Drivers causing decline of mangrove in West-Central Africa: a review

Figures & data

Figure 1. Distribution of mangroves and other coastal habitats in West-Central Africa.

Figure 2. Status of mangrove forests in West-Central Africa; including mean area change per country (1980–2006). Negative values indicate a gain in mangrove area.

Table 1. Extent, distribution, and status of mangroves in West and Central Africa (1980–2006)

						Mangrove area (km^2)
Region	Country	Land area (× 1000 km^2)	Coastline length (× 1000 km)	Population (million)	Number of mangrove plant species	1980	1990	1997	2000	2005	2006	Current
Western Africa	Mauritania	1,025.2	1.27	3.07	3	1.5	1.1	1.0	1.0	1.0	2.1	2
	Senegal	192.5	1.33	11.66	7	1,690.0	1,450.0	1,830.0	1,270.0	1,150.0	1,287.0	1,287
	Gambia	10.0	0.50	1.52	7	704.0	612.0	747.0	581.0	580.0	581.0	581
	Guinea Bissau	28.1	3.18	1.59	6	2,760.0	2,480.0	3,649.0	2,210.0	2,100.0	2,999.0	2,999
	Guinea Conakry	245.7	1.61	9.4	7	2,992.0	2,792.0	3,083.0	2,762.0	2,760.0	2,039.0	2,039
	Sierra Leone	71.6	1.68	5.53	6	1,677.0	1,454.0	1,695.0	1,053.0	1,000.0	1,052.0	1,052
	Liberia	96.3	0.84	3.28	6	193.0	143.0	427.0	92.5	67.5	110.0	110
	Ivory Coast	318.0	0.80	18.15	5	302.0	201.0	644.0	99.4	99.0	99.0	99
	Ghana	227.5	0.76	22.11	6	181.0	168.0	214.0	138.0	124.0	137.0	137
	Togo	54.4	0.05	6.15	3	10.0	10.0		10.0	10.0	11.0	11
	Benin	110.6	0.15	8.44	6	21.0	16.5	17.0	13.5	11.5	66.0	66
	Nigeria	910.8	3.12	131.53	8	9,990.0	9,980.0	11,134.0	9,970.0	9,970.0	7,386.0	7,386
	Total West Africa	3,290.7	15.29	222.4	8	20,521.5	19,307.6	23,441.0	18,200.4	17,873.0	15,769.1	15,769
Central Africa	Cameroon	465.4	1.80	16.32	8	2,720.0	2,563.0	2,494.0	2,515.0	2,500.0	1,957.0	1,957
	Equatorial Guinea	28.1	0.60	0.5	2	267.0	260.0	277.0	253.0	250.0	258.0	258
	São Tomé & Principe	1.0	0.27	0.157	4						1.4	1
	Gabon	257.7	2.02	1.384	7	2,185.0	1,858.0	1,759.0	1,529.4	1,500.0	1,606.0	1,606
	Congo	341.5	0.21	3.999	6	200.0	120.0	188.0	83.5	80.0	17.0	17
	Democratic Republic of Congo	2,267.1	0.18	57.549	6	606.0	353.0	374.0	220.0	220.0	201.0	201
	Angola	1,246.7	2.25	15.941	3	530.0	433.0	607.0	336.0	330.0	333.0	333
	Total Central Africa	4,607.3	7.32	95.9	8	6,508.0	5,587.0	5,699.0	4,936.9	4,880.0	4,373.4	4,373
	Total West & Central Africa	7,898.0	22.61	318.28	8	27,029.5	24,894.6	29,140.0	23,137.3	22,753.0	20,142.5	20,142
Source: Adapted from UNEP-WCMC (2007).

Table 2. Mangrove wood harvested from mangrove forest stands in seven coastal countries of the region

Country	Locality	Quantity (m^3)	Fish smoking (%)	Year	Source
Benin	N/A	47,613	N/A	2002	Kjerfve et al. (1997)
Cameroon	Douala Edea Wildlife Reserve	180,000	90	2000	Cameroon Wildlife Conservation Society (2001)
	Littoral	403,000	N/A	N/A	Din et al. (2008)
	South West Province	102,650	90.4	2006	Feka and Manzano (2008)
Côte d'Ivoire	Coastal areas of Côte d'Ivoire	3,000,000	N/A	1995	Abe et al. (2000)
Gambia	Gunjur	4,809,000	100	N/A	Satia and Hansen (1984)
Guinea^a	Guinea	572,271	N/A	N/A	Diop (1993)
	Guinea	7,555,003.12	N/A	1998	Samoura and Diallo (2003)
	Guinea	149,079	N/A	2002	Convention on Biological Diversity (2002)
	Guinea	289,662.1	N/A	1996	Samoura and Diallo (2003)
Nigeria	Nigeria	4,000,000	N/A		Diop (1993)
Sierra Leone	Yaliboya	24,600	97	1986	Fofanah (2002)
Notes: Original values of wood culled from sources in tons was converted to cubic meters (in order to harmonize measurement units), as follows 1 m^3 =  624 kg (fresh weight) for R. racemosa (Feka 2005) and standing volume or biomass  =  403 m^3/ha (Ajonina 2008). N/A, not available.
^aBecause of the possibility of data overlap in Guinea, we use data only for 1996, 1998, and 2002 in our calculations of wood extracted from mangrove stands.

Table 3. Frequency distribution indicating the intensity of major anthropogenic activities scooping mangrove forests in West-Central Africa^a

	Mangrove forest resource use and/or conversion
Country	Fish smoking	Construction	Cooking	Salt production	Rice farming	Urbanization	Petroleum exploration
Angola	*	*	*	N/A	N/A	**	***
Benin	***	**	**	***	**	***	N/A
Cameroon	*****	***	***	N/A	N/A	***	**
Congo	**	***	**	*	N/A	N/A	N/A
Cote Côte-d'Ivoire	**	***	*	N/A	N/A	***	**
Democratic Republic of Congo	*	*	N/A	N/A	N/A	N/A	N/A
Equatorial Guinea	*	N/A	N/A	N/A	N/A	**	***
Gabon	N/A	N/A	**	N/A	N/A	***	***
Gambia	***	*	**	*	*	**	N/A
Ghana	***	**	*	N/A	N/A	****	*
Guinea	****	***	**	*****	***	**	N/A
Guinea Bissau	***	**	***	***	*****	***	N/A
Liberia	**	*	*	N/A	**	N/A	N/A
Mauritania	**	*	*	*	N/A	N/A	N/A
Nigeria	*****	****	****	N/A	**	****	*****
Senegal	***	****	***	**	**	****	N/A
Sierra Leone	**	*	*	N/A	**	***	N/A
Togo	**	*	***	**	**	****	N/A
Source: Compiled by authors from Ibe and Awosika (1991), Abe et al. (2000), Da Silva et al. (2005), www.ramsar.org (cited November 2006), Ukwe, Ibe, Nwilo, et al. (2006), and UNEP-WCMC (2007).
Notes: ^aUrbanization here refers to various development activities such as population increase, house construction, and pollution from industries, households, dams, and houses. N/A, not available.
*Threat intensities are based on a five-point ranking scale (scale: *very low, **low, ***medium, ****high, and *****very high). This ranking might be based on expert knowledge and indications as major threats from the sources listed above. The scope of validity of the information provided in this table is limited to the coastal cities of the countries studied.

Table 4. Petroleum and oil and gas reserves – production by some countries of West-Central Africa

			Oil production (×1000 barrels/day)
Country	Oil reserves (×1000 million barrels) 2005	Gas reserves (×1000 million barrels)^a	1995	2000	2005
Angola	9.000	0.750	663	746	1242
Benin	0.0041	0.001	NA	NA	NA
Cameroon	0.090	0.110	106	88	58
Congo Brazzaville	1.800	0.092	180	275	253
Equatorial Guinea	1.800	0.100	7	117	355
Gabon	2.200	0.033	356	327	234
Ghana	0.008	0.0238	NA	NA	NA
Mauritania	1.000	NA	NA	NA	NA
Nigeria	35.900	4.984	1998	2155	2580
Source: British Petroleum (2006).
Notes: NA, not available.
^aData for unknown year.

Figure 3. Distribution of protected mangrove areas per country in West-Central Africa.

Figure 4. Projected wood harvest from mangrove stands in WCA for seven countries in West-Central Africa.

UNEP-WCMC . 2007 . Mangroves of Western and Central Africa , Cambridge , , UK : United Nations Environment Programme (UNEP) Regional Seas Programme/UNEP – World Conservation Monitoring Centre .

 Google Scholar

Lacerda LD , Kjerfve B and Diop , SH , eds. 1997 . Mangrove ecosystems studies in Latin America and Africa , Paris , , France : UNESCO .

 Google Scholar

Cameroon Wildlife Conservation Society . 2001 . Activity report, Douala-Edea forest project for 2000. Mounko (Cameroon) ,

 Google Scholar

Din , N , Saenger , P , Priso , RJ , Siegfried , DD and Basco , F. 2008 . Logging activities in mangrove forests: a case study from Douala, Cameroon . Afr J Enviorn Sci Tech , 2 ( 2 ) : 22 – 30 .

 Google Scholar

Feka , NZ and Manzano , MG. 2008 . The implications of wood exploitation for fish smoking on mangrove ecosystem conservation in the South West Province, Cameroon . Trop Conserv Sci , 1 ( 3 ) : 222 – 235 .

 Web of Science ®Google Scholar

Satia , PB and Hansen , LS. 1984 . Sustainability of development and management actions in two-community fishery center in the Gambia , Cotonou , , Benin : IDAF. Project Technical Report IDAF/WP/57 .

 Google Scholar

Diop , S. , ed. 1993 . “ Conservation and sustainable utilisation of mangrove forests in Latin America and Africa Regions ” . In Okinawa (Japan): ISME. Part II Africa ISME/UNESCO Project Mangrove Ecosystems Technical Reports 3

 Google Scholar

Samoura , K and Diallo , L. 2003 . Environmental issues associated with the main sectors of energy production in Guinea. AJEAM-RAGEE , 5 ( 1 ) : 28 – 38 .

 Google Scholar

Fofanah , AS. 2002 . Proceedings of a One-day Inaugural Seminar on Wetlands for Members of The National Wetlands Committee – Sierra Leone. Freetown (Sierra Leone): The National Wetlands Committee ,

 Google Scholar

Feka , NZ. 2005 . Perspectives for the sustainable management of mangrove stands in the Douala-Edea wildlife reserve, Cameroon [M.Sc. thesis] , Buea , Cameroon : University of Buea .

 Google Scholar

Ajonina , GN. 2008 . Inventory and modeling forest stand dynamics following different levels of wood exploitation pressures in the Douala-Edea Atlantic coast of Cameroon, Central Africa [PhD thesis] , Germany : University of Freiburg . Freiburg im Breisgau

 Google Scholar

Da Silva , SA , da Silva , CS and Biai , J. 2005 . Contribution de La Guinee-Bissau a L'élaboration d'une Charte Sous-Regionale Pour Une Gestion Durable des Ressources de Mangroves , Guinea Bissau : IUCN/IBAP .

 Google Scholar

Ukwe , CN , Ibe , AC and Kenneth Sherman , K. 2006 . A sixteen-country mobilization for sustainable fisheries in the Guinea Current Large Marine Ecosystem . Ocea Cotl Manag , 49 ( 7–8 ) : 385 – 412 .

 Web of Science ®Google Scholar

British Petroleum . 2006 . Statistical review of world energy, 2006 , London , , UK : BP P.L.C .

 Google Scholar