(Luận văn thạc sĩ) 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, QUA

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

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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

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

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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!

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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

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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

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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

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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

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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, sea-level 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

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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,

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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,

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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

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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:

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:

Figure 0-3: Temperature anomaly (average, max, and min) in Tien Yen weather

station in period 1990-2020 (Unit: o C)

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

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:

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

Figure 0-5: Total precipitation day of Tien Yen weather station in period

1990-2020 (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

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)

(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: o C)

(Values in parentheses are the variation around the mean with lower bound 10% and upper bound 90%)

(0.3÷1.2)

1.5 (1.0÷2.2)

2.0 (1.2÷2.8)

1.0 (0.6÷1.5)

2.0 (1.4÷2.8)

3.4 (2.6÷4.5)

Spring 0.7

(0.3÷1.1)

1.5 (1.0÷2.0)

2.1 (1.5÷3.0)

0.9 (0.5÷1.2)

2.0 (1.3÷2.8)

3.4 (2.7÷4.5) n

Summer 0.7

(0.4÷1.1)

1.6 (1.1÷2.5)

2.2 (1.6÷3.1)

0.9 (0.4÷1.3)

2.1 (1.4÷3.0)

3.7 (2.9÷5.0)

Autumn 0.7

(0.3÷1.1)

1.7 (1.1÷2.5)

2.2 (1.4÷3.1)

0.9 (0.4÷1.5)

2.1 (1.4÷3.3)

3.8 (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

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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%)

Season

RCP 4.5 scenario RCP 8.5 scenario 2016-2035 2046-2065 2080-2099 2016-2035 2046-2065 2080-2099 Winter 4.3

(-16.6÷25.6)

5.3 (-10.3÷20.2)

-2.3 (-17.5÷12.4)

3.2 (-19.6÷26.5)

-0.5 (-14.8÷14.4)

6.3 (-12.6÷27.2)

Spring 1.6

(-3.2÷6.7)

19.0 (7.9÷29.4)

34.4 (19.4÷49.2)

-1.0 (-9.5÷7.5)

11.1 (2.1÷20.0)

15.8 (3.5÷27.7)

Summer 15.7

(3.7÷26.5)

15.1 (9.7÷20.7)

25.2 (14.3÷36.1)

15.5 (5.4÷25.4)

24.2 (14.4÷33.4)

40.6 (28.8÷52.8)

Autumn 52.1

(-5.0÷102.2)

32.4 (7.2÷57.3

44.8 (6.9÷82.6)

28.1 (0.7÷56.4)

38.7 (10.8÷67.2)

50.9 (6.6÷93.7)

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)

53 (32 ÷ 75)

13 (9 ÷ 18)

25 (17 ÷ 35)

41 (28 ÷ 57)

72 (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

Region

Area (ha)

Inundation Percentage (% area) corresponding to rising

sea level 50cm 60cm 70cm 80cm 90 cm 100cm 200cm

Quang

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 level 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 low-lying 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,

sea-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 (Phước & 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

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addition, mangrove ecosystems help improve livelihood options and protect them from disasters (Barua et al., 2010)

Maintaining people's livelihood

In the research "Traditional and medicinal uses of mangroves" by W.M

Bandaranayake, the author mentioned the role of mangrove forests They listed the part of mangroves for social systems Traditionally, people exploit mangroves for firewood and charcoal The mangroves also use for the construction of furniture, dwellings, boats, and fishing gear In addition, the mangroves provide food and a variety of traditional products for the mangrove dwellers Besides, extracts and chemicals from mangroves are used mainly in folkloric medicine, insecticides, and piscicides (Bandaranayake, 1998)

In the southern coastal region of East Lombok, a large number of people's livelihoods depend directly on mangroves People catch crabs, shellfish, shrimp to sell and small shrimp as raw materials for shrimp paste Therefore, mangrove conservation is a solution for the livelihoods of local communities (Idrus et al., 2019)

In Khulna, Bangladesh, forest income accounted for 74% and 48% of total household income for low and middle-income households, respectively, but only 23% for higher-income families Although higher-income families have the lowest percentage of forest income, absolute values are the highest In addition, access to mangrove resources can significantly affect people's income, which affects the wealth gap between households who near the forest (Mohammad Abdullah et al., 2016)

Evaluation of the effectiveness of mangroves in Tien Yen district, Quang Ninh province, mangroves have a socio-economic role People exploit aquatic species to increase their income in terms of economic efficiency, and the average income is from 3.5-4.5 million VND Socially, mangroves help reduce wave heights during high tides, mitigate the impact of natural disasters, and slow water flows (Thoan, 2018)

The author team Steven Emmerson Orchard researched three typical mangrove areas

in northern Vietnam: Dong Rui Commune - Quang Ninh Province, Giao Xuan Commune - Nam Dinh Province, and Da Loc Commune - Thanh Hoa Province

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Mangrove-dependent communities have different levels of income, subsistence, and response to change The development of aquaculture can degrade mangrove systems and impact people's livelihoods dependent on mangroves (Orchard et al., 2016)

According to the literature described above, studies have focused on analyzing the

different roles of mangroves for society and nature The studies examine various aspects and have many practical meanings in proposing solutions on policy, governance, planning, sustainable use of resources, environmental protection, and response to CC However, these studies mainly analyze one aspect of the role of mangroves This makes it difficult for the reader to get an overview of the roles of mangroves, especially in the context of CC Although there have been so many studies worldwide, there is still a need to do so many research findings on that study area, which has to develop the current situation based on the above literature review

The novelty of the research: This study was conducted in Dong Rui and Hai Lang

communes of Tien Yen district, Quang Ninh province Most of the previous studies focused more on the role of mangroves in nature This study approaching both social and natural perspectives that will help provide a more comprehensive analysis of the role of mangroves, particularly in the context of CC In addition, this study used the latest survey and observed data to assess the role of mangroves These data have just been collected, so they are new and make the topic more practical

1.4 Objectives of the research

The hypothesis of this study is "Mangrove forest plays an essential role in provide ecosystem services for human society to respond to CC of Dong Rui and Hai Lang communes."

To analyze the role of mangrove forest, the study has two research questions include: (1) What do mangrove forests play essential roles in protecting and preserving coastal resources and coastal communities in the context of CC?

(2) How to increase the CC responding capacity of mangrove forests?

From research questions, the specific objectives of the study are:

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(1) Analyze the role of mangrove forests in maintaining the coastal resource

(2) Analyze the role of mangrove forests in supporting coastal communities under

CC impacts

(3) Propose solutions for suitable use of mangrove forests for CC response

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CHAPTER 2 DATA COLLECTION AND METHODOLOGIES

2.1 Logical framework

To analyze the role of mangroves in responding to CC, I built a framework based on the topic's goals, tasks, and research methods (Figure 2.1) The framework is divided into two main parts that include natural roles and social roles To analyze roles in nature, I divide into three more specific functions of mangroves: (1) maintaining biodiversity and food webs, (2) protect coastally, and (3) carbon storage On the other hand, I also divided the social role of mangroves into two specific parts, including (1) maintaining people's livelihood and (2) reducing the impact of CC To research and analyze the different roles of mangroves, I have used various research methods to suit other subjects and research content

Figure 0-1: Logical framework of the research

The roles of mangroves are interrelated, and they are not separate Mangrove provides ecosystem functions and services for local people And human activities also impact the diversity in mangroves The biodiversity of mangroves contributes to maintaining

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and improving people's livelihoods On the other hand, the exploitation of the people also affects the number of species in the mangrove forest

The carbon storage role of mangroves helps to reduce CC From there, it reduces weather variability, climate, and extreme weather events As a result, it helps to reduce pressure and impact on coastal areas In addition, mangroves protecting the coastal area also protect and reduce adverse effects on the communities inside

2.2 Data collection

This research will use two data sources: Secondary data and Primary data

Firstly, Collection secondary data through (1) Weather data (temperature, precipitation) of Tien Yen weather station, CC, and sea-level rise scenarios for Vietnam of CC and sea-level rise scenarios for Viet Nam-2016; (2) Explanation of current land use map in 2019 Dong Rui commune, Tien Yen district, Quang Ninh province; (3) Report on natural conditions, socio-economy and development potential

of salt and brackish aquaculture in Tien Yen district (4) Report on the implementation

of natural disaster prevention in the rainy season in 2020; (5) Recent research works of Dong Rui and Hai Lang communes; (6) Type of creature species in the mangrove forest of Dong Rui and Hai Lang Commune from Project to establish Dong Rui wetland conservation area - Tien Yen, Quang Ninh province (Nguyen Cao Huan, 2018); Carbon accumulated ability of mangrove forest from previous researches and (7) Types of forest function in Dong Rui and Hai Lang communes from Forestry Data Sharing System

Secondly, primary data collected by observation, household survey, and in-depth interview For observation: take photos showing the situation of mangroves, biodiversity, and people's livelihood For Household survey: 113 households (Survey respondents only reflect for the representative of the population of the study site) In-depth interview: 4 Local leaders and staff

Respondents have different questionnaires to collect relevant information for analysis

(1) For Household survey: The interview area was divided into two communes: Dong

Rui and Hai Lang

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Phase 1: Interviewed 19 families in Hai Lang and 34 families in Dong Rui at the end

of July 2020 (2 villages: Doi May and Ha Thu)

Phase 2: Interviewed 60 families in Dong Rui from 20-25 January, 2021 (4 villages: Thuong, Ha, Trung and Bon)

Hai Lang has a much narrower natural forest area due to conversion to aquaculture The number of people dependent on mangroves is small Besides, mangroves play a significant role for the people of Dong Rui commune Therefore, I surveyed Dong Rui commune to clarify the role of mangroves, especially in response to CC

During the interview, I tried to divide between the villages, having diverse livelihoods The household interview includes the following six primary information: (I) General information (family members, job, livelihood, income, etc.); (II) CC information (the type of disaster/extreme weather effect, warning information before the disaster, etc.); (III) General information about mangroves and the effects of CC on mangroves (type

of mangroves in the commune, the situation of mangroves : before and now); (IV) Benefit of mangroves (maintain livelihood, reduce the impact of the typhoon, protect the coastal area, etc.) (V) The cost of mangrove conservation (impact of mangrove conservation in communes, impact of mangrove conservation in livelihood, etc.); (VI) Perspectives on mangrove conservation (The importance of mangrove conservation for local socio-economic development and CC mitigation) (Detailed questionnaire at appendix)

(2) In-depth interview for four local leaders and staff includes some information: The

socio-economic situation of the locality; Impacts of natural disasters/CC on the livelihood; Situation of mangroves in these areas, and the role of mangroves forest in

CC response and developing livelihood

Table 0.1: Datatypes use in research

Mangroves area; aquatic species and mangrove species

(habitat, chain food, etc.), characteristics of mangroves

(height, density, age), the role of mangroves for the

Interview Hai Lang and Dong Rui Government; and others research

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Data types Data sources

coastal area (forest function)

CC/natural disaster/extreme weather event in Dong Rui

and Hai Lang Communes (Precipitation, temperature,

sea-level rise)

The survey, Interview local government, weather station, and other research Impact of CC/natural disaster/extreme weather event on

mangroves and ecosystem (erosion, reduce the amount of

aquatic animal, reduce mangrove forest area, etc.)

Survey local people; interview government and internet

Carbon storage (carbon accumulates at forest trees and in

the soil)

Previous researches

Impact of CC/natural disaster/extreme weather event on

coastal communities (typhoon, saline intrusion, etc.) and

the role of mangrove forests in reducing the impact of CC

(waves, saline intrusion, wind, etc)

Survey local people; interview government and Statistical yearbook

Type of livelihoods related to mangroves and natural

resources exploit (fishing, aquaculture, etc.) to increase

income

Survey local people; interview government and Statistical yearbook

The benefit of mangroves with local people (increase air

quality, protect biodiversity, etc)

Survey local people; interview government

2.3 Methodologies

In this research, I use some research methods In each phase or purpose, I will use appropriate research methods It helps to analyze problems accurately and following real-world conditions Table 2.2 lists the research methods used in this study

Table 0.2: Methods used in the research

Data

Collection

information about mangrove forests

M2 n

Methods Purposes Code

information about mangrove forests

M3

Data

analysis

Quantitative data analysis methods

Descriptive Analysis

Summarize the data and find trends (climate data, the impact of CC, etc.)

M4

Qualitative data analysis methods

Content analysis

Analyze the data from responses to survey

M5

Narrative analysis

information, and sharing from observation and survey

M6

2.3.1 Data collection method

For collecting secondary data, I used the synthesis method

Secondary data is provided by Dong Rui and Hai Lang Commune People's Committees and the weather forecast station Based on these data, the status of the socio-economic and natural development of the two regions is determined In addition,

I synthesized other CC and natural disaster data from the results of some existing researches

Furthermore, I collected data on the natural role of mangroves from previous studies The role of mangroves in maintaining biodiversity and food webs gathers data on the flora and fauna that live in the forest In addition, I also collected the carbon storage capacity of mangroves at Dong Rui and Hai Lang from previous studies This study uses existing data to analyze and compare the role of mangroves in the two communes Finally, I collected the role of mangroves in coastal protection from the Forestry Data Sharing System site

This study used the qualitative method to collect primary data through in-depth

interviews, observation, and quantitative methods

In-depth interviews

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In this study, in-depth interviews were used to interview local leaders of Dong Rui and Hai Lang communes in depth Face-to-face interviews contained open-ended questions that elicited and examined knowledge insights, perspectives, and own impact of responses related to the disaster of CC, natural on community, and the role of mangrove forest The qualitative method has an essential role in research because it helps to collect data from those who had a high specialization in the research area In-depth interviews also allowed to explore interviewees more for more understanding

Observation

I had a trip by boat to the mangrove forest Besides, I also used a motorbike to go along the dyke and observe the mangrove forest situation The actual observation was considered as a helpful tool that contributes trusted information for the data collection Photos and videos showed the observation result

While traveling on the boat, I observed mangroves species and animals in the mangrove forest I also observed local people exploit resources in the mangroves

Figure 0-2: Observation in the boat

I took a boat trip along the Ba Che River to more remote mangrove areas with less human impact It showed the fact that the mangroves in this area have well-developed and less affected by humans However, environmental pollution acted as a severe issue while a variety of plastic waste such as a bottle or plastic bags was washed ashore

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Figure 0-3: Observation of mangrove forest

Household survey

Samples of the interview were prepared and decided after identifying the objective of the research The household survey was designed as a questionnaire/close-ended questions This research focused on the role of mangrove forests in providing ecosystem services for human society to respond to CC

Interviewees are mainly local people in Dong Rui and Hai Lang communes During the interview, I try to interview different subjects regarding age, gender, livelihood, and living area for objective and diverse results

The sample size was also determined based on the time Due to the lack of time, I intended to do around 100 households and fulfilled my target with 113 families During the interview, the questions and scale were explicitly explained to the respondents, which helped them easy to understand and access the issue

Figure 0-4: Interview resident

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2.3.2 Data analysis method

The tool used for data processing is Microsoft Excel 2010 software The primary data were summarized and synthesized in an Excel sheet that acted as the base for creating figures Another tool used is QGIS It is used to create an administrative map of Dong Rui and Hai Lang communes

In details, the data results were processed as follows:

Manifestations of CC in Dong Rui and Hai Lang communes: secondary data were

collected and analyzed through descriptive analysis methods to show the main signs of

CC and natural disasters (such as temperature, precipitation, flood, drought, salinity intrusion, inundation, etc.) in the study area

Structure and characteristics of mangroves: secondary data were collected to describe

the characteristics of species, distribution, the height of the tree species in the mangrove forest

Maintaining biodiversity and food webs of mangroves: The data used for analysis is

secondary data Descriptive analysis methods are used to describe and analyze the relationships of mangrove species

Carbon storage: secondary data were collected and analyzed through descriptive

analysis methods The carbon storage capacity data in mangroves (mangroves tree and soil) were analyzed and compared in the two study areas

Coast protection: secondary data were collected and analyzed through descriptive

analysis methods to show the forest function (Protection forest, Protection forest for tide shielding) On the other hand, primary data from the survey were also used to assess the awareness of local people about the role of mangroves in coast protection by content analysis method

Reducing the impact of CC on population communities: Primary data from the survey

were used to assess the effect of CC on the lives of the locality It is also used to analyze the ability to reduce the impact of CC and natural disasters on people's lives

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Maintaining people's livelihood: The narrative analysis method was used to analyze

the data collected during the survey and in-depth interview (people's occupation, types

of resources extracted from mangroves, fishing methods in the forest, etc.)

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CHAPTER 3 RESULTS AND DISCUSSION

3.1 Structure and characteristics of mangroves in Dong Rui and Hai Lang

communes

Mangroves are distributed along the coastline of Tien Yen bay and along with islands Dong Rui and Hai Lang communes locate close to each other, so the species of mangrove forests are similar However, Dong Rui has a larger area of mangroves than the Hai Lang commune Besides planting mangrove forests, the topography of Hai Lang commune has many hills and mountains, so people also grow other industrial crops, especially acacia

Figure 0-1: Geo-vegetation map of wetland area in Dong Rui, Tien Yen

Source: Project to establish Dong Rui wetland conservation area - Tien Yen, Quang Ninh province (Nguyen Cao Huan, 2018)

In Dong Rui and Hai Lang, the main mangroves include Bruguiera gymnornitreza,

Rhizophora stylosa, Kandela obovata, Avicemia marina and Aegiceras corniculatum

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The plants here are mainly salt-tolerant, and brackish water plants appear less Mangrove ecosystems play an important role in maintaining biodiversity and providing livelihoods for local people Mangroves are the habitats for many valuable specialties such as mud crabs, octopuses, earthworms, and clams and provide essential sources of shrimp, crab, and fish for coastal areas

Figure 0-2: Mangrove ecosystems of Dong Rui and Hai Lang Communes

The mangrove system in the two communes is well developed, with different

distribution by region Corniculatum Aegiceras community mainly distributed in

low-tide areas, much affected by daily tidal inundation, tree height about 2-3m The

purebred kandelaobovata, Rhizophora stylosa, and Bruguera gymnornitreza

communities distribute in the tidal zone The bottom in this area consists of mud and

clay, under the influence of infrequent tides Kandela obovata and Rhizophora stylosa

communities 3-3.5m on average, even trees up to 8m high forming a lush green belt protecting the tidal zone The other shrubs communities, mainly distributed in high tide areas, are less affected by the daily flooding regime There are also anthropogenic

communities, such as the Kandela obovata plantation and the Bruguiera

gymnornitreza plantation (Nguyễn & Mai, 2018)

Table 0.1: Height and distribution of mangroves communities in Dong Rui

Ae Corniculatum + K obovata

3.0 Middle intertidal zones n

No Name of community Height

(m)

Distribution

+ A marina

intertidal zone

zones along the rivers and canals

+ A marina

2.1 In scattered lower intertidal

zones along the rivers and canals

Ae Corniculatum + K obovata

2.0 In middle intertidal zones

marina + K obovata

2.3 In middle intertidal zones

1.8 Along the dike into the island, in

scattered lower intertidal zones along the rivers

1.2-1.4 From lower to middle intertidal

zones, scattered along the rivers and canals

11 A marina in abandoned shrimp

2.5 In middle intertidal zones

Source: Nguyễn H H & Mai, 2018

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