08
SYSTEMATIC STUDY OF CARBON SEQUESTRATION OF MANGROVE FORESTS ATRAIGAD DISTRICT COAST, MAHARASHTRA, INDIA
Kulkarni Prasad*1, Kulkarni Shraddha2 and Aphale Priti2
Faculty of Sustainability Studies, MIT-World Peace University, Pune, India
2
Department of Environment Sciences, Fergusson College (Autonomous), Pune, India
Email: prasad.kulkarni@mitwpu.edu.in*1

How to cite this paper:
Kulkarni Prasad, Kulkarni
Shraddha and Aphale Priti(2023) Systematic Study ofCarbon Sequestration ofMangrove forests at Raigad
District Coast, Maharashtra,
India., Journal of Global
Resources, Vol. 09 (01)DOI:
10.46587/JGR.2023.v09i01.008

Received: 30 Sep. 2022
Reviewed: 18 Nov. 2022
Final Accepted: 09 Dec. 2022

Abstract: Mangrove forests are highly productive
ecosystems with carbon sequestration rate almost
equivalent to tropical green forests. Mangroves distributeproportionally more carbon below ground and possess
higher below to above ground carbon mass ratio ascompared to any other forests (Kathiresen, 2004).
Mangrove is amongst the most carbon rich biomes
containing more than 950 tC/H. The said study overlooks
destructive and non-destructive methods of the carbon
sequestration. It is conducted as a comparative assessmentof the carbon sequestration potential of mangrove and nonmangrove regions. By means of methodology of calculating
Soil Bulk Density (gcm -3) and Total Organic Carbon (TOC)in mangroves soils (El Wakeel and Riley, 1956) and Carbon
Sequestration Rate (CSR) is estimated based on thesediment rates and TOC content of the soil (Duan Xiaonan
et al (2008). The systematic assessment conducted at West
Coast of Maharashtra; shows mangrove region with
Avicinnia marina species and in non–mangrove region total
carbon in soil (%) recorded 17.15% and 4.52 percent
respectively. Total Soil Carbon Stock recorded is 431 milliong / Ha at mangrove region and 105.7 million g / Ha at non
mangrove region. After methodical estimation of biomass
and carbon stock of mangroves (English et.al, 1997 andKaufman and Donato, 2012), total carbon stock of mangrove
stand was recorded 393.14 mg/Ha and that of nonmangrove stand was recorded to be 91.7 mg/Ha. It showsthat mangroves absorb almost 315.14 percent more carbon
than non-mangrove region. In other words, carbon stock in
Avicinnia marina stand found to be almost 3 times more thannon-mangrove zone.
Key words: Mangrove, Biome, Carbon Sequestration.

79

Introduction
The tropical trees and shrubs which grow in inter-tidal region are known as “mangrove.”
Mangrove forests are often referred as one of the world’s most productive ecosystems andthus also known as ‘tidal woodlands,’ ‘coastal forests’ or even ‘coastal rainforests. The woody
plants those grow in tropical and sub‐ tropical regions lateral to the land and sea interface,estuaries, backwaters, and in the rivers. They even reach upstream to the point where thewater remains saline (Qasim, l998). The word is originated in the year 1613 which is a bilingual “mangue” and “grove” originated from Portuguese the English word respectively(Kathirasen, 2001). More often all the salt tolerating plants are referred as mangroves and arealso capable to grow in semi saline condition. A criterion was developed by Tomlinson (1986)
by which mangroves are designated as a “true or strict mangrove”:•
Follows and grows in coastal environment.
•
Forms the structure of the mangrove community and has the ability to form mangrove
stands.
•Physical specialization for adaptation to environment.
•
Functional specialization for adaptation to saline conditions.
•
Taxonomic separation from terrestrial members.
Thus, mangrove is a non-scientific term used to describe an assorted group of plant
species those are adapted to saline habitat. Mangrove may usually refer to an individual
species, terms such as mangrove forest, mangrove swamp, mangrove community, mangrove
ecosystem as well as mangle are used to describe the entire mangrove family.
Socio-economic of Mangroves
Mankind is directly as well as indirectly dependent on the mangrove ecosystem. It brings many
economic, ecological, and social values to mankind. Mangrove ecosystems have consistently
been undervalued, usually because only their direct goods and services have been includedin economic calculations (e.g., forestry resources), but this represents only a minor part of thetotal value of mangroves. Mangroves ecosystem support one of the richest biodiversity(Ellison, 2008). It is seen that they act as a protective layer during the storms and tsunamis.
Mangroves also possess quite a few economic benefits which range from valuable supply offorestry products and products like charcoal and firewood. Mangrove extracts are also used
in indigenous medicines and can be used in treatment of diseases like blood pressures leprosy
and epilepsy, rheumatic disorders, it is anti-diarrheal. They have also shown properties for thetreatment of incurable viral diseases like AIDS (Kathiresan, 2001).
It is observed that Mangrove conversion usually has short-term benefits but it has agreater ecological impact at the longer-term. Some of the non-market values, e.g., species
diversity and off-site functions such as nutrient exchange are not easily quantified, but havebeen significantly important to maintain the ecological cycle. Mangroves stand first in the row
as far as the importance in view of their protective and productive values is concerned. They
provide numerous tangible and intangible benefits (goods and services) along with thelivelihoods to the coastal communities (Vannucci 2004). The socioeconomic importance of
natural mangroves has been time and then highlighted addressed by many scholars andscientists (Ruitenbeek, 1994; Walters, 2008; Kathiresen, 2004; Barbier, et al 2008). In-fact theover-exploitation of various forest products, including timber, thatching materials and wood forfuel has been degrading Sundarbans mangrove forest (Islam and Gnauck, 2009). Wood is a
key resource from the forest which contributes over 80 percent of the revenue generated from80the Sundarbans. It acts as an important source of fuel wood for the markets of Bangladesh(Alam, et al 2012).
Threats to Mangroves Ecosystem
In the developing era and fast emerging world, the mangrove regions along with mudflats haveoften been considered as uncreative and unused land. Their elimination and destruction havebeen done for short-term utilization for instant economic benefit. One of the main causes ofloss of mangrove forests is increase in population and their dependence on coastal resources.
Ong (1995) stated that alarming increase in populations is possibly a biggest cause ofmangrove destruction and degradation. Study shows that around 60 percent of the global
population lives within roughly around 100 km of range from the coastline (WRI). Which means
more than 4.6 billion people directly rely on marine habitats and resources for livelihoods,
tourism, agriculture, and food, building sites and building materials, as well as recreational
areas. The coastal regions and mangrove forests are also seen to be utilised as a dumping
site for sewage, garbage and industrial wastes (Jennerjahn et al., 2002)
Moreover, huge population in the non-coastal region resides in agricultural region andurban communities concentrated along the rivers and in the surrounding hills. Pollution andunderprivileged land use practices within these low-lying areas bring more and more
sediments and pollutants which are ultimately washed into coastal waters affecting themangrove ecosystem (Breithaupt et al., 1997). Carbon sequestration is the process involvedin carbon capture and the long-term storage of atmospheric carbon dioxide or other forms ofcarbon to mitigate or defer global warming. It has been proposed as a way to slow theatmospheric and marine accumulation of greenhouse gases, which are released by burning
fossil fuels (Brunskil et al., 2002). Carbon dioxide is naturally captured from the atmospherethrough biological, chemical, and physical processes. Artificial processes have been devised
to produce similar effects, including large-scale, artificial capture and sequestration ofindustrially produced CO2 using subsurface saline aquifers, reservoirs, ocean water, aging oil
fields, or other carbon sinks (Sanders et al., 2010).
Goal and Objectives
The goal of this study was to assess soil carbon pools and sequestration rates in coastalmangrove ecosystems of West Coast of India with a special reference to Raigad Taluk in thestate of Maharashtra. The hypothesis is to assess carbon sequestration potential ofmangroves and non mangroves region along a disturbed and non-disturbed tidal creek.
Materials and Methods
The Raigad Coast and Mangroves
Maharashtra has 720 km of a coastline which stretches from district Thane to south region of
Sindhudurg till Terekhol creek spread across six districts and Mumbai’s urban region. Mumbai
sub-urban region forms the longest coastline whereas Thane district contributes the shortest
coastline. Raigad district stands fourth as far as length of the coastline is considered. The
Konkan coast is indented with number of beaches, fifteen small and large rivers, five major
estuaries and more than 30 backwater regions (Jagtap et al., 2001). Raigad coast whereas,is gouged with four major creeks, three creek-lets and five backwater regions. Raigad districtis spread over fifteen tehsils which falls in 170 51’ to 190 80’ North and 720 51’ to 730 40’ East
Longitudes, out of which Panvel, Uran, Pen, Alibaug, Murud, Roha Sriwardhan, Mhasala,Mangaon and Poladpur are the coastal tehsils covering about 4100 sq.km. of area with about811300 villages. Hence, Maharashtra has a strategic central location in the western region ofIndia. Moreover, Raigad falls strategically at the central location at west coast with Thane
district at the North and Ratnagairi district down south. The said study was conducted at
Dharamtar Creek at four different sites (table 1.1) which is a semi-diurnal, micro-tidal estuarine
system located at Northwest region in Raigad district.

Sr. No.
1.
2.
3.
4.

Table 01: Sampling Locations along the Dharamtar Creek
Name of nearest village/town Latitude
Longitude
Vitthalwadi
18°47'15.70"N
73° 0'47.30"E
Dadar
18°48'19.43"N73° 2'3.97"E
Khar Devli
18°40'45.12"N73° 3'4.29"E
Shahapur
18°43'31.77"N
72°58'42.30"E

Sampling• Sediments sampling using the 1.5 m corer• Temperature recorded using thermometer with 0.5 0C accuracy at different depths (010-30-50-100-above cms.)• pH measured using pH meter• Pour water salinity – hand refractometer• Soil samples at different depths kept for the sun drying for 48 Hrs.
• Soil Bulk Density using water displacement method
Oven dry weight of soil (g)Soil Bulk Density (gcm -3) = -------------------------------------------------Volume of water displaced (ml) of soil
El Wakeel and Riley (1956) Total organic Carbon in mangrove soil • Soil was dissolved in Chromic Acid
• Chromic Acid digestion and subsequent titration with ferrous ammonium sulphate
solution in presence of phenanthroline indicator• Light pink was an end point• Same procedure is followed without the soil – blank titerCalculations –• Ferrous Ammonium Sulphate consumed (ml) (T) = Titre for blank – Titre for sample• Total organic carbon (TOC) mgC/g (X) = 1.14 * 0.6 * T (Constant)• TOC in sediment soil (%) = X / 10
• Total Carbon in sediment soil (%) = TOC / 2• Carbon Stock in sediment soil (%) = bulk density * Total carbon * soil depth• CO2 equivalent (%) = carbon stock * 3.67
Carbon Sequestration Rate (CSR) potential of mangrove sediment • CSR is estimated based on the sediment rates and TOC content of the soil using Duan
Xiaonan et al (2008) method.
• CSR = p * TOC * R
Where,
p – Bulk density of soil g/cm2
R – Sediment rate of mangrove …mm/year
TOC – total organic carbon in %Similarly, Carbon Sequestration Potential (CSP) of different mangrove areas is made in thearea of forest or annual increase in forest cover
CSP = CSR * A (A = distribution area of forest in Ha)82

Estimation of biomass and carbon stock of mangroves –For Mean wood density (p in tm-3) of mangroves: English et al., 1997 and Kaufman andDonato, 2012 method was used in which Girth of mangrove plants was measured in cm at thetree height of 30 cm for Rhizophoraceae members and at 1.3 m for all other mangroves.
Tree diameter is calculated by multiplying girth with the constant factor 0.318.
Calculations –• Shoot biomass (SB) = 0.251 * p * D2.46• Root Biomass (RB) = 0.199 * p0.899 * D2.22• Total Biomass (X) = SB+RB (kg/plant)
Where D – tree diameter; p – wood density of trunk in ton per m3
Observations – Soil Carbon Stock Mangrove & Non-Mangrove zone
Results

A
B

Table 02: Soil Carbon Stock Mangrove & Non-Mangrove zone
Zonation
Soil Carbon
Percentage of control
Stock (mg/ha)
zone (A/B*100)
Avicennia marina Zone 426.5
4.03
Non Mangrove Zone
105.7
--

It was observed that the soil carbon stock was observed to be four folds than in the nonmangrove zone. Hence, the potential of mangroves in sequestration of carbon is almost fourtime to the normal climate.
Table 03: Consolidated Data Sheet for Carbon Stock of Mangrove Stand
Mangrove stand

Carbonbiomass(mg/ha)Soil carbon
stock in 1 m soil
depth (mg/ha)

Total carbon stock ofmangrove stands
Mg/ha

A
B

Avicennia marina standNon mangrove stand(control)

33.64
0

359.5
94.7

393.14
91.7% Increase overcontrol(A/B*100-100)
315.14--

It is observed that carbon stock in Avicinnia marina stand is almost 3 times more than nonmangrove zone.
Conclusion
The soil carbon stock of non-mangrove zone was calculated to be 105.7 mg/ha and that of
Avicennia marina zone was found to be 426.5 mg/ha; which is three times more than the nonmangrove zone. From the results of present study, it has been found that mangrove forests
absorb more carbon-di-oxide than any other terrestrial ecosystem. Moreover, when comparedwith Avicinnia marina and a non-mangrove area the consolidated carbon stock of mangrove
was found to be 33.64 mg/ha; soil carbon stock in one meter depth soil was 359.5 mg/ha and94.7 mg/ha, respectively and total carbon stock of mangrove stand was 393.14 mg/ha andnon-mangrove stand was 91.7 mg/ha. Hence total difference between mangrove and nonmangrove stock was found to be 315.14 mg/ha. Hence the study gives one more reason
towards conservation of mangroves towards fighting against climate change, tsunamis andsupporting the coast biodiversity.
83

Table 04: Soil Carbon Stock Mangrove & Non-Mangrove zone
Name of
Zone

Avicennia
marina Zone

Total
Non
Mangrove
Zone

Depth (cm)

Soil
temp

Soil
pH

Dry
weight ofsoil (g) X

Volumeof Soil(ml) Y

6.9
6.66
6.65
6.75
6.78

Pour
water
salinity
(ppt)
69
7
71
73
73

0 – 10
10 – 30
30 – 50
50 – 100
➢ 100

28.3
31.4
31.4
32.1
31.1

0 – 10
10 – 30
30 – 50
50 – 100
> 100

30.1
30.9
31.1
31.1
30.4

1
1
1
1
1

Soil Bulk
Density(g.m3)
Z=X/Y
1
1
1
1
1

Total
organic
carbon insoil (%) A
3.8
10
7
6.8
6.7

1
1
1
1
1

7.88
7.84
7.78
7.76
7.73

11
15
15
15
16

1
1
1
1
1

1
1
1
1
2

1
1
1
1
0.5

0.54
3
3.2
1.2
1.1

Total

Total carbon in
Soil (%) B=A/2

1.9
5
3.5
3.4
3.35
17.15
0.27
1.5
1.6
0.6
0.55
4.52

Soil Carbon Stock(milli g/Ha)
C=Z*B*soil depth
interval (cm)
19
100
70
175
67
431
2.7
30
32
30
11
105.7

CO2
equivalent= C*3.67
71.56
367
256.9
623.9
245.891565.259.9
110.1
117.44110.1
40.37
387.91

Table 05: Estimation of Biomass and Carbon Stock of Mangroves
#

Spp
name

1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.

AM
AM
AM
AM
AM
AM
AM
RM
RM
RM
RM
RM
RM

Tree
Girth
(cm)
43
36
33
25
56
56
24
12
14
16
13
12
13

Tree Diameter(D) = Girth *0.318 (cm) D
13.674
11.44810.4947.95
17.80817.808
7.632
3.816
4.452
5.088
4.134
3.816
4.134

Wood Density(t.m) p
0.506
0.506
0.506
0.506
0.506
0.506
0.506
0.701
0.701
0.701
0.701
0.701
0.701

Shoot
Biomass(kg/plant) SB
79
50.99
40.72
20.83
151.3
151.3
18.82
4.72
6.92
9.58
5.76
4.72
5.76

Root
Biomass(kg/plant) RB
35.83
24.13
19.2
10.75
64.38
64.38
9.81
2.81
3.97
5.33
3.36
2.81
3.36

84

Plant Biomass =SB+RB (kg/plant)X
114.83
75.12
59.92
31.58
215.68215.68
28.63
7.53
10.89
14.91
9.12
7.53
9.12

Carbon Biomass= X * 0.42 (kgC/plant) Y
48.2286
31.5504
25.1664
13.2636
90.5856
90.5856
12.0246
3.1626
4.57386.26223.8304
3.16263.8304336.226 / 13336.2268
25.8636

Carbon Estimation per
hectorA = Y*TreeB=
density/Ha
A/1000(kgC/Ha)(mgC/Ha

25.88 *
1300
33644

33644
/1000
33.644CO2 Equi33.64 *3.67
123.4588

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