Mahanadi carbon

JECET; December 2017- February 2018; Sec. A; Vol.7. No.1, 016-029. E-ISSN: 2278–179X

[DOI: 10.24214/jecet.A.7.1.01629.]

Journal of Environmental Science, Computer Science and

Engineering & Technology

An International Peer Review E-3 Journal of Sciences and Technology

Available online at www.jecet.org

Section A: Environmental Science

Research Article

16 JECET; ; December 2017- February 2018; Sec. A; Vol.7. No.1, 016-029.

DOI:10.24214/jecet.A.7.1.1629.

Carbon sequestration by mangrove vegetations: A case

study from Mahanadi mangrove wetland

Sangita Agarwal1, Kakoli Banerjee2, Nabonita Pal3, Kapileswar Mallik2,

Gobinda Bal2, Prosenjit Pramanick3 and Abhijit Mitra4

1Department of Applied Science, RCC Institute of Information Technology, Beliaghata, Kolkata

700015, India 2Department of Biodiversity & Conservation of Natural Resources, Central University of Orissa,

Landiguda, Koraput, Odisha 764 021 3Department of Oceanography, Techno India University, Salt Lake Campus, Kolkata-700091, India

4Department of Marine Science, University of Calcutta, 35 B.C. Road, Kolkata 700019, India

Received: 26 October 2017; Revised: 04 December 2017; Accepted: 12 December 2017

Abstract: We conducted a survey on the true mangrove floral stem biomass and stem

carbon during July 2012 and July 2017 with the aim to estimate the rate of stored

carbon per hectare (carbon sequestration) in the Mahanadi delta complex of Odisha.

A total of 26 species were documented from the region out of which Heritiera fomes

showed the highest population density (31.12 No./m2 in 2012 and 28.81 No./m2 in

2017). Considering the total stem biomass of all the 26 true mangrove floral species,

the rate of change of biomass was observed to be 16.20 tha-1y-1, which represents

carbon sequestration of 7.34 tha-1y-1. This sequestration value generates a CO2-

equivalent of 26.94 tha-1y-1, which calls for the conservation and restoration of

mangrove stands of Mahanadi delta region to minimize CO2 level at local scale.

Keywords: Mahanadi Delta Complex, Mangrove, Carbon sequestration, biomass

http://www.jecet.org/

Carbon … Sangita Agarwal et al.


DOI:10.24214/jecet.A.7.1.01629.

INTRODUCTION

India has a total mangrove cover of ~ 4628 sq.km1 which is 0.15% of countries land area, 8% of

Asia's mangrove and 3% of the global mangrove area. The top 10 mangrove dominated states in India

are West Bengal (2097 Km2) > Gujarat (1103 Km2) > Andaman and Nicobar Islands (604 Km2) >

Andhra Pradesh and Telengana (352 Km2) > Odisha (213 Km2) > Maharashtra (186 Km2) > Tamil

Nadu (39 Km2) > Goa (22 Km2) > Kerala (6 Km2) > Karnataka (3 Km2)2.

In the east coast of India mangroves are concentrated in the Sundarban region of West Bengal,

Subarnarekha, Bhitarkanika and Mahanadi delta of Odisha, Godavari and Krishna delta of Andhra

Pradesh, Pichavaram estuary and Cauvery estuary of Tamil Nadu3. Samal and Patnaik4 reported that in

Odisha, the mangroves spread over an area of 214 sq. km. Out of the total mangrove area of the state,

Mahanadi delta covers an area of 120 sq. km. The mangrove area in the Mahanadi delta (20°15′ to

20°70′ N latitude and 87° to 87°40′E longitude) extends from south eastern boundary of Mahanadi

river to river mouth of Hansua (a tributary of Brahmani) in the north, from the north eastern end of

Mahanadi river up to Jamboo river in east. Mahanadi mangrove wetland encompasses eight forest

blocks.

The delta region enjoys tropical monsoon climate with an average annual rainfall around 1800 mm.

75% of the rainfall occurs during months of August and September, although in 2017 the monsoon

extended till end of October. There are three main seasons prevailing in the region namely

premonsoon, monsoon and postmonsoon. Cyclonic storms are common during the monsoon season

and two cyclonic peaks are observed in the region, one during May-July and the other during October-

November.

The mangrove forests of the deltaic complex serve as the base of a productive marine and estuarine

food web (Figure 1).

Figure 1: Blue-carbon centric food web in delta complex



DOI:10.24214/jecet.A.7.1.01629.

In recent years, the region is under threat due to mushrooming of port-cum-industries and shrimp

farms in an around the mangrove forests (Figure 2).

Figure 2: Activities around Mahanadi delta complex (Map is not in scale)

The effluents from these industries and shrimp farms are discharged into the estuarine system thus

causing an adverse impact on the mangrove biodiversity as a whole3. On the basis of this background,

the present paper aims to study the mangrove biomass and stored carbon in the stem region of the

selected true mangrove species that were documented during our field programme.

MATERIALS AND METHODS

Study area: Mahanadi mangrove wetland is located in Kendrapara district between 20°18′ - 20°32′ N

latitude and 86° 41′ - 86° 48′ E longitudes in Odisha, which is a maritime state in the east coast of

India sub-continent (Figure 1). The region has dense mangrove, which extend from Hukitala Bay in

the north to Mahanadi river mouth near Paradeep port in the south.

Sampling: Simple random sampling method was used to collect the samples. Sample plots were laid

along line transects based on tidal variation in the study area. 15 random sampling plots of 10 m × 10

m were selected on the intertidal mudflats. To evaluate the stored carbon in the stem biomass, the

taxonomic diversity, population density and stem biomass of all the true mangrove floral species were

recorded. The sampling was carried out during low tide period and only the live trees with a diameter

at breast height (DBH) ≥ 5 cm were recorded.

Estimation of stem biomass: The DBH was measured at breast height, which is 1.3 m from the

ground level. It was measured by using tree caliper and measuring tape.



DOI:10.24214/jecet.A.7.1.01629.

Trees with multiple stems connected near the ground were counted as single individuals and bole

circumference was measured separately. Stem height was recorded by using laser based height

measuring instrument (BOSCH DLE 70 Professional model). The methodology and procedures to

estimate the stem biomass of the selected true mangrove tree species were carried out step by step as

per the VACCIN project manual of CSIR5 considering and measuring parameters like DBH, DBR

(Diameter of basal region), height of the stem, density of the stem wood and form factor. The

population density of each species was also documented to express the value of stem biomass in t ha-1.

Estimation of stem carbon: Direct estimation of percent carbon in the stem was done by Vario

MACRO elementar CHN analyzer, after grinding and random mixing the oven dried stems from 15

different sampling plots. The estimation was done separately for each species and mean values were

expressed as t ha-1.

In the combustion process (furnace at ~ 1000oC), carbon is converted to carbon dioxide; hydrogen to

water; nitrogen to nitrogen gas/ oxides of nitrogen and sulphur to sulphur dioxide. If other elements

such as chlorine are present, they will also be converted to combustion products, such as hydrogen

chloride. A variety of absorbents are used to remove these additional combustion products as well as

some of the principal elements, sulphur for example, if no determination of these additional elements

is required.

The combustion products are swept out of the combustion chamber by inert carrier gas such as helium

and passed over heated (about 600o C) high purity copper. The function of this copper is to remove

any oxygen not consumed in the initial combustion and to convert any oxides of nitrogen to nitrogen

gas. The gases are then passed through the absorbent traps in order to leave only carbon dioxide,

water, nitrogen and sulphur dioxide.

Detection of the gases can be carried out in a variety of ways including (i) a GC separation followed

by quantification using thermal conductivity detection (ii) a partial separation by GC (‘frontal

chromatography’) followed by thermal conductivity detection (CHN but not S) (iii) a series of

separate infra-red and thermal conductivity cells for detection of individual compounds.

Quantification of the elements requires calibration for each element by using high purity ‘micro-

analytical standard’ compounds such as acetanilide and benzoic acid.

Estimation of carbon sequestration: Carbon sequestration is defined as the rate of change of stored

carbon with time. In the present study, estimation of stored carbon in the stem of the selected

mangrove trees was done during July 2012 and July 2017 in the same locations. Hence the rate of

change of stored carbon in the stem biomass of the selected species (carbon sequestration) was

calculated by dividing the difference in stored carbon between years with the time factor (5 years in

this case).

RESULT

Taxonomic diversity: A total of 26 true mangrove floral species were documented from the study

area and the population density (in No./100m2) ranged from 0.17 (Lumnitzera racemosa) to 30.12

(Heritiera fomes) in 2012 and 0.06 (Lumnitzera racemosa) to 28.81 (Heritiera fomes) in 2017 as

shown in Figure 3.



DOI:10.24214/jecet.A.7.1.01629.

Figure 3: Taxonomic diversity of mangrove trees in Mahanadi delta region

Above Ground Stem Biomass and Carbon: A total of 26 true mangrove floral species were

documented in which the highest rate of change in biomass was observed in Avicennia officinalis

(3.85 tha-1y-1). The lowest value was observed Lumnitzera racemosa (0.03 tha-1 y-1). Also the rate of

change of stored carbon (carbon sequestration) was estimated for all the 26 species. The highest and

the lowest values were observed in Avicennia officinalis (1.73 tha-1y-1) and Lumnitzera racemosa

(1.01 tha-1y-1) respectively (Table 1, Figure 4).

Table-1: Check-list of Mahanadi delta true mangrove flora with salient features

Sl.

No. Species Identifying Character

ΔAGB/Δt

(t ha-1)

ΔAGC/Δt

(t ha-1)

1.

Aegialitis rotundifolia

Woody shrubs or small

trees with an average

height of 2.5 m

Leathery leaves arranged

alternately or spirally.

Individual flowers have

5 petals arranged in a

fused tube around the

white gamopetalous

corolla that has 5 petals

fused in short tube.

0.15 0.06



DOI:10.24214/jecet.A.7.1.01629.

2.

Aegiceras corniculatum

Shrub distributed in high

saline areas, bark reddish

brown with leaves

elliptical, leaf-tip

notched, cuneate at base.

Fruit green to reddish in

maturation, sharply

curved.

Fragrant white flowers,

curved yellow or pinkish

fruits in clusters.

0.35 0.16

3.

Avicennia alba

Trees are tolerant to high

salinity, pneumatophores

spongy, narrowly

pointed with slender stilt

roots.

Bark dark brown or even

black.

Leaves lanceolate to

elliptical, leaf-tip acute,

lower surface silver grey

to white; curved fruit

with relatively long

beak.

0.23 0.10

4.

Avicennia marina



pencil-like.

Bark yellowish brown.

Leaves elliptical, leaf-tip

rolling, lower surface

white to light grey.

Inflorescence terminal or

axillary, orange yellow

in colour.

0.99 0.46

5.

Avicennia officinalis



pencil-like.

Bark yellowish brown.

Leaves elliptical, leaf-tip

roundish, obtuse apex,

lower surface white to

light grey.

Inflorescence terminal or

axillary, orange yellow

in colour.

3.85 1.73



DOI:10.24214/jecet.A.7.1.01629.

6.

Bruguiera cylindrica

Trees can grow upto 20

m with smooth grey

bark.

The glossy, grey leaves

are opposite, simple and

elliptical with pointed

ends.

Presence of propagule.

0.07 0.03

7.

Bruguiera gymnorrhiza

Trees generally found on

elevated interior parts of

mangrove forest with

prominent buttress roots.

Bark dark grey. Leaves

simple, elliptical-oblong,

leathery and leaf-tip

acuminate.

Flowers axillary, single

with red calyx, red in

colour and almost 16

lobed; fruits are cigar

shaped, stout and dark

green.

0.09 0.04

8.

Bruguiera parviflora

Trees grow upto 30 m

with a trunk diameter

upto 0.45 m.

Presence of pale grey to

pale brown bark.

The fruits measure upto

4 cm in length.

0.04 0.02

9.

Bruguiera sexangula

The trees usually grow

as single stem tree or

multi-stem shrub.

The bark is smooth and

greyish brown in colour.

Presence of smooth,

glossy, green leaves,

which are simple and

opposite - elliptical to

elliptic –oblong.

0.07 0.03



DOI:10.24214/jecet.A.7.1.01629.

10.

Ceriops decandra

Stilt roots arising from

pyramidal stem base.

Light grey barked stem.

Leaves elliptic-oblong,

emarginated at apex,

cuneate at base.

Flowers axillary in

condensed cymes.

0.44 0.21

11.

Ceriops tagal

Trees upto 25 m with a

trunk diameter of upto

0.40 m.

The leaves are opposite

pairs, glossy, yellowish

green above and

obovate.

The flowers are borne

singly in the leaf axils.

0.11 0.05

12.

Excoecaria agallocha

Prominent main root

absent, many laterally

spreading snake-like

roots producing elbow

shaped pegs.

Poisonous milky latex

highly irritating to eyes.

Leaves light green with

wavy margin.

Catkin inflorescence

terminal or axillary,

orange yellow.

1.48 0.65

13.

Heritiera fomes

Trees with numerous

peg-like pneumatophores

and bind root suckers.

Young branches covered

with shining golden-

brown scales. Leaves

elliptic with lower

surface shining with

silvery scales.

Flowers golden yellow

with reddish tinge inside.

2.86 1.29

14.

Heritiera littoralis

Presence of silvery

scales on the underside

of the leaves.

Leaf blade large, silvery

white to dull and very

abruptly narrowed.

Seeds surrounded by

fibrous pericarp.

0.37 0.16



DOI:10.24214/jecet.A.7.1.01629.

15.

Kandelia candel

Trees with prominent

stilt roots.

Leaves narrowly

elliptical, leathery

midrib, lower leaf

surface yellowish green.

Flowers in 2 cymes on

stout peduncle; fruit

viviparous with

cotyledonary collar, red

when mature.

0.10 0.05

16.

Lumnitzera racemosa

Presence of succulent

small leaves with

obovate shape.

Fruit is fleshy and

flattened while on trees

but becomes fibrous after

floating in water.

Absence of well

developed above ground

root system.

0.03 0.01

17.

Phoenix paludosa

Palm tree like

appearance with no

aerial roots, generates

found on hard muddy

soil of mangrove

swamps.

Leaves held in crown

above the trunk, petiole

armed with hard spines.

Flowers dioecious,

yellowish white,

trimerous spadices

arising in between

leaves; Spathes about 30

cm long, enclosing the

flowers; fruit drupe,

oblong, 1 seeded, shining

black when ripe.

0.05 0.02

18.

Rhizophora apiculata

Average height of the

tree around 10 m with

grey bark.

Presence of elliptic-

oblong to sub-lanceolate

leaf blade.

Presence of sessile

flowers.

0.05 0.02



DOI:10.24214/jecet.A.7.1.01629.

Rhizophora mucronata

Trees upto 25 m and

have large number of

aerial stilt roots

buttressing the trunk.

Presence of elliptical

leaves with elongated

tips.

The flowers develop in

axillary clusters on the

twigs. Each flower has a

hard cream colour calyx

with 4 sepals and 4 white

hairy petals.

0.30 0.13

Rhizophora stylosa

Trees are usually around

5 m in height.

The propagules grow

upto 30 cm in length.

Presence of prominent

stilt roots.

0.29 0.13

Sonneratia alba


and sometimes even upto

25 m.

The tree is surrounded

by thick blunt

pneumatophores.

Evergreen tree with a

broad spreading crown.

1.46 0.67

Sonneratia apetala

Trees are with long,

corky, forked

pneumatophores and

stem light brown in

colour.

Leaves thick, coriaceous,

narrowly elliptic oblong

tapering towards apex.

Flowers are cream

coloured in axilliary

cymes with globose

berry seated in flattened

calyx tube.

1.58 0.74



DOI:10.24214/jecet.A.7.1.01629.

Sonneratia caeseolaris

Trees grow up to 20 m in

height with a trunk

diameter of 0.5 m.

Presence of apple-like

fruits.

Presence of slender

pnuematophores.

0.14 0.07

Xylocarpus granatum

Pnuematophores

completely absent. Bark

yellowish white, peeling

off as papery flakes.

Leaflets bijugate or

unijugate, obovate,

rounded apex and

tapering base.

White flowers with

reddish gland within;

large fruit with

pyramidal seeds.

0.80 0.35

Xylocarpus mekongensis

Presence of blind suckers

and plank like roots.

Bark is pale greenish or

yellowish with alternate,

elliptical to obovate,

rounded leaf tip and

tapering at base.

Flowers small, white,

axillary; fruits yellowish

brown, small ball

shaped.

0.13 0.06

Xylocarpus molluccensis


with a trunk diameter

reaching upto 0.7 m

Presence of creamy

white flowers.

Presence of round

shaped fruits measuring

up to 11 cm in diameter.

0.15 0.07



DOI:10.24214/jecet.A.7.1.01629.

Figure 4: Rate of change of stem biomass and stored carbon in true mangrove species of Mahanadi

delta

DISCUSSION

The rapid pace of climate change is an issue of concern in the present century, which is keenly related

to the rise of carbon dioxide. In the past 60 years the amount of carbon dioxide emitted to the

atmosphere is primarily due to the increased use of fossil fuels. This has resulted in the rise of carbon

dioxide level from pre-industrial level of 280 ppm to present level of 407.25 ppm as on July 20176.

To keep this trend stable by retarding the accelerating pace of carbon dioxide level, it is essential to

lock this gas within the vegetative sink. This process has multiple benefits like generation of wood

(for timber, fuel etc.), oxygen (which is the life jacket of human civilization), food products (like

fruits, cereals etc.). The litter/detritus produced by mangroves serves as the base of fishery by

triggering the growth of phytoplankton. This paper highlights the ecosystem benefit of Mahanadi

delta mangroves (26 true mangroves as documented in this study) in context to carbon sequestration

by the stem biomass of the species. The branch, twigs and leaf carbon has not been considered due to

conservative approach of this study, which otherwise need to be cut down for carbon estimation in

these vegetative parts. It is interesting to note that in the present study site the rate of change of true

mangrove biomass is 16.20 tha-1y-1, which represent a carbon sequestration value of 7.34 tha-1y-1. This

value is definitely an under- estimation in the domain of carbon sequestration as a major portion of the

stored carbon is locked in the branches, twigs and leaves of the mangrove trees. However, the

sequestrated carbon in the stems of selected mangrove trees represents a CO2-equivalent value of



DOI:10.24214/jecet.A.7.1.01629.

26.94 tha-1y-1, which means that 1 ha of the mangrove patch in Mahanadi delta region has the potential

of absorbing 26.94 tonnes of CO2 from ambient atmosphere in 1 year. Conversely, it can be concluded

that clearance of 1 ha mangrove patch in the present geographical locale may lead to an emission of

26.94 tonnes of CO2 in the ambient air. This may lead to rise of temperature at local level as pointed

out by several researchers7,8,9,10,11,12,13,14. Thus to keep an overall stability of the ecosystem,

conservation of mangrove should be given highest priority in the Integrate Coastal Zone Management

Plan (ICZMP) for the maritime state of Odisha. Threats like over exploitation of mangrove resources,

habitat destruction for tourism, shrimp culture and effluent discharge from port- cum-industrial

complex of Paradeep should be minimized so as to achieve the goal of sustainable management action

plan placing the role of mangroves as the key regulator of GHG emission in the epicentre.

ACKNOWLEDGEMENT

The authors acknowledge the financial support provided by the Ministry of Earth Sciences, Govt. of

India. The infrastructural facilities provided by the Forest Department, Govt. of Odisha are gratefully

acknowledged.

REFERENCES

1. FSI, India State of Forest Report. Forest Survey of India, Dehradun, 2013.

2. https://www.mapsofindia.com/top-ten/geography/mangrove-forest.html.

3. A. Mitra, In: Sensitivity of Mangrove Ecosystem to Changing Climate by Dr. Abhijit

Mitra. Publisher Springer New Delhi Heidelberg New York Dordrecht London,

2013 edition (August 31, 2013); ISBN-10: 8132215087; ISBN-13: 978-

8132215080., copyright Springer, India 2013; ISBN 978-81-322-1509-7 (eBook),

2013.

4. R.C. Samal, & J.M. Patnaik, Management strategies for Bhitarkanika mangrove

forest. In: INDO-US workshop on Wetlands, Mangroves and Bio-spere Reserves.

Govt.of India, Ministry of Env. & Forests, New Delhi, 1989, pp. 96-99.

5. A. Mitra A. & J. Sundaresan, How to study stored carbon in mangroves, published

by CSIR-National Institute of Science Communication and Information Resources

(NISCAIR), ISBN: 978-81-7236-349-9, 2016.

6. https://www.co2.earth/annual-co2

7. A. Mitra, The Northeast coast of the Bay of Bengal and deltaic Sundarbans. In Seas

at the Millennium – An environmental evaluation, Sheppard C. (Ed.) Chapter 62,

Elsevier Science, UK, 2000, pp. 143-157.

8. K. Banerjee, K. Sengupta, A. Raha & A. Mitra. Salinity based allometric equations

for biomass estimation of Sundarban mangroves. Biomass Bioenergy, 2013, 56, 382-

391.

9. A. Mitra & S. Zaman, Carbon Sequestration by Coastal Floral Community,

published by The Energy and Resources Institute (TERI) TERI Press, India, 2014.



DOI:10.24214/jecet.A.7.1.01629.

* Corresponding Author: Sangita Agarwal

1Department of Applied Science, RCC Institute of Information Technology,

Beliaghata, Kolkata 700015, India

Date of publication on line 12.12.2017

10. A. Mitra A. & S. Zaman, Blue carbon reservoir of the blue planet, published by

Springer, ISBN 978-81-322-2106-7 (Springer DOI 10.1007/978-81-322-2107-4),

2015.

11. A. Mitra & S. Zaman, Basics of Marine and Estuarine Ecology, Springer, ISBN 978-

81-322-2705-2, 2016.

12. S. Agarwal, S. Zaman, S. Biswas, N. Pal, P. Pramanick & A. Mitra, Spatial variation

of mangrove seedling carbon with respect to salinity: A case study with Bruguiera

gymnorrhiza seedling. International Journal of Advanced Research in Biological

Sciences, 2016, 3(8): 7-12.

13. N. Pal, A. Gahul, S. Zaman, P. Biswas & A. Mitra, Spatial Variation of Stored

Carbon in Avicennia alba Seedlings of Indian Sundarbans. Int. J. Trend Res. Dev.,

2016, 3(4) 100-103.

14. S. Zaman, S. Biswas, N. Pal, U. Datta, P. Biswas & A. Mitra, Ecosystem Service of

Heritiera fomes Seedlings in terms of Carbon Storage. International Journal of

Trend in Research and Development, 2016, 3(4): 183-185.

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