Environmental Engineering Reference
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densities. The BC/EF used in the study was 1.18 (Ajonina
2008
) which is comparable to that reported for humid
tropical forests by Brown (
1997
).
Belowground
root
biomass
per
tree
was
determined
using the equation (Ajonina
2008
):
Root biomass per tree ¼ 1
:
385
Stem Diam
0
:
4331
Stem volume
:
ð
4
Þ
The algometric equation derived for estimating biomass
samples after drying (temperature constant at 105 C) of 52
mangrove fern (Acrosticum aurerum)is
y
¼
b
þ
a
H
D
2
ð
5
Þ
where D and H are the diameter and height of mangrove
fern.
Biomass and carbon in grasses was estimated from a
composite sample of grass collected in 15 quadrants of
1m
2
systematically placed along the first subplot
(10 9 10 m) in each plot (20 9 10 m), and their weight
was measured in the field with a balance. Dry weight and
the carbon concentration were determined by the Labora-
tory of Soil Science, Water and Environment of the Centre
for Agricultural Research Agonkammey-Benin.
Fig. 4
Diameter
measurement
and
tagging
trees
(Photo
Gordon
Ajonina 2012)
Deadwood
Deadwood volume was estimated using the protocol of
Kauffman and Donato (
2012
):
¼ P
2
P
i¼1
d
i
8L
m
3
=
ha
Volume
ð
6
Þ
where d
i
= d
1
, d
2
… d
n
are diameters of intersecting pieces
of deadwood (cm) and L = the length of the intersecting
line (transect axis of the plot) generally L = 20 m being the
length of each plot or 100 m being the length of transects.
Deadwood volumes were converted to carbon density esti-
mates by using the different size-specific gravities provided
by Kauffman and Donato (
2012
).
Fig. 5
Collecting soil samples (Photo Gordon Ajonina 2012)
biophysical data were entered into prepared data sheets.
Standing volume was determined using locally derived al-
gometric relations from sample data with dbh as the inde-
pendent variable following Eq. (
3
):
Total Ecosystem Carbon Stock and CO
2
e
Emission Factor in Degraded Mangrove Forests
V ¼ a
D
b
ð
3
Þ
where
The total ecosystem carbon stock to soil depth of one meter
was obtained by adding the aboveground and belowground
carbon densities. The carbon dioxide equivalent was cal-
culated by multiplying the total ecosystem carbon stock by
the carbon dioxide emission factor 3.67. Carbon dioxide
emission factors for top 30 cm soil in the different man-
grove degradation regimes were expressed as excess over
the non-wooded mangrove site.
Volume (m
3
/ha)
V
D
diameter: 1 cm B D \ 30 cm
a and b
are coefficients.
Biomass conversion/expansion factor (BC/EF), which is
the ratio of total aboveground biomass to stand volume, and
shoot/root ratio (SRR) developed by Ajonina (
2008
), were
used for the estimation of total tree biomass and carbon
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