Forest management and ecosystem sustainability

1. 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
i Mrumba E. John
2014

2. 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

3. iii

4. 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…………………………………………………………...... 4
2.1 Over view of mangrove forests……………………………………………………….. 4
2.2 Composition structure of mangrove forests…………………………………………....4
2.3 Role of mangrove forest’s biomass in carbon cycle……………………………….......5
CHAPTER THREE............................................................................................................. 9
3.0 MATERIAL AND METHOD…………………………………………………………7
3.1 Description of the Study area……………………………………………………….....7
3.1.1 Location……………………………………………………………………………...7
3.1.2 Climate……………………………………………………………………………….7
3.1.3 Soil and vegetation type……………………………………………………………...7
3.1.4 Population and Human economic activities………………………………………...8
3.2 Materials…………………………………………………………………………….. 8
3.3 Methods…………………………………………………………………………….. 9
iv

5. 3.3.1 Sampling techniques……………………………………………………………… 9
3.3.2 Data collection.......................................................................................................... 10
3.3.3 Data analysis……………………………………………………………………… 11
CHAPTER FOUR............................................................................................................ 14
4.0 RESULTS AND DISCUSSION…………………………………………………… 12
4.1 Tree species composition of Salenda Bridge patch………………............................. 12
4.2 Tree species percentage composition of Salenda bridge mangrove patch……............15
4.3 Above-ground biomass and carbon stock of Salenda bridge mangrove patch…….... 16
CHAPTER FIVE.............................................................................................................. 24
5.0 CONCLUSION AND RECOMMENDATION…………………………………….. 22
5.1 Conclusion……………………………………………………………………… 22
5.2 Recommendation………………………………………………………………….... 22
REFERENCES………………………………………………………………………… 24
LIST OF APPENDICES………………………………………………………………… 25
v

6. 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

7. 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

8. LIST OF ABBREVIATION AND SYMBOLS
CABG Above-ground carbon stock per individual specie
viii
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
π Pi, 3.14

9. CHAPTER ONE
1
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

10. 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).
2
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).

11. 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 M e l iaceae (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

12. CHAPTER TWO
4
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

13. 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

14. generally between 150 and 350 t / ha in well developed tropical mangroves (Alongi
2009).
6

15. CHAPTER THREE
7
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.

16. 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.
8
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

17. 9
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)

18. 10
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.

19. 11
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 =Σ CABG; where Σ CABG = summation of CABG

20. CHAPTER FOUR
12
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).

21. Plate 2: Leaves morphology of Avicinnia marina
13

22. Table 2: Botanical description of Avicinnia marina
14
Plot
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

23. 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
15
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

24. Figure 1: DBH characteristics of Salenda Bridge
30
25
20
15
10
5
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
0
11-14 cm 14-17 cm 17-20 cm 20-23 cm 23-26 cm
Frequency
DBH class

25. 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
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
17
N =112

26. Figure 2: Tree parameter’s frequency variation of Salenda Bridge
35
30
25
20
15
10
5
30
25
20
15
10
5
Figure 3a: Tree species biomass variation, frequency and parameters of Salenda Bridge
18
0
1 2 3 4 5
Tree parameter
Dbh (cm)
Mean height (m)
Frequency
0
1 2 3 4 5
DBH
Height
Frequency
Biomass in tone

27. 30
25
20
15
10
5
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
0
1 2 3 4 5
DBH
Height
Frequency
Carbon stock in tone

28. Table 5a: Above-ground biomass, carbon stock and basal area of Salenda Bridge
Table 5b: Basal area, biomass and carbon stock per DBH class of Salenda Bridge
20
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
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

29. 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
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).
22%
Figure 4: Tree species DBH class’ percentage above-ground biomass of Salenda Bridge
21
9%
15%
14%
41%
11-14 cm
14-17 cm
17-20 cm
20-23 cm
23-26 cm

30. CHAPTER FIVE
5.0 CONCLUSION AND RECOMMENDATION
22
5.1 Conclusion
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.

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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,
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.

32. 24
REFERENCES
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Biomass expansion factor standard value for tropical mangrove forests-IPCC (2006)
Biomass & Species composition, <http://www.wikipedia,
(Retrieved May 10, 2013)
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33. 25
APPENDICES
LIST OF APPENDICES
Appendix 1: Data collection form
Ecological survey summary
Plot
no.
Species name
Tree specie’s characteristics ( parameters)
DBH(cm)
>11cm
Height(m)
>3m
fi DBH-class(cm) Mean height(m) fc