Inventory of Peatlands in U Minh Ha Region, Ca Mau Province, Viet Nam

Inventory of Peatlands in
U Minh Ha Region, Ca Mau
Province, Viet Nam
Le Phat Quoi,
Institute for Environment and Natural Resources,
National University at HCM City
August 2010


Acknowledgements

This report was produced for Richard McNally, SNV REDD+ Coordinator, as
part of a larger study on Climate Change Mitigation, Adaption and Livelihoods
in and around U Minh Ha National Park.
The author would like to thank Ms. Shashi Kumaran - Prentice (Coordinator,
Peatland Programme Global Environment Centre) and Mr. Chee T Y
(Manager, Global Environment Centre) for their support in the surveys.
The staff of the Ca Mau Forest Protection Department, U Minh Ha National
Park and the 3rd Regional Office for Forest Protection – Vietnam FDP
contributed to surveys and the content of this report through their knowledge
and experience and we extend our sincere thanks to all of them. The names of
some of these people appear in the list of participants.
Cover photograph courtesy of Nguyen Huu Thien.

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Table of contents

Acknowledgements

Page

List of figures
List of table
Summary

i
ii
iii

1 Introduction

1

2 Objective

3

3 Methodology
3.1 Secondary Data Collection
3.2 Satellite Interpretation
3.3 Ground Truthing

4
4
4
5

4 Results and Discussion
4.1 Natural Factors
4.2 Peatlands
4.3 Land cover
4.3.1 Melaleuca forest
4.3.2 Other vegetation
4.3.3 Crops and fruit tree in buffer zone
4.4 Carbon storage

6
6
8
10
10
12
14
16

5 Conclusions

18

References

19

List of participants

20

ANNEX 1:
Plant species found in U Minh Thuong National Park

21

ANNEX 2:
Some typical vegetation in U Minh Ha National Park

22

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List of figures

Figure

Page

Fig 1
Peatlands in the U Minh Region of Lower Mekong Basin,
Vietnam

2

Fig 2

2

Peatland in U Minh Ha (Vo Doi district, Ca Mau Province),
part of the peatland area has been established as a
National Park.

Fig 3
Satellite images covered in UMH region were used or
intepretation

3

Fig 4

Sampling in peatland in UMH region, August 2010

3

Fig 5


Topogrphical map of U Minh Ha National Park, Ca Mau
Province, Vietnam

7

Fig 6

Pyritic materials in sulfidic horizon formed in marine swamp
sediment and Jarosite mineral, and iron hydroxides were
fomred by oxidation and hrydrolysis processes in peatland
of UMH region.
8

Fig 7


Irrigation canal system being used for fire control in U Minh
Ha National Park, Ca Mau Province
8

Fig 8


Distribution of peatlands in U Minh Ha region of Vo Doi
district, Ca Mau Province, Vietnam.

10

Fig 9


Map of peatlands in U Minh Ha National Park, Ca Mau
Province, Vietnam

10

Fig 10

Some typical peat profiles in UMHNP

10

Fig 11


Melaleuca forest mixed with brushwood and grasses in
peatland of U Minh Ha National Park, Ca Mau Province

11

Fig 12


Map of Land cover in peatlands of U Minh Ha area,
Ca Mau Province, Vietnam

11

Fig 13



Many species of vegetation, particularly Fragmitex and
Stenochloena, cover in peatland of U Minh Ha National

Park, Ca mau, Vietnam

12

Fig 14


Map of land cover in U Minh Ha National Park,
Camau Province, Vietnam

13

Fig 15

Some wild vegetations inside the UMH National Park

14

Fig 17


Peat materials on ground surface have been decomposed
as exposing to the air.
15

Fig 18

Models of farming system in peatlands of UMH buffer zone 16

Fig 19

Acacia nursery and planting in peatland of buffer zone

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List of tables

Table

Page

Table 1 Current status of peatlands and thickness of peat layer in

the U Minh Ha region

9

Table 2 Peatlands and thickness of peat layer from 40 – more than

120 cm in the UMH region

9

Table 3 Land cover in U Minh Ha region, Ca Mau province

12

Table 4 Current land cover in the U Minh Ha National Park,

Do Doi district

12

Table 5 Carbon content and calculation of equivalent of CO2

stored in peatland of UMHNP.

18

Table 6 Carbon content, and equivalence of CO2 stored in good

management in peatland of UMH region

18

Table 7 Carbon content, and equivalence of CO2 stored in

peatlands of UMH National Park

18

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Summary

Vietnam has a comparatively small area of peatland compared to its regional
neighbours. Peatlands are found in various areas in Vietnam, but occur mainly
in U Minh region of the Mekong Delta, with a total area of about 35,000 ha.
However, peatlands of U Minh Ha region have been degraded due to the
impact of natural factors and human activities. Survey results showed that only
about 9,853.41 hectares of peatland have remained, with thickness of peat
layers ranging from 0.4 - 1.2 m.
The underneath of peat layer is mainly marine swamp sediment which
contains sulfidic material that will be oxidised and produce a high amount of
acidity in peatland.
A part of the peatland has been converted into U Minh Ha National Park, with
a total area of about 8,286 hectares. 6,063.89 hectares have peat thickness
from 0.4 - 1.2 m and peatland with peat thickness from 1.0 - 1.2 m is only
about 792.04 ha. Average peat bulk density is about 0.23 g/cm3, average
carbon is about 52.6 % in dried peat and 0.134 tons/m3.
Although Melaleuca forest (M. cajuputi) covers most of the peatland in
U Minh Ha National Park (8.552 ha), there is a biodiversity of flora such
as Stenochloena palustris, Lygodium microphyllum, Cayratia trifolia,
Trichosanthes cucumerina, Flagellaria indica, Psychotria serpens and
Passiflora foetida. The most widespread grassland community is dominated by
Phragmites sp., (Phragmites vallatoria, Phragmites karka), Leersia hexandra,
Eleocharis dulcis and E. attropurpea.
Some reports show a biodiversity of fauna with many species of valuable
animals such as Manis javanica, Aony cinerea, Lutra sumatrana, Viverra
zibetha, Viverricula megaspila, Viverricula indica, Prionailurus bengalensis, P.
viverius, Cynoterus branchyotis, Pteropus vampirus, but they are however not
in the scope of this report.

Peatlands in buffer zones have varied land use. Melaleuca plantation
proposed to convert to Acacia, covers a significant area of peatland. Crops
and fruit trees cover a large area of farmer’s peatlands. Leveling of the ground
surface for crop cultivation has resulted in rapid oxidation and degradation of
peat materials.

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Introduction1

Tropical peatlands are widely distributed throughout Indonesia, Malaysia and several other
countries in South East Asia. Peat swamp forests are unique habitats for flora and fauna,
containing a high proportion of endemic species (Page et al., 1999). They play an important
role in stabilizing the ecosystem, particularly in regulating drainage, microclimate, and water
quality and soil formation.
In Vietnam, approximately 183,000 ha of peat swamps can befound, mainly located in the
Lower Mekong Basin (Rieley & Page, 2005). There are two main areas of peat located in the
U Minh area; in Kien Giang and Ca Mau provinces. The first peatland area is protected as a
nature reserve for the conservation of biodiversity and Melaleuca forest; this area lies within
the U Minh Thuong National Park and the Vo Doi Nature Reserve (Figure 1).
The second peatland area is situated in an area of freshwater wetlands, which comprises
peat swamp forests, seasonally inundated grasslands and open swamps. This area is also of
national and international significance for biodiversity conservation.
Vo Doi Nature Reserve, being part of the larger U Minh peat swamp forest, was converted to
U Minh Ha National Park, (from 9°12’30’’ to 9°17’41’’ N and from 104°54’11’’ to 104°59’16’’
E) (Figure 2), and the park is considered one of the key wetland areas in the lower Mekong
basin. Following the occurrence of forest fires, six to ten years ago, and the application

of defoliant agents up to thirty years ago, the area had to be replanted in the recent past.
The total area of the Vo Doi Nature Reserve is 3,688 hectares, most of which comprises
planted Melaleuca peat forests. The rest of the peatland area is scattered across the Ca Mau
Province, particularly in the surrounding areas of U Minh Ha National Park; most of these
peat areas have been converted for paddy rice cultivation or as Melaleuca plantations and
other uses.

Figure 1. Peatlands in the U Minh Region of Figure 2. Peatland in U Minh Ha (Vo Doi
Lower Mekong Basin, Vietnam
district, Ca Mau Province), part of the
peatland area has been established as a
National Park.

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Fauna; many species are found in U Minh Ha National Park where there are also many
species of valuable animals such as Manis javanica, Aony cinerea, Lutra sumatrana, Viverra
zibetha, Viverricula megaspila, Viverricula indica, Prionailurus bengalensis, P. viverius,
Cynoterus branchyotis and Pteropus vampirus.
Fires and conversion to agriculture have reduced the area of intact peatland in the lower
Mekong delta significantly in the past decade. Fires have been a major problem for the
Melaleuca forest on peatland. Only about 800 ha of virgin forest in U Minh Ha survived
the fires in 1994 and 1998, and this area has become part of the Vo Doi Protected Forest.
Another 3,300 ha of Melaleuca forest in Vo Doi and U Minh Ha were destroyed by fires in the
dry season of 2002. Fire not only affects the forest in the U Minh Ha National Park but also
the cultivated areas of peatland in the buffer zone of the national park.
Management of remaining peatlands, cultivated crops and planted Melaleuca forest still

has some problems because there is no proper inventory of the area and no record of any
sustainable use practices. There is clear evidence that fires and human-related activities
have reduced the area of intact peatlands in the National Park and have degraded the
peatlands, but there are no clear records of this. The loss of peat in this area has led to the
exposure of the underlying acid sulphate soils.
However, drainage, extraction and fires, combined with climate change, are converting more
peatlands into sources of carbon rather than stores. Despite the importance of peatlands
they are barely mentioned in standard texts on global warming or emissions scenarios.
The report is the result of a rapid assessment of the peatlands in Ca Mau Province to initiate
the establishment of a peatland inventory in Ca Mau to ensure the sustainable management
of wetland resources toward climatic change mitigation. The rapid assessment formed part
of the activities under the Conservation of Peatland Biodiversity in South East Asia Project
(Phase II), which was supported by the ASEAN Centre for Biodiversity through the Global
Environment Centre. Field data was updated with support from SNV in 2010.

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Objective2

The objective of this activity was to carry out an inventory
of peatlands and land cover in U Minh Ha region, Ca Mau
Province.

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Methodology

The steps implemented to collate information for the inventory of
peatlands in Ca Mau were as follows:
3.1 Secondary Data Collection
Some material and reports prepared by the local scientists and institutions were used as
initial reference material in the study.

3.2 Satellite Interpretation
Interpretation of satellite images (Spot image taken in 2008, and Landsat TM7 taken in
2009)) was used to identify peatland areas in Ca Mau, particularly in UMH region.
Polygons of identified peatland areas were transposed onto GIS maps and hard copies were
printed for the field trip.
The area of peatlands identified in the drawn polygons were surveyed and land-use and/or
vegetation was recorded and recorded onto a map.
The peat was characterized by describing augered samples collected at every polygon
interpreted from satellite images, and at 300 m interval.
The peat colour, degree of humification, and decomposition were only described until 200
cm below the surface while the peat thickness and characteristics of the underlying mineral
substratum were described beyond this depth. Soil and water samples were collected at
diagnostic horizon from 10 – 200 cm depths for testing and analysis.
During the survey/field trip, GPS equipment was used to record the exact geographical
location of study sites.
Carbon content calculation:
Peat bulk density values from peat sample analysis (Mg/m3)
Peatland volume (m3) = area (m2) x thickness of peat layer (m)
Weight of peatland (tons/ha) = peat volume (ha) x bulk density (tons/ha)
Carbon content (tons/ha) = weight of peatland in one hectare x % C (tons/ha)
Capable storage of carbon dioxide release to atmosphere from carbon content if total

amount of peat will be destroyed in peatland (tons/ha)

tC-CO2 e (capable CO2 storage) = Carbon content x 3.67

Note: CO2 emission factor for carbon: 3.67

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3

Figure 3. Satellite images covered in UMH region were used for intepretation.

Spot image (Feb, 2008) at 10x10 m resolution was used
for intepretaion to detect peatland and landcover in UMHNP
(SPOT, 2008).

WorldView-1 imagery (Panchromatic) at waveleghth of 0,40,9 µm, on January, 2008, 30x30m resized resolution.

3.3 Ground Truthing
Grouth truthing was taken from April – May 2009 and August of 2010. Three groups of staff
from the Ca Mau Forest Protection Department, UMHNP and the 3rd Regional Office for
Forest Protection – Vietnam FPD carried out the survey for ground truthing. The location of
the survey sites were recorded by GPS and the data was then transferred and processed by
using GIS multi-software.
The survey was conducted in peatland of the U Minh Ha region covering a total area of
35,654 hectares, of which approximately 8,575 hectares were U Minh Ha National Park and
the remainder was buffer zone, with a total area of about 16,933 hectares.

Figure 4. Sampling in peatland in UMH region, August 2010

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Results and Discussion

4.1 Natural Factors
Landform characteristics: the peat swamp in Ca Mau region is low-lying and relatively flat.
However, in U Minh Ha the peat shape is similar to an inverted saucer with a ‘steeper’ slope
at the edge and a flat to slight curve in the middle. The rise in the elevation of the surface at
the edge of the dome is above 1.2 meters, and about 2.8 meters in middle of dome
(see Fig 5).
In general, the peat lands have higher topography areas of mineral land. There is higher
elevation at the top of the dome and lower toward the margin of the peat plate. Some peat
land areas had higher topography, but became lower resulting from peat forest fire in 2002.
The UMHNP comprises mostly of organic material (peat) with mineral soils confined to flats
of new alluvium in surrounding area. The peat depth generally increases gradually towards
the centre of the peat swamp with a slope of up to about 2 %. The topography of the mineral
ground underneath the peat is irregular giving a wide range of peat thickness (30 to more
than 120 cm).
Figure 5. Topogrphical map of U Minh Ha
National Park, Ca Mau Province

Geology and Soil: The area of peatlands belongs to a young sediment formed from Holocene
period and the soil is classified mainly as Histosols (classified by USDA/Soil Taxonomy) with
a thick Histic horizon. Sediment material underlying the peat layer belongs to marine and

marine swamp sediments. Marine swamp sediment contains a lot of sulfidic materials that
will be oxidized if exposed to the air resulting in very high acidity in soil environment.
Due to impacts from natural factors and human activities, original soil characteristics were
changed, and now some soil types are classified as acid sulphate soils that contain sulfuric
and/ or a sulfidic horizon in the soil profile.
Histic horizon (peat layer) changed normally with topography is a surface horizon and/or
subsurface horizon occurring at variable depths. Analysed data shows a high organic carbon
content in peat layer. While mineral soils contain dominantly clayic materials. Pyritic mineral
(FeS2) in clay subsoil layer was detected in UMH region.

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4

Figure 6. Pyritic materials in sulfidic horizon formed in marine swamp sediment and

Jarosite mineral, as well as iron hydroxides, were fomred by oxidation and

hrydrolysis processes in peatland of UMH region.

Pyrire (FeS2) in subsoil of marine
swamp sediment.

Jarosite (1/3KFe3(SO4)2(OH)6) along
root channels below a
peat layer.

Fe(OH)3 mottles were formed by
hydrolosys process.

In some lower areas, where fire destroyed peat in 2002, a large quantity of water in soil was
lost in the dry season and oxygen penetrated into soil body resulting in oxidation of pyritic
mineral to form actual acid sulphate soils with high acidity. Jarosite mottles showing oxidation
of pyrite were recognized in soil profiles in UMHNP. Clearly acid sulphate soils exposed after
the peat was burned have much lower vascular plant biodiversity than intact peat areas.
Hydrology; seasonal inundation characterized the hydrological regime followed by a
dry season (from Dec - May) with gradual recession of water levels. For fire control and
agricultural cultivation, a system of irrigation canals was built in the peat area. Very low
bulk density of peat (less than 0.25 g/cm3) and high porosity resulting in rapid horizontally
movement of water in peatland.
Dense systems in peatland will suffer from water loss resulting from groundwater infiltration
from peatland to canals, particularly in peat dome area. In such cases, the presence of the
canals has altered the natural water regime of these peat forests, causing lower than normal
groundwater levels that increase the severity and extent of seasonal drying and fragment the
habitat of the area.
Figure 7. Irrigation canal system being used for fire control in U Minh Ha National

Park, Ca Mau Province

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4.2 Peatlands
Based on result of satellite interpretation and on the ground surveys, there is wide distribution
of peatlands in the province. A large area of peatlands in U Minh Ha region was considered

for the survey to identify the presence of peat here. The general map of peatlands in the U
Minh Ha region showed that most of the peatland area is concentrated in the national park
although there are still some peatland areas left outside the national park (see Figure 4).
Of the total area of 35.653.73 ha surveyed, an estimated 9,853 ha (thickness of peat layer
from 40 to more than 120 cm) have been identified as peatlands although many of the areas
recorded have a very shallow peat layer. Thickness of the peat layer from the soil surface
varied from place to place as a result of human activity and fires (see Table 1 and 2). Peat
thickness varied from 40 cm to more than 120 cm but the peat layer category shown in the
map, shows some small patches of shallower peat layers.
Outside the area of peatlands of the UMHNP, peatlands with thickness of peat layer from 40
to 100 cm in the buffer zone cover about 3,492 ha. The area of peatlands with a peat layer
of over 100 cm was estimated at 792 ha, which are concentrated in the core zone of the
national park (Table 2). In addition, scattered peat was found in U Minh Ha region, covering
about 15,000 ha. The two lower categories - Category (1) and (0) - are peatlands that have
been degraded by fires and agricultural cultivation.
Table 1: Current status of peatlands and thickness of peat layer in the U Minh Ha region

Peatlands in UMH region (ha)

Peatland in buffer zone (ha)

Peatland in
UMHNP (ha)

4

100 - > 120

792.04

0

792.04

3

70 - 100

3,855.47

1,665.44

2,190.03

2

40 – 70

5,205.90

1,827.08

3,378.82

15,114.15

13,441.16

1,672.99

None

10,686.17

10,144.44

541.73

Total

35.653.73

27,078.12

8,575.61

1
0

Table 2: Peatlands and thickness of peat layer from 40 – more than 120 cm in the UMH region

Peatlands in UMH region (ha)

Peatland in buffer zone (ha)

Peatland in
UMHNP (ha)

4

100 - > 120

792.04

0

792.04

3

70 - 100

3,855.47

1,665.44

2,190.03

2

40 – 70

5,205.90

1,827.08

3,378.82

Total

9,853.41

3,492.52

6,360.89

Within the U Minh Ha National Park and its marginal areas, peatland areas were found
to cover a total of 8,575.61ha. Peatland with thickness of peat layer from 40 cm to more
than 120 cm was estimated at 6,369 ha, mostly within the national park. However, area of
peatlands that have peat layer from 70 cm - more than 120 cm thick was estimated only
2,982 ha. Area with peat patches scattered within national park occupied about 1,672.99 ha
(Table 1).

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Figure 8. Distribution of peatlands in U
Minh Ha region of Vo Doi district, Ca Mau
Province. U Minh Ha National Park located
in center of region.

Figure 9. Map of peatlands in U Minh Ha
National Park, Ca Mau Province, Vietnam

From the general map of peatlands in the U Minh Ha region (Figure 8) and that of the U Minh
Ha National Park (Figure 9), clearly the area with peat layer over 100 cm (about 792 ha) is
concentrated in the core zone of the national park. This is the area with the deepest peat
layer remaining in the province. Although the national park is considered as a protected area

of peatlands, land without peat layer in the soil profile was identified to cover about 541,73
ha. An umbric or humic surface horizon with high carbon content was also identified in the area.
The peat itself, in UMHNP, has in average a bulk density of 0.19 - 0.26 g/cm³ (average is of
0.23 g/cm3) and the average of C organic content is 52.6% (from seven samples, from 0 120 cm peat depth). From the analyzed data above, calculations estimated peat weight in
square meters. Calculations showed one hectare of peat land with 1 m depth contains about
1,342 tons of C.
Figure 10

Peat layer with 0.5m depth above a
sufidic materials.

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Peat layer with over 1.2 m depth in U
Minh Ha National Park.

Organic matter was formed from
decomposed vegetation residues
on surface horizon in peatland in
UMHNP.

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4.3 Land cover
4.3.1. Melaleuca forest
Melaleuca forest (Melaleuca cajuputi) is dominant in the areas surveyed, with a total
area of about 24,226 ha, in which 15,685 ha is in the buffer zone (Table 3). Based on
the data collected, clearly the forested area has declined significantly as a result of
fires and human activities in the past decades. There is, however, some re-planting

in the peatland area. The age of the Melaleuca forest varied from 3 to more than 12
years. The oldest Melaleuca forest covers only 182 ha in the core zone of the national
park and is considered as semi-natural Melaleuca forest (see Figure 6). Another area
of 1,152 ha is covered by regenerating semi-Melaleuca forest (see Table 3).
Satellite interpretation and other data collected showed that the Melaleuca forest 3-6
years ago occupied a large area, 18,740 ha, and the area was re-planted after the
fire in 2002. There is also brushwood and grass mixed into this area of
Melaleuca forest.
Figure 11. Melaleuca forest mixed with brushwood and grasses in peatland of U Minh

Ha National Park, Ca Mau Province

Figure 12. Map of Land cover in peatlands
of U Minh Ha region, Ca Mau Province,
Vietnam

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Table 3.

Land cover in U Minh Ha region, Ca Mau province

Code

Landcover Types

UMH region (ha)

Buffer zone (ha)

UMHNP (ha)

1

Mellaleuca 3 years old

9,831.26

5,932.19

3,906.20

2

Melaleuca 3 – 6 years old

8,909.01

6,010.57

2,906.55

3

Melaleuca 6 – 9 years old

4,151.31

3,574.68

574.10

4

Melaleuca 9 – 12 years old

1,152.02

163.34

986.84

5

Melaleuca > 12 years old

182.54

4.39

178.14

6

Paddy rice and forest plantation

1,024.95

1,024.95

0

7

Grass land

619.90

615.03

4.86

8

Paddy rice

9,227.35

9,216.47

0

9

House land

152.42

152.42

0

Total

35,250.76

26,694.06

8,556.69

In the U Minh Ha National Pak and its marginal area most of the area (8,557 ha) is
covered by Melaleuca forest(see Figure 14 and Table 4). There was a small area
classified as grassland, 4.86 ha. Semi-natural Melaleuca forest occupied a small
area, about 178 ha. Melaleuca forest that was re-planted after the fire in 2002 was
over 7,000 haacross the national park. Although three year old Melaleuca forest
covered a large area, 3,900 ha, brushwood and grasses were also identified in the
forest area. The forest was dominated by Melaleuca cajuputi but other tree species
were also seen: Trema orientalis and Combretum acuminatum were confined to the
forest edge (see Figure 8).
Figure13. Many species of vegetation, particularly Fragmitex and Stenochloena, cover

in peatland of U Minh Ha National Park, Ca mau, Vietnam

Phragmites vallatoria and woodtree in banks of canal
system inside of U Minh Ha National Park

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Stenochloena palustris is one of species of liana vegetation
dominatetely in Melaleuca forest

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Table 4.

Current land cover in the U Minh Ha National Park, Do Doi district

Landcover

Area (ha)

Mellaleuca 3 years old

3,906.20

Melaleuca 3 – 6 years old

2,906.55

Melaleuca 6 – 9 years old

574.10

Melaleuca 9 – 12 years old

986.84

Melaleuca > 12 years old

178.14

Grass land

4.86

Total

8,556.69

Although this report considered only general land cover of forest in the national park,
it was found that the diversity of vegetation species was quite high in the peatland
areas. We noted that an earlier survey recorded 33 species of vascular plants in the
area; of this 22 species were found in undisturbed peatland areas (Guong et al, 2006)
(See also Annex 1).
Figure 14. Map of land cover in U Minh Ha
National Park, Camau Province

4.3.2. Other vegetation
A wide range of vegetation species is found in U Minh Ha National Park and
seasonally inundated grassland and shrubs.
Semi-natural Melaleuca forest covers a large area in the west of the core zone.
Although other tree species are present, Melaleuca cajuputi is dominant in U Minh Ha
region. Melaleuca was planted after fires in 2002 and later years, therefore Melaleuca
plantations of varying ages are distributed in many places in the park. In the peat
dome of the park other trees such as Alstonia spathulata, Eugenia spp., Eugenia
oblata Roxb, Acronychia laurifolia Blune and Ilex thorelii Pierre are mixed with

Melaleuca, grass and shrubs. Annona glabra also are common along canals.

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Figure 15. Some wild vegetation inside the UMH National Park

Blechnum serrulatum Rich

Colocasia esculenta (L.) Schott

Ilex thorelii Pierre

Bố rừng Muntingia

Common species of liana are found in the Melaleuca forest, such as Stenochloena
palustris, Lygodium microphyllum, Cayratia trifolia, Trichosanthes cucumerina,
Flagellaria indica, Psychotria serpens and Passiflora foetida.
The most widespread grassland community is one dominated by Phragmites sp.,
(Phragmites vallatoria, Phragmites karka), Leersia hexandra. Eleocharis dulcis and E.
attropurpea are common in acid sulphate soils.
According to Barry Clough et al (2008), the species diversity was higher on intact
peatland (28 species) compared with that of the burned area with exposed acid
sulphate soils (14 species). Of the eight tree species found on intact peatland, only
one (M. cajuputi) was also present on the exposed acid sulphate soils of the burned
area. Similarly, of the six climbers common on intact peatland, only one (C. trifolia)
was found in much smaller numbers on exposed acid sulphate soils in the burned
area. Shrub and herb species were also poorly represented in the burned area with

exposed acid sulphate material.

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4.3.3. Crops and fruit trees in buffer zone
Although some peatland area is covered by Melaleuca, a large area of peatland in
the buffer zone has been converted to agricultural land.
Because of high topography of peatland, ground surface leveling, which has resulted
in acceleration of rapid oxidation and then degradation of peat materials, has been
done for crop cultivation in peatlands. Raised bed method has also been applied in
lower peatland, through which peat materials in soil body were brought up to ground
surface. In such cases peat materials were exposed to the air and thenoxidized
rapidly.
As well as peat materials, pyritic materials (bottom peat layers) in marine swamp
sediment were taken from the peat body. They have been brought to the ground
surface and have oxidised to form jarositic materials (1/3KFe(SO4)2(OH)6). Apparently
a large area of actual acid sulphate soils has been formed by drainage in past years
(Fig. 16).
Figure 16. Peat and pyritic material was brought up in peatland. Part of pyritic material

was oxydized to form Jarosites mottles on ground surface.

Peat and pyritic materials (FeS2) were ditched and brought
up to ground surface in peatland.

Pyritic materials (FeS2) were oxidized to formed Jarositic
minerals (3KFe(SO4)2(OH)6). on ground surface.

Deforestation and drainage for agricultural production has resulted rapidly in organic
decomposition in peatland. Loss of water in dry season has been a big problem for
peatland management in UMH region (Fig. 17).
Figure 17. Peat materials on ground surface have been decomposed from exposure to

the air.

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A diversity of crops and fruit trees have been planted in buffer zone. Crops planted
include maize, pineapple, cassava, banana, rice, jam, and tomato. Banana was also
planted in many places in high organic soils, which is good for banana (Fig. 18).
As mentioned above, Melaleuca has been planted in a considerable area of buffer
zone. However, the low price of Melaleuca product nowadays necessitates a
switch tooptions which are more economically valuable to local people and forest
enterprises. Acacia is one of the valuable trees intended to replace Melaleuca in
buffer zones (Fig. 19).
Figure 18. Models of farming system in peatlands of UMH buffer zone

Pineapple planted in raised bed of peatlands

Dioscorea esculenta crop planted in peatland after making
levelling and raised bed

Derris tonkinensis were planted directly in peatland in
buffer zone of UMH Region.

Cassava planting on raised bed and paddy rice cultivating in
small ditch in peatlands.

Acacia planting on a large area will be a problem for peatlands environment. Acacia
is not appropriate in submerged conditions for a long period of the year; therefore,
the raised bed method applied for planting Acacia will result in rapid decomposition of
organic matter after exposure to the air.

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Figure 19. Acacia nursery and planting in peatland of buffer zone

Acacia nursery in garden of household

Acacia planting in farming land in buffer zone

4.4 Carbon storage
Peatland drainage for afforestation and conversion of peatland forest for agricultural
production will damage peatlands, releasing many tonnes of carbon into the atmosphere.
Apparently if peatland is lost, it is unable to sequester further carbon and most of the former
carbon store is suddenly released into the atmosphere.
Based on the results of physical-chemical analysis of peat samples, calculation of carbon
organic content in peatland of U Minh Ha region was shown in Table 5. Percentage of
Carbon (C) in each peat horizon is variable, with an average value of 53.64%. Peatlands
in U Minh Ha region have different thickness of peat layers, hence there is a difference of
carbon content in each peatland area. In areas with peat layer thickness of 70 cm, the carbon

content is up to 813.58 tons/ha, and in areas with peat layer thickness of up to 120 cm, the
carbon contained in peatland is of 1,482.69 tons/ha (Table 5).
Data also showed that peatlands in UMH region, particularly in UMHNP, have stored a
significant quantity of Carbon that will be able to be transformed to carbon dioxide (CO2) to
release into the atmosphere if peatland is drainaged or converted to agriculture for a
long period.
Estimating calculated data shows total equivalent amount of C-CO2 is about 32,373,798.35
tons in the whole UMH region. While UMH National Park is about 21,150,939.10 tons C-CO2
(Table 6 and 7).

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Table 5.


Carbon content and calculation of equivalent amount of CO2 stored in peatland
of UMHNP.

Dep
(m)

Bulk Density
(Mg/m3)

Area
(m2)

Volume
(m3)

Weight
(tons/ha)

C
(%)

Carbon content
(tons/ha)

t C-CO2e
(tons/ha)

0.10

0.22

10000.00

1,000

220

53.40

117.48

431.15

0.20

0.22

10000.00

2,000

430

53.80

231.34

849.02

0.30

0.21

10000.00

3,000

620

54.03

335.01

1,229.47

0.40

0.21

10000.00

4,000

830

54.00

448.20

1,644.89

0.50

0.21

10000.00

5,000

1,050

53.96

566.58

2,079.35

0.60

0.21

10000.00

6,000

1,270

53.40

678.18

2,488.92

0.70

0.22

10000.00

7,000

1,520

53.54

813.85

2,986.83

0.80

0.22

10000.00

8,000

1,780

53.40

950.52

3,488.41

0.90

0.23

10000.00

9,000

2,030

53.50

1,086.05

3,985.80

1.00

0.23

10000.00

10,000

2,280

53.52

1,220.26

4,478.34

1.20

0.23

10000.00

12,000

2,771

53.51

1,482.69

5,441.47

Table 6.

Thickness
of peat
layer
(cm)

Carbon content, and equivalence of CO¬2 stored in good management in
peatland of UMH region
Av.
thick
(m)

Area
(ha)

Bulk
Density
(Mg/m3)

Volume
(m3/ha)

Average
weight
(tons/ha)

Weight
(tons/area)

Average
Carbon
(%)

Average
Carbon
content
(tons/ha)

Carbon
content
(tons/area)

t C-CO2e
(tons/ha)

t C-CO2e
(stored)
(tons/area)

100 - 120

1.10

792.04

0.23

11,000.00

2,530.00

2,003,861.20

53.55

1,354.82

1,073,067.67

4,972.17

3,938,158.36

70 - 100

0.90

3,855.47

0.23

9,000.00

2,028.17

7,819,548.59

53.47

1,084.46

4,181,112.63

3,979.98

15,344,683.36

40 - 70

0.60

5,205.90

0.21

6,000.00

1,277.62

6,651,161.96

53.63

685.19

35,67,018.16

2,514.64

13,090,956.64

scattered

15,114.15

-

-

-

-

-

-

-

-

-

None

10,686.17

-

-

-

-

-

-

-

-

-

16,474,571.75

-

8,821,198.46

Total

Table 7.

Thickness
of peat
layer
(cm)

35,653,73

-

-

-

-

32,373,798.35

Carbon content, and equivalence of CO¬2 stored in peatlands of U Minh Ha
National Park
Av.
thick
(m)

Area
(ha)

Bulk
Density
(Mg/m3)

Volume
(m3/ha)

Average
weight
(tons/ha)

Weight
(tons/area)

Average
Carbon
(%)

Average
Carbon
content
(tons/ha)

Carbon
content
(tons/area)

t C-CO2e
(tons/ha)

t C-CO2e
(stored)
(tons/area)

100 - 120

1.10

792.04

0.23

11,000.00

2,530.00

2,003,861.20

53.55

1,354.82

1,073,067.67

4,972.17

3,938,158.36

70 - 100

0.90

2,190.03

0.23

9,000.00

2,028.17

4,441,753.15

53.47

1,084.46

2,375,005.41

3,979.98

8,716,269.84

40 - 70

0.60

3,378.82

0.21

6,000.00

1,277.62

4,316,848.01

53.63

685.19

2,315,125.59

2,514.64

8,496,510.90

scattered

1,672.99

-

-

-

-

-

-

-

-

-

None

541.73

-

-

-

-

-

-

-

-

-

10,762,462.35

-

5,763,198.67

Total

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8,575.61

-

-

-

-

21,150,939.10

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Conclusions5

The survey results on the distribution of peatlands and land covered in the U Minh Ha area
can be summarized as follows:
The total area of peatlands in the U Minh Ha area in the Ca Mau province was large,
approximately over 35,000 ha, but the peatlands have been degraded because of war, fires
and human activity in the past few decades.
The total peatland area with thickness of peat layer from 50 to more than 100 cm was
estimated at only 4,647.51 ha; half of this area (2,982.07 ha) is protected and located in the
national park. The area is covered by Melaleuca forest.
The area of peatlands outside the national park has been under extensive rice cultivation and
the peat layer in the soil has been degraded.
The main threat to the remaining peatlands in the area is fire. Serious fires, the latest in
2002, have destroyed large areas of peat. Forest fires have been found to affect not only the
thickness of the peat layer but also the quality of peat found in the area.
A canal system for fire control built in the peatland area has resulted in subsidence of the
peat because of increased loss of water in the dry season.
Peatland areas within the national park have been assessed as areas of high biodiversity, but
a monitoring system needs to be considered and established and fire prone areas (hotspots)
need to be identified to enhance the management of the remaining peat areas.
Peatland in UMH region stores a large quantity of carbon. If of oxidation, either as a result of
increased decomposition on improved drainage, deforestation, conversion of peatlands to
agricultural land or by burning, all CO2 produced goes to the atmosphere.

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References

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biodiversity in Vo Doi National Park, U Minh Ha, Mekong Delta.
CTU, 2006.
Bird Life International, 2000. Wetlands in the Balance. A strategy for
balance and harmony in wetland resource management in the Mekong
Delta. 2000.
Bradford M. Sanders, 2004. Fire Incident Assessement: U Minh Ha and
U Minh Thuong National Park.
Hoa, N.M., Linh, B.T., Bang, P.T., Guong, V. T., 2007. Soil and water
characteristics of burn peatswamp forest underplain of acid sulphate
soils at U Minh Ha National Park in the Mekong Delta in Vietnam.
CTU, 2008.
ICEM, 2003. Vietnam: National Report on Protected Areas and
Development. ICEM, Indooroopilly, Queensland, Australia, 2003.
Minh, V. Q. and Guong V. T., 2008. Spatial Variogram of peat soil
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CTU, 2009.
Minh, V.Q., Diep, V.T.H., Guong, V.T., 2006. Using remote sensing for
evaluating the chage of peatswamp forest in the Mekong Delta, Vietnam.
CTU, 2006.
MWBP, 2006. Overview of Wetlands Status in Viet Nam Following 15
Years of Ramsar Convention Implementation. IUCN, 2006.
Rekilä Teppo, 2007. Tropical Peat Interactions with Acid Sulphate Soil.
Joutsjoki Tiina
Couwenberg J., 2009. Emission factors for managed peat soils (organic
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