3rd Biennial Conference of Tropical Biodiversity IOP Publishing

IOP Conf. Series: Earth and Environmental Science 1277 (2023) 012003 doi:10.1088/1755-1315/1277/1/012003

Carbon Storage of Mangrove Forests in Sarawak, Malaysia

Seca Gandaseca1,3*, Chandra Iman Ariyanto2, Rahmawaty4,5 and Ahmad

Mustapha Mohamad Pazi2
1
Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM) Shah Alam,
Selangor Darul Ehsan, Malaysia
2
Faculty of Agriculture and Forestry, Universiti Putra Malaysia Bintulu Sarawak
Campus, Sawarak, Malaysia
3
Institute for Biodiversity and Sustainable Development (IBSD), Universiti Teknologi
MARA (UiTM) Shah Alam, Selangor Darul Ehsan, Malaysia
4
Forestry Study Program, Faculty of Forestry, Universitas Sumatera Utara, North
Sumatra, Indonesia
5
Natural Resources and Environmental Management Study Program, Postgraduate
School, Universitas Sumatera Utara, Indonesia.

*Corresponding author’s e-mail: seca@uitm.edu.my

Abstract. The emission of carbon dioxide (CO2) gases into the atmosphere is caused by human
activities such as manufacturing, vehicle smoke, open burning, and clearing areas of agriculture
or development activities. This is a major contributor to global climate change. Mangrove forest
is one of the potential areas for carbon storage. For many years, the number of Mangrove forests
in Malaysia has been decreasing due to some anthropogenic activity and the exploitation of them
for economic gain. This study aims to compare and measure the carbon storage of two different
types of mangroves in Malaysia, namely the WSSM and AALL mangroves. The soil samples
were randomly collected using peat augers at depths between 0 and 30 cm, and 40 samples were
analyzed with a CHNS analyzer. The total carbon content of the soil samples was found to be
12.11% for WSSM and 2.64% for AALL. The significant results and the total soil carbon of
humic acid observed at both study sites as well as the seasonal variation led to the conclusion
that the soil of mangrove has carbon sequestration potential. As a wildlife sanctuary, Sibuti
Mangrove Forest has higher carbon sequestration due to less anthropogenic activity than AALL
Mangrove Forest. The conclusion is that the soil of WSSM Mangrove Forest is better in terms
of location effect than the soil of AALL. During seasonal sampling comparison, higher soil total
carbon content was observed.

1. Introduction
Mangrove is a woody tree and shrub that thrive in mangrove habitat, which is almost but not quite a
tautology [1]. Mangrove is a coastal forest that is affected by tides, soil structure and marine salinity.
Mangrove trees and shrubs are well-adapted to grow in sea or brackish water. Their roots grow into
anaerobic sediment, and they receive oxygen from the air through aerating tissue that communicates to
the air via lenticels on their aerial roots and trunks [2]. One of the world’s most productive and biodiverse
wetlands, Mangrove forests grow in unique conditions and are often found along sheltered coastal areas
in subtropical or tropical regions [3]. However, they are widely distributed in intertidal areas between
land and sea of the world [4, 5].

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3rd Biennial Conference of Tropical Biodiversity IOP Publishing
IOP Conf. Series: Earth and Environmental Science 1277 (2023) 012003 doi:10.1088/1755-1315/1277/1/012003

Mangroves play a unique and complex role in coastal zones in the tropics and subtropics. They are
also one of the transitional ecosystems where the sea, land, and freshwater come together. The main
vegetation components of mangroves are usually evergreen trees, or shrubs, that grow along coastal
areas, brackish seeps, or delta habitats, and their habitat is easy to identify as they are found at the bottom
of tideland mud, or sand flats that are constantly inundated with seawater. Mangroves not only play a
vital role in the sustainability of coastal ecosystems, but they also provide important socio-economic
advantages to coastal communities [6]. A carbon dioxide sink, in combination with other aggressive
conservation measures, helps to mitigate the increasing negative impact on the environment of global
warming. In addition, mangroves, like the coastal forest, contribute to global carbon cycling as they
store a large amount of carbon, as well as potential carbon sinks and contributors to the atmosphere [7].
Carbon storage is the long-term storage of carbon in the form of carbon in soil, in oceans, in soils,
in vegetation (especially in forests), and in geologic formations. The carbon stored in forest ecosystems
is made up of many different components, including biomass carbon, soil carbon, and soil carbon [2].
Carbon is the primary source of life on Earth and is present in all living things. It is mainly found in
plant biomass and soil organic matter, as well as the CO2 (carbon dioxide) in the air and dissolved in
sea water. The carbon content of soil organics can be as low as 48%, as high as 60%, or as high as more
than 90%, depending on the weight of the soil organic matter [8]. Soil carbon contains about 75% of all
the carbon on land and is three times the amount of carbon stored by living plants and animals [2].
Sequester carbon in combination with other conservation efforts helps to reduce the growing negative
effects of global warming and mangroves as the coastal forest.
In recent years, the burning of fossil fuels has become more and more of a problem than nature's
natural recycling process. In addition to global warming issues, these are the environmental issues we
have been talking about since the early 1990s. These issues are happening due to the accumulation of
the greenhouse effect in the atmosphere. In addition, the concentration of the main long-lived
greenhouse gases in the atmosphere continues to increase due to human activity [9], such as
manufacturing, vehicle smoke, open burning, and clearing areas for agriculture or development
activities. Mangrove forest is one of the potential areas for carbon storage. Most of the carbon released
in the atmosphere will absorbed by plants and store in the soil. Therefore, a study of carbon storage in
soil was carried out in the mangrove forest in Sarawak, Malaysia. The main focus of this study is the
carbon storage of the mangrove forests in Sarawak Malaysia.

2. Materials and methods

2.1 Study site
Figures 1 and 2 show the study sites of this study. The study sites are Sibuti mangrove forest, Miri
(WSSM), and Awat-Awat mangrove forest, Lawas, Limbang (AALL), Sarawak, Malaysia.

2.2 Soil sampling

The soil samples were taken at random from the seaward zone 0-20m from the sea edge, the middle
zone 20-40m, and the landward zone 40-60m using the peat auger from 0 to 30 cm depth. 40 samples
were taken in this study period. Samples were air-dried, grinded, and passed through a sieve of 0.2 mm
thickness.

2.3 Soil analysis

2.3.1 Soil total carbon and organic matter. The total C content of the soil samples was determined with
the help of a CHNS analyzer (TruSpec Micro Elemental Analyzer [NCHS] [LECO, US], while soil
organic matter is determined with the aid of a conversion factor of 1,724. These conversion factors are
used to convert the organic matter to the organic carbon assuming that organic matter contains 58% of
the organic carbon (g organic matter /1,724 = g organic carbon)[10]. Then using the formula given by
Donato [11].

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3rd Biennial Conference of Tropical Biodiversity IOP Publishing
IOP Conf. Series: Earth and Environmental Science 1277 (2023) 012003 doi:10.1088/1755-1315/1277/1/012003

2.3.2 Statistical analysis. SAS Version 9.2 was used for statistical analysis and the t test was used to
evaluate the significance of soil carbon sequestration between two sites.

Figure 1. Location of study areas at Wildlife Sanctuary Sibuti Miri (WSSM) Mangrove Forest Miri
Sarawak Malaysia.

Figure 2. Location of study areas at Awat-Awat Mangrove Forest Reserve Lawas Sarawak Malaysia.

3 Results
There were differences in soil organic matter in the Wildlife Sanctuary of Sibuti between three zones,
with the highest found in the middleward zone (21.34±0.29%) and the lowest found in the seaward zone
(20.63±0.33%; Table 1.). On the other hand, soil organic matter in the Awat-Awat Mangrove forest
varied between the three zones, with the highest was found in landward zone (4.83±0.56%) whereas the
lowest was found in the middle zone (4.16±0.29%; Table 1.).

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3rd Biennial Conference of Tropical Biodiversity IOP Publishing
IOP Conf. Series: Earth and Environmental Science 1277 (2023) 012003 doi:10.1088/1755-1315/1277/1/012003

Table 1. Mean of soil organic matter of Wildlife Sanctuary Sibuti, Miri (WSSM) and Awat-Awat Lawas
Limbang (AALL) Sarawak, Malaysia.
Mean (%) Soil Organic Matter
Location Landward
Seaward zone Middle zone
Zone
WSSM 20.63±0.33a 21.34±0.29a 20.91±0.56a

AALL 4.51±0.33b 4.16±0.29b 4.83±0.56b

* Different alphabets within a row or a column indicate significant difference between the mean of selected chemical
properties of different depth using Tukey’s test at P≤ 0.05. Plus and minus symbols at the beginning of the number
represent the decrease and increase in each item. Values in parenthesis represent standard error of the mean.

There were also differences in soil total carbon in the Wildlife Sanctuary of Sibuti between three
zones, with the highest was founded in midleward zone (12.21±0.33%) and the lowest was founded in
seaward zone (11.97±0.29%; Table 2.). On the other hand, soil total carbon in Awat-Awat Mangrove
forest varied between the three zones, with the highest was founded in landward zone (2.80±0.32%)
whereas the lowest was founded in middle zone (2.51±0.14%; Table 2.).

Table 2. Mean of soil total carbon of Wildlife Sanctuary Sibuti, Miri (WSSM) and Awat-Awat Lawas
Limbang (AALL) Sarawak, Malaysia.
Mean (%) Total Carbon
Location Landward
Seaward zone Middle zone
Zone
WWSM 11.97±0.29a 12.21±0.33a 12.15±0.56a

AALL 2.62±0.19b 2.51±0.14b 2.80±0.32b

* Different alphabets within a row or a column indicate significant difference between the mean of selected chemical
properties of different depth using Tukey’s test at P≤ 0.05. Plus and minus symbols at the beginning of the number
represent the decrease and increase in each item. Values in parenthesis represent standard error of the mean.

4 Discussions
Soil carbon analysis of mangrove trees has been carried out in many places around the world with
different site characteristics. The soil carbon content of the Awat-Awat mangrove forest compared to
the values recorded elsewhere can be seen in Table 3. It was found that the soil carbon content in Awat-
Awat mangrove forests in Malaysia was relatively lower than the soil carbon in soil in East Kalimantan
Indonesia, and in Sibuti Malaysia [12]. The soil carbon in the Awat-Awat mangrove forest in Malaysia
showed higher results than soil carbon in the Sundarbands in India [13]. In the current study, soil organic
matter in Malaysia showed comparatively lower results compared to the soil organic matter in East
Kalimantan, Indonesia [14] and in Sibuti, Malaysia [12], but it showed higher results compared to soil
organic matter in Maldives [15]. In the present study, carbon content of the soil under the dominance of
R. apiculata in Awat-Awat mangrove forest was comparatively similar to carbon content in soil under
R. mangle in Sepetiba Bay, Brazil [16]. Studies revealed that the soil carbon content is different and
varies from one different place to another. Different species dominance gave different results to the
content of soil carbon. Moreover, Lacerda et. al. [16] also noted an accumulation of strong evidence for
significant differences among mangrove soils due to the presence of different mangrove species.
With a total area of 678 ha, six study plots of dominant mangroves were established in the Wildlife
Sanctuary Sibuti Miri area to obtain the mean and represent the soil carbon mass according to formula
by Donato [11] in this area. The total mass of soil carbon in the Wildlife Sanctuary Sibuti Miri mangrove

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3rd Biennial Conference of Tropical Biodiversity IOP Publishing
IOP Conf. Series: Earth and Environmental Science 1277 (2023) 012003 doi:10.1088/1755-1315/1277/1/012003

forest was 1,524,6 Mgha-1 of soil carbon, whereas in the Awat-Awat Mangrove forest reserve with a
4372 ha area, the mass of soil carbon was 381,16 Mgha-1 as compared to other studies (Table 4).
Soil carbon and organic matter were found to be 2.64% at WSSM and 4.5% at AALL. The soil
carbon content was highest at the landward zones while the soil organic matter was lowest at the middle
zones. There is a significant difference in soil carbon and carbon mass between the two study areas. Soil
total carbon was 12.11% higher at WSSM than at AALL, and soil carbon mass was found to be 1.524.6
mg ha-1 at WSSM, while it was 381.16 mg h-1 at AALL. It is thought that WSSM, as a wildlife
sanctuary, has higher carbon storage due to fewer anthropogenic activities, as compared to the mangrove
forest at AALL. Therefore, soil carbon content for WSSM and AALL was comparable.

Table 3. Comparison of the found results for carbon concentration with other studies
Author Site Characteristics Organic matter (%) Carbon Content (%)
Sukardjo Mangrove forest of the Apar 6.81% (Avicennia 3.96% (Avicennia forest)
[14](1994) Nature Reserve, East forest) 11.40% (Ceriops forest)
Kalimantan, Indonesia 19.61% (Ceriops forest)
Lacerda et. al. Itacuruca Experimental - 2.70% - 2.80% (under
(1995)[16] Forest, Sepetiba Bay, Brazil Rhizophora mangle) and
3.80% - 6.10% (under
Avicennia schaueriana)
Chmura et. al. World mangrove and salt - 11.1%
(2003)[17] marshes (western and
eastern Atlantic and Pacific
coasts)
Shazra et. al. Mangrove forest of 0.34% and 0.03% 0.196% and 0.017%
(2008)[15] Maldives
Rambok et. al. Sibuti, Malaysia 20.96% 12.11%
(2010)[12] (Wildlife sanctuary
mangrove forest)
Ray et. al. Sundarbands, India - 0.51% - 0.65%
(2011)[13] (natural mangrove forest)

Chandra et. al. Awat-Awat mangrove 4.5% 2.64%

(present study) forest, Malaysia

Table 4. Comparison present study with other studies.

Location Carbon Mass (Mg ha-1)
Coastal Fringe Yap, Federated States of Micronesia [18] 877.0
Sundarbans, Bangladesh [11] 600.1
Coastal Fringe, Republic of Palau [19] 481.8
Kalimantan, Indonesia [20] 1119.4
Wildlife Sanctuary Sibuti Miri mangrove forest [present study] 1,524.6
Awat-awat Mangrove Forest, Lawas [present study] 381.16

5 Conclusion
Soil total carbon at WSSM was found 12.11% better than at AALL where it was found 2.64%, and for
carbon mass were found 1,524.6 Mg ha-1 in WSSM and 381.16 Mg ha-1 in AALL. There is a significance
different in soil total carbon and carbon mass in WSSM and AALL mangrove forests. WWSM as a
wildlife sanctuary has higher carbon storage because of fewer anthropogenic activities compared to the

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3rd Biennial Conference of Tropical Biodiversity IOP Publishing
IOP Conf. Series: Earth and Environmental Science 1277 (2023) 012003 doi:10.1088/1755-1315/1277/1/012003

AALL mangrove forest. Meanwhile, there is a resettlement or villages inside the AALL mangrove forest
with some anthropogenic activities gives influence quality of mangrove forest as well as the carbon
storage in this mangrove area.

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IOP Conf. Series: Earth and Environmental Science 1277 (2023) 012003 doi:10.1088/1755-1315/1277/1/012003

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Acknowledgments
We acknowledge the financial support of the Ministry of Education Malaysia which was given via
Universiti Putra Malaysia. This research was funded through the Research University Grants Scheme
(RUGS). Heartfelt acknowledgements are also expressed to Sarawak Forest Department for their help
in this study.