Assessment Of Mangrove Planting Models And Propose Technical Solutions To Improve The Effectiveness Of Mangrove Conservation At Xuan Thuy National Park Nam Đinh Province Viet Nam

MINISTRY OF EDUCATION

AND TRAINING

MINISTRY OF AGRICULTURE

AND RURAL DEVELOPMENT

VIETNAM NATIONAL UNIVERSITY OF FORESTRY

TRAN VAN SANG

ASSESSMENT OF MANGROVE PLANTING MODELS

AND PROPOSE TECHNICAL SOLUTIONS TO IMPROVE

THE EFFECTIVENESS OF MANGROVE

CONSERVATION AT XUAN THUY NATIONAL PARK,

NAM DINH PROVINCE, VIETNAM

MAJOR: FOREST SCIENCE

CODE: 8620201

MASTER THESIS IN FOREST SCIENCE

SUPERVISOR:

ASSOC. PROF. DR. BUI THE DOI

DR. CAO THI THU HIEN

Hanoi, 2022

i

ABSTRACT

Mangroves are tropical/subtropical communities of tree species that grow in

the estuary areas, in intertidal mudflats and along coastlines, where they are

regularly inundated by saline or brackishwater. The mangrove is also vital for

protecting the sea dyke system that protect the highly productive Red-river delta

and highlight populated rural area of Nam Dinh and Thai Binh Provinces. With the

mangroves forest, it helps to limit the effects of floods and storms and high tides;

reducing waves, limit erosion and protection of sea dykes. In addition, the

mangroves forest is contributing in securing livelihoods for thousands of people

who live in the buffer zone of the Park. Recognizing the important role of mangrove

ecosystem at Xuan Thuy National Park, recent years, there were several mangrove

planting models have been implemented. This study provides information on

present mangroves planting models in Xuan Thuy National Park, the first Ramsar

site in Vietnam. The study results indicated that survival rate, growth and

regeneration trees characteristic between mangrove planting model. The results

demonstrated that in the period of time from 1998 to 2020 in the study area, there

were a several mangrove planting models have been implemented, including: The

monoculture model of Kandelia obovate implemented by the Danish Red Cross in

the period from 1998 – 2005; The mixed species model of Sonneratia caseolaris -

K. obovata under SP-RCC program implemented in 2016; The mixed species model

of Rhizophora stylosa - Bruguiera gymnorhiza implemented by the WIP,

implemented in 2015. The study showed that, the mixed species model of R.

stylosa - B. gymnorhiza at the age 5 years old achieved the highest survival rate

among the 3 research models. Survial rate of monoculture model of K. obovate at

the age of 22 was lowest, at about 50.17%. The number of regeneration trees in

three planting models was mainly concentrated in height classes I (<0.5m) and II

(0.5-1m), height classes III (<0.5m) and II (0.5-1m) 1-1.5m) and IV (>1.5m) were

almost absent in models. Our study suggests that long-term planning for mangrove

planting and techniques solutions for mangrove afforestation is a crucial rule

towards sustainable management of Xuan Thuy National Park.

Keywords: Mangroves planting, mangroves conservation, planting

techniques, Xuan Thuy National Park.

ii

PUBLICATION DURING MASTER THESIS

1. T.T. Loi, T.V. Sang, N.Q. Huy., 2019. Mangroves restoration in

response to climate change: A case study in Xuan Thuy National park, Vietnam.

Proceedings of the 10th International Conference on Asian and Pacific Coasts

Hanoi, Vietnam, September 25-28, 2019, P.P.1163-1168 (scopus index).

https://doi.org/10.1007/978-981-15-0291-0_159

2. Trần Văn Sáng, Nguyễn Hoàng Hanh, Đỗ Quý Mạnh, 2019. Hiện

trạng rừng ngập mặn Vườn quốc gia Xuân Thủy, tỉnh Nam Định (Current status

of Mangroves in Xuan Thuy National Park of Nam Dinh Province). Vietnam

Journal of Forest and Environment, Vol 98, 2019, PP63-69. (In Vietnamese)

3. Đỗ Quý Mạnh, Nguyễn Hoàng Hanh, Trần Minh Cảnh, Trần Văn

Sáng, Nguyễn Thị Bình, 2020. Phân chia lập địa ngập mặn và đề xuất giải pháp

phục hồi rừng ngập mặn tại Vườn quốc gia Xuân Thủy, tỉnh Nam Định (Use of

salt-marsh site classification and some solutions reforestation for mangroves in

Xuan Thuy National Park of Nam Dinh Province). Vietnam Journal of Forest and

Environment, Vol 103, 2020, PP18-24. (In Vietnamese)

iii

CONTENTS

ABSTRACT............................................................................................................... i

PUBLICATION DURING MASTER THESIS..................................................... ii

CONTENTS............................................................................................................. iii

ABBREVIATIONS ................................................................................................. vi

LIST OF TABLES ................................................................................................. vii

LIST OF FIGURES .............................................................................................. viii

Chapter 1. INTRODUCTION..................................................................................1

Chapter 2. LITERATURE REVIEW .....................................................................2

2.1. Research results on the world...........................................................................2

2.1.1. Research on mangrove ecosystems............................................................2

2.1.2. Research on mangrove rehabilitation on the world...................................4

2.2. Research on mangroves in Vietnam.................................................................6

2.2.1. Research on mangrove ecosystems in Vietnam..........................................6

2.2.2. Some studies on mangroves in XTNP, Nam Dinh province.....................12

Chapter 3. RESEARCH OBJECTIVES AND METHODS................................15

3.1. Research goal, ofjectives................................................................................15

3.1.1. Goal..........................................................................................................15

3.1.2. Specific objectives....................................................................................15

3.2. Methods ..........................................................................................................15

3.2.1. Literature review......................................................................................15

3.2.2. Data collection .........................................................................................15

3.2.3. Mapping method.......................................................................................17

3.2.4. Data analysis............................................................................................18

Chapter 4. GEOGRAPHIC CONDITIONS AT XUAN THUY NATIONAL

PARK .......................................................................................................................21

4.1. Location ..........................................................................................................21

4.2. Topography.....................................................................................................22

4.3. Climate............................................................................................................23

4.4. Hydrology.......................................................................................................23

iv

4.5. Tidal................................................................................................................24

4.6. Salinity............................................................................................................24

4.7. Mangrove forests status..................................................................................25

Chapter 5. RESULTS AND DISCUSSION ..........................................................27

5.1. Mangrove forest status in Xuan Thuy National park .....................................27

5.1.1. Mangrove area in Xuan Thuy National park ...........................................27

5.1.2. Distribution characteristics of mangrove forest in XTNP .......................27

5.2. Current status of some mangrove planting models in XTNP.........................30

5.2.1. The models of K. obovate monoculture....................................................30

5.2.2. Planting model of K. obovata and S. caseolaris......................................30

5.2.3. Plantation models of R. stylosa and B. gymnorhiza ................................32

5.3. Effectiveness evaluation of mangroves planting models ...............................34

5.3.1. Survival rate of mangrove planting models.............................................34

5.3.2. The growth situation of the plantation model evaluation ........................37

5.3.3. Growth quality of mangroves in plantation models.................................40

5.4. Characteristics of natural regeneration in forest restoration models..............43

5.4.1. Density of regenerated trees ....................................................................43

5.4.2. Distribution of regenerated trees according to height ............................44

5.4.3. Quality of regeneration trees...................................................................45

5.5. Characteristics of natural regeneration in mangrove planting models...........46

5.5.1. Density of natural regenerated trees in mangrove planting models........46

5.5.2. Distribution of regeneration trees according to height class..................48

5.5.3. The quality of the regenerative trees........................................................49

5.6. Proposing some solutions to improve the efficiency of mangrove restoration ...50

5.6.1. Sellecting suitable species........................................................................50

5.6.2. Solutions for restoring mangroves at erosion areas, high wave energy..53

5.6.3. Technical solutions to improve the effective of mangrove restoration in

XTNP..................................................................................................................54

5.6.4. Solutions for planning the development of mangroves forest in XTNP...56

v

Chapter 6. CONCLUSION ....................................................................................58

6.1. Conclusion ......................................................................................................58

6.1.1. Evaluating the effectiveness of mangroves planting models....................58

6.1.2. Proposing some techniquecal solutions to improve the effectiveness of

mangrove restoration in XTNP..........................................................................60

6.2. Limitation .......................................................................................................61

6.3. Recommendation ............................................................................................62

ACKNOWLEDGEMENTS....................................................................................63

REFERENCES........................................................................................................64

APPENDIX ................................................................................................................1

vi

ABBREVIATIONS

Abbreviations Description

Ac

AR

Bg

Doo

Ha

Hvn

mm

MRC

cm

Ko

Ramsar

Rs

Sc

SD

SP-RCC

XTNP

WIP

: Aegiceras corniculatum

: Average

: Bruguiera gymnorhiza (L.) Lam.

: Diameter at stump height

: Hectare

: Overall height

: Milimet

: Danish Red Cross

: Centimet

: Kandelia obovata

: Convention on Wetlands of International Importance

Especially as Waterfowl Habitat

: Rhizophora stylosa Griff.

: Sonneratia caseolaris

: Standard deviation

: Support Program to Respond to Climate Change

: Xuan Thuy National Park

: Institute of Ecology and Works protection

vii

LIST OF TABLES

Table 5.1. Current status of mangrove forest area in XTNP ....................................27

Table 5.2. Standards for seedlings of the K. obovata and S. caseolaris model ........31

Table 5.3. Standards for seedlings of the R. stylosa and B. gymnorhiza model.........32

Table 5.4. Planting technical for planting models at XTNP between 1998 and 2016....33

Table 5.5. Survival rate of planting models at XTNP ................................................35

Table 5.6. Growth characteristics of mangrove species in mangrove plantation models......38

Table 5.7. Growth quality of mangroves in plantation models.................................41

Table 5.8. Composition and density of regeneration trees in the plantation models..........43

Table 5.9. Height distribution of regenerated trees...................................................44

Table 5.10. Quality of regenerated tree layers in plantation models ........................45

Table 5.11. Composition and density of regenerated tree layers in planted forest

models .......................................................................................................................47

Table 5.12. Height distribution of regeneration trees ................................................48

Table 5.13. Quality of regeneration trees in mangroves planting models................49

Table 5.14. Table of criteria for selecting species for mangrove restoration project at

XTNP ........................................................................................................................52

Table 5.15. Proposing technical solutions for mangrove restoration........................54

Table 5.16. Area of nautural condition sites for mangrove restoration ....................56

viii

LIST OF FIGURES

Figure 3.1. Research framework…………………………………..……………….21

Figure 4.1. Map of study area ...................................................................................21

Figure 4.2. Diagram of average salinity of each month in XTNP, 2014 ..................25

Figure 5.1. The community Aegiceras corniculata - K. obovata - S. caseolaris

at XTNP....................................................................................................................28

Figure 5.2. The community of K. obovata - R. stylosa - S. caseolaris XTNP..........29

Figure 5.3 The community of Aegiceras corniculata - S. caseolaris in XTNP........29

Figure 5.4. Techniques for applying K. obovate monoculture afforestation model in

1998 at XTNP ...........................................................................................................30

Figure 5.5. Techniques for applying Planting model of K. obovata and S. caseolaris

in 2016 at XTNP .......................................................................................................31

Figure 5.6. Techniques for applying Planting model of R. stylosa and B. gymnorhiza

in 2015 at XTNP .......................................................................................................32

Figure 5.7. Map of the current mangroves planting models in XTNP, Nam Dinh

province between 1998 and 2016..............................................................................34

Figure 5.8. Survival rate of mangrove plants in plantation models..........................37

Figure 5.9. Average growth chart of plantation models ...........................................40

Figure 5.10. Current status of the planting models in XTNP ...................................42

Figure 5.11. Naturally regeneration trees in mangroves planting models................48

Figure 5.12. The permeable dam model used bamboo material for reducing high

wave and preventing erosion the Red River Delta....................................................54

Figure 5.13. The map of mangroves planning restoration solution at XTNP...........57

1

Chapter 1.

INTRODUCTION

Wetlands as defined by the Ramsar Convention are considered as a

homeland of a variety of flora and fauna and provide a multitude of ecological

economic and social benefits. Xuan Thuy National Park (Nam Dinh province) is the

first Ramsar site in Southeast Asia. The park is also recognized as one of the nine

Biosphere Reserve in Vietnam by UNESCO’s Man and Biosphere Program. The

recognization confirms the biodiversity richness and the globally important of the

park and its mangrove forest [21, 22, 47].

Mangrove forest in Xuan Thuy National park (XTNP) play the role

providing sprawning ground for aquatics species but they are also important site

migratory birds including critically endangered species such as black-faced

spoolbill (Platalea minor) and spood-billed sandpiper (Calidris pygmaea) [21,

22]. The mangrove is also vital for protecting the sea dyke system that protect the

highly productive red-river delta and highlight populated rural area of Nam Dinh

and Thai Binh Provinces. With the mangroves forest, it helps to limit the effects of

floods and storms and high tides; reducing waves, limit erosion and protection of

sea dykes; in addition, the forest is contributing in securing livelihoods for

thousands of people who live in the buffer zone of the Park [9, 15, 16, 119].

However, the rapid extension of aquatic species farming, and agriculture extension

have reduced much of the mangroves and create serious threat to the forest by

cutting, thinning that made significant change the ecological condition of the

forest as well and the whole ecosystem of the area then reduce the ecosystem

services that the forest is providing for the area and the human well-beeing [20].

Recognizing the important role of mangrove ecosystem at XTNP, recent

years, there were several mangrove planting models have been implemented [8, 35,

46]. Until now, there has been no comprehensive evaluation of the results of

implementation of mangrove planting models. Therefore, the thesis will focus on

researching and evaluating the current status of some mangrove planting models

and proposing technical solutions to improve the effectiveness of conservation and

development mangrove forest in XTNP, Nam Nam province.

2

Chapter 2.

LITERATURE REVIEW

2.1. Research results on the world

2.1.1. Research on mangrove ecosystems

Mangroves are the common name for a belt of coastal forest that is frequently

or periodically flooded by tides. Mangroves are mainly found only from latitude 25

above the equator and 25 below the equator, covering approximately 17 million

hectares, they are distributed in 112 countries and territories in Asia, Africa, Australia

and the Americas (Aizpuru et al., 2000) [53]. Currently, Southeast Asia has the

largest mangrove forest area in the world, accounting for 4.9 million hectares,

equivalent to 35% of the total area of mangroves in the world. There are 52 species

out of 268 plant species that are considered true mangrove species, the rest are

participating species, which can live outside of mangrove environments. There are 18

species of mangrove plants that are endemic, and eight of them are true mangrove

species (Giesen et al., 2006) [75].

Mangroves provide fuel wood and many valuable aquatics and marine

products, capable of fixing mud, sand, windbreak, breakwater to protect residents,

fields and economic and cultural works along the coast, contributing to an important

part of protecting the environment in many coastal regions (Kathirestan, 2000) [83].

Tomlinson (1986) [111] divided mangrove communities into two groups

with different tree species composition: eastern group and western group. The

Eastern group corresponds to the Indo-Pacific region with a diverse and rich

number of species. The western group consists of tropical coasts of Africa, the

Americas in both the Atlantic and the Pacific. The number of species here is small,

only 1/5 of that in the East (Spalding et al., 1997) [108]. The main species in the

West are: Rhizophora mangle, A. germinans, Laguncularia racemosa. However, the

size of some species of trees is larger than the Eastern group, for example, in Brazil

this species is over 50 m high and in Ecuador it is over 60 m high.

According to Larsson et al. (1994) [89], mangroves are mainly distributed in

warm climates (from 2000C and above) and heavy rainfall (average annual rainfall

3

over 1,000 mm). Mangrove soils contain many nutrients brought by tidal waters, but

are very low in oxygen. Daily tidal activity makes soil salinity an average of about

1.5 - 2.5%. The physical and chemical properties of the soil are highly dependent on

the origin of alluvium and sediment (Lugo and Snedaker, 1974; Hutchings et al.,

1987; Sammut et al., 1996) [93, 81, 104].

The list of mangrove vegetation with a number of species about from 50 to

75 species (Lugo and Snedaker, 1974; Saenger et al., 1983; Blasco, 1984) [93, 103,

55]. The most common genera of mangroves are: Avicenia, Rhizrophora,

Bruguiera, Ceriops tagal, Excoecaria and Soneratia. Mangroves often have a simple

element due to the high inundation and salinity conditions. The phenomenon of

species dominance is usually very clear with a main structure of one tree layer, with

very few species of shrubs and grass under the mangrove forest.

In the tropical hot and humid region with fertile alluvium, mangroves often

grow fast and have a large size of several tens of meters, with reserves reaching

hundreds of m3

/hectares. In contrast, in sub-tropical regions, on poor soils,

mangroves are usually shrubland with tree height limited to a few meters and the

total biomass not exceeding 50m3

/hectares. The growth rate of mangroves in the

early years usually increases, by about 10-15 years, the growth is stable and starts to

decrease gradually. At about 35-40 years old, the mangroves turn to natural

maturity, the size of the tree does not increase anymore and begins to age and fall.

However, scientists also warn that coastal mangroves are some of the most

threatened ecosystems in the world, and their scale of distribution is changing day

by day. This is the result of population growth, economic development including

land reclamation of urbanization and industrial development, expansion of shrimp

farming areas and pollution. According to Khan and Ali (2007) [85], the rate of loss

of mangroves is increasing.

Kathiresan (2002) [84] when studying the functional variation of mangrove

ecosystems, compared the ecological variables, the physicochemical index in 5 very

rich mangrove areas and 25 zones has been degraded in the Pichavaram mangrove

forest in India and found that the causes of natural mangrove degradation are mainly

4

due to the high salinity, low nutrients and poor microorganisms in the soil. Onrizal

et al. (2009) [97] suggests that when the mangrove forest environment is degraded,

if there is a recovery with participating mangrove species to replace mangroves that

really cannot be. function as desired.

2.1.2. Research on mangrove rehabilitation on the world

Havanond (1994) and Aksornkoae (1996) [80, 49], Rhizophora apiculata and

Rhizophora mucronata are the two main mangrove species in Thailand, of which,

the double mangrove forest is planted with shoots and seedlings have a rather high

survival rate greater than 80%. and planting Rhizophora mucronata forest with

survival rate > 94%. Francis E. Putz and H.T. Chan (1996) [73], in Malaysia, from

1987 to 1992, there were 4,300 hectares of mangroves, with the main crops being:

R. apiculata and R. mucronata. In Indonesia, there are four main cultivated species

of mangroves, namely R. apiculata, R. stylosa, R. mucronata and B. gymnorrhiza.

Koko M., (1986) [86] used a planting method based on species

characteristics and germination ability of the seed or propagules. According the

author, there are 3 methods applied in some Asian countries: (i) Planting directly by

propagules; (ii) Planting with seedlings planted in nurseries; and (iii) Planting from

naturally occurring seedlings.

Soemodihardjo et al. (1996) [106] in Indonesia have 2 planting techniques

that are applied directly by seed stalks and planted with container seedling. The

applied density is 2,500 trees/hectares (2.0 x 2.0 m), the main crops are Rhizophora,

R. apiculata, R. mucronata and B. gymnorrhiza. Planted directly by seed stalks,

the survival rate reached 55-70% and indirectly planted with seedlings 3 - 4 months

old, the survival rate was higher, reaching 85%.

Siddiqi N. A., and Khan M.A.S., (1996) [107] the appropriate level of tidal

inundation and salinity are important determinants of the survival and growth of

newly planted seedlings. In the new coastal alluvial condition in Bangladesh,

species of S. apetala and Avicennia marina were selected. Planting density varies

from 1.2 x 1.2 m; 1.5 x 1.5 m and 1.7 x 1.7 m. Planting from 6-7 months of age

container seedling, the survival rate of the S. apetala is from 29 to 52%, an average