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CARBON POOLS AND MULTIPLE BENEFITS OF MANGROVES
ASSESSMENT FOR REDD+ IN CENTRAL AFRICA
27
Analysis of Drivers
The deforestation rates described above reveal
that 771 km
2
of mangroves were cut down in
the Central African region between 2000 and
2010, although the net loss was of 68 km
2
due
to regrowth. While causes of mangrove loss may
vary from one country to another, the major
direct or proximate drivers are over-exploitation
of mangrove wood and non-wood products,
conversion of mangrove areas for urban
development and infrastructure, degradation
due to pollution from pesticides and fertilizers
(eutrophication) and from hydrocarbon and gas
exploitation, as well as clearance of mangroves
for palm plantations particularly in Cameroon
(Table 4) (UNEP-WCMC, 2007; Ajonina et al.,
2008; Ajonina, 2008; Ajonina and Usongo, 2001).
The most important cause of mangrove loss
in most countries is urbanization and coastal
infrastructure development, except in DRC,
where pollution is seen as the major threat.
Over-exploitation of mangrove products is
also a major cause of loss in most countries.
Of the threats and pressures described here,
the most amenable to management and
reduction through REDD+ activities are
agriculture and over-exploitation of wood and
non-wood forest products. National REDD+
strategies could explore actions to reduce these
threats to mangroves in an economically and
environmentally sustainable manner, under
the aims of conservation and sustainable
management of forests under REDD+.
These could include introducing alternative
technology to reduce the use of mangrove
wood for energy use, introducing regulations
surrounding sustainable forestry and increasing
capacity to enforce protected areas. Cross-
sectoral approaches are necessary to promote
the Green Economy concept in the region.
Table 4: An overview of severity of major threats of mangroves in Central Africa (UNEP-WCMC, 2007)
The underlying or indirect drivers of the loss
andmodification of mangroves in Central Africa
are associated with population pressure, poor
governance, economic pressure in rural and
urban and poverty status of local communities.
In addition, climate change related factors
such as increased sedimentation have affected
the fringing mangroves in Cameroon, Gabon,
DRC and Congo. These factors have collectively
led to loss of mangrove cover, shortage of
harvestable mangrove products, reduction
in fisheries, shoreline change and loss of
livelihood (UNEP-WCMC, 2007).
Floristic composition and
Distribution
Structural attributes (species composition, tree
height, basal area, stand density etc.) of the
mangroves of Central Africa are provided in
Tables 5 and 6. The dominant and prominent
species is
Rhizophora racemosa
that occurs in
expansive pure stands across the countries.
Only two species were found in Congo and
DRC. These results are in conformity with
earlier surveys (e.g. UNEP-WCMC, 2007;
Ajonina, 2008; Ajonina et al., 2009); and
confirm Central African mangroves as being
generally species poor as compared to the
Indo-west Pacific mangroves that may have
up to 52 species (Tomlison, 1986; Spalding et
al., 2010). Common mangrove associates that
were encountered include
Hibiscus sp., Phoenix
sp
, and
Acrostichum aureum
.
There is no obvious zonation that is displayed
by the dominant mangrove species in Central
Africa. However, one will find the seaward
side as well as creeks mostly occupied by
R.
racemosa
, whereas
R. mangle, A. germinans
, and
Acrostichum aureum
mosaic covers the middle
and outer zones. In a few places in Cameroon,
we found the invasive Nypa palms growing in
association with
R. mangle and R. racemosa
on
creek margins.
!
Threats
Countries
Cameroo
n
Gabon RoC
DRC
Urbanization and coastal infrastructure
development
xxx
xxx
xxx
x
Agriculture (e.g. palm plantations)
xx
x
-
-
Over-exploitation of wood and non-wood forest
products
xxx
xx
x
x
Pollution (including eutrophication, oil &gas
pollution)
xx
x
xxx
xx
Invasive species (e.g. Nypa fruticans)
x
-
-
-
(x = low, xx = medium, xxx = high)