Upload
trandat
View
235
Download
0
Embed Size (px)
Citation preview
SOIL PHYSICOCHEMICAL PROPERTIES AFTER ESTABLISHMENT OF OIL PALM PLANTATION IN PEAT SWAMP FORESTS AT MUKAH,
SARAWAK
Zulfaqar bin Sa'adi
S Master of Environmental Science .598
(Land Use and Water Resource Managment) Z94 20112011
Pusat Kbidmat MakJumlit AJcad mi RSm MALAY, fA . R W. •
P.KHIDMAT MAKLUMAT AKADEMIK UNIMAI
1111111111111111111111111 1000246267
SOIL PHYSICOCHEMICAL PROPERTIES AFTER ESTABLISHMENT OF OIL PALM PLANTATION IN PEAT SWAMP FORESTS AT MUKAH, SARA W AK
ZULFAQAR BIN SA'ADI
A dissertation submitted in partial fulfillment of the requirements for the degree of Master of Environmental Science
(Land Use and Water Resource Management)
Faculty of Resource Science and Technology UNIVERSITI MALAYSIA SARA W AK
2011
DECLARATION
No portion of the work referred to in this description has been submitted in support of an
application for other masters of qualification of this and any other university or
institution ofhigher learning.
Zulfaqar bin Sa'adi
Masters of Enviromnental Science
(Land Uses and Water Resource Management)
Faculty of Resource science and technology
Universiti Malaysia Sarawak
APPROVAL SHEET
Name of candidate: Zulfaqar bin Sa'adi
Title of dissertation: Soil physicochemical properties after establishment of oil
palm plantation in Peat Swamp Forests at Mukah, Sarawak
.'
Dr Mohd Effendi Wasli
Supervisor
ACKNOWLEDGMENTS
Firstly, I would like to thank Allah for His blessing upon me to complete my
project. Besides, special thanks go to Dr Mohd Effendi Wasli as Supervisor for his full
encouragement, guidance, supervision and professionalism. Furthermore, Thanks also to
our lab assistants, for their materials provided, patience and helps concerning the lab and
equipment preparation. Lastly, to fellow friends and people that involved direct or
indirectly in finishing this project. The author also wishes to thank University Malaysia
Sarawak for equipment, material and financial support .
.'
Pusat Khidmat Maklumat Akademik UNTVERSITI M LAY tA tU VAf<
Contents
LIST OF FIGURE Page
Figure 1: Distribution ofPeat forest in Sarawak (Department of Irrigation and Drainage, Sarawak).......................................... .. ...................................................... 10 Figure 2: Map ofKampung Igan, Mukah, Sarawak and sampling locations (Red dotted: Peat soil sampling sites) .......................................................................................21
Figure 3: Sampling location ......... ........................................................................ .24
Figure 4: Map ofSarawak Land Capability Classification and Evaluation for Agricultural
Crops ofKampung Igan, Mukah (Maas, 1986) .......................................................29
Figure 5: Soil pH under peat swamp forest (PI), 2 years old young oil palm (P2) and mature
oil palm ofmore than 15 years old (P3) ...............................................................38
Figure 6: Soil bulk density under peat swamp forest (PI), 2 years old young oil palm (P2)
and mature oil palm ofmore than 15 years old (PJ) ................ . ............................... 39
Figure 7: Soil porosity under peat swamp forest (PI), 2 years old young oil palm (P2) and
mature oil palm ofmore than 15 years old (P3) ..................................................... .41
Figure 8: Soil water content under peat swamp forest (PI), 2 years old young oil palm (P2)
and mature oil palm ofmore than 15 years old (P3) ..... ... ........................................ .42
Figure 9: Soil hardness ~der peat swamp forest (PI), 2 y€(ars old young oil palm (P2) and
mature oil palm ofmore than 15 years old (P3) ... '; .............................. ... ............... .43
Figure 10: Soil dry matter under peat swamp forest (p 1), 2 years old young oil palm (P2) and
mature oil palm ofmore than 15 years old (P3) ....................................... . ............ .44
Figure 11: Soil moisture content under peat swamp forest (PI), 2 years old young oil palm
(P2) and mature oil palm of more than 15 years old (P3) ................................... . ...... .46
Figure 12: Soil organic matter under peat swamp forest (PI), 2 years old young oil palm (P2)
and mature oil palm ofmore than 15 years old (P3) ..................................... ...... ..... .48
LIST OF TABLE
Table 1: Collection of soil samples from different Sites ............... .... .........................23
Table 2: Summarization of Sarawak Land Capability Classification and Evaluation for
Agricultural Crops ofKampung Igan, Mukah .......................................................31
Table 3: Selected Physicochemical soil properties at oil palm plantation in Kampung Igan,
Mukah Sarawak ..........................................................................................35
. ABSTRACT........ ..... ............................................... ... ............... ....... .................. ...... . 1
ABSTRAK................. .. ............................. ................. .... .. ........ .... ... .... ...................2
CHAPTER 1: INTRODUCTION...... .. ..... .... ........................ ......... ...............................4
CHAPTER 2: LITERATURE REVIEW
Tropical peat swamp forest ........................................ ... ...........................................8
Peat Soils ofSarawak.. ~'............................................ ... . .. ... ............................. 11
Benefits and importance ofpeat swamp forest. ... : .................................................. 12
Effects of human activity in peat swamp forest. ... : ............. ... .. .. ..... . ........ ... ........ .. .. 16
Agricultural development through peat swamp forest in Sarawak.... ................................ .18
CHAPTER 3: MATERIALS AND METHODS
Soil classification of the study area ...................................... .............. . .......... .. ...20
Study area ..................................................................................................20
Sample collection ............. . ..... . .....................................................................23
Laboratory Analyses ........ . .................................................................. ..........24
DeteITIlination of soil physiochemical properties ....................................................25
Soil bulk density, Soil water content and Porosity ...................................................25
Soil pH deteITIlination ...................... . ..... . ........................................................25
Soil dry matter content (DM) .......................................... . ..................... . ..........26
Soil moisture content (MC) ........................................................................... 26
Soil Organic matter content. ......................................... . ...................................27
CHAPTER 4: RESULTS AND DISCUSSION
Capability of the land for agricultural purpose ........................................................28
Suitability and capability of the soil in the study area for agricultural purpose .................34
Compruisons of soil physicochemical properties of oil pahn under various stand ages with
the peat swamp forests ..................................................................................36
Tropical peat swamp forest soil under various form ofland use ........................................... .48
CHAPTER 5: CONCLUSIONS ......................................................... . . .. ... ... ..............52
REFERENCES
APPENDIX
I
Soil physicochemical properties after establishment of oil palm
plantation in peat swamp forests at Mukah, Sarawak
Zulfaqar bin Sa'adi
Masters Environmental Science (Land use and water resource management)
Faculty of Resource science and technology
Universiti Malaysia Sarawak
ABSTRACT
(Soil properties determination is important towards an improvement of both strategy and
techniques for future development of conversion peat swamp forest into oil palm plantation. This
study discusses soil properties of peat swamp forest under oil palm plantation in Kampung Igan,
Mukah, Sarawak. in comparison with the sUlTounding peat swamp forests. Peat soil samples in
this study were collected from peat swamp forest (PI), Ladang Rakyat Pelita Igan Jaya oil palm
plantation for young oil palm plantation of 2 years old (P~) and Felcra Bhd oil palm plantation
for mature oil palm plantation of more than 15 years old (P3)) The size of each experimental plot
was 20 x 20m. Soil samples were collected at 0-25 cm depths at each site. For P2 and P3, soil
samples were collected and differentiate as no fertilizer point and fertilizer point. Undisturbed
cores and bulk samples were collected for analysis of bulk density and moisture content. Soil
1
~~,
physicochemical properties were determined by standard procedures. The findings showed that
PI and P2 classifies as 05gn (peat soil) while P3 was 4fw-05gn (mixed mineral and peat soil).
Soil pH, soil bulk density, water content and soil hardness was increased while soil organic
matter and soil porosity was decreased. Dry matter content and moisture content show
inconsistency between the sites. As the differences between fertilizer point and no fertilizer point
in P2 and P3 showed various trend for each analysis. Results of this study will be useful in
predicting the soil condition trend between ages ofoil palm plantation in various perspectives and
ensure continuous benefits from the development of peat swamp forest especially involving
plantation activities and soil management.
ABSTRAK
Penentuan sifat-sifat tanah dalam penukaran hutan tanah gambut kepada ladang kelapa sawit
penting dalam membangunkan strategi dan teknik untuk pembangunan di masa depan. Kajian ini
membincangkan sifat-sifat tanah di bawah penanaman ladang kelapa sawit oleh syarikat
berasaskan kelapa sawit di Kampung Igan, Mukah, Sarawak, dengan membandingkannya dengan
keadaan semasa hutan tanah gambut di sekitamya. Sampel tanah gambut dalam kajian ini diambil .'
dari hutan tanah gambut (PI), Ladang Rakyat Pelita Igan Jaya untuk kelapa sawit yang masih
mud a iaitu berusia 2 tahun (P2) dan Felcra Bhd untuk kelapa sawit yang sudah matang melebihi
15 tahun (P3). Saiz setiap plot eksperimen ialah 20x20m. Sampel tanah dengan kedalaman 0-25
cm di hutan tanah gambut diambil manakala sampel tanah diambil di kawasan yang tidak dibajai
dan dibajai di P2 dan P3. Fisikokimia tanah ditentukan dengan prosedur standard. Jenis tanah di
2
PI dan P2 diklasifikasikan 05gn (tanah gambut) manakala P3 ialah 4fw-05gn (campuran tanah
mineral dan tanah gambut). PH tanah, isipadu ketumpatan tanah, kandungan air dan kekerasan
tanah bertambah manakala kandungan bahan organik tanah dan keporosan tanah menurun. Bahan
kandungan kering dan kandungan lembapan menunjukkan nilai yang tidak konsisten di setiap
kawasan kajian. Untuk perbezaan antara kawasan yang dibajai dan tidak dibajai menunjukkan
keputusan mengikut kecenderungan yang berlainan bagi setiap analisis. Keputusan daripada
kajian ini berguna dalam menjangka perubahan usia ladang kelapa sawit dari perspektif yang
pelbagai dan memastikan keuntungan berterusan daripada pembangunan hutan tanah gambut
terutama melibatkan aktiviti perladangan dan pengurusan tanah.
3
I
CHAPTER!
INTRODUCTION
Peat is a type of soil that contains a high amount of dead organic matter, mainly plants
that have accumulated naturally over thousands of years . It takes approximately a staggering 10
years for I cm of peat to fonn (DOE, 2011). The thickness of the peat layer varies per location,
but in South-east Asia it can reach up to 25 meters. Dead plants in peatlands are different to other
ecosystems as they do not fully decompose. Micro-organisms such as bacteria and fungi are
prevented from rapidly decomposing the dead plants as the waterlogged conditions reduce the
amount of oxygen in the soil. The factors which cause peat to accumulate may be the same the
world over, but different types of peatlands develop because of differences in climate, soil type
and plant species. Peatlands are found in almost every country in the world. They cover over 4
million km2 worldwide, or 3% of the world's total land area, and represent half of the Earth's
wetland areas (WI, 2007). The largest areas are found in the cold tundra regions of Northern
Russia and Canada, called boreal peatlands while Southeast Asia contains the largest areas of
tropical peatlands. Tropical lowland peatlands were originally covered by dense rainforest (WI,
2007). ..
Peatlands may be naturally forested or naturally open and vegetated with mosses, sedges
or shrubs. Examples of naturally forested peatlands are the Alder peat forests in Europe and the
lowland humid tropical peat swamp forests in Southeast Asia ((Rieley et aI., 1992; Page et aI.,
2006). Tropical peatlands are widely distributed throughout the world. Small tracts are found in
parts ofLatin America, Africa and the Caribbean. The vast majority, however, is found in South
4
I'u at Khidmat MakJumat Akade,mik UNlVERSnl MALAYSIA SARAwAJ<
east Asia, covering 60% of the total tropical peatland area and over 85% of tropical peatland
carbon storage (WI, 2007). Examples of naturally open peatlands are the permafrost areas of
Russia and Canada, the Everglades in North America, and the high mountain peatlands (Paramos)
ofthe Andes and Himalayas (WI, 2007).
Peat soils often possess nutrient-poor soils, and tend to be the poorest areas for agriculture
which support only low population densities. Despite this, millions of people live in and depend
on the world's peatlands for their livelihoods. These include herding cattle, catching
fish, harvesting reeds, farming, forestry and collection of many valuable non-timber forest
products (WI, 2007). Efforts to improve the agricultural production of peatlands by conversion,
drainage and fertilizing the soils are generally unsuccessful and very unsustainable in the past.
These areas often tum into wastelands within decades where as a result of soil subsidence, they
become prone to long periods of inundation. Many tropical peatlands are underlain by potential
acid sulphate soils which become active when drainage levels become too deep, causing severe
acidification of the area and its surroundings. Drainage also causes significant increase of fire
risks (WI, 2007).
Human exploitation has destroyed 25% of the peatlands on earth. The enormous peatlands
of Northern America 0/ Russia are still relatively unaffcrcted. However in many countries in
Europe and Central Asia peatlands have been severely affected by agriculture and mining (WI,
2007). Even if degraded, decomposition processes in the cold northern peatlands and southern
peatlands of Argentina or Chile take place at a much slower rate than in the tropics. In particular
the magnitude of the loss of the boreal peatlands in Canada or Russia is enormous. If these are
degraded, global greenhouse gas emissions would rise dramatically as these areas currently store
5
1
,p
over 50 times more carbon than all annual anthropogenic fossil fuel emissions (WI, 2007). Of
even greater concern is that the threat of climate change on peatlands themselves is alarming and
could forms a vicious circle. Climate change driven by global warming could lead to degradation
of the peatland areas and in tum lead to massive emissions of carbon from the organic peat. In
addition, the combination of relatively young (seasonal) vegetation and temporary flooding leads
in boreal peatlands to production of methane, a very potent greenhouse gas. There is also a risk
that fossilised methane, stored under the permafrost areas, could be released (WI, 2007).
The conservation ofpeatlands is important for a number of reasons including biodiversity,
archaeology, carbon storage and water storage and also because of their landscape value. A
number of measures including Government policy, legislation, protected sites and education are
currently utilized as part of a strategy for the protection ofpeatlands.
This study was conducted at Kampung Igan, Mukah, Sarawak (20 49' 50.82"N, 111 0 41'
17.53"E) (Figure 2), located at the estuary of Batang Igan River in Matu district cover about
244.58 km2• At the inland area of Kampung Igan, consist of large acreage of peat swamp forest.
Peat swamp forest in Kampung Igan was under increasing pressure from development such as
human settlement but agriculture conversion of oil palm plantation, sago plantation and other
agricultural activities was a particular concern. All thi~ development will subsequently arise
various environmental problems especially soil .subsidence in the near future if not manages
properly. Subsidence lowering of ground surface will occurred unavoidably due to compaction
and decomposition of organic material at Kampung Igan as it originally cover mostly by peat
swamp forest. These situations as a result ofmechanization used in agricultural activity cannot be
stopped under drained conditions as effectiveness of the drains decrease but can only be
6
tJc
minimized. In the end, if not manage properly, water management would be more complex and
costly. Drainage system intended to slow down soil subsidence will in the end altered the
topography of the area, thus changing the flow pattern which would increase the occurrence of
flooding. In case ofover drainage, impacts that foreseen to happen such as rate of subsidence and
flooding increase, occurrence of acid-sulphate soils, forest fires, irreversible drying, pest and
tennite attack, nutrient imbalance and low crop yield.
The objectives of this study was to compare physicochemical properties of peat swamp
forest, young oil palm plantations and mature oil palm plantations that were previously peat
swamp forest to determine the effect of forest conversion and changes of peat soil condition
through oil palm development so that the data collected could be used by various stakeholder to
help management practices and improve development techniques which intended to be done at
the area ofpeat swamp forest or originally peat swamp forest.
.'
7
CHAPTER 2
LITERATURE REVIEW
Tropical peat swamp forest
Peatlands may be naturally forested or naturally open and vegetated with mosses, sedges
or shrubs. Examples of naturally forested peatlands are the Alder peat forests in Europe and the
lowland humid tropical peat swamp forests in Southeast Asia (Rieley et aI., 1992; Page et al.,
2006). Tropical peatlands are widely distributed throughout the world. Small tracts are found in
parts of Latin America, Africa and the Caribbean. Most of the world's tropical peatlands (about
62%) are found in the Indo-Malayan region where 80% in Indonesia, 11 % in Malaysia, 6% in
Papua New Guinea, with small pockets and remnants in Brunei, Vietnam, the Philippines and
Thailand (Rieley et aI., 1992; Page et aI., 2006). These peat swamp formations are geologically
recent, mostly <5,000 years old. They largely overlie marine muds and sands in the coastal
lowlands of Peninsula Malaysia, and the islands of Borneo, Sumatra, Papua New Guinea,
Sulawesi and the Moluccas. Some older peat swamps (up to 11,000 years old) overlie riverine
sediments at slightly higher elevations in central Kalimantan in Borneo (Rieley et aI., 1992; Page ",'
et aI., 2006).
Peat swamps forests are an important component of the world's wetlands with the
dynamic link between land and water, a transition zone where the flow of water, the cycling of
nutrients and the energy of the sun combine to produce a unique ecosystem of hydrology, soils,
flora and fauna. The tropical peat swamp forests of the Indo-Malayan region are unusual
8
ecosystems and they differ dramatically from north temperate and boreal peat lands which are
dominated by Sphagnum spp., grasses, sedges and shrubs. Trees in the peat swamp forests can
grow to over 70 m high, despite the extreme conditions of low pH (2.9-4), low nutrients and
anaerobic acidic water regimes with unstable and spongy substrate of peat that may be 20 m deep
or more. The forest floor is flooded during wet seasons, but even during dry seasons the peat
remains waterlogged, with pools amongst the trees. Their continued survival depends on a
naturally high water level that prevents the soil from drying out to expose combustible peat
matter. This harsh waterlogged environment has led to the variation of many species of flora
uniquely adapted to these conditions Borneo (Rieley et aI. , 1992; Page et ai., 2006).
There are about 2.7 million hectares of peat swamps in Malaysia accounting for 8% of the
total area of the country, of which 1.7 million hectares or 63 % are in the deltas and coastal plains
of Sarawak (Rieley et ai. 1992; Page et aI. 2006). Almost all of the peat swamp forests of
Peninsular Malaysia, as in aU the other locations, have been destroyed or degraded over the past
50 years and none remain in a pristine condition. Precise estimates are difficult, but they have
declined from about 1 million ha (Coulter, 1957) to 0.67 million ha in 1981, to 0.34 million ha in
1991 (Rieley et aI. 1996), to 0.30 million ha in 2005 (UNDP, 2006). Since then there has been
further decline and more than half of the remainder is degraded. Only about 100 ha is fully
'protected' in Virgin JUngle Reserve, but this is an ar~a too small to ensure preservation of
ecosystem functioning, since the water table cannot be maintained in its original state. About
67% is now in Permanent Forest Reserves but these are targeted for sustainable logging. The rest
is available for conversion to other land uses. The only large tract of pristine peat swamp forest
remaining on mainland Asia is the Pekan peat swamp forest, in the state of Pahang on the east
coast of the Malaysian peninsula. Despite its high biodiversity and ecosystem value, it has been
9
designated as Production Forest Reserve (i.e. logging is allowed). Small areas of peat swamp
forest also still remain in Sabah, and although significant areas remain in Sarawak, they have
mostly been degraded by logging (Catherine, 2010). Sarawak, the largest state in Malaysia, has
the biggest reserve of peat swamp forest. Peat swamps in Sarawak account for 13% of the State's
total land area. The coastal and riverine area covers about 19% of the state land area. This
includes both the fresh water peat (l.698 million hectares) and mangrove (154,000 hectares)
areas. In general, peat soils are found mostly within the delta and stretching inland along the
riverine of the Samarahan-Sadong, Lupar-S arib as, Rajang, Baram and Limbang river system
(Figure 1).
t 5O\JI'H CHINA SEA
KAlIMANTAN,
Figure 1: Distribution of Peat forest in Sarawak (Department of Irrigation and Drainage, Sarawak)
10
Peat soils of Sarawak
Tie (1979) refers to peat as organic soils on the basis of mass composition i.e. soils that
contain at least 65% organic matter or conversely, less than 35% mineral content. The more
recent definition for organic soils as adopted by the Soil Division of Sarawak is based on profile
partition, i.e. soils that have 50 cm or more organic soil matter within 100 cm or more than twice
that of mineral soil materials overlying bedrock within 50 cm (Teng, 1996).
In Sarawak, the landscape for lowland organic soils ranges from basin swamps to valley
swamps. The morphological characteristics of lowland organic soils are quite similar throughout
the region. The convexity of coastal and deltaic peat swamps surfaces are increasingly
pronounced with distance from the sea (Murtedza et aI., 1992). In the natural state, the water table
is always high, often at or near the surface (fie and Kueh, 1979; Andrieese, 1988; Murtedza et
aI., 1992). In drained areas, the organic soils are transformed to a compact mass consisting of
partially and well-decomposed plant remains with large wood fragments and tree trunks
embedded in it (Murtedza et aI., 1992). Sulfidic marine clay is often found underlying the organic
materials in organic soils (Andriesse, 1964). The common soil profile in drained organic soils
consists of three distinct layer which categories as upper layer (20 - 30 cm thick) consisting of
well-decomposed organic materials of the sapric type, a middle layer (30 - 40 cm thick)
consisting of semi-deco~posed organic materials of the ,hemic type and a lower layer of fibric
materials which is mainly large wood fragments and branches and tree trunks (Murtedza et aI.,
1992).
11
Benefits and importance of peat swamp forest
Peatlands contain globally at least 550 Gigatonnes of carbon equivalent to all other
terrestrial biomass (forests, grass and scrublands', etc.) and twice as much as all carbon stored in
the world's forests. In the sub (polar) zone, peatlands contain on average 3.5 times more carbon
per hectare than above-ground ecosystems on mineral soil, in the boreal zone 7 times more and in
the humid tropics over 10 times the amount of carbon stored in above-ground habitats (WI,
2007).
Due to their capacities to store and maintain large quantities of water, peat swamp forests
play an important role in flood mitigation and ensure a continuous supply of clean water
throughout the year. Mountain peatlands, for example in the Himalayas, Tibetan Plateau and the
Andes, playa crucial role in reducing extremes in water flow and reducing floods or droughts.
The Paramos are called the "Water Towers" of the Andes because of their value for water supply
(WI, 2007).
Although the total species richness in peatlands in temperate climates is low, they al'e the
only available habitat for many endemic plant and animal species. Tropical peat swamp
forests represent, despite.,the lack of nutrients, a very high biodiversity ecosystem with thousands
of species, including many endemics, rare and endangered species. The black peat waters
support the highest density of freshwater biodiversity of the world (WI, 2007).
Malaysia's peat swamp forests not only comprise unique ecosystems that are home to
many endemic species but also provide sanctuary for viable populations of more than 60 animal
species listed as globally threatened including the Orang utan, Proboscis Monkey, Sumatran
12
Rhinoceros, Asian Elephant, Tiger, Civet Otter, Stonn's Stork and Wrinkled Hombill. Sebastian
(2002) provides an assessment of the current status of the mammal and bird fauna of both West
and East Malaysian peat swamp forest habitats where 57 mammal and 237 bird species recorded
in peat swamp forest, 51 % and 27% respectively are listed as globally threatened species (WI,
2007).
These moist forests also serve as a natural gene bank of potentially useful plant species as
well as providing highly valuable forest products such as high quality timber like ramin,
Gonystylus bancanlls and food. Many unknown species still remain to be discovered. Anderson
(1963) recorded 927 species of flowering plants and ferns in the peat swamp forests of Borneo. In
Peninsular Malaysia 260 species of plants were recorded from the Pekan Peat Swamp Forest
(Latiff,2005).
A total of 200-300 fish species are recorded from the peat swamps of Peninsular
Malaysia, Borneo and Sumatra (Dennis and Aldhous 2004) with 65 species recorded from Pekan,
and 47 from North Selangor Peat Swamp Forest (Ng et al., 1992, 1994). The Asian arowana
(Scleropages jormosus) which is a popular aquarium fish occurs in blackwater rivers in the
regional peat swamps. The world's smallest known fish (Paedocypris progenetica), <8 mm long,
was recently discovered· in the peat swamp forests of Sumatra (Kottelat et aI., 2006). The North
Selangor peat swamp forest is the most well studied area, from which 48 peat swamp fishes have
been recorded (Ng et al., 1992, 1994), include rare species, such as Encheloclarias, Bihunichthys,
Betla and Parosphromenus (Ng and Lim 1993; Ng and Kottelat, 1992, 1994). Far from being a
depauperate ecosystem, peat swamps possess an interesting fish fauna, which is diverse and
unique, and many of the species have narrow niches and restricted ranges.
13
d'
The reptile and amphibian fauna of regional peat swamp forests are not well known. A
survey of amphibians at Pekan revealed 19 species «30% of the species known from Malaysia)
ofwhich two are on the IUCN red list as 'near threatened' (Norhayati et al., 2005). Sharma et al.,
(2005) studied reptiles at Pekan and encountered 22 species, including four species of freshwater
turtles. The reptile and amphibian fauna of regional peat swamp forests are not well known. A
survey of amphibians at Pekan revealed 19 species «30% of the species known from Malaysia)
ofwhich two are on the IUCN red list as 'near threatened' (Norhayati et aI., 2005).
Coastal peat swamps act as a buffer between marine and freshwater systems, preventing
excessive saline intrusion into coastal land and groundwater. Intact peat swamps can contribute to
maintaining the water level in rivers that run through them during dry periods (UNDP, 2006). The
water from floods held in peat swamps is released gradually over a long period. By maintaining
base flows in rivers, peat swamps can prevent the intrusion of saline water up rivers and maintain
fresh groundwater in coastal areas. Intact peat swamp forests can diminish peak flood flows
mainly by reducing water velocity but also by providing a large area for storage of flood waters in
terms of spatial area and, to a very limited degree dependent on how waterlogged the peat is
already, through the water-holding capacity of the peat due to their flat topography and poor
drainage, during the wet season they store water above the forest floor (UNDP, 2006). When a
peat swamp area is flooded, the reduction in water velo~ity associated with it spreading over a
wide area, together with the retarding effects of vegetation, allows suspended sediments to settle.
Water flowing back into rivers will then be largely sediment free. Nutrients are often adsorbed
onto the surfaces of suspended particles and deposited along with them. These nutrients are likely
to be incorporated into biomass quite rapidly (UNDP, 2006).
14
Peat is very effective in binding metals. This largely accounts for the micronutrient
deficiencies (such as copper) that are encountered when using peat soils for agriculture. Other
metals (such as mercury and arsenic) are often bound in peat soils that are accumulated from
waterborne and airborne sources over long periods. Some such metals are toxic in large quantities
and peat acts as a reservoir for them (UNDP, 2006).
Numerous studies have suggested that peat deposits are well suited to the reconstruction
of both longer term and recent environmental changes. Thus, peat profiles can, for example,
provide records of the deposition of pollutants (e.g., Lee and Tallis 1979; Livett et aI., 1979;
Madsen 1981; Shotyk et aI., 1992; Jones and Hao 1993; Shotyk 2002). Recognition of this
function has gained importance in recent years due to the implication of raised C02 levels in
contributing to global warming. Tropical peat lands, besides acting as stores of carbon, actively
accumulate carbon in the form ofpeat. Because decomposition is incomplete, carbon is locked up
in organic form in complex substances formed by incomplete decomposition. Estimates suggest
that 5,800 tonnes ofcarbon per hectare can be stored in a 10-metre deep peat swamp compared to
300-500 tonnes per hectare for other types oftropical forest.
Peat swamp forest are used and managed for many different purposes. Undrained peat
swamp forests are valuable habitats for a wide range of biodiversity and ecosystem services and
many are managed as nature reserves. Drained peat swamp' forests are used mostly for agriculture
and forestry but also for peat extraction to provide energy, growing media and other products.
Peat swamp forests are also 'used' or managed indirectly as a result of other landscape activities,
for e~ample, urbanization, mining, recreation, reservoir construction, minerals extraction and
wind farms.
15
Effects of human activity in peat swamp forest
Of the original 27 million ha of peat forests in Southeast Asia, by 2006, 12 million ha
(45%) had been logged and almost as much had been drained (Hooijer et al. 2006). The drivers
that are leading to the loss of the peat forests are global market forces which demand especially
highly for oil-palm products, uses for food industry, and the growing demand for biofuels.
Regional peat swamp forests are primarily managed for timber production (Ng and Ibrahim
2001). In the past, prior to the introduction of mechanization, trees were selectively logged, and
only trees larger than. 45 cm dbh of high commercial value were taken (Ng and Ibrahim 2001).
Selective logging thus removes emergent trees, and when it is extensive it can reduce the canopy
height, reduce diversity (pioneer species colonize gaps) and decrease the stratification of forest
layers. Railway lines were constructed to remove logs by train, and then in the 1980s canal
systems, 3 m wide and 4 m deep, were developed" for log removal (Ng and Ibrahim, 2001). These
leave open scars that last for decades and are usually used in peat forests that are to be converted
to agriculture. Canals cause drainage alteration of the peat swamps hydrology and this adversely
impacts the peat substrate and vegetation, and makes them more susceptible to fires (Hooijer,
2006).
In addition, clearance ofthe peat swamp forest removes the source of freshly fallen leaves •. providing dissolves organic carbon, while burning, dramage and the application of lime and
fertilizers change the physicochemical conditions' further. When peat swamp forest are drained,
the aerobic conditions lead to breakdown and subsidence of the peat, and water holding capacity
is reduced to between 2 and 6 times their weight (Boeder, 1969), so the amount ofwater that can
be retained is far less than in the original peat forest and this will decrease the nutrients available
16