Using landsat 8 data and GIS to estimate above ground biomass and carbon stocks of coastal mangroves in xuanthuy national park nam dinh province

MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT
VIETNAM FORESTRYUNIVERSITY

STUDENT THESIS
Title

USING LANDSAT 8 DATA AND GIS TO ESTIMATE
ABOVE-GROUND BIOMASS AND CARBON STOCKS OF
COASTAL MANGROVES IN XUANTHUY NATIONAL PARK,
NAM DINH PROVINCE

Major: Natural resource management
Faculty: Forest resource and environmental management

Student: Nguyen Dinh Quang Tuan
Class: K57 Natural resource management

Student ID: 1253100989
Course: 2012 – 2016

Advanced Education Program
Developed in collaboration with Colorado State University, USA

Supervisor: Dr. Nguyen Hai Hoa

Hanoi, 2016


ACKNOWLEDGEMENT
With the consent of the Vietnam National University of Forestry, Faculty of Forest
resources and Environmental Management, the study caried out the study of“Using

Landsat 8 data and GIS to estimate above-ground biomass and carbon stocks of coastal
mangroves in XuanThuy National Park, Nam Dinh province”.
On the occasion of completing this scientific research, I would like to express deep
gratitude to Dr. Hai- Hoa Nguyen who has guided and helped me in the process of the
implementation and the completion of this study.
I sincerely thank teachers in Faculty of Forest Resources and Environmental
Management for the encouragements and suggestions and for helping me to improve the
quality of my study.
I would also like to express our gratitude to the staff and local people in XuanThuy
National Park communes for the enthusiastic help during my works.
Due to the limited knowledge and experiences, this report is not finalized yet. I‟m
looking forward to receiving feedback from teachers and friends to improve this scientific
research.
Ha Noi: 01 November.


ABSTRACT
The Vietnam mangroves have been larger and rich and they play an important role
for forest ecosystems, biodiversity and local livelihoods and development. However, the
management of mangroves in Vietnam is still facing many challenges. The process of
transition to market economy under reform policy has brought high economic growth from
7 to 8% in the first 5 years of the twenty-first century with the changes in livelihood
patterns. Vietnam faces big challenges of environmental problems as a result of
overfishing, mismanagement of natural resources and the pressures of globalization. The
changes in the social, ecological, economic and institutional schemes gave the livelihood
systems of mangroves increasingly complex and vulnerable. To contribute develop
sustainable management of coastal mangroves, the study of “Using Landsat 8 data and
GIS to estimate above-ground biomass and carbon stocks of coastal mangroves in
XuanThuy National Park, Nam Dinh province” was conducted. The study is based on
using NDVI values to identify the distribution of mangroves, apply formula of scientific

research to calculate total of above- ground biomass and then calculate the carbon stocks of
mangroves in XuanThuy National Park. Thereby we can make recommendations for the
conservation and management of mangrove forests more efficiently.


ACRONYMS

ABBREVIATION
GPS:

Global Positioning System

GIS:

Geographic Information System.

NDVI:

Normalized Difference Vegetation Index

IPCC (2016):

Intergovernmental Panel on Climate Change

RS:

Remote-Sensing


TABLE OF CONTENTS

ACKNOWLEDGEMENT
ABSTRACT
ACRONYMS
LIST OF TABLE AND DIAGRAM
LIST OF FIGURES
CHAPTER I INTRODUCTION ........................................................................................ 1
CHAPTER II LITERATURE REVIEW ........................................................................... 4
2.1. Overview of mangroves coastal ...................................................................................... 4
2.1.1. Roles and function of coastal significance. ................................................................. 4
2.2. Mangroves biomass and carbon stock in worldwide ...................................................... 6
2.2.1. Mangroves biomass in the world ................................................................................. 6
2.2.1. Mangroves biomass in Vietnam: ................................................................................. 8
2.3. Application of GIS and Remote sensing to estimate mangrove biomass and carbon
stock ..................................................................................................................................... 10
CHAPTER III GOAL, OBJECTIVES, CONTENT AND METHODOLOGY .......... 14
3.1. Goal and objectives ....................................................................................................... 14
3.1.1. Overall goal................................................................................................................ 14
3.1.2. Specific objectives ..................................................................................................... 14
3.2. Scope and framework of study ..................................................................................... 14
3.3.1. Examining the status of mangroves and management schemes in XuanThuy National
park, Nam Dinh province..................................................................................................... 14
3.3.2. Quantifying spatial distribution of mangrove extents in XuanThuy National Park,
Nam Dinh province .............................................................................................................. 15
3.3.3. Thematic map of mangroves extent and quantification of carbon stock and biomass ....... 15
3.3.4. Proposing solutions to improve the management of mangrove in XuanThuy National
park ...................................................................................................................................... 15
3.4: Methods ........................................................................................................................ 15
3.4.1. Examining the status of coastal mangrove management in XuanThuy National Park,
Nam Dinh Province ............................................................................................................. 15

3.4.2. Quantifying spatial distribution of mangrove extents in XuanThuy National Park,
Nam Dinh province .............................................................................................................. 16
3.4.3. Thematic map of mangroves extent and quantification of carbon stock and biomass ....... 18
3.4.3.1. Mapping status and distribution of mangroves in 2015:........................................ 18
3.4.4. Proposing solutions to improve the management of mangrove forests in XuanThuy
National park........................................................................................................................ 22
CHAPTER IV STUDY SITE, NATURAL AND SOCIAL FEATURE ........................ 22
4.1. Study area ..................................................................................................................... 22
4.1.1. Natural characteristics................................................................................................ 23
4.1.2. Resource development ............................................................................................... 25
4.2. Socio-economic conditions ........................................................................................... 28
4.2.1. Population .................................................................................................................. 28
4.2.2. Economy .................................................................................................................... 28
CHAPTER V RESULTS AND DISCUSSION ................................................................ 31
5.1. Mangrove structures and its management in study sites ............................................... 31
5.1.1. Mangrove structures .................................................................................................. 31
5.1.2. Mangrove management.............................................................................................. 33
5.2. Spatial distribution of coastal mangroves in XuanThuy National Park ........................ 34
5.3. Thematic map of mangroves extent and quantification of carbon stock and biomass . 38
5.4. Effective measures to improve the management of mangroves ................................... 40
CHAPTER VI GENERAL CONCLUSION, LIMITATIONS AND FURTHER
STUDY ................................................................................................................................ 43
6.1. General conclusion ....................................................................................................... 43
6.2. Limitations and further study ........................................................................................ 44
REFERENCE
APPENDIX


LIST OF TABLE AND DIAGRAM

table 2.1. About wood density of tree in mangrove forest. .................................................... 7
table 3.1.Landsat and sentinel data used in the study. ......................................................... 16
table 3.2. Sampling of data collection form. ........................................................................ 18
diagram 3.3. Methods of constructing mangrove maps using ndvi. .................................... 19
table 5.1. Plots information and mangrove characteristics in study site .............................. 32
table 5.2. Assessing accuracy of classified map(landsat 8). ................................................ 37
table 5.3. Total area of mangroves by using ndvi. ............................................................... 38


LIST OF FIGURES
Fig. 3.1. Layout of sampling plot and subplots this study ................................................... 17
Fig 4.1. Study site (national park management, 2016) ........................................................ 24
Fig 5.1. Spatial distribution of mangroves using ndvi ......................................................... 35
Fig. 5.2. Spatial distribution of mangrove extents in xuanthuy nation park 2016 (landsat 82016) .................................................................................................................................... 36
Fig 5.3: Spatial distribution of mangrove extents in xuanthuy national park in 2016
(sentinel) .............................................................................................................................. 37


CHAPTER I
INTRODUCTION
Vietnam has more than 3200 km of coastline, a lot of estuaries. With a developing
country, the existence of the mangroves ecosystem has a very important significance. The
mangroves contribute to fighting natural disasters, flooding, environmental protection of
coastal areas, climate regulation and development economic and social of the country.
Mangroves imbibe a lot of CO2 by industrial activities and daily life discharge and they
produce a lot of oxygen and make the air clean. As effects of climate changeViet Nam is
one of the most affected countries from rising sea levels and the continuous storms which
have caused severe damage to people and assets. The mangroves have been known not
only as “green lung” but also as “soft andgreen bioshield” to reduce the effects of wind and

wave attacks. Mangroves bring huge economic values and provide many products for
human such aswoods, building materials, sea foods and medicine.
XuanThuy National Park is located at the estuary of the Red River in Nam Dinh
province, about 150 km south-east of Hanoi, Vietnam. The area was declared the country‟s
first Ramsar site by the Bureau of the Convention on Wetlands of International Importance
3 in January 1989. Since then, the Government of Vietnam has worked very hard to
preserve the value of this area through the establishment of new laws, policies and
investments. In 2003, it was upgraded from its status as a nature reserve and approved as a
national park by the Prime Minister, and was also included as part of the Red River Delta
World Biosphere Heritage Site by UNESCO in October 2004. Xuan Thuy National Park is
a vast wetland, which covers an area of about 7,100 hectares of the core zone, and 8,000
hectares of the buffer zone. Endowed with rich alluviums, the park boasts a unique wetland
habitat with diversified species of flora and fauna, especially migratory birds. Besides,
human activities, natural changes caused by sedimentation, water flow, climate change and
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sea level rise, are contributory factors adding more pressure and concern for XuanThuy
National Park management board in terms of fulfilling their mandates as a national park
and a Ramsar site. Consequently, XuanThuy has faced with various environmental and
social issues that are threatening the sustainable use of resources and habitat for waterfowl.
Three major issues in XuanThuy National Park were identified in the strategic plan (2008),
including (I) Negative changes and degradation of natural resources (II) Unsustainable
livelihood practices of local communities, and (III) Limited capacity of concerned
institutions in wetlands management. Though many problems are the results of external
factors that the local have no or low control over, like global climate change, pollutants
from upstream of Red River and National Laws, among others, local partners of the
XuanThuy National Park Network has acknowledged the fundamental issues that link
directly to limited awareness and capacity of local authorities and communities. Protecting
and regenerating mangroves in coastal regions have becoming an extremely important task

of the Government, local authorities, organizations and individuals. The coastal mangroves
extents of XuanThuy district, Nam Dinh province is not out of this trend. Although,
XuanThuy has been considered as a Ramsar site found only Vietnam, but the capital
investment for the region is very relatively low with poor infrastructure, lack of equipment,
the training of staff limitations. From these difficulties, the management of protected areas
has not been effective and thus not meeting the conservation of biodiversity. Mangroves
are one of the most important resources of Nam Dinh province, and in the development
process, as well as one of the forest resources are threatened the most havoc. In recent
years, efforts to protect forests in the province of Nam Dinh has many remarkable results,
the XuanThuy commune had set up a specialized forest protection task force with 4
members and some equipment. Realizing the impact of tides and storms, Nam Dinh
province has launched hundreds of mangroves plantation campaign to counter typhoons
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and climate change, and has planted tens of thousands of hectares of trees. To promote a
forestation, coastal communities have sought to allocate forest land to household
management and a forestation. Accordingly, the growers will enjoy the planting and care
funding from the district and commune, and they would enjoy all the marine resources
brought from the forest, so people are actively involved in this project. Forest development
efforts has brought significant changes in the scale and quality of forests in XuanThuy.
One of the environmental management tools is common in the world today is GISGeographic information systems. However, in recent years, new GIS just been developed
in Vietnam. This is to introduce topics and more widespread tool for field GIS
environment sector. Here, the subject will introduce one of GIS tools that vegetation index
NDVI in geographically remote sensing. The secondary vegetation index separated from
the near-infrared band, infrared and red strip intermediate parameters from which could see
the different characteristics of vegetation, such as biomass, index leaf area, photosynthetic
capacity, total biomass products of seasonal plants can create. These properties are related
and depend greatly on the type of plant cover and weather, physiology, biochemistry and
insect Technology for monitoring approximate characteristics of different ecosystems that

allow identification standards and comparisons between them. Multispectral satellite
imagery, multi-resolution, including very large, repeat the cycle time to help gather
information quickly, sync, objectivity is ideal for monitoring a number of factors affecting
the forests in XuanThuy as temperature and humidity. This is a technical one rather strange
for users in Vietnam. Stemming from this reality our group chose the project name is
“Using Landsat 8 data and GIS to estimate above-ground biomass and carbon stocks of
coastal mangroves in XuanThuy National Park, Nam Dinh province”.

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CHAPTER II
LITERATURE REVIEW
2.1. Overview of mangroves coastal
2.1.1. Roles and function of coastal significance
Mangrove forests are one of the ecosystems with high biodiversity level on the
planet and the typical ecosystems of tropical and subtropical coastlines. It is the very large
repository of the carbon. According to estimates of the carbon generated by mangrove
forest is approximately 1.5 tons of carbon per year; in the mangrove sediments about 10%.
Ecosystem of mangrove forest is one of important part of carbon sequestration because it
stores a large fraction of organic carbon in the ground and the change of CO2 to the
atmosphere. Trees act as a reservoir Carbon by the constant carbon during photosynthesis
and store the carbon is known as biomass in the mangrove forest.
Definition of mangroves: A mangrove is defined as a tree, shrub, palm or ground
fern, generally exceeding one half meter in height, that normally grows above mean sea
level in the intertidal zone of marine coastal environments and estuarine margins. A
mangrove is also the tidal habitat comprising such trees and shrubs (Duke, 1992).
Roles of mangroves: Mangrove has the role of ecological, economic, and social
issues are very important in supporting the development of coastal areas. The rehabilitation
is very priority before the negative impact of mangrove loss is widespread and can‟t be

resolved. Mangroves protect shorelines from damaging storm and hurricane winds, waves,
and floods. Mangroves also help prevent erosion by stabilizing sediments with their
tangled root systems. They maintain water quality and clarity, filtering pollutants and
trapping sediments originating from land.

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Function of mangroves
Mangrove soils are actively growing in many places. Mangroves contribute to an
increase in soil volume by capturing riverine or coastal sediments that pass through, as
well as adding their own organic matter in the form of roots, leaves and woody material.
The fine mangrove roots also help to trap and bind the particles. Due to a lack of oxygen in
the waterlogged soil, organic matter is not broken down by soil organisms. This allows the
organic matter to build up over time, producing the deep peaty soils that underlie
mangroves in some areas. Mangrove root growth also pushes the soil upward, resulting in a
higher soil level.
2.1.2. Mangrove biomass and coastal services
Biomass is the amount of organic matters in an area at the certain period and
calculate by ton per hectare. The forest biomass is classified as the above ground and
below-ground biomass. Above ground biomass is the fresh terrestrial biomass included:
stems, roots, branches, barks, seeds and leaves. Below – ground biomass is all living
biomass off root trees.
Biomass is the amount of organic matters in an area at the certain period and
calculate by ton per hectare. The forest biomass is classified as the above ground and
below-ground biomass. Above ground biomass is the fresh terrestrial biomass included:
stems, roots, branches, barks, seeds and leaves .Below – ground biomass is all living
biomass off root trees.
Main part of the biomass is focused on the continent with advantage in the favor of
plant biomass. The volume of biomass in the biosphere estimated n=1014 – 2.1016 tons.

Earth biomass accounts for very small percentage compared to the weight of the whole
earth and very little compared to the hydrosphere lithosphere .However, in the long
5


geological period, since have appeared in 3 billion years ago. Earth‟s biomass
sequestration that practice a powerful change a large amount of material on the earth.
Biomass is almost sediment rocks .metamorphic and sediment minerals, from the earth in
the form of organic materials.
2.2. Mangroves biomass and carbon stock in worldwide
2.2.1. Mangroves biomass in the world
Golley and Vu Doan Thai (2003) studied about the biomass of Rhizophora mangle.
In 1975, they discovered biomass of Rhizophora brevistyla in Panama and showed the total
biomass

of

R.mangle

is

62.7tons/hectare

and

278,9

tons/hectare

of

R.brevistyla.Lieth(1964), demonstrated the worldwide capacity by the yield chart .and the
International Biological Program “ IBP” (1964) and the Man And Biosphere program
(MAB ) 1971 appeared and impacted strongly to the biomass research. The study in this
phase focused on the object grassland, evergreen rainforest.
Canell (1982) has published the research: “World forest biomass and primary
production data “In these ,composed of 600 study has been published about the dry
biomass of stems, branches, leaves and other parts .primary products of more than 1.200
forests in 46 nations in the world. S.Aksornkoae (1987) has studied about natural
mangrove forest in Thailand included species Soneratia, Rhizophora, Bruguinera. The
results showed that the Rhizophoraapiculata is highest biomass approximately 701.9 tons
per hectare, the second one is Bruguiera) is 243.75 tons per hectare and the lowest one is
Ylocarpus is only 20.1 tons/hectare
G.Saena and D.S .Kamat( India,1956 ) have introduced their research : “access
biomass by application of remote sensing “ mentioned generally the issue of biomass
products and evaluate the biomass by satellite image (Ly Thu Quynh ,2007)
6


In addition, Transnean (1926),Huber (Germany,1952), Moteith

(

England,1960 -1962 ), Lemon ( USA,1960 -1987 ), Inone (Japan, 1965 -1968 ),…used
method of carbon to determine biomass. Therefore , biomass is evaluated by determining
assimilation rate of CO2.
Komiyama and his partner (1987) have studied the biomass and the size of roots
below ground with the total biomass approximately 437,5 tons/hectare: the percentage of
biomass on the ground of Da Voi (Ceriopstagal) is 1,05 tons /hectare and the biomass of
stem: 53,35 tons/hectare, branches: 23,61 tons/hectare, leaves: 13,29 tons/hectare, roots:

1,99 tons/hectare and below –ground is 87,51 tons/hectare. Two scientist: Clough and
Attiwil (1982) have discovered percentage biomass of root vary 14-64 percent in the total
of biomass (based on Ha Quang Anh,2003).
To define the above ground biomass, we use the structure of Komiyama (2005)
AGB= 0,251x p x DBH 2,46
In which:

P: wood density.
DBH: Diameter at breast height.

Table 2.1. About wood density of tree in mangrove forest.
Species

Science name

Proportion-Volume

Vẹt trụ

Bruguiera cylindrical ( L ) Blume

0,668 ± ,057 (n=6)

Vẹt dù

Bruguieragymnorrhiza

0,7273 ± 0,016 (n= 3)

Vẹt tách

Bruguieraparviflora ( Roxb) Wright

0,6256 ± 0,031 (n= 3)

&Griff
Dà vôi

Ceriopstagal ( Perr ) C.B. Rob

0,6952 ± 0,028 (n= 6)

7


Đước Đôi

RhizophoraapiculataBlume

0,7417 ± 0,032 (n= 6)

Đưng

Rhizophoramucronata Lam

0,6723 ± 0,054 (n= 6)

Mấmtrắng

Avicennia alba Blume

0,5220 ± 0,021 (n= 6)

Mấm Đen

Avicenniaofficinalis (L) Blume

0,5362 ± 0,051 (n= 6)

Bần Trắng

Sonneratia alba

0,4110 ± 0,042 (n= 5)

Su Ổi

Xylocarpusgranatum Koenig

0,5894 ± 0,021 ( n=6)

Su Sung

Xylocarpusmoluccensis Lam

0,5495 ± 0,034 (n= 6)

Cui Biển

Heritieralittolaris ( Dryand ) Aiton

0,6010± 0,105 (n= 6)

Source: Mida Creek, Kenya, Komiyama (1987)
2.2.1.Mangroves biomass in Vietnam
Ngo Dinh Que (1971) estimated the biomass of Pine forest in Lam Dong province
with density of 2500 trees/hectare, valued at 330 tons/hectare (Ly Thu Quynh, 2007). In
1986, Nguyen Hoang Tri adopted the method of “Tree model” to estimatethe biomass yield
of Duoc Doi forest communities (Rhizophoraapiculata) coastal mangrove in Minh Hai.T
his is a highly significant contribution in both theory and practice for study of ecology and
coastal mangrove forests.. Findings of forest

biomass and Duoc Doi communities

(R.apiculata) in the jungle, natural regeneration forest and forest plantations 7 years in Ca
Mau of the author showed the total of three forest types respectively 119,335 dry tons
/hectare, 33,159 dry tons/hectare; 34,853 dry tons /hectare. For the mature mangrove
forests, the total of biomass is 276,892 kilograms /hectare. In which include stem:
158034,12; bark: 8990,09 kilograms/hectare: tree branches: 4015,49 kilograms/hectare
(1.45%) supported ground roots: 34158,70 kilograms/hectare (12,33 %) root bark :4767,12
kilograms/hectare (1,72): leaves: 9304,52 kg/hectare (3,36%) ;buds: 812,36 kg/hectare
8


(0,29%); flowers and fruits: 6771,91 kg/hectare (2,44%) and below ground root: 19701,60
kg/hectare (7,11%) (My Thi Hong, 2006).
Ha Van Tue (1994) also used the method of “tree model” of Newboul D.J (1967)
studied productivity, biomass of some pulpwood plantations in permanently endowed
Midlands in VinhPhu (Ly Thu Quynh, 2007), research: “evaluate the growth, development,
biomass and forest production of Pinus KeysiaRoillexGordm) in Da Lat –Lam Dong

province “by Le Hong Phuc (1996), Nguyen Trong Binh (1996) discovered the rule of
biomass development and structure of facts stem biomass development. Percentage of
fresh and dry biomass of parts of trees include stem, branches, leaves, roots, amount of
falling, the total biomass of individuals and communities. After that, he created some
programs which showed the interrelation between biomass and other parts have 3m in
diameter.
Ly Thu Quynh(2007),studied about biomass and carbon sequestration capability of
Mangletia conifer Dandy in TuyenQuang, PhuTho showed that: Biomass structure consists
of 4 parts retail leaved stems, leaves and roots, in which fresh biomass respectively 60%,
8%, 7%, 24%, of the total fresh biomass of a hectare plantation Manglietia conifer Dandy
ranges from 53.440 -30.9689 kg / ha (in which conclude 86 % is biomass wood floors,6%
is biomass shrub vegetation and 8% as biomass falling objects).
In addition,several other research projects as Vien Ngoc Nam and Nguyen Duong Thuy
(1991) studied forest biomass in the mangrove forest in Can Gio, Nguyen Van Be (1999) studied
mangrove biomass in Ben Tre; Dang Trung Tan (2001) with the work "Mangrove forest biomass"
identified a total dry biomass of mangrove forests in Ca Mau is 327 m3 / ha.
XuanThuy National Park is wellknown by its mangrove forest biosphere in reserve
areas of the Red River Delta. This is the first mangroves in Vietnam are internationally

9


recognized Ramsar. This is the 50th mangroves forest of the world. XuanThuy National
Park is located in the southeast in GiaoThuy district, Nam Dinh Province, at the mouth of
Red River Ba Lat. The core zone of the park is mangrove area on three dune estuary is Con
Ngan, Con Lu and Con Xanh in Giao Thien district.The entire of buffer zone and core
area of the park are located on the territory of GiaoThien, GiaoAn, and Giao Lac, Giao
Xuan and Giao Hai. The area of approximately 7,100 hectares entire garden, including
3,100 hectares of floating forest land and 4,000 hectares mangrove land.
There are annual about 100 species of migratory birds choose this area is their

migration place on the migratory routes of the Southern winter, including up to 1/5 of the number
worldwide Co Mo Thia. In the garden is estimated there is 215 water birds species live, many
nearly extinct species listed in the Red Book in the world such as Re Mo Thia, Mong Bien, Diec
Dau Do…On this salty wetlands, tidal waters there are about 165 species of zooplankton and
bottom 154 animal species, a total of about 500 animal species.
For plants, there are 120 species of vascular plants, including the main mangrove
species and the species involved in the mangrove forest of 101 genera and 41 families,
floating flora 112 species belonging to 43 genera.
In this study, I examine the current situation and spatial distribution of mangroves
at Xuan Thuy National Park in Nam Dinh, select method for calculation of above-ground
biomass of mangrove and estimate the carbon in above-ground biomass. The study
thenprovides solutions howto improve the effective management of mangrove forests
contributed to mitigate the effects of regional climate change at research area.
2.3. Application of GIS and Remote sensing to estimate mangrove biomass and
carbon stock
GIS and Remote sensing to estimate mangrove biomass and carbon stock:
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Remote sensing is a useful tool for rapidly mapping large areas that are
difficult to study by means of conventional field surveys, as is the case for mangrove
forests.
Traditional biomass assessment methods based on field measurements are the most
accurate methods. However, they are difficult to conduct over large areas and are costly,
time consuming, and labor intensive. Recently, remote-sensing (RS) procedures have been
applied to and established for natural resources management. Currently, RS is widely used
to collect information regarding forest AGB and vegetation structure as well as to monitor
and map vegetation biomass and productivity on large scales by measuring the spectral
reflectance of the vegetation. However, optical RS does not directly assess above-ground
forest biomass, and radiometry is sensitive to vegetation structure (i.e., crown size and tree

density), texture, and shadow, which are correlated with AGB, particularly in the infrared
bands. RS data are now considered to be the most reliable method of estimating spatial
biomass in tropical regions over large areas. RS technology has been applied to biomass
assessment in many studies because it can obtain forest information over large areas at a
reasonable cost and with acceptable accuracy based on repetitive data collection with
minimal effort.
Estimating of above ground biomass of mangroves
In general, estimating the AGB in mangroves is a challenging task because of their
complex forest structures and diverse species. Many studies have shown that the method of
determining relationships between field measurements and RS data and then extrapolating
these relationships over large areas is very useful (Michael A. Wulder, 2008, Nagesh
Kumar, 2012). To determine the relationship between above-ground field biomass and RS
data, researchers have used linear regression models with or without log transformations of
field biomass data and multiple regressions with or without stepwise selection. Artificial
11


neutral networks, semi-empirical models, nonlinear regression, and nonparametric
estimation techniques have also been used. Although no model can determine this complex
relationship absolutely, researchers continue to use multiple regression models as one of
the best options. Vegetation index models are generally used to estimate biomass in many
studies.
Vegetation indices (VIs) are calculated from mathematical transformations of the
original spectral reflectance data and can be used to interpret land vegetation cover. VIs are
applied to remove the variations caused by spectral reflectance measurements while also
measuring the biophysical properties that result from the soil background, sun view angles,
and atmospheric conditions. Many previous studies have shown significant positive relationships
between biomass and VIs; however, other studies have shown poor relationships. Many methods
can be used to map and estimate above-ground forest biomass for different land-cover types; one
such method is the use of Landsat imagery (medium-resolution satellite images) to estimate the

attributes of forests through direct correlations or stepwise regression analyses with spectral
bands, band ratios, or Vis. In general, land-cover change mapping cannot be accurately
performed based on low- and medium-resolution satellite images. However, the use of Remote
Sens. Landsat is commonly used for many applications because it can be obtained for free
or at a low cost.
A combination of many data sources (e.g., forest inventory, land use, elevation, and
RS data) can be used to predict vegetation variables over large areas. A hybrid
supervised/unsupervised classification approach coupled with a geographical information
systems (GIS) analysis has been employed to improve land use/cover mapping for Landsat data.
In tropical regions, forest plot-based field measurements have been correlated with RS data, and
these measurements have been used to estimate that carbon stocks are limited, particularly in
Southeast Asian countries. The present study seeks to characterize the carbon stock of
12


mangroves forest types using forest-plot-based field measurements and RS data to develop a
simple RS-based methodology. The field-based measurement and RS approach might also
help to improve forest carbon estimation in order to reduce emissions resulting from
deforestation and forest degradation (REDD+) and to design incentive programs;
furthermore, this approach might improve forest management with regard to climatechange mitigation.(Phutchard Vicharnakorn- 2014- Carbon Stock Assessment Using
Remote Sensing and Forest Inventory Data in Savannakhet.)

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CHAPTER III
GOAL, OBJECTIVES, CONTENT AND METHODOLOGY
3.1. Goal and objectives
3.1.1. Overall goal
Study aims to provide a scientific basis for proposing quantitative methods of

above ground biomass and carbon stock in mangroves.
3.1.2. Specific objectives
- Evaluate the current situation of mangroves in Xuan Thuy National Park.
- Quantify above ground biomass of mangrove forest on the study field.
- Propose solution to improve the managed effect to mangrove forest to distribute
reducing the impacts of climate change on study field.
3.2. Scope and framework of study
Scope of study: The entire coastal area of XuanThuy National Park while focus ofs
livelihoods of residents of communes includes GiaoHai, GiaoXuan, Giao Lac, GiaoAn,
GiaoThiên,
Framework of study: In this study, effectiveness of coastal mangroves should be
understood as dynamics of mangroves area, improvement of local livelihoods and
mangroves quality.
3.3. Research contents
3.3.1. Examining the status of mangroves and management schemes in XuanThuy
National Park, Nam Dinh province

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3.3.2. Quantifying spatial distribution of mangrove extents in XuanThuy National Park,
Nam Dinh province
3.3.3. Quantifying above-ground biomass and carbon stocksof mangroves
3.3.4. Proposing solutions to improve the management of mangrove inXuanThuy
National park
3.4: Methods
3.4.1. Examining the status of coastal mangrove management in XuanThuy National
Park, Nam Dinh Province
Status of coastal mangrove management
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 Kandelia obovata, Rhizophora mucrolata can provide a clue for obtaining a high
accuracy 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

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Field survey method
Questionnaires were conducted to interview the local people. In this questionnaire:
• Target groups include local administrators; communities who live in coastal zone.
Totally, 30 local households were chosen in each commune GiaoHai, GiaoXuan, Giao Lac,
Giao An, GiaoThiên.
• Collected information include history, and the dynamics of the mangroves along
the investigated time periods; The policies and projects about mangroves in XuanThuy
National Park; changing of livelihood through periods of time.
3.4.2. Quantifying spatial distribution of mangrove extents in XuanThuy National Park,
Nam Dinh province
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.
Remote sensing data for study:
The multi-temporal Landsat images were used in this study (Table 3.1)
Research materials:
Table 3.1. Landsat and Sentinel data used in the study.
Resolution
ID

Landsat and sentinel image code

Date

Path/Row
(m)

1

LC81260462015191LGN00

17/08/2016

30

126/46

2

S2A_OPER_PRD_MSIL1C_PDMC_20160119

16/08/2016

10

126/46

Source: ,

/>
3.4.2.1. Field survey method
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Questionnaires were conducted to interview the local people. In this questionnaire:
• Target groups include the local administrators; communities who live in coastal
zone. Totally, 30 local households were chosen in each commune GiaoHai, GiaoXuan,
Giao Lac, Giao An, GiaoThiên.
• Collected information include: history, and the dynamics of the mangroves along
the investigated time periods; the policies and projects about mangroves in XuanThuy
National Park; changing of livelihood through periods of time.
Sampling method (stratified random sampling) and plot establishment
Before plot establishment, this study was carried out a survey of vegetation in study
areas and used visual interpretation on the Landsat images to determine location of plots.


Stratified random sampling: A stratified random sampling is obtained by separating

the population elements into non-overlapping groups, called strata, then selecting a simple
random sample from each stratum:

Based on visual interpretation, plots were chosen randomly and distributed along the
coastal side of mangroves area. The coordinates of plots then were added into GPS devices
before doing the fieldwork.


Plot establishment:

Totally, 4 square plots were conducted with the total area 400m2 (20m x 20m). Each big
plot had five sub – plots (four plots at the corners and one plot at the center of plot).

Fig. 3.1. Layout of sampling plot and subplots this study.
3.4.2.2.Data collection and analysis
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