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Research Article Open Access
Oxygen Generation by Dominant Urban Trees: A Case Study
from Konnagar Municipality, West Bengal, India
Abhijit Mitra*
1
, Tanmay Ray Chaudhuri
2
, Nabonita Pal
2
, Sufia Zaman
2
and Ankita Mitra
3
1
Department of Marine Science, University of Calcutta, India
2
Department of Oceanography, Techno India University, India
3
Center for Oceans, Rivers, Atmosphere and Land Sciences (CORAL), Indian Institute of Technology, India
Received:
May 20, 2017; Published: May 31, 2017
*Corresponding author:
Abhijit Mitra, Department of marine science, University of Calcutta, 35 B.C. Road, Kolkata 700091, India
Introduction
Net oxygen production by trees is a function of the amount
of oxygen produced during photosynthesis minus the amount
of oxygen utilized during respiration [1]. If the carbon dioxide
uptake during photosynthesis exceeds carbon dioxide release by
respiration during the year, the tree will accumulate carbon (carbon
sequestration). Thus, a tree that has a net accumulation of carbon
during a year (tree growth) also has a net production of oxygen.
This net production of oxygen is estimated as per the following
expression
Net O
2
release (Kg/yr) = Net C sequestration (Kg/yr) ×32/12
The entire methodology of estimating oxygen production
conducted during 2016 involved four phases.
Methodology
Phase 1: Site selection
Konnagar is located on the west bank of the River Hooghly
between 22.7°N and 88.35°E and has an average elevation of ~
13.56metres. It is positioned between Rishra and Hindmotor
on the Howrah-Bardhaman Main Line and Grand Trunk Road.
Approximate area of Konnagar is 4.32km
2
. A wide spectrum
of tree species is a noted feature in the landscape of Konnagar.
The dominant tree species includes Mangifera indica (Mango),
Azadirachta indica
(Neem), Aegle marmelos (Bel), Terminalia arjuna
(Arjun), Eucalyptus globus (Eucalyptus), Psidium guajava (Guava),
Acacia auriculacformis
(Akashmoni), Peltophorum pterocarpum
(Radhachura), Delonix regia (Krishnachura) etc.
Phase 2: Biomass estimation of dominant trees
The entire network of the present study initiated with the
selection of six sampling zones in the Konnagar Municipality area.
In each zone 10m×10m quadrat was selected (at random) for
the study and the average readings were documented from each
such quadrate by involving the school students and teachers after
imparting a training to the team members on biomass estimation of
trees. A form was supplied to all the participating schools where the
students measured and estimated the Diameter at Breast Height
(DBH) and Relative Abundance (RA) of the tree species under the
supervision of their teachers. The mean relative abundance of each
tree species was evaluated for assessing the order of dominance of
tree species in the study area. Only those species occupying equal
to and above 70% in the study area were considered for carbon
estimation. This exercise (by involving the teachers, students and
staffs of Konnagar Municipality) was carried out to aware the
people of all ranks of the society regarding the values of trees in
upgrading the environmental health.
The Above Ground Biomass (comprising of stem, branch and
leaf) of individual trees of dominant species in each quadrate
was estimated as per the standard procedure stated here and the
average biomass values (of all quadrates of each zone) were finally
expressed as tonnes per hectare. The methodologies adopted for
assessing the above ground biomass (sum total of leaf, stem and
root) in the present study are explained in details through three
sections.
Cite this article:
Abhijit M, Tanmay R C, Nabonita P, Sufia Z, Ankita M. Oxygen Generation by Dominant Urban Trees: A Case Study
from Konnagar Municipality, West Bengal, India. Biomed J Sci & Tech Res. 1(1)-2017.
Abstract
Urban vegetation, particularly trees provides a wide spectrum of ecosystem services which include upgradation of air quality, stabilizing
temperature, reduction in ultraviolet radiation, oxygen generation, carbon sequestration, habitat of several flora and fauna (enhancement of
biodiversity) aesthetic beauty etc. Oxygen production is one of the most commonly cited benefits of urban trees. The purpose of this article is
to estimate the oxygen production by the dominant trees in the urban area of Konnagar, compare it with the estimated oxygen consumption by
the population of the area and illustrate why oxygen production by urban trees is an important ecosystem service.
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Section 1: Stem biomass estimation
The stem biomass for each tree species in every plot was
estimated using non-destructive method in which the Diameter
at the Breast Height (DBH) was measured after assessing the
circumference with a measuring tape and height with laser beam
(BOSCH DLE 70 Professional model). Form factor was determined
with Spiegel relascope as per the method outlined by Koul and
Panwar[2]. The stem volume (V) was then calculated using the
expression FHΠr
2
, where F is the form factor, r is the radius of the
tree derived from its DBH and H is the height of the target tree.
Specific gravity (G) of the wood was estimated taking the stem
cores, which was further converted into stem biomass (B
S
) as per
the expression B
S
= GV.
Section 2: Branch biomass estimation
The total number of branches irrespective of size was counted
on each of the sample trees. These branches were categorized on
the basis of basal diameter into three groups, viz. <6cm, 6–10cm
and >10cm. Dry weight of two branches from each size group was
recorded separately using the equation of Chidumaya [3].
Total branch biomass (dry weight) per sample tree was
determined as per the expression:
B
db
= n
1
bw
1
+ n
2
bw
2
+ n
3
bw
3
= Σ n
i
bw
i
Where, Bdb is the dry branch biomass per tree, n
i
the number of
branches in the i
th
branch group, b
wi
the average weight of branches
in the i
th
group and i = 1, 2, 3, …..n are the branch groups. This
procedure was followed for all the dominant tree species separately
for every quadrate.
Section 3: Leaf biomass estimation
Leaves from nine branches (three of each size group as stated in
section 2) of individual trees of each species were removed. One tree
of each species per quadrate was considered for estimation. The
leaves were weighed and oven dried separately (species wise) to a
constant weight at 80 ± 50C. The leaf biomass was then estimated
by multiplying the average biomass of the leaves per branch with
the number of branches in a single tree and the average number of
trees per plot as per the expression:
L
db
= n
1
Lw
1
N
1
+ n
2
Lw2N
2
+ ……….n
i
Lw
i
N
i
Where, L
db
is the dry leaf biomass of the tree species per
quadrate, n
1
..….n
i
are the number of branches of each tree species,
Lw
1
…….Lw
i
are the average dry weight of leaves removed from the
branches and N
1
………N
i
are the number of trees per species in the
quadrate.
Phase 3: Estimation carbon and carbon sequestration
Direct estimation of percent carbon was done by a CHN
analyzer. For this, a portion of fresh sample of stem, branch and leaf
from selected trees (two trees/species/plot) of individual species
(covering all the selected plots) was oven dried at 700C, separately
ground to pass through a 0.5mm screen (1.0mm screen for leaves).
The carbon content (in %) was finally analyzed for each part of
each species through a Vario MACRO elementar CHN analyzer. The
total stored carbon in the above ground biomass was estimated
by considering the mean relative abundance of each species in the
selected quadrats and finally the stored carbon in the above ground
biomass was estimated for each species by dividing the values with
the respective age of the species. The information on the age of the
tree was collected from the local inhabitants.
Result
The AGB of the study site was in the order Eucalyptus globus
(5853.95) > Tamarindus indica (4195.60) > Aegle marmelos
(3202.00) > Arecea catechu (3111.52) > Delonix regia (2854.98)
> Magnifera indica (2474.53) > Ficus religiosa (2143.11) > Acacia
auriculacformis
(1961.45) > Ficus bengalensis (1095.66) > Psidium
guajava
(924.92) > Cocos nucifera (914.90) Bombax ceiba (830.03)
> Peltophorum pterocarpum (604.14) > Tectona grandis (542.72) >
Dalberegia sissoo
(486.62) > Terminalia arjuna (481.24) > Swietenia
mahagoni
(455.35) > Albizia saman (448.24) > Polyalthia longifolia
(341.39) > Azadirachta indica (307.89) > Ziziphus mauritiana
(301.74) > Terminalia catappa (233.12) > Artocarpus heterophyllus
(228.67) > Alstonia scholaris (116.54) > Murraya koenigii (34.10) >
Syzygium samarangense
(30.10) > Santalum album (5.96) (Table 1).
Similarly the AGC followed the sequence of Eucalyptus globus
(2716.23) > Tamarindus indica (1929.98) > Aegle marmelos
(1501.74) > Arecea catechu (1481.08) > Delonix regia (1350.41)
> Magnifera indica (1328.82) > Ficus religiosa (1073.70) >
Acacia auriculacformis
(927.77) > Ficus bengalensis (540.16) >
Psidium guajava
(454.14) > Cocos nucifera (432.74) > Bombax
ceiba
(392.60) > Peltophorum pterocarpum (275.69) > Tectona
grandis
(249.11) > Terminalia arjuna (223.30) > Dalberegia sissoo
(222.87) > Albizia saman (220.09) > Swietenia mahagoni (219.02)
> Polyalthia longifolia (156.70) > Ziziphus mauritiana (145.44)
> Azadirachta indica (141.01) > Terminalia catappa (114.23) >
Artocarpus heterophyllus
(111.82) > Alstonia scholaris (55.71)
> Murraya koenigii (15.96) > Syzygium samarangense (14.21) >
Santalum album
(3.27) (Table 1).
The net oxygen release varied as per the order Tamarindus
indica
(429.42) > Arecea catechu (395.45) > Eucalyptus globus
(381.70) > Aegle marmelos (364.51) > Acacia auriculacformis
(225.19) > Delonix regia (200.30) > Magnifera indica (186.74) >
Psidium guajava
(134.73) > Cocos nucifera (105.04) > Ficus religiosa
(95.56) > Swietenia mahagoni (83.54) > Bombax ceiba (58.23) >
Borassus flabellifer
(56.34) > Albizia saman (41.97) > Peltophorum
pterocarpum
(40.85) > Terminalia arjuna (39.70) > Tectona grandis
(39.12) > Terminalia catappa (38.15) > Dalberegia sissoo (33.05) >
Polyalthia longifolia
(32.17) > Ziziphus mauritiana (29.88) > Ficus
bengalensis
(22.19) > Azadirachta indica (19.81) > Artocarpus
heterophyllus
(13.16) > Alstonia scholaris (12.39) > Murraya
koenigii
(6.09) > Syzygium samarangense (4.22) > Santalum album
(0.72) (Table 1).
Discussion
The production of oxygen by the trees is undoubtedly an
important ecosystem service as this gas regulates the metabolic
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activities of living organisms. An average adult human being
consumes 0.84 kg of oxygen per day, which is equivalent to 1.85 lb per
day [4]. Considering this value, the average oxygen consumption in
Konnagar Municipality is 306.6Kg/year/head. As per 2011 census,
Konnagar had a population of approximately 80,000 and therefore
there is a necessity of 24,528 tonnes of oxygen per year to sustain
this population. The present study shows that the yearly generation
of oxygen by the 28 dominant species in Konnagar Municipality is
2959.68, which indicates that there is an approximate deficit of
oxygen in the Municipality area by 8 times to balance the need
of oxygen by the population of Konnagar Municipality. In other
words 8 times more plantations are required to meet the oxygen
requirement of the people of the area. This calculation, however,
has uncertainty as the seedlings and grassy vegetations have not
been considered in the present estimation. The water bodies of
Konnagar Municipality have also been overlooked in this estimation
process, although phytoplankton are the major sources of oxygen in
the ambient environment. Our first order analysis, however, reports
that trees like Tamarindus indica, Arecea catechu, Eucalyptus globus,
Aegle marmelos
need to be planted to restore the oxygen depletion
in the present municipality area. A more detailed study considering
the seedlings, herbs and shrubs along with oxygen generated by
phytoplankton is needed to achieve a comprehensive picture of
floral based oxygen budget in the present geographical locale.
Table 1:
List of dominant tree species in Konnnagar Municipality with their respective AGB, AGC, C-sequestration and O
2
release values.
Sl. No.
Species
AGB (tonnes ha
-1
)
AGC (tonnes ha
-1
)
C sequestration
(tonnes ha
-1
y
-1
)
O
2
release (tonnes
ha
-1
y
-1
)
1
Cocos nucifera
(Coconut)
914.90
432.74
(47.3%)
39.34 (11)
105.04
2
Murraya koenigii
(Curry tree)
34.10
15.96
(46.8%)
2.28 (7)
6.09
3
Albizia saman
(Shirish)
448.24
220.09
(49.1%)
15.72 (14)
41.97
4
Azadirachta indica
(Neem)
307.89
141.01
(45.8%)
7.42 (19)
19.81
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25
Borassus flabellifer
(Sugar palm)
348.77
168.80
(48.4%)
21.10 (8)
56.34
26
Areca catechu
(Betel palm or Supari)
3111.52
1481.08
(47.6%)
148.11 (10)
395.45
27
Ficus religiosa
(Peepul)
2143.11
1073.70
(50.1%)
35.79 (30)
95.56 95.56
28
Ficus benghalensis
(Banyan)
1095.66
540.16
(49.3%)
8.31 (65)
22.19
References
1.
Salisbury FB, CW Ross (1978) Plant Physiology. Wadsworth Publishing
Company, Belmont, CA, USA, pp. 422.
2.
Koul DN, Panwar P (2008) Prioritizing Land-management options for
carbon sequestration potential. Curr Sci 95: 5-10.
3.
Chidumaya EN (1990). Above ground
woody biomass structure and
productivity in a Zambezian woodland. For Ecol & Manage 36: 33-46.
4.
Perry JL, MD LeVan (2003) Air Purification in Closed Environments.
Overview of Spacecraft Systems. U.S. Army Natrick Soldier Center, USA.