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Table 5: Mangroves and associated species
encountered in the study areas
Mangrove species
Country
Ca
m
Gab
on
RoC DRC
Avicennia germinans
x x x x
Conocarpus erectus
x x
Laguncularia racemosa
x x
Rhizophora harrisonii
x
Rhizophora mangle
x
Rhizophora racemosa
x x x x
Hibiscus sp
x x
Phoenix sp.
x
Total
5 8 2 2
Stand density, volume and biomass
The average stand density ranged from 450
trees/ha in heavily exploited forest in the
RoC, to 3255.6 trees/ha in undisturbed stands
in Cameroon. In most undisturbed plots,
the stem density decreased exponentially
with increasing diameter. These are typical
reversed ‘J’ curves for stands with a wide
range of size classes and by inference also age
classes. This pattern was, however, distorted
in heavily exploited mangroves stands in the
region where size classes above 30cm were
literally missing, see (Figure 3).
0-10 cm
10-30 cm
30-50 cm
50-100 cm
100+ cm
0-10 cm
10-30 cm
30-50 cm
50-100 cm
100+ cm
0-10 cm
10-30 cm
30-50 cm
50-100 cm
100+ cm
0-10 cm
10-30 cm
30-50 cm
50-100 cm
100+ cm
0
500
1000
1500
2000
2500
3000
Density (Nr/ha)
Cameroon - Pristine
0
500
1000
1500
2000
2500
3000
Density (Nr/ha)
Gabon - Pristine
0
500
1000
1500
2000
2500
3000
Density (Nr/ha)
Congo - Pristine
0
500
1000
1500
2000
2500
3000
Density (Nr/ha)
DRC- Pristine
0
500
1000
1500
2000
2500
3000
Density (Nr/ha)
Cameroon - Degraded
0
500
1000
1500
2000
2500
3000
Density (Nr/ha)
Gabon - Degraded
0
500
1000
1500
2000
2500
3000
Density (Nr/ha)
Congo - Degraded
0
500
1000
1500
2000
2500
3000
Density (Nr/ha)
DRC- Degraded
Diameter class
Diameter class
Diameter class
Diamater class
Figure 3: Stem size class distributions in Central African mangrove forest
Standing volume in undisturbed forests ranged
from 213.0 m
3
/ha in the RoC to 427.5 m
3
/ha in
Cameroon; corresponding to above ground
biomass values of 251.3 and 504.5 Tonnes/ha
respectively. Together with the deadwoods, the
total vegetation biomass in undisturbed sites
ranged from 435.14 Tonnes/ha in the RoC to
884.6 Tonnes/ha in Cameroon (Table 6).
Carbon stocks
The following discussion presents the results
of biomass and soil measurements for carbon
content in the mangroves. However, we present
the data with the important caveat that this is
a first order exploration of carbon values in the
region. A relatively low number of samples were
taken, and the result is that there is a relatively
large amount of variability in the data. Therefore,
we present here just an approximation for
carbon content in biomass and soils for the
mangroves with error bars, and we hope that
these data can be refined with more intense
research efforts in future.
Soil Organic Carbon
There was high variability in the amount of soil
organic carbon (p < 0.05) with undisturbed sites
showing higher carbon concentrations than
exploited forests. Across the region, the average
quantity of soil organic carbon amounted to
827.2 ± 169.9 Tonnes C/ha. The undisturbed
stands recorded the highest amount of average