TREE SPECIES COMPOSITION AND ABOVE-GROUND TREE BIOMASS ESTIMATION OF

SALENDA BRIDGE MANGROVE PATCH May 30, 2014

TREE SPECIES COMPOSITION AND ABOVE-GROUND

TREE BIOMASS OF SALENDA BRIDGE MANGROVE

PATCH, ILALA, DAR-ES-SALAAM REGION

Tanzania

Mrumba E. John

2014

i

ABSTRACT

Mangrove tree species composition and above ground tree biomass estimation of Salenda bridge

mangrove patch study was done at Salenda bridge area, Ilala District in Dar es Salaam region. The

study was aimed at assessing mangrove tree species composition and above-ground tree biomass

estimation of Salenda Bridge mangrove patch. The specific objectives of the study were to

identify and determine tree species composition, above-ground biomass and carbon stock tree

estimation. Stratified sampling was employed, the area was stratified into two strata; the left and

right hand sides of the river, equal sample size were taken where by a random sampling was

engaged to allocate the first plot in each stratified area while the other plots were obtained by

systematic sampling. Circular plot of 5m diameter (19.63 m 2 ≈ 1.963 × 10 -3 ha) was employed

and hence 12 plots with the total area of 235.62 m 2 ≈ 2.356 × 10 -2 ha were established. The

recoded data were species name, diameter at breast height in centimetres, height in metres, and

frequency. Data analysis was done by using Microsoft excel, Percentage composition

determination was obtained by taking the number of individual species in a sample size multiplied

by 100% and then divided by overall individuals’ species of the sample area. Above ground tree

biomass obtained as the product of wood density, volume of a trunk and Biomass expansion factor

(1.0). Results showed that only a single mangrove tree species (Avicinnia marina-family

Avicinniaceae) was identified with estimated above-ground tree biomass and carbon stock of

458.3t/ha and 221.67t/ha respectively. This is a proof from different literatures that there have

never been possible to find all the 68 mangrove species growing in one area. This study concludes

that, Salenda bridge mangrove patch has well developed mangrove forests and relatively high

management conservation and protection. In addition the study recommends that, in order to

enhance the level of biomass and subsequent carbon storage of mangrove forests at Salenda bridge

mangrove patch, efforts to protect and restore the forests will be worthwhile to all stakeholders,

including the Government and international institutions, NGO’s and local community. Moreover,

this study calls for more studies on tree species diversity, focused on studying mangrove

ecosystem dynamic change and tree species distribution in terms of spatial arrangement.

ii

iii

TABLE OF CONTENTS

ABSTRACT……………………………………………………………………………… ii

CHAPTER ONE.................................................................................................................. 1

1.0 INTRODUCTION……………………………………………………………………..1

1.1 Background Information of mangrove forests………………………………………... 1

1.1.2 Global composition of mangrove forests………………………………………….... 2

1.1.3 Mangrove forests in Tanzania………………………………………………………. 2

CHAPTER TWO..................................................................................................................6

2.0 LITERATURE REVIEW…………………………………………………………...... 6

2.1 Over view of mangrove forests……………………………………………………….. 6

2.2 Composition structure of mangrove forests…………………………………………....6

2.3 Role of mangrove forest’s biomass in carbon cycle……………………………….......7

CHAPTER THREE............................................................................................................. 9

3.0 MATERIAL AND METHOD…………………………………………………………9

3.1 Description of the Study area……………………………………………………….....9

3.1.1 Location……………………………………………………………………………...9

3.1.2 Climate……………………………………………………………………………….9

3.1.3 Soil and vegetation type……………………………………………………………...9

3.1.4 Population and Human economic activities………………………………………...10

3.2 Materials…………………………………………………………………………….. 10

iv

3.3 Methods…………………………………………………………………………….. 11

3.3.1 Sampling techniques……………………………………………………………… 11

3.3.2 Data collection.......................................................................................................... 12

3.3.3 Data analysis……………………………………………………………………… 13

CHAPTER FOUR............................................................................................................ 14

4.0 RESULTS AND DISCUSSION…………………………………………………… 14

4.1 Tree species composition of Salenda Bridge patch………………............................. 14

4.2 Tree species percentage composition of Salenda bridge mangrove patch……............17

4.3 Above-ground biomass and carbon stock of Salenda bridge mangrove patch…….... 18

CHAPTER FIVE.............................................................................................................. 24

5.0 CONCLUSION AND RECOMMENDATION…………………………………….. 25

5.1 Conclusion……………………………………………………………………… 25

5.2 Recommendation………………………………………………………………….... 25

REFERENCES………………………………………………………………………… 27

LIST OF APPENDICES………………………………………………………………… 28

v

LIST OF TABLES

Table1: Mangrove Tree Species of Tanzania............................................................................3

Table 2: Botanical description of Avicinnia marina...............................................................16

Table 3: Average vegetation characteristics of Salenda bridge mangrove patch............. 17

Table 4: Tree parameter variation of Salenda Bridge mangrove patch.............................19

Table 5a: Above-ground biomass, carbon stock and basal area of Salenda bridge.......... 22

Table 5b: Basal area, biomass and carbon stock per DBH class......................................... 22

vi

LIST OF FIGURES AND PLATES

Plate 1: Mangrove tree species of Salenda Bridge patch....................................................3

Plate 2: Leaves morphology of Avicinnia marina.............................................................15

Figure 1: DBH class of Salenda bridge mangrove patch………………………………..18

Figure 2: Tree parameter’s frequency variation of Salenda bridge mangrove patch........ 20

Figure 3a: Variation of mangrove tree species biomass, frequency and parameters…... 20

Figure 3b: Variation of tree species carbon stock, frequency and tree parameters…...... 21

Figure 4: DBH class percentage biomass of Salenda bridge mangrove patch…………. 23

vii

LIST OF ABBREVIATION AND SYMBOLS

CABG Above-ground carbon stock per individual specie

cm Centimetres

CPLOT Carbon stock per single plot

D Distance

DBH Diameter of a tree at a breast height (d)

FAO Food and Agriculture Organization

fc Frequency of tree species diameter class

ff Form factor

fi Frequencies of individual tree species

FTI Forestry Training Institute

g Basal area

g/cm3 SI units of wood density

h Height of trees

ha Hectares

m Meters

m2 Square meters

PS Plot size

R Radius of a circular plot

REDD+ Reducing Emission from Deforestation and forest Degradation

Si Sampling intensity

t/ha Tones per hectares (SI Unit of carbon stock)

TA Total forest area

V Volume of tree species biomass

viii

π Pi, 3.14

ix

CHAPTER ONE

INTRODUCTION

1.1 Background Information of mangrove forests

Mangroves are defined as an association of halophytic trees, shrubs and other plants

growing in brackish to saline tidal waters of tropical and subtropical coastlines (Mitsch

and Gosselink 2007). Mangroves are generally restricted to the tidal zone. As such,

mangroves in fringe areas will be inundated by practically all high tides, while those at

the higher topographic boundaries may be flooded only during the highest of tides

(spring tides) or during storm surges. Mangroves are typically found along tropical and

subtropical coastlines between about 250 N and 250 S (Kauffman et al, 2012).

The term Species composition refers to the contribution of each plant species to the

vegetation. Botanical composition is another term to describe species composition

species. It is generally expressed as percent, so that all specie component add up to 100%

also can be expressed on either individual species basic or by specie group that are

defined to the objectives of the inventory or monitoring program (Rangelands west,

2013).

According to ecological studies, Biomass can be defined as the amount of living matter

in a given habitat expressed either as weight of organism per unit volume of habitat

(Wikipedia foundation, 2013). It is the total quantity or weight of organism in a given

area or volume (Dictionary.com, 2013).

Trees and shrubs make the bulk of above ground biomass in a forest, with the total

biomass of a stand varying markedly depending on the climate and soil and, in the case

of mangrove vegetation, the frequency and duration of tidal inundation. The age of the

forest and its constituent trees is also a factor. In relatively young forests the carbon store

builds over time as the trees and forest growth. The relationship between the size of trees

and their biomass is not linear meaning that as the diameter and height of the tree

1

increases its biomass increases in a disproportionally greater way. A typical mangrove

tree may increase in dry biomass by greater than 5 times with every doubling of its trunk

diameter of which about half is carbon (German Development Cooperation, 2011).

1.1.2 Global composition of mangrove forests

Globally, there are at least 68 mangrove-obligate species. The centre of diversity of

mangroves is the Indo-Pacific region where Giesen et al. (2007) listed 52 plant species

that occurred only in mangroves and 268 species that can be found in mangroves and

other wet environments. In contrast, the Americas have only about 10 mangrove species

(Mitch and Gosselink 2007). Mangroves vary greatly in structure and function, largely as

a result of topography, substrate, latitude and hydrology (Saenger and Snedaker 1993).

Dominants in mature mangroves may range from trees with trunk diameters >1 m to

shrub-like stands <1 m in height. Aboveground biomass may range from >500 Mg/ha in

riverine and fringe mangroves of the Indo-Pacific region to about 8 Mg/ha for dwarf

mangroves (Kauffman and Cole 2010, Kauffman et al. 2011).

1.1.3 Mangrove forests in Tanzania

In Tanzania mangrove forest occur on the sheltered shores of deltas, alongside river

estuaries, and in creeks where there is an abundance of fine-grained sediment (silt and

clay) in the upper part of the inter-tidal zone. The establishment of mangrove vegetation

is governed to some extent by the degree of exposure to strong winds. The largest

continuous mangrove areas are to be found on the coast of Tanga district in the north, the

delta of the Rufiji River in Kilwa and Lind districts, and in Mtwara, where the Ruvuma

River forms an estuary close to the Mozambique border. Thus, the mangrove forests

stretch along coastal districts from Tanga to Mtwara and cover an area of 79,937 ha.

Mangroves are also well represented on the coasts of the main islands, Zanzibar, Pemba,

and Mafia. On Pemba mangrove cover an area of 12,146 ha, while on Zanzibar there are

6,073 ha under mangroves (Silvicultural management of mangrove forest, FTI

Olmotonyi, 2013).

2

Table1: Mangrove Tree Species of Tanzania

Tree species Family Local name

Avicennia marina Verbenaceae Mchu

Bruguiera gymnorrhiza Rhizophoraceae Msinzi or muia

Ceriops tagal Rhizophoraceae Mkandaa

Heritiera littoralis Sterculiaceae Msikundazi or mkungu

Lumnitzera racemosa Combretaceae Kikandaa or mkandaa dume

Rhizophora mucronata Rhizophoraceae Mkoko

Sonneratia alba Sonneratiaceae Mililana

Xylocarpus granatum Meliaceae Mkomafi

Xylocarpus molluccensis Meliaceae (none)

In Ilala district mangrove forests have been distributed along Msimbazi River as well as

an Indian Ocean shore particularly at Salenda bridge area, mangrove forests have been

developed.

Plate 1: Mangrove tree species of Salenda Bridge patch

3

CHAPTER TWO

2.0 LITERATURE REVIEW

2.1 Over view of mangrove forests

Mangroves are coastal forests found in sheltered estuaries and along river banks and

lagoons in 124 tropical and subtropical countries and areas, mainly growing on soft

substrates (FAO 2007). They are distributed in the inter-tidal region between the sea and

land between approximately 30° N and 30° S latitude (Giri et. al.,2010) Their global

distribution is believed to be delimited by major ocean currents and the 20° C isotherm

of sea water in winter and are typically distributed from mean sea level to highest spring

tide (Alongi, 2009). The current estimate of mangrove forests of the world is less than

half of what it once was (Spalding et al., 1997; Spiers, 1999) and much of what remains

is in a degraded condition (Giri et. al.,2010).

2.2 Composition structure of mangrove forests

The structure of a mangrove forest at any point in time is a function of its succession

stage, species composition, zonation, propagate dispersal, growth and survival. These are

all influenced by a number of biotic factors such as propagation variables, broadcast

predation, herbivore, human interference and inter-specific competition. Additionally,

abiotic factors are also influential including storm damage, rainfall, tidal influence,

freshwater input, temperature, sedimentation rate, nutrient availability and light (Krauss

et al. 2008). To analyse all of the above components and relate them to mangrove forest

structure, and each other, is a complicated exercise in ecological modelling but attempts

have been made (Schaeffer-Novelli et al. 2005, Twilley & Rivera-Monroy, 2005).

Mangrove forest ecosystems fulfil a number of important functions and provide a wide

range of Services; they are among some of the most productive and biologically

important ecosystems of the world because they provide important and unique ecosystem

goods and services to human society and coastal and marine systems (FAO, 2007). The

forests help stabilize shorelines and reduce the devastating impact of natural disasters

4

such as tsunamis and hurricanes. They also provide breeding and nursing grounds for

marine and pelagic species, and food, medicine, fuel and building materials for local

communities (Giri et al. 2010). Mangroves, including associated soils, could sequester

approximately 22.8 million metric tons of carbon each year. Covering only 0.1% of the

earth’s continental surface, the forests account for 11% of the total input of terrestrial

carbon into the ocean (Jennerjahn & Ittekot, 2002) and 10% of the terrestrial dissolved

organic carbon (DOC) exported to the ocean (Dittmar et al., 2006). The rapid

disappearance and degradation of mangroves could have negative consequences for

transfer of materials into the marine systems and influence the atmospheric composition

and climate. Mangroves support the conservation of biological diversity by providing

habitats, spawning grounds, nurseries and nutrients for a number of animals. These

include several endangered species and range from reptiles (e.g. crocodiles, iguanas and

snakes) and amphibians to mammals (tigers – including the famous Panthera tigris

tigris, the Royal Bengal tiger – deer, otters, manatees and dolphins) and birds (herons,

egrets, pelicans and eagles). A wide range of commercial and non-commercial fish and

shellfish also depends on these coastal forests. Mangrove organic productivity (Odum

and Heald,1972) has been suggested to support near shore fisheries production (Lee,

1999).Mangrove ecosystems are also used for aquaculture, both as open-water estuarine

marine culture (e.g. oysters and mussels) and as pond culture (mainly for shrimps).

2.3 Role of mangrove forest’s biomass in carbon cycle

Mangroves play an important role in the global carbon cycle and it has been estimated

that a loss of 35% of the world’s mangroves over the last two decades (Valiela et al.

2001 in UNEPWCMC 2006) has resulted in the release of large quantities of stored

carbon, further aggravating the global warming phenomenon. Ecosystems that can no

longer provide their full ecosystem goods and services have a social and economic

“cost” to humanity, which can be felt even in areas far away from the degraded

ecosystem (UNEPWCMC 2006).

According to German Development Cooperation (2011), Above ground biomass (AGB)

figures of more than 600 t / ha have been recorded in mangrove forests, but they are

5

generally between 150 and 350 t / ha in well developed tropical mangroves (Alongi

2009).

6

CHAPTER THREE

3.0 MATERIAL AND METHOD

3.1 Description of the Study area

The study was proficient at the Salenda Bridge patch. It is situated in the eastern coast of

Ilala district particularly in Dar-es-salaam City, It is a small portion area of about 500 m2

(≈0.05 ha) occupation. The area is openly seen as one pass along the main road from

Coco beach via Posta road.

3.1.1 Location

The area is located at latitude 60 51’ 41” S and 390 07’ 02” (Collins maps, 2013) situated

along the Indian Ocean shore to the main road from Msasani via Kivukoni road.

3.1.2 Climate

Salenda bridge is located close to the equator and the warm Indian Ocean particularly in

Ilala, the area experiences generally tropical climatic conditions, typified by hot and

humid; the mean annual temperature is 260C, 96% in the morning and 67% afternoon

humidity weather throughout much of the year. It has a tropical wet and dry climate,

with two different rainy seasons. Annual rainfall is approximately to be 1,100 mm, and

in a normal year there are two distinct rainy seasons: "the long rains", which fall during

April and May, and "the short rains", which fall during October and November

(Wikipedia foundation, BBC Weather, 2013).

3.1.3 Soil and vegetation type

The area is swamp and characterized with sand and mud clay soil type. It is well

typically covered with dense mangrove species to form a patch of mangrove forest.

7

3.1.4 Population and Human economic activities

Ilala has a total population of 1,220,611 (National Bureau of statistics, 2013) and their

main economic activities are such as commercial, industrial and informal sector as well

as agriculture and fishing.

3.2 Materials

The following materials were used during data collection:-

Tape measure, Blumeleiss, Calliper and compass were used to measure distance

between plots and plot’s radius, height, diameter (DBH) and transect angle

within a transect line each respectively

Recording material: Shit of papers and Pen; purposeful for keeping records

during primary data collection in the field

Library materials which includes various books and internet sources were used to

capture secondary data

8

3.3 Methods

3.3.1 Sampling techniques

Stratified sampling was employed; since the area of the patch has been alienated by

Msimbazi River, therefore in order to include all individual tree species in measurement

the area was stratified into two strata; the left and right hand sides of the river, equal

sample size were taken where by a random sampling was engaged to allocate the first

plot in each stratified area respectively followed by systematic sampling plots.

Circular plot, 5 m diameter was employed, 12 plots were established. Along the transect

line, each plot was separated by distance of 6.5 m from one plot to another. 19.63 m 2

(1.963 × 10 -3 ha) and 235.62 m 2 (2.356 × 10 -2 ha) Sampling unit and total sample size

was covered each respectively. 117.81 m 2 (1.1781 × 10 -2 ha) was covered in each strata.

Plot interval distance, Sample plot size, number of plots and total sample size were

calculated as follows:-

Plot interval distance (D) = √(Area of the forest / Number of sample plot)

Sample plot size: Circular Area of a plot = πR2; where R = radius of a circular

plot

Total sample size = Sample plot size × Number of sample plot

Number of plot: n = TA × Si PS × 100%

Where: TA = Total forest area; Si = sampling intensity, 50%; PS = plot size (πR2)

9

3.3.2 Data collection

3.3.2.1 Primary Data

Sampling procedures

In the field, individual tree species per plots were observed, counted and

recorded; for the sake of identifying tree species composition as well as their

percentage composition constituted by each mangrove tree species

Tree species parameter measurement: merchantable height and diameter (DBH)

of a tree species in each plot were measured by using Blumeleiss and Calliper

each respectively and recorded

Both height and diameter measurement were required specifically for above-

ground Biomass and carbon stock estimation

Data entry and Recording, A shit form titled “ecological survey summary” was

used to capture data in the field as shown in appendix 1

3.3.2.2 Secondary data

From various sources including library and internets; secondary data were detained.

10

3.3.3 Data analysis

With aid of Microsoft excel; statistically, data were analysed and results were presented

in form of charts which includes figures and tables.

Tree species percentage composition: was calculated as follows:-

Percentage composition = Number of individual specie in a sample size × 100%

Overall individuals’ species of the sample area

Tree species Above-ground Biomass and Carbon stock tree estimation: the following

calculations were required to compute both biomass and carbon stock:-

Basal area (g): g = πd2/40,000; where d = diameter at breast height (cm), π = 3.14

Volume (V): V = ffgh; where ff = form factor, h = height (m)

Above ground tree Biomass = Wood density × Volume of a trunk × BEF; where

BEF = biomass expansion factor, wood density = 0.61 g/cm3 for Avicinnia

marina, (Bibliotheca Alexandria-EOL Ar, tropical mangrove forests, 2013)

Carbon stock of an individual species: CABG = Biomass × 0.5 (Bhishma P.S,

2010); where CABG = Above-ground carbon stock per individual species, 0.5 =

conversion factor

Carbon stock per single plot: CPLOT =∑ CABG; where ∑ CABG = summation of CABG

11

CHAPTER FOUR

4.0 RESULTS AND DISCUSSION

4.1 Tree species identification

Giesen et al. (2007) reported that, there are at least 68 mangrove-obligate species

globally still it is not possible to find all the mangrove species in one area. This proves as

to why there are only about 10 mangrove species in America (Mitch and Gosselink

2007). In Tanzania it is believed that there are not less than eight mangrove species

(Table 1). The findings from this study confirm that it is not possible to get all the

mangrove species in one area since the results shows that, only a single species of

mangrove (Avicinnia marina) was identified to be growing and colonizing the study

area. The species (Avicinnia marina), (Plate 2) belongs to the family Avicinniaceae

(Table 2). It is a common spreading tree, usually found on the higher levels of swamps.

It is willow like in general appearance and has light yellowish green foliage. Vertically

pointed pneumatophores arise in great abundance from the long, spreading, horizontal

roots. The bark is smooth and greenish yellow when young, and variegated green and

reddish in the older trees. The trunks are used for making small dug-out canoes, and the

tree is generally used for building carts, for chow and canoe fittings and masts, for

furniture such as bedsteads and chairs, and for fitting such as handles. It is also used

extensively as fuel for lime burning (Silvicultural management of mangrove forest, FTI

Olmotonyi, 2013).

12

Plate 2: Leaves morphology of Avicinnia marina

13

Table 2: Botanical description of Avicinnia marinaPlot number

Specie name Family Habitat Description

1-12 Avicennia marina Avicinniaceae -Coastal zone areas

-Found on the high levels of swamps

-It willow-like in general appearance and has a light yellowish green foliage

-Vertically pointed pneumatophores arise from abundance from long, spreading, horizontal roots

-The bark is smooth and greenish yellow when young and variegated green and reddish in the older trees

14

4.2 Tree species percentage determination

In this study, the findings shows that, 100% of the entire Salenda Bridge mangrove

forest patch was determined to be Avicinnia marina with average number of 10 trees per

plot, for mature tree stand; diameter range from 12-24cm (figure 1) with height ranging

from 4m to 8m high (table 3). Avicinnia marina is highly distributed in the patch in view

of fact that the patch geographically is located near the Indian Ocean as well as

environmental factors which includes soil type particularly on nutrients availability, rate

of regeneration, plant adaptability and ecological factors which favours the distribution

and growth of the mangrove tree species. (Valiela et al. 2001 in UNEPWCMC 2006)

reported that, mangroves play an important role in the global carbon cycle and it has

been estimated that a loss of 35% of the world’s mangroves over the last two decades

has resulted in the release of large quantities of stored carbon, further aggravating the

global warming phenomenon.

Table 3: Average tree vegetation characteristics of Salenda Bridge

Characteristics Range Overall average

Height 4-8m 6m

The tallest height

6-8m 7m

Small height 4-6m 5m

Diameter

12-24cm 18cm

Large 20-24cm 22cm

Small 12-19cm 15.5cm

15

11-14 cm 14-17 cm 17-20 cm 20-23 cm 23-26 cm0

5

10

15

20

25

30

DBH class

Freq

uenc

y

Figure 1: DBH characteristics of Salenda Bridge

4.3 Tree species above-ground biomass and carbon stock

(Kauffman and Cole 2010, Kauffman et al. 2011) reported that, above ground biomass

may range from >500 Mg/ha in riverine and fringe mangroves of the Indo-Pacific region

to about 8 Mg/ha for dwarf mangroves. German Development Cooperation (2011)

reported that, above ground biomass (AGB) figures of more than 600t/ha has been

recorded in mangrove forests. Elsewhere (Alongi, 2009) reported that, above ground

biomass are generally between 150 and 350t/ha in well developed tropical mangroves. In

this study, the findings confer the information that; the total biomass and carbon stock of

Salenda bridge mangrove patch were 22.9tonnes and 11.8tonnes respectively. The study

findings revealed that, tree species above ground biomass and carbon stock, per sample

area as well as per hectare were 11t, 5.32t, 458.3t/ha and 221.67t/ha respectively which

reflect that, Salenda Bridge area has well developed mangrove forests. According to

(German Development Cooperation, 2011), the relationship between the size of trees and

16

their biomass is not linear meaning that as the diameter and height of the tree increases

its biomass increases in a disproportionally greater way. A typical mangrove tree may

increase in dry biomass by greater than 5 times with every doubling of its trunk diameter

of which about half is carbon (German Development Cooperation, 2011). In this study,

the measured tree species parameters in a study area, detailed that most of tree

parameters have variation in terms of number and growth parameters due to age,

nutrients and light demand competition, genetically, geographical location, soil type

factors and degree of disturbance of a particular locality where by a tree species has been

gown. The tree parameters variations have an influence on biomass quantity and carbon

storage of tree species. The estimated biomass (figure 3a) and carbon stock (figure 3b)

vary considerably as tree parameter increases in magnitude (quantity), according to the

study results, frequency per sample plot of trees and basal area were ranged from 11 to

30 trees (Table 4) and 0.02 to 0.05m2 (Table 5b) respectively.

Table 4: Tree parameters variation of Salenda Bridge

17

DBH class (cm) DBH (cm) Mean height (m) Number of trees

11-14 12.5 4.5 27

14-17 15.5 5 28

17-20 18.5 5.5 16

20-23 21.5 6.5 30

23-26 24.5 7.5 11

N =112

1 2 3 4 50

5

10

15

20

25

30

35

Dbh (cm)Mean height (m)Frequency

Tree parameter

Figure 2: Tree parameter’s frequency variation of Salenda Bridge

1 2 3 4 50

5

10

15

20

25

30

DBHHeightFrequencyBiomass in tone

Figure 3a: Tree species biomass variation, frequency and parameters of Salenda Bridge

18

1 2 3 4 50

5

10

15

20

25

30

DBHHeightFrequencyCarbon stock in tone

Figure 3b: Tree species carbon stock variation, frequency and parameters of Salenda

Bridge

Table 5a, 5b and 5c depicts field data result findings of estimated basal area, biomass

and carbon stock per DBH class, sample area, forest area and hectare in the study area.

19

Table 5a: Above-ground biomass, carbon stock and basal area of Salenda Bridge

Measured quantity

Estimated value/ sample area

Estimate value/ forest area Estimated value/ ha

Basal area 0.16m2 0.3m2 6.67m2

Biomass 11tonnes 22.9 tonnes 458.3tonnes

Carbon stock 5.32tonnes 11.8tonnes 221.67tonnes

Table 5b: Basal area, biomass and carbon stock per DBH class of Salenda Bridge

Basal area/ DBH class Biomass/ DBH class Carbon stock/ DBH class

0.03m2 0.9tonne 0.45tonnes

0.03m2 1.6tonnes 0.81tonnes

0.02m2 1.4tonnes 0.72tonnes

0.05m2 4.3tonnes 0.16tonnes

0.02m2 2.4tonnes 1.19tonnes

Total 0.16m2 11tonnes 5.32tonnes

The research domino effect showed that, at Salenda bridge mangrove patch the DBH

class under range of 20-23cm was relatively highly in biomass percentage composition,

about 41% compared to others in view of the fact that, has large total basal area,

frequency, n=30 and average height of 6.5m. Though stand trees with large diameter

have greater significant on biomass and carbon storage as depicted in figure 4, DBH

class of 23-26 have high basal area, biomass percent (22%) and relatively small number 20

of trees, n= 11 compared to the rest due to the large size of the diameter, height and age.

According to German Development Cooperation (2011), older forests have higher

biomass and greater diversity. Dealing out for trees to grow to the maximum size is the

most excellent way to maximize tree species biomass (Development Cooperation, 2011).

9% 15%

14%

41%

22%

11-14 cm14-17 cm17-20 cm20-23 cm23-26 cm

Figure 4: Tree species DBH class’ percentage above-ground biomass of Salenda Bridge

CHAPTER FIVE

5.0 CONCLUSION AND RECOMMENDATION

5.1 Conclusion

21

The study findings discovered that, at Salenda Bridge mangrove patch has realistically

good quality mangrove tree species composition and above-ground biomass which

reflect that, the patch has relatively high management conservation and protection from

the mangrove authorities particularly in Ilala and Kinondoni districts. The ending results

of this study seal the knowledge gap existed before concerned about the potentials of

Salenda bridge mangrove patch on environmental conservation particularly on climate

change; carbon sequestrations mitigation, soil conservation as well as ecological benefits

particularly on ecosystem sustainability of the mangrove community of the Salenda

bridge mangrove patch by enlightening the facts about mangrove tree species

composition and above-ground biomass estimation. Elsewhere proves that, it is

impossible to find all the 68 mangrove species in one area.

The schoolwork showed that, the acknowledged tree species composed and characterises

the entire mangrove patch at Salenda Bridge vicinity; 100% was merely Avicinnia

marina with height and diameter characteristics arrayed 4-8m and 12-24cm respectively.

The total number of mangrove tree species, above ground biomass and carbon stock for

Avicinnia marina mangrove tree species were estimated to be 4753trees/ha, 458.3t/ha

and 221.67t/ha respectively which reflect that, Salenda Bridge has well developed

mangrove forests. In relation to carbon storage, this information reflects that, the

mangrove patch particularly at Salenda Bridge, stores high amount of carbon from the

atmosphere which has been exposed by various industrial activities. Regardless that,

mangrove patch at Salenda Bridge provides socio-economic benefits but also

environmental conservation and protection, and elsewhere ensure ecosystem

sustainability.

5.2 Recommendations

5.21 Forests protection and restoration

In order to enhance the level of biomass and subsequent carbon storage of mangrove

forests at Salenda bridge mangrove patch, efforts to protect and restore the forests will be

worthwhile for all stakeholders including the Government and international institutions,

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NGO’s and local community. The protection and restoration of the forests is significant

for climate mitigation strategies and will confer considerable economic benefits to

Salenda bridge mangrove patch, nationally and internationally.

5.22 Researcher’s support, good coordination and working environment

Government, institutions, company, projects, program and other organizations should

ensure support, good coordination and working environment with research institutions

and scholars (researchers). They should provide the necessary working tool includes

instruments and financial requirements for the researchers.

5.23 Study on mangrove ecosystem dynamic change and distribution

Further study should be done on tree species diversity by other scholars, additional

emphasizes should be focused on studying mangrove ecosystem dynamic change and

tree species distribution in terms of spatial arrangement, being studying those two

parameters will determine the associated threats facing mangrove forests community at

Salenda bridge patch as well as to assess how spatially do the mangrove tree species are

arranged? Do they crump? Or evenly as well as randomly distributed? By studying the

mangrove tree species distribution will offer a good means for supervision of the

mangrove forests patch at Salenda Bridge principally on conservation purpose as well as

protection and absolutely to guarantee mangrove forests ecosystem sustainability.

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REFERENCES

Alongi, DM. (2009), Guidelines for measuring carbon stocks in community-managed

Forests, the Energetic of Mangrove Forests

Alongi, DM. (2002), Bosire J., Okemwa G., Ochiewo J, Participatory modelling

Frameworks to understand well being tradeoffs in coastal ecosystem services:

Mangrove sub-component

Bibliotheca Alexandria-EOL Ar (2013). Journal for tropical mangroves wood density

Biomass expansion factor standard value for tropical mangrove forests-IPCC (2006)

Biomass & Species composition, <http://www.wikipedia,

(Retrieved May 10, 2013)

Bhishma, P. S. Shiva, S. P. Ajay, P. Eak, B. R. Sanjeeb, B. Tibendra, R. Shambhu,

C. Rijan T. (2010), Guidelines for measuring carbon stocks in community-

Managed forests

Collins maps, <http://www.wikipedia, (Retrieved May 15, 2013)

FTI Olmotonyi (2013), Silvicultural management of mangrove forests,

Forest tending lecture notes.

Giesen, W. Wulffraat, S. Zieren, M., Scholten, L. (2007), Mangrove Guide book for

South East Asia Mangrove Ecology, Silviculture and Conservation. Kluwer

Academic. Dordrecht, Netherlands. Gilman, E., Ellison, J., Duke, N.C., and Field, C.,

(2008), Food and Agricultural Organization and Wetlands International, Bangkok,

Thailand.769p

Giri, C. Ochieng, E., Tieszen, L.L., Zhu, Z., Singh, A., Loveland, T. Masek, J. Duke, N.

(2011), Aquatic Botany 89: 237-250. State and future of the world’s mangrove

forest, Status and Distribution of mangrove forests of the world. Threats to mangroves

From climate change and adaptation options: a review. Present using earth

observation satellite data. Global Ecology and Biogeography 20: 154-159, Saenger P

(2002), Mangrove species, Springer New York.

Matta and Malimbwi (1997), form factor for Pinus and mangroves, ranged 0.45 to 0.6≈1

For mangrove, resource assessment lecture pamphlet notes at FTI-Olmotonyi

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APPENDICES

LIST OF APPENDICES

Appendix 1: Data collection form

Plot

no.

Species name

Tree specie’s characteristics ( parameters)

DBH(cm)

>11cm

Height(m)

>3m

fi DBH-class(cm) Mean height(m) fc

Ecological survey summary

25