Assessment of Mangrove Carbon Stocks in Cameroon, Gabon, the Republic of Congo (RoC) and the Democratic Republic of Congo (DRC) Including their Potential for Reducing Emissions from Deforestation and Forest Degradation (REDD+) - The Land/Ocean Interactions in the Coastal Zone of West and Central Africa - page 175

Socioeconomic Importance
Fishing is a major economic activity along the West-Central
African coastline especially in Central Africa with a pop-
ulation of about 4 million living in or around mangrove
ecosystems (UNEP-WCMC 2007 ). About 60 % of fish
harvested in these rural areas is of artisanal origin. Open
drying, salting, icing, refrigerating and smoking are the
common methods used to preserve fish in the region (Feka
and Ajonina 2011 citing others). Mangrove wood is widely
preferred for fish smoking within coastal areas of this region
because of its availability, high calorific value, ability to
burn under wet conditions and the quality it imparts to the
smoked fish (Oladosu et al. 1996 ). Fish-smoking and fish-
processing activities are largely responsible for more than
40 % degradation and loss of mangroves in the West-
Central African coastal region (UNEP-WCMC 2007 ).

Table 2 Mangrove woody species found in the pilot areas
Mangrove species

Country
Cameroon Gabon RoC DRC

Avicennia germinans x x x x

Conocarpus erectus x x

Laguncularia racemosa x x

Rhizophora harissonii x

Rhizophora mangle x

Rhizophora racemosa x x x x

Associated species
Hibiscus sp

x x

Phoenix sp x

Total 5 8 2 2

Quantification of Carbon Pools
Carbon density was estimated with data from existing and
newly established rectangular 0.1 ha (100 m 9 10 m) per-
manent sample plots (PSP). Existing PSPs in Cameroon
provided an excellent opportunity to model stand dynamics
and carbon sequestration potential of the mangroves in the
region. Based on mangrove area coverage in each country 5
PSPs in Cameroon, 4 in Gabon, 3 in RoC and 3 in DRC were
selected for the study (Table 1 ). Measurement protocol
consisted of species identification, mapping, tagging and
measurements of all trees inside the plot using modified
forestry techniques for mangroves (Pool et al. 1977 ; Cintron
and Novelli 1984 ; Kauffman and Donato 2012 ). Transect and
plots boundaries were carefully marked and GPS points
taken. Detailed procedures for establishment of PSP are
given in Ajonina ( 2008 ). Four carbon pools were considered
in the present study, including: vegetation carbon pools (both
above and belowground), litter, coarse deadwood and soil.

Composition and Distribution of Mangroves
in Central Africa

Mangrove formation in Western and Central Africa is
characterized by low species composition common with
new world mangroves (Tomlinson 1994). In Central Africa,
there are 8 mangrove species of economic importance
(UNEP-WCMC 2007 ). The largest blocks of mangroves in
the region are found in deltas and large rivers estuaries in
Cameroon and Gabon (UNEP-WCMC 2007 ). The dominant
species is Rhizophoraceae racemosa which accounts for
more than 70 % of the forest formation. The species fringes
most shorelines and river banks, attaining up to 50 m in
height with tree diameter of over 100 cm around the Sanaga
and Wouri estuaries marking one of the tallest mangroves in
the world (Blasco et al. 1996 , p. 168). Other important
mangrove species in the region are Rhizophora mangle,
Rhizophora harissonii, Avicennia germinans (Avicennia-
ceae), Laguncularia racemosa and Conocarpus erectus
(both Combretaceae) (Table 2 ). Undergrowth in upper
zones can include the pantropical Acrostichum aureum
(Pteridaceae) where the canopy is disturbed. Nypa fruticans
(Arecaceae) is an invasive mangrove palm introduced in
Nigeria from Asia in 1910 and has spread to Cameroon.
Common mangrove associates in Central Africa include
Annonaceae, Cocos nucufera (Areaceae), Guiboruti de-
mensei (Caesalpiniaceae), Achornea cordifolia (Euphor-
biaceous), Dalbergia ecastaphylum and Drepenocarpus
lunatus (both Fabaceae), Pandanus candelabrum (Pandan-
aceae), Hibiscus tilaeceus (Malvaceae), Bambus avulgaus
(Poaceae)

Measurement of Vegetation Carbon
An important carbon stock in forestry is the aboveground
component. Trees dominate the aboveground carbon pools
and serves as indicator of ecological conditions of most
forests. In each PSP, three plots of 20 m 9 10 m were
established along transect at 10-m intervals (Fig. 3 a). Inside
the plots, all trees with diameter of the stem at breast height
(dbh 130 ) C1.0 cm were identified and marked. Data on
species, dbh, live/dead and height were recorded for all
individuals. In Rhizophora, dbh was taken 30 cm above
highest stilt root. Aboveground roots and saplings
(dbh B 1 cm) were sampled inside five 1-m 2 plots placed
systematically at 1 m intervals along the 10 m 9 10 m plot
(Fig. 3 b). Newly recruited saplings were enumerated, while
missing tags were replaced by reference to initial plot maps.

and Paspalum vaginatum (Poaceae), among

others (Ajonina 2008 ).