Environmental Engineering Reference
In-Depth Information
Table 3 Carbon budget in the different degraded mangrove sites in southern Benin
Component
Carbon density (t/ha)
Site 1: Kpétou
Site 2: Djègbadji
Site 3: Adounko
Site 4: Adounko
Non-wooded
mangroves
Degraded
mangroves
Degraded
mangroves
Non-degraded
mangroves
Mean
±SE
Mean
±SE
Mean
±SE
Mean
±SE
Basal area (m 2 /ha)
0.00
0.00
1.16
0.01
4.12
0.17
10.14
0.03
Aboveground
Live
Trees and stems (woody vegetation)
3.03
1.79
0.15
0.05
0.68
0.11
Roots
0.22
0.12
1.52
0.56
0.10
0.04
Seedlings with herbs
3.52
1.77
0.01
0.01
22.70
11.66
Herbs
1.48
0.09
Subtotal (live)
1.48
0.09
6.77
1.25
1.67
0.18
23.48
1.97
% total
0.82
2.28
0.70
10.72
Dead
Deadwood
0.74
0.19
1.18
0.13
3.56
0.35
Dead roots
0.00
0.00
2.87
1.32
0.02
0.02
Dead seedlings with herbs
1.12
1.12
0.57
0.53
8.01
2.38
Subtotal (dead)
1.86
0.28
4.62
0.38
11.59
0.89
% total
0.00
0.62
1.94
5.29
Subtotal (aboveground)
1.48
0.09
8.63
0.78
6.29
0.21
35.07
1.25
% total
0.82
2.90
2.94
16.01
Belowground
Tree roots
0.32
0.12
0.08
0.02
0.33
0.05
Sediments
0-15 cm depth
60.31
3.01
59.72
1.42
52.87
0.85
59.85
25.96
15-30 cm depth
63.22
12.12
53.54
15.66
38.62
1.93
41.56
7.29
30-50 cm depth
12.85
2.97
48.28
3.20
20.61
0.36
24.52
1.82
50 cm-100 m depth
43.01
2.40
126.92
23.31
119.46
56.97
57.75
1.63
Subtotal (sediments)
179.39
6.65
288.45
11.35
231.57
16.57
183.68
7.19
Subtotal (belowground)
179.39
6.65
288.77
10.49
231.64
12.73
184.01
5.93
% total
99.18
97.10
97.36
83.99
Total (ecosystem)
180.87
5.12
297.40
5.00
237.94
5.51
219.08
2.67
Total CO 2 e of the ecosystem
663.18
18.79
1,090.47
18.35
872.43
20.22
803.29
9.80
CO 2 e up to 30 cm depth
458.79
55.86
448.51
65.99
359.15
11.05
502.09
126.80
CO 2 e emission factor up to 30 cm depth
0.00
0.00
-10.28
10.13
-99.64
-44.81
43.31
70.94
CO 2 e emission factor up to 30 cm depth (%)
0.00
-2.24
-21.72
9.44
belowground carbon stock component ranged from 179.39
to 288.77 t/ha (Fig. 7 ), being highest in degraded mangrove
sites due to organic matter accumulation and leaching. This
difference in the distribution of carbon stock at below-
ground and aboveground from degraded to non-degraded
mangrove ecosystems in southern Benin reveals the
important role of vegetation in the carbon budget estima-
tion. The trend in the carbon balance within the surveyed
mangrove sites is also typical of a mangrove ecosystem that
stores most of its carbon as belowground (Kauffman and
Donato 2012 ). These figures are close to those reported by
Kauffman and Donato ( 2012 ) who obtained total stock of
carbon of 278.0 t/ha for the large mangrove delta of the
river Ganges in Bangladesh Sunderbans with an above-
ground component of 83.7 t/ha (30.1 %) and underground
component of 194.9 t/ha (69.9 %). However, the values are
much lower than those obtained for the mangroves of
Central
Africa
(Cameroon,
Congo,
Gabon,
and
DRC):
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