter inputs that are relevant
for peat accumulation. More importantly it may havemade the hydraulic structure of the acrotelm more
‘open.’ Pioneer and secondary species may (temporarily) have less effect for hydrologic self-regulation thanthe original vegetation. Restoration of the latter byplanting should focus on species that are indigenous to
the spatially differentiated zones of the dome.
4.5 Moderate degradation
In the ‘moderate’ degradation stage, where the shapeis still preserved, in any case anthropogenic drainage
has to be stopped. Important in this respect is to think incoherent rewetting ‘systems’ and to work ‘with’ nature,
not against her.
Firstly, one should keep in mind that enormous volumes of water ‘have’ to leave the bog, also in pristineconditions. Similar to the Tibetan percolation mires itthus makes no sense to try and make the dams fully
impermeable and to dam up as much water as possible.
The hydrologic restoration measures should be designed
to allow the strongly varying surplus water to leave thebog without causing too much damage, but to retain asufficient store for drier periods.
The main channels have to be blocked in such a waythat the water is impounded above the surface of thepeatland to rewet as much of the dome peat as possible.
This will often mean constructing a dense network ofdams cascading with little head differences (Ritzema &Wösten, 2006).
To disperse the water, damming should proceed
centrifugally starting from the centre of the dome. By
guiding the water over the largest possible area, flow
velocity and erosive power are reduced. Preferential
channelling around the dams can be restricted byallowing/stimulating a protective plant cover to reestablish before raising the water level. This may imply
that continued peat oxidation is temporarily allowed toprevent later erosion.
When the vegetation and therewith the major naturalhydrologic regulation device is largely removed, a kindof catch-22 situation exists. A water reservoir large(= deep) enough to keep the whole peat body wet in thedry season can only be realized when the vegetation
effectively holds back the discharging water in the wet
season. Pioneer species like ferns, however, do not
sufficiently slow down water flow, whereas the species,that under natural conditions realize the AC/DC-converter,
only germinate on raised hummocks and cannot survive
the harsh, pioneer conditions after degradation and rewetting. The result is that in the wet season the waterdrains away too quickly and that in the dry season thesurface peat becomes too dry and oxidizes.
The solution to this dilemma could be applying a two
step approach to restoration:• first establish vegetation, that can hold back discharging water, can withstand rather high waterlevels, and – more importantly – can act as a facili-tator for the necessary AC/DC-converter species and• later, when the latter species have re-established,raise the wet season water level to the ‘natural’ level.
In developing such re-vegetation strategy, care has to betaken that planting ‘commercial’ species like rubber inthe first phase may later result in conflicts when new or
higher dams and further rising water levels will restrict
access and annul investments.
4.6 Major degradation
In general peatland restoration should start withlooking at peatland shape and relief, because these features determine the long-term perspectives of hydrologic
restoration. When the peatland shape has substantiallyand irreversibly been changed (‘major’ degradation
stage, Table 1) the prospects of full regeneration are
extremely low. It will be impossible to recreate coherenthydrologic and vegetational conditions over the fulldome and continued oxidation will progressively
degrade the dome. Good three-dimensional elevation
models must give insight in to what extent a balanced
shape is still present, will spontaneously re-develop (byoxidation of too dry protuberances), or can easily berestored. When such shape is guaranteed, additionalhydrologic and vegetational restoration measures (seeabove) may resurrect a living dome. If not, the area will
spontaneously develop to the stage of ‘maximal’ degradation and solutions have to be found to limit thedamage.
4.7 Maximal degradation
The maximal degradation stage involves areas thatare intensively drained where the dome peat body isdamaged or disrupted to such an extent that one or more(new) balanced peat domes (with the associated hydrologic and vegetational conditions) cannot be restored
anymore. In some areas peat accumulating conditions
might be restored locally but only through costly andcomplicated water control devices. In general, however,the focus has to be on restricting peat oxidation andpeatland fires by rewetting the area as far as possible.
The challenge for these areas is to develop andimplement production techniques that combine economic benefits without impacting the environmental
functions of peatlands: wet agriculture, wet forestry, or
fishery (Wichtmann & Joosten, 2007).
4.8 Perspectives
As peat domes with limited damage (degradation
stage ‘minimal’) are extremely rare in Southeast-Asia (ifstill existing) high priority must be given to conserving
these areas, and to restore those domes that still havegood perspectives for full restoration to self-regulating
peat-accumulating entities (degradation stages ‘minor’and ‘moderate’). It is of utmost importance that suchareas are rapidly identified and adequately protected,
restored, and managed.
Probably most of the intensively drained tropicalpeatland area is already in the stage of ‘major’ toHydrogenetic Aspects of Peatland Restoration in Tibet and Kalimantan‘maximal’ degradation. The proposal of the recent
Indonesian Presidential Instruction (No. 2/2007, 16 March
2007) to designate 62% of the 1.5 million ha large
Central Kalimantan Peatlands Development Project(formerly Mega Rice Project) to ‘conservation’ seems
therefore both too optimistic and not ambitious enough.
In the ‘conservation’ area an artificial separation is madebetween conservation of ‘flora and fauna,’ ‘black water
ecosystem,’ ‘hydrology,’ and ‘deep peat.’ The central
characteristic of peatlands, however, is that these components are inextricably interwoven. Furthermore, it isdoubtful whether self-regulating living mire conditions
can be restored and maintained over the whole area inthe long term.
On the other hand, to prevent further peat degradation and environmental damage the peat also has to beconserved in the agricultural and forestry areas. The
challenge for the project will be to develop for areas thatcannot be maintained or restored to living peat swamps
a win-win situation between productive utilisation andenvironmental conservation by implementing wet agriculture and forestry.

5. Conclusions
Living peatlands are intricate systems with important
self-regulation mechanisms to maintain the balance between ‘vegetation,’ ‘water’ and ‘peat.’ Self-regulation
based on negative feedback is common in nature but
often overlooked. The fact that both Tibetan percolationand surface-flow mires and tropical peat swamp forests
have existed in a similar form for many thousands ofyears and over periods in which climatic conditions
have changed substantially indicates that a wide spectrum of negative feedback mechanisms ‘must’ exist. An
important part of this self-regulation is directly associated with vegetation, a component that – except for its
evaporation – is generally ignored or insufficiently acknowledged in hydrological approaches to peatland
restoration.
Both in Tibetan groundwater-fed surface-flow mires,
where also the vegetation in the upland catchment isimportant, and in Kalimantan peat swamp forests which
are solely fed by rainwater, the role of the vegetation inwater retention and storage is indispensable to prevent
erosion of the peat body.
Restoration research should therefore pay more
attention to the interrelations between vegetation, waterand peat as the basis of self-organisation and selfregulation. This is certainly opportune when planningand evaluating restoration measures.
As the vegetation in both peatland areas is the main
object of human action, the restoration of peatlands is not
only a matter of technical management, but has an important social dimension that needs to be acknowledged.

203

Acknowledgements
We thank Wetlands International China, Wetlands
International Indonesia, the Global Environment Centre(Malaysia), the Sichuan Provincial Workstation for
Wildlife Resources Survey Conservation and Management, and the Gansu Wildlife Administration Bureau forfacilitating field work and providing good company, andUNEP-GEF, the Central Kalimantan Peatland Project(CKPP), and the EU-China-Biodiversity Project (ECBP)
for financial support.
References
Bakker, T.W.M. (1992) The shape of bogs from a hydrologicalpoint of view. International Peat Journal Peat, 4: 47-54.
Bragg, O. (1997) Understanding ombrogenous mires of the temperate zone and the tropics: an ecohydrologist's viewpoint. In:
J.O. Rieley and S.E. Page, eds., Biodiversity and Sustainabilityof Tropical Peatlands, Samara Publishing, Cardigan, 135-146.
Clymo, R.S. (1991) Peat growth. In: L.C.K. Shane and E.J. Cushing, eds., Quaternary Landscapes, University of Minnesota
Press, Minneapolis, 76-112.
Couwenberg, J. and H. Joosten (1999) Pools as missing links: therole of nothing in the being of mires. In: V. Standen, J. Tallis
and R. Meade, eds., Patterned Mires and Mire Pools – Origin
and Development; Flora and Fauna, British Ecological Society,Durham, 87-102.
Evans, M. and J. Warburton (2007) Geomorphology of UplandPeat. Blackwell, Oxford.
Hoekman, D.H. (2006) Satellite radar observation of tropical peatswamp forest as a tool for hydrological modelling and environmental protection. In: Parish, F. and P. Canadell, eds.,
Vulnerabilities of the Carbon-climate System: Carbon Pools in
Wetlands/Peatlands as Positive Feedbacks to Global Warming,
Global Environment Centre / Global Carbon Project, 31-32.
Hooijer, A., M. Silvius, H. Wösten and S. Page (2006) PEAT-CO2,
Assessment of CO2 Emissions from Drained Peatlands in SE
Asia. Delft Hydraulics report Q3943.
Ijzerman, J.W., J.F van Bemmelen, S.H. Koorders and L.A.
Bakhuis (1895) Dwars Door Sumatra. Tocht van Padang naar
Siak. Bohn, Haarlem/Kolff, Batavia.
Ingram, H.A.P. (1978) Soil layers in mires: function and terminology. Journal of Soil Science, 29: 224 - 227.
Ivanov, K.E. (1953) Gidrologija Bolot. (Mire hydrology).
Gidrometeoizdat, Leningrad.
Ivanov, K.E. (1981) Water Movement in Mirelands. Academic
Press, London.
Joosten, H. (1993) Denken wie ein Hochmoor: Hydrologische
Selbstregulation von Hochmooren und deren Bedeutung fürWiedervernässung und Restauration. Telma, 23: 95 - 115.
Joosten, H. (2008) The challenge of being domed: hydrologicalself-regulation, conservation, and restoration of Southeast
Asian peat swamps. Mires-and-Peat, 3. (submitted)
Joosten, H. and D. Clarke (2002) Wise Use of Mires and Peatlands– Background and Principles Including a Framework for
Decision-making. International Mire Conservation Group/
International Peat Society, Saarijärvi.
Joosten, H., A. Haberl and M. Schumann (2008) Degradation andrestoration of peatlands on the Tibetan Plateau. Peatlands
International, 2008/1.
Kayama, M., H. Takahashi and S.H. Limin (2000) Water balanceof a peat swamp forest in the upper catchment of the Sebangau
River, Central Kalimantan. Proceedings of the International
Symposium on Tropical Peatlands Bogor, Indonesia, 22-23
November 1999, Hokkaido University & Indonesian Institute204

H. JOOSTEN and M. SCHUMANN

of Sciences, 299-306.
Potonié, H. (1907) Ein von der Holländisch-Indischen
Sumatra-Expedition entdecktes Tropenmoor. Oesterreichisches
Moorzeitschrift, 8: 161-173.
PS Konsultant (1998) Detailed Design and Construction Supervision of Flood Protection and Drainage Facilities for Balingian
RGC Agricultural Development Project, Sibu Division,
Sarawak (Inception Report). Department of Irrigation andDrainage, Kuching.
Ritzema, H. and H. Wösten (2006) Hydrology and Water Management Issues in Tropical Peatlands.
(www.restorpeat.alterra.wur. nl/p_download.htm)
Schultz, J. (2005) The Ecozones of the World 2n ed. Springer,
Berlin Heidelberg, New York.
Schumann, M. and H. Joosten (2007) Development, Degradation
and Restoration of Peatlands on the Ruoergai Plateau: A first
Analysis. Wetlands International China Programme, Beijing.

Schumann, M., N. Thevs and H. Joosten (2008) Extent anddegradation of peatlands on the Ruoergai Plateau (Tibet,
China) assessed by remote sensing. Proc. Intern. Peat Congress
Tullamore.
Sieffermann, R.G. (1988) Le système des grandes tourbières
equatoriales. Ann. Géo., 544: 642-666.
Takahashi, H., M. Kayama and S. Limin (2000) The Effects ofEnvironmental Factors on Diurnal Changes of Ground Water
Table in a Tropical Peat Swamp Forest. Proceedings of theInternational Symposium on Tropical Peatlands Bogor,
Indonesia, 22-23 November 1999. Hokkaido University &Indonesian Institute of Sciences, 321-327.
Wichtmann, W. and H. Joosten (2007) Paludiculture: peat formation and renewable resources from rewetted peatlands. IMCG
Newsletter, 2007/3: 24-28.

(Received 14 March 2008, Accepted 25 March 2008)