Landsat imagery and ndvi differencing to detect coastal mangrove changer case study in dai hop and bang la communes, hai phong

MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT VIETNAM FORESTRY UNIVERSITY STUDENT THESIS LANDSAT IMAGERY AND NDVI DIFFERENCING TO DETECT COASTAL MANGROVE CHANGES Case study in Dai Hop

MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT

VIETNAM FORESTRY UNIVERSITY

STUDENT THESIS

LANDSAT IMAGERY AND NDVI DIFFERENCING TO DETECT

COASTAL MANGROVE CHANGES Case study in Dai Hop and Bang La communes, Hai Phong

Major: Natural Resources Management (Advanced Curriculum) Code: D850101

Faculty: Forest Resources and Environmental Management

Student: Nguyen Cong Quang Student ID:1053090504 Class: K55 Natural Resources Management Course: 2010 - 2014

Advanced Education Program

Developed in collaboration with Colorado State University, USA

Supervisor: Dr Nguyen Hai Hoa

Hanoi, November 2014

ACKNOWLEDGMENTS

This thesis could not have been completed without the assistance, advice and support of a number of people Firstly, I would like to thank my supervisor, Dr Hai Hoa Nguyen for his and advice throughout my undergraduate thesis In particular, I am deeply appreciative of the time and consideration given by him whenever I needed it

This study depended to a large extent on the co-operation of my mangrove friends and coastal inhabitants in Dai Hop and Bang La communes, who not only provided access to their properties for my field studies, but often also opened their homes to me and allowed me to gain an understanding of life on the coast

I would like to say a very big thank you to my friends and family for putting up with me and providing encouragement and moral support when I most needed it Special mention goes to

my lecturers in Faculty of Forest Resource and Environmental Management, Vietnam Forestry University who encouraged and morally supported whenever I most needed To my parents, thank you so much for your unconditional love and moral support

Due to the limited research capability and time budget, the shortcoming of thesis is inevitable I therefore would like to receive feedbacks from lecturers, researchers and friends for enhancing the quality of my thesis

ABSTRACT

Fringe mangroves are recognized as a highly valuable resource due to their provision of

multiple ecosystem services In this study, we propose a vegetation change detection analysis

based on the NDVI differencing technique in order to assess mangrove forests changes related

to mangrove forest expansion for the Kien Thuy and Do Son coasts, Hai Phong, Vietnam

using multi-temporal imageries from 2003 to 2014

Using the method techniques and algorithms used to detect changes in the different phases of

the objects on remote sensing have been established based on the development of remote

sensing technology in the space characteristics, spectral, thermal and time Method to detect

changes in mangroves is a way of comparing the differences between two images (Singh,

1989) In this study, NDVI (Normalised Differencing Vegetation Index) is applied to detect

changes in coastal mangroves and other coastal land use/covers Two pairs of images are used

to analyze changes, including a pair of 2003 - 2009 and 2009- 2014 And use GIS applications

to detect mangrove changes

To assess the accuracy of classification methods on the thematic use of the same set of test

data points on the field in the state forests, other objects and other countries in the area of

investigation, determining the GPS and proceed to compare the actual value with the value on

image classification, which assess the accuracy of classification methods and compare the

accuracy of the years during the period 2003-2014 The accuracy of classification,

interpretation performed on image classification in 2003, 2009 and 2014

Mangrove forests have large fluctuations in the period 2003 - 2014 In 2003, there were

219.87 ha of mangroves which were the lowest land cover by mangrove extent in comparison

with 2009 (401.13 ha) and 2014 (181.26 ha) The results showed that the increase of the area

of mangroves 2003-2014 was derived from policies to protect the mangroves good, concrete

support of government agencies, local government advocacy, educational programs

KEY WORDS

Bang La, Coastal areas, Dai Hop, Landsat image, Land Use/Land Cover, Local people,

NDVI, Mangroves

ACRONYMS

TABLE OF CONTENTS

ACKNOWLEDGMENTS ii

ABSTRACT iv

KEY WORDS iv

ACRONYMS Error! Bookmark not defined TABLE OF CONTENTS vi

LIST OF TABLES vii

LIST OF FIGURES viii

1 INTRODUCTION 1

2 STUDY GOALS AND OBJECTIVES 4

3 STUDY SITES AND MATERIALS 5

4 METHODS 8

4.1 Investigation of coastal mangrove structures and its management status 8

4.2 Quantification of spatial-temporal dynamics of coastal mangroves over 11 years 13 4.3 Identification of the main drivers of changes in coastal mangrove extent 14

4.4 Implications for enhancing sustainable mangrove management in study areas 14

5 RESULTS AND DISCUSSION 14

5.1 Mangrove management and its structures in study sites 14

5.2 Spatial-temporal dynamics of coastal mangrove extent during 2003 -2014 17

5.3 Potential of mangrove changes during the period of 2003- 2014 26

5.4 Effective measures to improve the management of mangroves 27

6 CONCLUSION, EXISTENCE AND FURTHER STUDY 31

6.1 Conclusion 31

6.2 Existence and study 32

References 33

APPENDIX 36

LIST OF TABLES

Table 4.1 Landsat Data used for detecting changes in coastal mangroves 9

Table 5.1 NDVI values for mangroves and non-mangroves for studied sites different

years

18

Table 5.2 Mangrove area in studied sites in different years 18

Table 5.3 Accuracy of image classification in 2003 21

Table 5.4 Accuracy of image classification in 2009 21

Table 5.5 Accuracy of image classification in 2014 21

Table 5.6 Changes in mangrove areas during periods 2003-2009, 2009-2014 (ha) 22

LIST OF FIGURES

Figure 3.1: Study sites in Hai Phong where: (a) Viet Nam map, (b) Hai Phong city

map, (c) Selected sites as Kien Thuy District and Do Son County

5

Figure 4.1 Processes of Landsat image interpretation using of NDVI 11

Figure 5.1 Distribution of coastal mangroves: (a) Mangrove areas in 2003, (b)

Mangrove areas in 2009, (c) Mangrove areas in 2014

19-20

Figure 5.2 Mangroves changes in Hai Phong during the period of (a) 2003-2009 and

(b) 2009-2014

23

Figure 5.3 Mangrove changes in Hai Phong during the period of 2003 – 2014 24

Figure 5.4 Mangrove changes in different periods 25

1 INTRODUCTION

Globally, mangroves have been recognized as having an important functional role in preventing coastal erosion, mitigating effects of wind-induced waves, currents and storm surges, and protecting coastal habitats and adjacent shoreline land-uses from extreme hydrodynamic and meteorological phenomena (Kathiresan and Rajendran, 2005; Tamin et al., 2011) Fringe mangroves or tide-dominated mangroves are distributed along shallow shorelines with modest slopes, where they may receive freshwater runoff and nutrients from rainfall and have a high salinity concentration (Rivera-Monroy et al., 2004) Moreover, they are subject to wave actions and storm surges (Baldwin et al., 2001), and are flushed by regular tides (Lugo and Snedaker, 1974) As being very effective in their role as a protective barrier for coastal land use and human infrastructure (Ewel et al., 1998), their function in dissipating wave energy is particularly important for the protection of the shoreline from erosion as a result of the increased frequency and intensity of damaging storms associated with climate change (Mendez and Losada, 2004; Suzuki et al., 2011) Despite these significant functional values, mangroves are still being destroyed and degraded globally for human settlement and aquaculture, leading to a loss of ecosystem services and associated economic benefits Consequently, a rapid decline of fringe mangrove extent linked to the associated impacts of increased severity of storms has the potential to impact on coastal communities referring to catastrophically incidents In Vietnam mangroves are recognized as a highly valuable resource These unique coastal forests provide multiple ecosystem services including carbon storage, wood production for the building sector, fish trap construction and firewood, habitat for aquatic food resources, and shoreline stability and erosion control being considered as most significant The area of mangroves has rapidly declined over time in Vietnam; from an estimated 408,500 ha in 1943 to 290,000 ha in 1962, to 252,000 ha in 1982; and to 155,290 ha

in 2000 (Government of Vietnam, 2005; Sam et al., 2005) However, there is evidence that the area of mangroves increased by 51,450 ha in 2006 due to a National Action Plan for

mangrove protection and development (Government of Vietnam, 2005) Despite this national increase, some areas are still in decline

In addition to the standardized techniques for pre-processing and differencing images, the most important step for vegetation change detection analysis is the differentiation between real changes and seasonal or inter-annual variability, represented by a threshold between these factors, which is generally determined by applying the standard deviation (SD) from the NDVI differencing image (Hayes & Sader 2001, Coppin et al 2004, Desclée et al 2006, Sepehry & Liu 2006, Pu et al.2008) In this study, we propose a vegetation change detection analysis based on the NDVI differencing technique in order to assess mangrove forests changes related to mangrove forest expansion for the Kien Thuy and Do Son coasts, Hai Phong, Vietnam using multi-temporal imageries from 2003 to 2014

Hai Phong is a coastal city with a length of 125 km of sea dykes, with a natural land area of nearly 152,000 ha, located in the downstream region of the Thai Binh river systems Together with the provinces of Nam Dinh, Thai Binh, Quang Ninh, Hai Phong is one of the potential area for local mudflats and mangroves In particular, the area of mangroves can mainly be divided into four coastal districts and three counties, namely Thuy Nguyen, Kien Thuy, Tien Lang, Cat Hai, Do Son, Duong Kinh and Hai An

Recently, many major storms have struck the coastal areas of mangroves plantations where the protection of the sea dyke remained firm against large waves On the other hand, deforestation leads to an increase in wind speed at the earth’s surface altering the mode of heat and moisture in the air layer near the ground and an increase in the intensity of total evaporation Furthermore, as a consequence of deforestation climate change over large distances can adversely affect the living conditions of the organism This will result in an increase in water vapor condenses, a reduction of the amount of rain fall, a loss of shelter and

a reproduction of organisms increasing temperature, etc Aiming to reduce the adverse effects

of natural disasters, Hai Phong has enlisted the province for being supported in planting

mangroves to protect the coast from big storms and constructing a levee system from erosion caused by tidal With regard to the rising sea levels these methods are to promote and protect the coastal areas Thus, in this area systems of coastal protection forests are constantly expanding While in 1990 the forest area amounted to 293 ha, the protected area is now scaling to over 4,700 ha The sea dike was built up outside of the safety area of the forests when the typhoons are entering Forests are not only aiming to protect the sea dikes and frequently reduce repair cost and repair embankments, they also provide aquatic resources to the local people

Those storms affecting Vietnam and countries around the world It is clear that mangroves protect coastal areas more than any solid concrete constructions due to destruction

by salt water and sea waves In fact, conservation of mangrove forests has an enormous value regarding the reduction of up to 50% of the impact energy waves, the prevention of the rising sea level and the important contribution to protect people and infrastructure at coastal facilities Mangroves have the effect of sharply reducing the height of the wave at high tide, such as the waves felling sharply when passing mangroves with a change from 75% to 85%

In general, forests alter wind speed Thus, the wind of the forest belt movement is gradually lowering the air on the opposite side and supporting the back movement under the surface with the lower speed There is an increase in rainfall due to atmospheric evaporation processes by the forest Many studies have proven that there will be a rainfall increase of 2.5%, if there is an increase in forested area of 10% The increase in rainfall related to the evaporation process of the forest causes a forest canopy heated by solar radiation The mangrove forest communities and forest protection organizations are aiming for a cooler climate, the reduction of the maximum temperature and a lower temperature boundary Forest ecosystems help to balance O2 and CO2 in the atmosphere, conduct climate controls (temperature, precipitation) and reduce the greenhouse gas emissions, in order to participate

actively in the process of protecting the ozone layer Additionally, forests have a great significance for the prevention of wind damage to fields and residential areas

There are few studies examining the relationship of spatial-temporal changes in coastal mangroves and coastal adjacent land-use in association with coastal development policy, such as the relationship between drivers of mangrove destruction and institutional arrangements and policy over coastal resources, and other socio-economic influences Therefore, certain questions remain unanswered, including what is the relationship between coastal mangroves and coastal shoreline erosion; and how resilient are coastal mangrove ecosystems to increasing frequency and intensity of extreme events?

In this study, I test the hypothesis that: human-induced drivers have significantly changed the extent of coastal mangroves over the last 11 years on the Kien Thuy and Do Son coasts, Hai Phong, Vietnam This thesis also defines possible solutions for improving sustainable mangrove management and local livelihoods

2 STUDY GOALS AND OBJECTIVES

Study goal:

The aim of the study is to detect and analyze changes in coastal mangrove cover by using multi-temporal Landsat images covering Dai Hop and Bang La communes in Hai Phong from 2003 to 2014 These findings provides good scientific foundation for enhancing mangrove rehabilitation and restoration in the face of climate change and sea-level rise in Hai Phong

Study objectives

In order to reach the main goal of study, a number of specific objectives are given as below: Objective 1: This objective is to compile and investigate the status of coastal mangrove management and its structures in Dai Hop and Bang La communes, Hai Phong

Objective 2: This objective aims to quantify the spatial-temporal dynamics of coastal mangrove extent in Dai Hop and Bang La communes in Hai Phong by using multi-temporal imageries over 11 years (2003 – 2014)

Objective 3: This objective aims to identify the main drivers of changes in coastal mangrove extent by analysing the relationships between the changes in coastal mangrove extent and other associated land-use/covers

Objective 4: This objective proposes possible solutions for sustainable management of coastal mangroves in study areas

3 STUDY SITES AND MATERIALS

Study sites and scope

Figure 3.1: Study sites in Hai Phong where: (a) Viet Nam map, (b) Hai Phong city map, (c) Selected sites as Kien Thuy District and Do Son County

In Hai Phong, coastal mangroves mainly distribute in the Dai Hop commune in Kien Thuy district and Bang La commune in Do Son County Therefore, Dai Hop and Bang La are selected as case studies in Hai Phong (Figure 3.1)

This study used Landsat imageries with a 30-m spatial resolution spanning 11 years, namely Landsat 5 in 2003, Landsat 7 in 2009 and Landsat 8 in 2014 (Table 4.1)

Geography

Kien Thuy is a suburban district located in the southeast of Hai Phong city and has an area of 102.56 km2, with a population over 12.5 thousand people Kien Thuy is located in the north and east of Duong Kinh and Do Son district, south of Tien Lang district and in the west

of Kien An and An Lao district

In contrast, Do Son is a small peninsula of Dragon mountains reaching up to a 5-km long sea, with dozens of high hills from 25 to 130 m It has a natural area of 31 km2 with population of 35,000 inhabitants, distributing in four districts and one commune The annual economic growth in Do Son account for 16% with the economic structure as follows: tourism and services account for 67.2% while fisheries and agriculture; and industry are 25%, 7.8% respectively

Climate

Hai Phong is characterised by the belt of tropical Asian monsoon In particular, Northern Vietnam is characterized by a warm and humid subtropical climate There are two distinct seasons, namely winter and summer: hot and rainy in the summer, and cold and dry in the winter North wind season (winter) lasts from November to April The Monsoon period (summer) is hot and rainy lasts from May to October with average temperatures around 32.5

°C The average temperature in winter is 20.3 °C while the annual average temperature in summer is around 23.9 °C Average monthly temperature varies between 20 - 23 °C, with a

maximum temperature of 40°C and a minimum of 5°C The average humidity is between 80%

to 85%, with a maximum humidity of 100% in July, August and September, and the lower humidity values in December and May During the year, there are about 1692.4 hours of sunshine Ground radiation is 117 Kcal cm/min as an annual average The average annual rainfall is about 1600 - 1800 mm Typhoons usually occur from June to December Notetably, Kien Thuy district and Do Son County are impacted by one or two typhoons yearly In general, the climate and weather in study sites are quite favorable for crops and livestock

Do Son district and Kien Thuy district are adjacent to the East Coast In the north and south of the county, there are two estuaries, namely Lach Tray and Van Uc The Thai Binh river system empties into the sea carrying more silt Moreover, they have to widen the sea dykes in order to build Hon Dau Island Resort on a high quality level, causing the sea water in this area to be more likely polluted

Values of mangrove ecosystems

Coastal mangroves are an integral part of the marine ecosystem The role of mangroves like the green walls of the area protecting against wind and waves The "Green lung" is very important for the city, above all mangroves play a very important role In addition, there are mangroves specific roles such as:

Provision of wood and materials: Wood mangrove trees, parrots (Bruguirea

gymnorrhiza), hard and durable smooth It is used as columns, planks, beams, furniture

Mangrove belong to the family of cypress trees The fish can eat from the plywood Furthermore, numerous household items can be made from mangrove wood

Provision of tannins: Tannins are extracted from mangrove bark in good quality and at

a high rate using dyed fabric, mesh, leather tanning Additionally, they can be used to cure diarrhea

Provision of fuel: The mangrove trees are fuel sources for the coastal people The rational exploitation and plantation development can be of long-term use Moreover, charcoal from mangrove and parrot trees have a high heating value

Mangroves can grow on mudy areas, saltwater and deep submergence, so they can be planted in coastal areas like coastal mudflats and estuarine Thus, they contribute to increase the biodiversity through supplying nourishment to the bio-system It is the pioneer species invade bogs Due to the dense root respiration in the mud it helps to silt deposition rapidly and

supports gradual accretion of land Hence, the mangrove species such as parrots (Bruguirea

Mangrove forests are also located on many popular beaches in estuaries Nowadays, coastal area become of high economic value Another indispensable role of mangroves is to provide humus and organic matter (from branches, leaves, fruits fall off the microbial decomposition) as food for animals

Mangrove forests are also attracting many local and migratory birds, since they offer

an ideal living environment for the birds during the breeding season Many rare bird species are listed in the Red Book of Vietnam

4 METHODS

4.1 Investigation of coastal mangrove structures and its management status

Methodology

Techniques and algorithms used to detect changes in the different phases of the objects

on remote sensing have been established based on the development of remote sensing technology in the space characteristics, spectral, thermal and time Method to detect changes

in mangroves is a way of comparing the differences between two images (Singh, 1989) In this study, NDVI (Normalised Differencing Vegetation Index) is applied to detect changes in

coastal mangroves and other coastal land use/covers Two pairs of images are used to analyze changes, including a pair of 2003 - 2009 and 2009- 2014

GIS applications to detect mangrove changes

(a) Remote sensing data for study

In this study, Landsat imageries in 2003, 2009 and 2014 with a 30-m spatial resolution are used to detect coastal mangrove changes as shown in Table 4.1

Table 4.1 Landsat Data used for detecting changes in coastal mangroves

Year Image code Date of capture Resolution Path/Row

2003 LT51260462003350BJC00 16/12/2003 30 (15) m 126/046

2009 LE71260462009310EDC00 6/11/2009 30 (15) m 126/046

2014 LC81260462014284LGN00 11/10/2014 30 (15) m 126/046

Sources: http://earthexplorer.usgs.gov/

(b) Status of coastal mangrove management and mangrove structures

Investigate interviewed households to keep forests: The first job is to conduct direct

interviews of households contracted for forest protection in coastal mangroves, targeting at those who were born and are living very closely to coastal mangroves Therefore, they have a very good understanding of coastal resources in studied sites Also, interviews are conducted with households who are assigned to protect and manage mangrove forests In addition, interviews with personnel are directly involved in the management of mangrove protection in areas such as ranger stations, social forestry officials, officials of the contracting unit to

protect the forests in the area

Interview content generally refers to coastal mangroves that they have clearly known about mangroves, their local species and species appearance Recognizable species such as

when classifying images Also, this study gave the color photo or color drawings to farmers

for further clarity in the document; to identify species in order to provide more information about the venue, the growth of the species they are not aware of the consultation of experts

Field survey: A number of mangrove structures are investigated during field survey,

including canopy cover, mangrove species, root density and its height:

Canopy closure/coverage (%): An estimation of canopy closure is made using the

densitometer approach This device is made from piece of 2.5 cm diameter duct pipe approximately 40 cm long with cross-hairs added at both ends using fine wire threaded evenly across the diameter of the tube (Duke et al., 2010; Hai-Hoa et al., 2013) The densitometer is held vertically and an estimate made of the percentage of the view through the duct pipe covered by sky, or less or more than 50% of a leaf, branch and tree trunk (recorded as 0, 0.5

or 1 respectively) Readings are taken every metre along the transect length within a 100 m2plot, resulting in about 100 readings

Mapping status of mangroves in different year (2003, 2009, 2014)

Mapping the status of coastal mangroves and their distribution in different years are used this study Process of mapping the status of mangroves and classifying a single image is illustrated in Figure 4.1

Calibration classification results

Digital map data

In this study, a number of steps are described as below

Step 1: Data Processing image

Image Clustering channel: Data collected included individual spectral channels, thus

need to conduct image collection channels to serve the image interpretation

Crop the image: Because the study area forms only a part of the image, it is necessary

to cut separating the study area A file containing the study area boundaries are used to cutting areas of research topics from newspaper photographs

Step 2: Classifying Landsat images

This study was carried out using a number of different vegetation indices (NDVI) to determine the current status of land cover and land use types coastal study area in 2003 and

2014 Additionally, subjects evaluate the degree of each different vegetation indices as the basis for selection of scientific image classification method based on vegetation indices for the study area

Evaluate the precision and image processing after sorting

Assessment accuracy of image classification: This step is used to assess the quality of

the interpretation of satellite images or compare the reliability of the results obtained when applying different methods in remote sensing classifying images

After sorting Handling: After sorting process should perform post-processing to create

the classification ability of the class map by generalizing information

Step 3: Mapping the distribution of coastal mangroves

Rules calculate the relationship between map scale resolutions of the sample is divided

by 1000 rate map to find out the size of the unit in m The formula for calculating the rate of resolution maps were developed as follows: The rate of maps = resolution (m) * 2 * 1000

Remote sensing data used in this subject spatial resolution is 30 m, according to the above formula, the rate of appropriate maps for the study area is 1:60 000 Additionally, to establish the complete map, adding details such as projection systems, annotations, ruler and compass orientation ratio

4.2 Quantification of spatial-temporal dynamics of coastal mangroves over 11 years

Quantifying coastal mangrove extent in the different year:

To quantify the coastal mangrove extent in each year (2003, 2009 and 2014), this study uses the Normalized Difference Vegetation Index (NDVI), which is a function of two bands: the red band and near-infrared spectral band It is calculated for both bands of images using the following relationship (Equation 1):

( 1 )

Where: BandIR is near-infrared band (e.g TM5) and BandRed is red band (e.g TM4)

Quantifying the dynamics of coastal mangrove extents in each period (2003-2009 and 2009 - 2014):

To identify the changes in coastal mangrove extent, the NDVI differencing is applied This technique compares and computes NDVI values between images acquired on two different dates In order to apply NDVI image differencing, the individual NDVI image of each date is generated with a range of values from -1 to +1 Histogram equalization enhancement is used to modify these values so that all values occurred with equal probability

to range 0-255 for both images This step is followed by creating NDVI difference image

through the subtraction of the NDVI image of one date from that on another date (Equation 2)

NDVIchange = NDVIyear 2 - NDVIyear 1 ( 2 )

4.3 Identification of the main drivers of changes in coastal mangrove extent

The main drivers of changes in coastal mangrove extent each period are identified through analysing the relationships between the changes in coastal mangrove extent each period and other associated land use/cover together with field surveyed questionnaires

4.4 Implications for enhancing sustainable mangrove management in study areas

The findings are used to inform coastal management planning and policy development, particularly in relation to improve coastal mangrove management and local livelihoods in study areas

5 RESULTS AND DISCUSSION

5.1 Mangrove management and its structures in study sites

5.1.1 Mangrove structures

Mangrove features

Coastal mangroves are stretching along southeast of Hai Phong, distributiing mainly in the coastal communes of Kien Thuy district and Do Son, Hai Phong Mangrove areas has 408.96 ha over the tidal mangrove areas Beautiful scenery is very convenient for sightseeing, eco-tourism and attracting investment projects and aquaculture As a result shown that study sites with mangroves are often muddy, low oxygen levels, high water level and low salinity with slow tide

Mangrove structures in Dai Hop commune, Kien Thuy district

As the result of field survey showed that there were two main mangrove species

identified, namely Kandelia obovate and Sonneratia caseolaris Besides, Kandelia obovate

Sonneratia caseolaris, Sonneratia caseolaris and Kandelia obovate at Dai Hop commune

were found distributing along the dike area near Van Uc estuary to the drainage territory and adjacent to the area of Bang La commune, Do Son County

Further field survey and interviews have found that coastal mangroves were planted in

1999 with the number of species Mangroves were planted in the middle of the Kandelia

obovate and beyond Sonneratia caseolaris; adjacent sea dikes with Kandelia obovate and Sonneratia caseolaris; sea and sea embankments with Sonneratia caseolaris species as main

mangrove species

Stratification in the forest: At the time of the study (May 8/2014), there was a lot of floor regeneration and the soil was often washed into the sea near the foot of the dike with a

height of 80 - 90cm However, the majority of the Kandelia obovate trees and Sonneratia

caseolaris trees were found there, but there was almost no seedling regeneration

The root density of Sonneratia roots is 120 roots/m2 and its average height of breathing roots is 45cm found near the main trunk In about 1m distance away to the main trunk, the number of roots is 50 roots/m2 and the average height of breathing roots is 38-48cm

Canopy cover: During the mangrove plantation program, two mangrove types in the

study area were established towards the sea Kandelia obovate species was planted at a

density rate of 0.7m x 0.7m, spacing evenly trees As result shown that canopy cover was around 98% in studied sites These mangrove types are stretched over the study area with the width from 650m to 720m toward to the sea

Mangrove structures in Bang La commune, Do Son County

This study survey showed that there are two major mangrove species found in Bang

La commune, namely Kandelia obovate and Sonneratia caseolaris species, where they are