The role of mangroves in response to climate change in dong rui and hai lang communes, tien yen district, quang ninh province

VIETNAM NATIONAL UNIVERSITY, HANOI

VIETNAM JAPAN UNIVERSITY

NGUYEN THI HOA

THE ROLE OF MANGROVES IN RESPONSE TO
CLIMATE CHANGE IN DONG RUI AND HAI
LANG COMMUNES, TIEN YEN DISTRICT,
QUANG NINH PROVINCE

MASTER'S THESIS


VIETNAM NATIONAL UNIVERSITY, HANOI
VIETNAM JAPAN UNIVERSITY

NGUYEN THI HOA

THE ROLE OF MANGROVES IN RESPONSE
TO CLIMATE CHANGE IN DONG RUI AND
HAI LANG COMMUNES, TIEN YEN
DISTRICT,
QUANG NINH PROVINCE

MAJOR: CLIMATE CHANGE AND DEVELOPMENT
CODE: 8900201.02QTD

RESEARCH SUPERVISOR:
Dr. LUU VIET DUNG
Dr. KOTERA AKIHIKO

Hanoi, 2021


PLEDGE
I assure that this thesis is the result of my own research and has not been published.
The use of other research's result and other documents must comply with regulations.
The citations and references to documents, books, research papers, and websites must
be in the list of references of the thesis.

Author of the thesis

Nguyen Thi Hoa


ACKNOWLEDGMENTS
I would like to express my deep gratitude to Vietnam Japan University and Program
Climate change and Development for all the thoughtful guidance.
I am extremely grateful to my supervisor Dr.Luu Viet Dung, sub-supervisor Dr.Kotera
Akihiko, and other lecturers for their invaluable advice, continuous support, and
patience during my thesis progress.
I want to thank local authorities, local residents of Hai Lang and Dong Rui communes,
Tien Yen district, Quang Ninh province provided information and supported me when
I went on to field trip and collected data here.
I would like to thank my friends and my family for all the support you have shown me
through the study and research.
Thank you very much!


TABLE OF CONTENT

LIST OF TABLES ...................................................................................................... i
LIST OF FIGURES .................................................................................................... ii
CHAPTER 1. INTRODUCTION ............................................................................... 1
1.1 Introduction ....................................................................................................... 1
1.2 Study area .......................................................................................................... 2
1.2.1 Geographical features ................................................................................. 2
1.2.2 Climate features .......................................................................................... 3
1.2.3 Social - Economic Status of Hai Lang and Dong Rui communes .............. 4
1.2.4 Some manifestations of CC in Dong Rui and Hai Lang communes .......... 4
1.3 Literature Review ............................................................................................ 12
1.3.1 The concept of mangrove ecosystem ........................................................ 12
1.3.2 Impact of CC on mangrove....................................................................... 13
1.3.3 The role of the mangrove ecosystem in response to CC .......................... 13
1.4 Objectives of the research ............................................................................... 19
CHAPTER 2. DATA COLLECTION AND METHODOLOGIES ......................... 21
2.1 Logical framework .......................................................................................... 21
2.2 Data collection ................................................................................................ 22
2.3 Methodologies ................................................................................................. 24
2.3.1 Data collection method ............................................................................. 25
2.3.2 Data analysis method ................................................................................ 28
CHAPTER 3. RESULTS AND DISCUSSION ....................................................... 30
3.1 Structure and characteristics of mangroves in Dong Rui and Hai Lang communes
............................................................................................................................... 30
3.2 The role of mangrove forests in the natural system ........................................ 33
3.2.1 Benefit from maintaining biodiversity and food webs ............................. 33
3.2.2 Benefit from carbon storage ..................................................................... 38
3.2.3 Benefit from coast protection ................................................................... 42
3.3 The role of mangrove forests in the social system .......................................... 47
3.3.1 Benefit from reducing the impact of CC on the local community ........... 47
3.3.2 Benefit from maintaining people's livelihood .......................................... 51

3.4 Recommendation............................................................................................. 63
CHAPTER 4. CONCLUSION ................................................................................. 66
REFERENCE ........................................................................................................... 68
APPENDIX ………………………………………………………………………..72


LIST OF TABLES
Table 1.1: Variation of average temperature in winter, spring, summer, and autumn
compared with the baseline period of Quang Ninh .................................................... 9
Table 1.2: Change of precipitation in winter, spring, summer, and autumn compared to
the base period of Quang Ninh province .................................................................. 11
Table 1.3: Sea level rise scenarios in Mong Cai-Hon Dau ..................................... 11
Table 1.4: The inundation risk due to rising sea levels caused by CC for Quang Ninh
province .................................................................................................................... 12
Table 2.1: Datatypes use in research ........................................................................ 23
Table 2.2: Methods used in the research .................................................................. 24
Table 3.1: Height and distribution of mangroves communities in Dong Rui commune
.................................................................................................................................. 31
Table 3.2: Total carbon accumulated in the biomass of mangrove trees at Dong Rui
Commune.................................................................................................................. 38
Table 3.3: Total carbon accumulated in the biomass of mangrove trees at Hai Lang
Commune.................................................................................................................. 38
Table 3.4: Total carbon accumulated in mangroves Dong Rui Commune .............. 39
Table 3.5: Total carbon accumulated in mangroves Hai Lang Commune ............... 40
Table 3.6: Forest function of mangroves in Dong Rui commune in 2016 - 2017 .. 42
Table 3.7: Forest function of mangroves in Hai Lang commune in 2016 - 2017 ... 43
Table 3.8: Forest function, sub-class of mangroves in Đồng Rui commune in 2016 and
2017 .......................................................................................................................... 45
Table 3.9: Forest function, sub-class of mangroves in Hai Lang commune in 2016 and
2017 .......................................................................................................................... 45

Table 3.10: Number of people participating in occupations in Dong Rui and Hai Lang
commune ................................................................................................................. 51
Table 3.11: Values of using mangrove forest in Dong Rui commune ..................... 59

i


LIST OF FIGURES
Figure 1-1: Administrative map of Dong Rui and Hai Lang communes ................... 3
Figure 1-2: The lowest, highest, and average temperatures of Tien Yen weather station
in the period 1990-2020.............................................................................................. 5
Figure 1-3: Temperature anomaly (average, max, and min) in Tien Yen weather station
in period 1990-2020 ................................................................................................... 6
Figure 1-4: The highest precipitation and average precipitation of Tien Yen weather
station in the period 1990-2020 .................................................................................. 7
Figure 1-5: Total precipitation day of Tien Yen weather station in period 1990-2020
.................................................................................................................................... 8
Figure 1-6: Precipitation anomaly (max and average) in period 1995-2019 ............. 8
Figure 2-1: Logical framework of the research ........................................................ 21
Figure 2-2: Observation in the boat .......................................................................... 26
Figure 2-3: Observation of mangrove forest ............................................................ 27
Figure 2-4: Interview resident .................................................................................. 27
Figure 3-1: Geo-vegetation map of wetland area in Dong Rui, Tien Yen ............... 30
Figure 3-2: Mangrove ecosystems of Dong Rui and Hai Lang Communes ........... 31
Figure 3-3: Cormorants includes 28 birds in the mangrove forest of Dong Rui
commune .................................................................................................................. 33
Figure 3-4: Different species of animals in the mangroves (a) crab, (b) sea snail, (c)
sea oysters, and (d) mussels...................................................................................... 36
Figure 3-5: Total carbon accumulated in mangroves Dong Rui and Hai Lang
Communes ................................................................................................................ 41

Figure 3-6: Forest function of mangroves in Dong Rui commune .......................... 43
Figure 3-7: Forest function of mangroves in Hai Lang commune ........................... 44
Figure 3-8: Map of forest function in 2017 in a) Dong Rui and b) Hai Lang Communes
.................................................................................................................................. 44
Figure 3-9: Map of forest function, sub-class in 2017 in a) Dong Rui and b) Hai Lang
Communes ................................................................................................................ 46
Figure 3-10: Mangroves reduce the impact of erosion in Dong Rui Commune ...... 46
Figure 3-11: Mangroves reduce the impact of waves in Dong Rui Commune ........ 46
Figure 3-12: Natural disasters affecting households in Dong Rui and Hai Lang
communes ................................................................................................................. 48
Figure 3-13: The role of mangroves in reducing the impact of the typhoon in Dong Rui
.................................................................................................................................. 49
Figure 3-14: The percentage of respondents answering that they know about "CC" in
Dong Rui Commune ................................................................................................. 50
Figure 3-15: Information channels providing knowledge about CC in Dong Rui
Commune.................................................................................................................. 50
Figure 3-16: The role of mangroves in CC response in Dong Rui .......................... 51
ii


Figure 3-17: Duck farming area near the mangrove forest ...................................... 53
Figure 3-18: People sell seafood to traders after returning from fishing ................. 54
Figure 3-19: Some methods of fishing in mangroves a) shovel and b) fishing net.. 58
Figure 3-20: Values of using mangrove forest in Dong Rui commune ................... 60
Figure 3-21: The role of mangrove protection in socio-economic development ..... 61
Figure 3-22: Mangrove conservation in Dong Rui commune .................................. 62
Figure 3-23: Long Vang beach in Dong Rui mangrove forest, Tien Yen district .... 65

iii

CHAPTER 1. INTRODUCTION
1.1 Introduction
Vietnam is one of the most vulnerable countries to climate change (CC). According to
the Global Climate Risk Index 2020 of Germanwatch, Vietnam ranked 6th on the
global vulnerability scale in 2018 (1999-2018), increasing three ranks than 1998-2017
(VietnamPlus, 2019). Recently, Vietnam's weather has changed more and more
erratically. In particular, phenomena such as droughts, floods, landslides, storms, sealevel rise have complicated developments.
Vietnam has 28 coastal provinces with a total length coastline of 3260 km (MOFA,
2020). Therefore, mangroves appear everywhere along the coastal area. The area in
Vietnam is more than 200000 hectares. Vietnam has become one of the countries with
the largest mangrove forest area in the world. Some extensive mangroves such as Can
Gio mangroves, mangroves in Tam Giang lagoon, Ca Mau mangroves, etc (Binh,
2019).
Quang Ninh is located in the North of Vietnam, where have mangrove forest
development. In Quang Ninh, the mangroves in Dong Rui and Hai Lang communes,
Tien Yen district has the typical characteristics of the mangroves in the North of Viet
Nam. Mangroves include many different types of trees and aquatic species (Climate
change, 2019). Especially, mangrove forests provide ecosystem services for human
society to respond to CC.
Nowadays, extreme weather events and natural disasters are challenging to predict.
Therefore, the role of mangroves is becoming more and more important. Mangroves
have an important role in maintaining biodiversity and the food web. Besides, It helps
to reduce the impact of CC on communities and develop the economy. Moreover,
mangrove forest is one of the largest carbon pools in the world (Donato et al., 2011). It
helps reduce carbon dioxide, which is the main cause leading to global warming.
Mangrove forest in Dong Rui and Hai Lang communes, Tien Yen district is a specific,
sensitive, and highly biologically diverse ecosystem. The area of mangrove forest

1

accounts for a large proportion of the natural area of the two communes. Therefore, the
socio-economic activities of the two communes are strongly related to mangroves.
However, at present, mangrove forests in these two communes face many challenges
in exploitation, use, and management. Economic and social development activities;
The pressure of population growth and the degradation of natural resources, and the
pollution environment due to over-exploitation are increasingly threatening the
mangroves in this area.
Because of the increasing impacts of CC on coastal areas, it is necessary to assess the
role of mangroves in CC response. In particular, the mangrove forests in Dong Rui and
Hai Lang have a typical ecosystem of Vietnam's northern region. Moreover, Quang
Ninh Province is preparing documents to establish Dong Rui Wetland Reserve - Tien
Yen District, demonstrating the important role of mangroves in Dong Rui and should
be conserved.
Because of the substantial impacts of CC and the vital role of mangroves in Hai Lang
and Dong Rui Communes, I chose the topic: "The role of mangroves in response to
climate change in Dong Rui and Hai Lang Communes, Tien Yen District, Quang
Ninh Province."
This study assesses mangrove forests' role in providing ecosystem services for human
society to respond to CC. Besides, the study also gives some suggestions to improve
the ability of mangroves to respond to CC. The study was carried out in two areas with
relatively similar natural and social conditions for comparison and analysis.
1.2 Study area
1.2.1 Geographical features
This study was conducted in two communes Dong Rui and Hai Lang, Tien Yen
district, Quang Ninh province (Figure 1.1). These two communes are located in the
northeastern region of Vietnam. Dong Rui commune has a total natural area of
5045.08 ha, located southwest of Tien Yen district, 18 km away from the district
center. Dong Rui is a plain commune surrounded by the sea that is a good area for

concentrated farming and aquaculture, population development, mangrove planting,
2


etc. In recent years, the commune has built a system of dykes around the commune to
limit the influence of natural disasters. Outside the dike are mangroves and some
aquaculture areas. In addition, the commune has a concrete road running from Ba Che
bridge connecting with National Highway 18A to the commune center. This is the
main route for goods exchange with neighboring districts (Thuyết minh bản đồ hiện
trạng sử dụng đất năm 2019 xã Đồng Rui, 2019).
Hai Lang is a coastal commune, lowland, located at the gateway of Tien Yen district,
characterized by mountainous coastal terrain. The total natural land area is 8183 ha.
The commune has a diverse geography, including mountains, hills, midland plains,
aquaculture areas within the dike, intertidal areas - rivers and canals outside the dike
(Điều kiện tự nhiên xã Hải Lạng, 2019).

Figure 0-1: Administrative map of Dong Rui and Hai Lang communes
1.2.2 Climate features
Dong Rui and Hai Lang are located in the humid tropical climate typical of eastern
Quang Ninh province. The annual average temperature is 22.4oC, the winter is cold
and dry for many days with frost, and the weather is sometimes below 4oC.
Rain usually focuses from June to September with thunderstorms. Drizzly rain occurs
from December to April, focusing on February. Summer often has thunderstorms,
3


storms, and cyclones with a frequency of about 3-4 storms per year. The annual
rainfall average is 2427 mm, drizzly and often foggy in winter (Nga, 2011).
1.2.3 Social - Economic Status of Hai Lang and Dong Rui communes
Firstly, Dong Rui commune is home to many different ethnic groups, including Kinh,

Tay, San Chi, San Diu, Dao, of which the Kinh majority accounts for 84% (Thuyết
minh bản đồ hiện trạng sử dụng đất năm 2019 xã Đồng Rui, 2019). On the other hand,
unlike Dong Rui commune, Hai Lang commune has up to 68% of ethnic minorities.
The commune has 13 villages, including 03 villages with 100% ethnic minorities
include Doi Che, Khe Ho, Thanh Hai. The commune has 1510 households with 6100
people (Điều kiện tự nhiên xã Hải Lạng, 2019).
Secondly, Dong Rui is a mountainous coastal commune with complicated topography.
The people's life still faces many difficulties, the people's income is still meager. At
present, the commune is mainly engaged in agricultural production and livestock and
poultry farming, afforestation and forest protection, and near-shore and offshore
fishing and aquaculture. Over the years, Dong Rui commune has strived to overcome
and improve difficulties in people's life and economic development. The commune
Party committee had many activities: develop agriculture - forestry, fishery,
husbandry, and commercial services, create diversified trades, socio-cultural
development, national defense and security (Thuyết minh bản đồ hiện trạng sử dụng
đất năm 2019 xã Đồng Rui, 2019).
Hai Lang commune is a coastal commune favorable for developing agriculture,
forestry, and fishery. The agricultural development situation is becoming more and
more stable. In the fields of culture and society, there are many innovations in a more
positive direction. The contingent of cadres is trained in the basic, enthusiastic, and
creative construction of a new countryside. Cultural movements are increasingly
promoted.
1.2.4 Some manifestations of CC in Dong Rui and Hai Lang communes
Weather station plays a vital role in measuring hydro-meteorological data and
transmitting information, hydro-meteorological monitoring data. In Tien Yen district, a
weather station was installed in Tien Yen town, located relatively close to the two
4


communes of Dong Rui and Hai Lang. This weather station about 24.9 km from Dong

Rui commune and about 14.3 km from Hai Lang commune. Therefore, I use the Tien
Yen weather station data to analyze weather changes from 1990-2020 in the study
area.
1.2.4.1 Temperature
Figure 1.2 below shows the highest, lowest, and average temperature of the Tien Yen
weather station during the period 1990-2020:
50
40
30
20
10
0

Ta

Tmax

Tmin

Figure 0-2: The lowest, highest, and average temperatures of Tien Yen weather
station in the period 1990-2020 (Unit: oC)
Source: Tien Yen Weather station (Tien Yen Weather station, 2020)
Figure 1.2 illustrates that the temperature difference is markedly between the highest
and lowest. The difference between the highest and lowest temperature is 30-33oC.
The lowest temperature ranges from 3-7oC in December and January. The highest
temperature ranges from 35-37oC from May to August.
Followed by figure 1.3 showing the temperature difference compared to the period
1990-2020 average:

5

3.0
2.0
1.0
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014

2015
2016
2017
2018
2019
2020

0.0
-1.0
-2.0
-3.0
-4.0
-5.0
Linear (Ta)

3.0

1.0

1.0

-1.0

1990
1992
1994
1996
1998
2000
2002

2004
2006
2008
2010
2012
2014
2016
2018
2020

3.0

-1.0

-3.0

-3.0

-5.0

-5.0
Tmax

Linear (Tmax)

1990
1992
1994
1996
1998

2000
2002
2004
2006
2008
2010
2012
2014
2016
2018
2020

Ta

Tmin

Linear (Tmin)

Figure 0-3: Temperature anomaly (average, max, and min) in Tien Yen weather
station in period 1990-2020 (Unit: oC)
Source: Tien Yen Weather station (Tien Yen Weather station, 2020)
Looking at figure 1.3, temperature anomaly (average, max, and min) changes
continuously over the years. On the one hand, the highest and average temperatures
tend to increase over time. On the other hand, the lowest temperature tends to decrease
gradually over time. Thus, extremely hot and extreme cold tend to increase over time.
However, because the maximum temperature rises more than the minimum
temperature decrease, the annual average temperature in this area still increases over
the years.
In 2011, there was a sharp decrease in temperature compared to 2010. The cause of
this phenomenon is the La Nina phenomenon affecting the climate of Northern

Vietnam. This La Nina phenomenon has made the 2011 winter colder, with many cold
spells throughout the North.

6


The temperature trend of two communes is quite similar to the temperature trend of
Vietnam and the Northern region. The temperature tends to increase across the
country, especially the temperature has risen rapidly in recent decades. Temperature
extremes tend to increase in most areas, except extreme hot decreasing in some
southern weather stations. It leads to droughts occur more frequently during the dry
season. Although the number of extremely cold days tends to fall, there are unusual
cold spells (Tran et al., 2016).
1.2.4.2 Precipitation
Figure 1.4 shows total rainfall and most significant precipitation statistic in the period
1990-2020 in Tien Yen in the below:
3500
3000
2500
2000
1500
1000
500
1990
1991
1992
1993
1994
1995
1996

1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020

0

Day max

Total

Linear (Day max)

Linear (Total)

Figure 0-4: The highest precipitation and average precipitation of Tien Yen
weather station in the period 1990-2020 (Unit: mm)
Source: Tien Yen Weather station (Tien Yen Weather station, 2020)
Total rainfall and maximum rainfall change continuously over the years. In general,
both tend to decrease gradually over time. Heavy rains usually occur in the rainy
season, from June to September. The reduced total rainfall may increase water scarcity
in these areas.
250

200
150
100
50
0

Number of rainy days

Linear (Number of rainy days)

7


Figure 0-5: Total precipitation day of Tien Yen weather station in period 19902020 (Unit: day)
Source: Tien Yen Weather station (Tien Yen Weather station, 2020)
Looking at figure 1. 5, the number of rainy days tends to increase slightly. However,

the total rainfall for the whole year decreased (Figure 1.6). Therefore, precipitation is
more evenly distributed between periods. Consequently, it can reduce the risk of
inundation and flooding in the area.
400

1500

300

1000

200

500

100
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
2016

2018
2020

-100
-200

-500

1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
2016
2018
2020

0

0

-1000

Day max

Linear (Day max)

Total

Linear (Total)

Figure 0-6: Precipitation anomaly (max and average) in period 1995-2019 (Unit:
mm)
Source: Tien Yen Weather station (Tien Yen Weather station, 2020)
The annual precipitation compared to the average rainfall in the 1990-2020 period
changes continuously. In general, the total yearly rainfall and highest precipitation
tend to decrease (Figure 1.6). Thus, the level of extreme rainfall tends to decrease
compared to the past.
In Dong Rui and Hai Lang, rainfall tends to change relatively similar to the whole
North of Vietnam. The average annual rainfall tends to decrease at most of the
northern weather stations. In addition, extreme rainfall is significantly reduced in the
Northern Delta, and the number of strong storms tends to increase. Observational data
shows that unseasonal rains and unusually heavy rains occur more frequently. In
recent years, heavy rains have occurred more irregularly in time, location, frequency,
and intensity (Tran et al., 2016).
1.2.4.3 Climate Scenarios
In the 21st century, the climate of global and Vietnam have many changes. Globally,
the average global temperature increased by 1.1÷2.6°C (RCP4.5) and 2.6°C÷4.8°C
8


(RCP8.5) compared with the average period 1986-2005. Although rainfall tends to
decrease in tropical regions, extreme temperature and extreme rain tend to increase.

According to the RCP8.5 scenario, by the end of the 21st century, the coldest day
temperature will increase by 5÷10°C; the hottest day temperature increased by 5÷7°C;
the number of frost days decreases; the number of hot nights increased sharply. In
addition, intense storms tend to increase, heavy rain due to storms increases.
Vietnam's climate at the end of the 21st century has changes similar to the general
changing trend of the region and the world. The average annual temperature increases
by 1.9÷2.4°C (RCP4.5) and 3.3÷4.0°C (RCP8.5). Extreme hot tends to increase
markedly.
In terms of rainfall, annual rainfall increases from 5÷15%. According to the RCP8.5
scenario, the maximum increase could be over 20% in most North. In the whole of
Vietnam, the maximum daily rainfall tends to increase compared to the baseline
period. Besides, the number of strong to extreme storms tends to increase. Droughts
may become more severe in some regions due to rising temperatures and the
possibility of reduced rainfall during the dry season.
The average temperature in Quang Ninh tends to increase in the 21st century, and
Table 1.1 shows temperature changes in different periods:
Table 0.1: Variation of average temperature in winter, spring, summer, and
autumn compared with the baseline period of Quang Ninh (Unit: oC)
(Values in parentheses are the variation around the mean with lower bound 10% and
upper bound 90%)
Season

Winter

Spring

RCP 4.5 scenario

RCP 8.5 scenario

2016-

2046-

2080-

2016-

2046-

2080-

2035

2065

2099

2035

2065

2099

0.7

1.5

2.0

1.0

2.0

3.4

(0.3÷1.2)

(1.0÷2.2)

(1.2÷2.8)

(0.6÷1.5)

(1.4÷2.8)

(2.6÷4.5)

0.7

1.5

2.1

0.9

2.0

3.4

(0.3÷1.1)

(1.0÷2.0)

(1.5÷3.0)

(0.5÷1.2)

(1.3÷2.8)

(2.7÷4.5)
9


Summer

Autumn

0.7

1.6

2.2

0.9

2.1

3.7

(0.4÷1.1)

(1.1÷2.5)

(1.6÷3.1)

(0.4÷1.3)

(1.4÷3.0)

(2.9÷5.0)

0.7

1.7

2.2

0.9

2.1

3.8

(0.3÷1.1)

(1.1÷2.5)

(1.4÷3.1)

(0.4÷1.5)

(1.4÷3.3)

(3.0÷5.2)

Source: CC and sea-level rise scenarios for Viet Nam-2016 (Tran et al., 2016)
In Table 1.1, temperatures tend to increase in both scenarios and at all periods.
Temperatures rise more in summer and autumn in both scenarios. In addition, the
temperature increase more at the end of the 21st century.

10


Next, Table 1.2 shows the change in rainfall in the 21st century:
Table 0.2: Change of precipitation in winter, spring, summer, and autumn
compared to the base period of Quang Ninh province (Unit: %)
(Values in parentheses are the variation around the mean with lower bound 20% and
upper bound 80%)
RCP 4.5 scenario

RCP 8.5 scenario

Season

2016-2035

2046-2065

2080-2099

2016-2035

2046-2065

2080-2099

Winter

4.3

5.3

-2.3

3.2

-0.5

6.3

(-16.6÷25.6)

(-10.3÷20.2)

(-17.5÷12.4)

(-19.6÷26.5)

(-14.8÷14.4)

(-12.6÷27.2)

1.6

19.0

34.4

-1.0

11.1

15.8

(-3.2÷6.7)

(7.9÷29.4)

(19.4÷49.2)

(-9.5÷7.5)

(2.1÷20.0)

(3.5÷27.7)

15.7

15.1

25.2

15.5

24.2

40.6

(3.7÷26.5)

(9.7÷20.7)

(14.3÷36.1)

(5.4÷25.4)

(14.4÷33.4)

(28.8÷52.8)

52.1

32.4

44.8

28.1

38.7

50.9

(-5.0÷102.2)

(7.2÷57.3

(6.9÷82.6)

(0.7÷56.4)

(10.8÷67.2)

(6.6÷93.7)

Spring
Summer
Autumn

Source: CC and sea-level rise scenarios for Viet Nam-2016 (Tran et al., 2016)
In general, precipitation tends to increase most of the time at all periods. However,
precipitation varies unevenly between different seasons and periods. Rainfall increases
more in autumn and summer. In winter and spring, some periods of rainfall decrease.
In the future, sea-level rise is also one of the significant threats to Vietnam. Table 1.3
shows sea-level rise changes under different scenarios and periods:
Table 0.3: Sea level rise scenarios in Mong Cai-Hon Dau (Unit: cm)
RCP4.5 scenario

RCP8.5 scenario

2030

2050

2070

2100

2030

2050

2070

2100

13

22

33

53

13

25

41

72

(8 ÷ 18) (13 ÷ 31) (20 ÷ 47) (32 ÷ 75) (9 ÷ 18) (17 ÷ 35) (28 ÷ 57) (49 ÷ 101

Source: CC and sea-level rise scenarios for Viet Nam-2016 (Tran et al., 2016)
The Vietnam coastal mean sea level rise scenario is likely to be higher than the global.
So, sea level rise has a relatively significant impact on the coastal area of Quang Ninh.
In table 1.3, sea-level rise is higher towards the end of the century. By the end of the
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21st century, the coastal area from Mong Cai to Hon Dau has a sea-level rise of 53 cm
(32 ÷ 75 cm) (RCP4.5) and 72 cm (49 ÷ 101 cm) (RCP8.5).
Rising sea levels lead to the inundation risk in coastal areas. Table 1.4 shows the
inundation risk in the Tien Yen district at different sea-level rise:
Table 0.4: The inundation risk due to rising sea levels caused by CC for Quang
Ninh province
Inundation Percentage (% area) corresponding to rising
Area

sea level

Region

(ha)

50cm

60cm

70cm

80cm

90 cm

100cm

200cm

Tien Yen

66673

1.41

1.51

1.60

1.68

1.79

1.96

4.37

Quang

967655

3.33

3.62

3.88

4.10

4.40

4.79

7.25

Ninh
Source: CC and sea-level rise scenarios for Viet Nam-2016 (Tran et al., 2016)
If the sea level rises, Tien Yen district has an average flooding rate compared to other
districts of Quang Ninh. For example, if the sea level rises by 100 cm, about 1.96% of
the area of Tien Yen district will be flooded, and 4.79% of the scope of Quang Ninh
province will be flooded.
1.3 Literature Review
1.3.1 The concept of mangrove ecosystem
Mangrove forests are located in the tropics and sub-tropics but extend into temperate
regions to reach their geographical limits (Hogarth, 2015). These trees grow in areas
with low-oxygen soil, where slow-moving waters allow fine sediments to accumulate.
Mangrove forests only grow at tropical and subtropical latitudes near the equator
because they cannot withstand freezing temperatures. Several mangrove species have
developed root systems, especially breathing roots. These roots help the plant stand

and grow in conditions often flooded by tides (NOAA, 2021). The term 'mangrove' is
also used more generally to describe both the plant communities they form and their
habitat. Together with the animals and other organisms that live in the same habitat,
they start a unique type of ecosystem, the "mangrove ecosystem" (Clough, 2013)
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1.3.2 Impact of CC on mangrove
Recent studies on the impact of CC on mangroves and the role of mangroves in the
adaptation and mitigation of CC are critical. It is the basis for stakeholders to plan for
the conservation and development of mangroves in the future.
The study "Impact of expected CC on mangroves" by Colin Field mentioned factors
affecting the distribution and development of mangroves. Sea level rise is the most
critical factor affecting mangroves, but this impact also varies from region to region.
Rising air temperatures are likely to have little effect on mangroves. Although it
depends on other factors, increased temperatures could also cause mangroves to move
further North and south. It is unclear how CO2 in the atmosphere affects mangroves. In
addition, CC can increase the risk of saline intrusion, coastal erosion, flooding, and
storm surge (Field, 1995).
Another study by Eric L.Gilman and colleagues on "Threats to mangroves from CC
and adaptation options: A review." The author emphasizes that CC threatens the
mangrove ecosystem. Sea level rise is possibly the biggest threat to mangroves. As a
result, mangroves in the Pacific Islands are at high risk of significant decline. To limit
the impact of CC on mangroves, planning measures should be taken: coastal planning;
manage activities in the basin that affect long-term trends in mangrove sediment
elevations; restoration of degraded mangrove areas, etc (Gilman et al., 2008).
1.3.3 The role of the mangrove ecosystem in response to CC
Mangrove forest is a special ecosystem of coastal areas. It is providing ecosystem
services for human society to respond to CC. In the world, there are many types of
research on the role of mangrove forests.

In the "Mangrove manual secondary Vietnamese," Daniel G. Spelchan and Isabelle A.
Nicoll divided the role of mangrove forest into six parts, include (1) Provide livelihood
for people; (2) Protect against natural disasters; (3) Reduce erosion and protect soil;
(4) Reduce pollutant; (5) Minimize the impact of CC, and (6) Provide food and habitat
for many animals (Mangrove Manual Secondary Vietnamese, n.d.).

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So, the role of the mangrove forest can divide into two parts, including the role in the
natural system and the role in the social system. Mangroves have extensive trunks,
branches, and roots that help protect the shoreline and the land from erosion and the
impacts of waves. It also helps in the encroachment process, which helps to increase
the land area. Mangroves help filter eutrophication, sediment, and pollutants from
oceans and rivers. Mangroves are also very effective in storing carbon and carbon
dioxide, which are the leading cause of CC. Mangroves provide habitat and food for
various fish, shellfish, birds, and mammal's breast. Some of the animals that live in the
mangroves include fish, birds, crabs, cockles, clams, oysters, shrimp, etc.
On the one hand, mangrove helps create and maintain the livelihood of mangrove
dwellers. Humans catch and sell many species of fish and other animals that live in
mangroves. It also provides many materials and ecosystem services for people's lives,
such as firewood and coal, tourism, and coastal protection. Furthermore, CC can lead
to the increase of natural disasters and extreme weather events. Mangroves protect
people, houses, and fields from natural disasters/extreme weather events such as
typhoons, floods, waves, saline intrusion, etc. The bodies of trees, branches, and roots
of mangroves act as barriers to reducing tides, flooding, and strong wind.

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1.3.3.1 The role in the natural system
Maintaining biodiversity and food web
The study "The habitat function of mangroves for terrestrial and marine fauna: A
review" by I.Nagelkerken and colleagues analyzed the role of mangroves in
maintaining biodiversity and food webs. In mangroves, each area provides habitat for
different species. Above the water is the habitat of insects, reptiles, birds, and
mammals. Under the water is the habitat of bivalves, sponges, tunicates, and algae.
Besides, the soft substratum in the mangroves forms the habitat for various infaunal
and epifaunal species. The space between the tree roots is the habitat of shrimp, fish,
and crab species. Fallen leaves and wastes in mangroves are essential sources in the
mangrove food web. Plankton, epiphytes, and microorganisms also form a necessary
basis for the mangrove food web (Nagelkerken et al., 2008).
The study "Managing mangroves with benthic biodiversity in mind: Moving beyond
roving banditry" assessed the diversity of mangrove benthos. Mangrove benthic fauna
can affect tree formation and growth. Despite this, mangrove management often pays
little attention to benthic species (Ellison, 2008). Peter J. Hogarth published a book
title "The Biology of Mangroves and Seagrasses." Mangroves host a wide variety of
biodiversity, where they are habitats of many faunas, including aquatic and terrestrial
insects, fish, reptilian, mammalian, etc. The author also analyzed the impact of CC and
human activities on the biodiversity of mangroves and seagrasses (Hogarth, 2015).
Carbon storage
Mangrove forest is one of the largest carbon pools in the world. For example, in the
Indo-Pacific region, each hectare of forest contains an average of 1.023 Mg of carbon,
and mangrove deforestation generates 0.02 - 0.12 Pg carbon emissions per year,
equivalent to about 10% of emissions from deforestation globally, despite accounting
for only 0.7% of the rainforest area (Donato et al., 2011).
In another study in China, mangroves stored about 6.91 ± 0.57 Tg C, of which 81.74%
were in the 1m high soil layer, 18.12% were in mangrove biomass, and 0. 08% at
ground level (mangrove mats and seedlings). On average, mangroves in China contain
355.25 ± 82.19 Mg C ha−1, consistent with the global mean C densities of mangroves

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at similar latitudes but higher than C densities average in terrestrial forests China.
Thus, it is possible to increase C storage in mangroves by selecting species with high
C densities for afforestation and reforestation, and even more by increasing mangrove
area (Liu et al., 2014)
Mangroves make an essential contribution to conservation, restoration, and helping to
reduce greenhouse gas emissions. Although mangroves cover only 0.5% of the global
coastal area, they can store 10 - 11% of carbon in sediments and export 10 - 11% of
the terrestrial particulate carbon to the ocean. Moreover, mangroves have the same
carbon storage capacity as tropical humid evergreen forests and coral reefs (Alongi,
2014).
The carbon storage capacity of wetlands is increased as mangroves expand into salt
marshes, but CC could alter the ecosystem's ability to store carbon. Salt marshes
replaced with mangroves could double carbon storage capacity due to differences in
biomass. In addition, mangrove forest coverage also increased to 69%. As a result,
Wetland C storage within the wildlife refuge increased at a rate of 2.7 MgC ha-1 yr-1,
more than doubling the natural high coastal wetland carbon sequestration rates
(Doughty et al., 2016).
Can Gio Mangrove Forest Park is the largest restored mangrove forest in the Mekong
Delta Vietnam. The study measured tree biomass, roots, woody debris, organic
sediment carbon, and overall depth to estimate carbon storage capacity. Eventually,
average aboveground C storage was 102 ± 24.7, 298.1 ± 14.1, and 243.6 ± 40.4 MgC
ha−1 for the fringe forest, transitional forest, and inland forest, corresponding.
Therefore, high carbon stocks above ground and below ground lead to high C stocks in
the ecosystem (Dung et al., 2016).
In Dong Rui and Northeastern Vietnam, the average aboveground and belowground
carbon reserves are 48.6 ± 11.7 and 554.8 ± 112.2 MgC ha-1. In which the sediment C
pool contributed >80% proportion to the C storage. So that, mangroves play an

important role in storing carbon and reducing CO2 into the atmosphere (Tue et al.,
2020).
Coast protection
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Mangroves have been remarkably resilient to coastal evolution, especially the sealevel rise. Mangroves can limit the impact of tsunamis. The extent of energy
absorption is strongly dependent on tree density, trunk and root diameters, bank slope,
depth, spectral characteristics of incoming waves and tides entering the forest (Alongi,
2008). Mangroves provide a natural physical barrier against soil erosion, tsunamis, and
storm surge. The threat of sea-level rise is quite prominent for small islands and lowlying coastal zones (IPCC 2007). In terms of commercial ecosystem services,
mangroves also filter chemical and organic pollution from the water, which keeps the
waters on reefs and seagrass beds cleaner. There has been scant monetization of such
regulating services, but these could potentially finance conservation activities. Other
co-benefits of maintaining mangroves are their function as a nursery for juvenile fish
and shrimp and habitat for crabs, oysters, clams, estuarine crocodiles, and snakes.
Seabirds and fruit bats use mangroves as resting and breeding grounds (D. et al., 2009)
Mangrove forests stabilize the coastline, reducing erosion from storm surges, currents,
waves, and tides. The intricate root system of mangroves also makes these forests
attractive to fish and other organisms seeking food and shelter from predators (NOAA,
2021). In the study "Role of mangroves in coastal zone management," the author
emphasized the role of mangroves in preserving soil and dissipating wave energy
when transmitted to mangroves. Wave energy can be dissipated after entering 50m if
the density of mangroves is thick. Otherwise, the wave can drop about 20% from the
height of the original wave. Suspended Sediment Concentration increases
proportionally with wave strength and directional current. After a day, large amounts
of sediment are retained by the mangroves. It shows that mangroves play an essential
role in soil retention and shore protection (Phƣớc & An, 2010).
1.3.3.2 The role in the social system
Reduce the impact of CC

Healthy coastal forests can reduce the impact of tsunamis. However, mangrove forests
are in sharp decline worldwide. Therefore, it is necessary to restore and protect coastal
forests to shield against tsunamis and ensure optimal socio-economic, ecological, and
environmental benefits (Osti et al., 2009). Mangroves play an important role in helping
people cope with natural disasters such as storms, coastal erosion, and sea-level rise. In
17