Mangrove map
Distribution and changes in mangrove area in West Africa between 1975 and 2013
Download High Resolution (33 MB)
Mangrove Senegal
Mangroves in Senegal © Gray Tappan/USGS

Mangroves are coastal forests that grow where ocean, freshwater, and land meet. They are among the most productive and complex ecosystems on the planet, thriving in salty and brackish conditions that would kill most other plants (Wetlands International, 2012). They have evolved clever mechanisms to enable them to cope with high concentrations of salt and the regular inundation of their root systems by incoming tides (Corcoran, Ravilious, and Skuja, 2007). Throughout the Sahel and West Africa, the livelihoods of coastal populations depend heavily on access to natural resources. Mangroves fulfill important functions: they provide wood and non-wood forest products, coastal protection, conservation of biological diversity, provision of habitat, spawning grounds and nutrients for a variety of fish and shellfish, and salt production (Corcoran, Ravilious, and Skuja, 2007). Mangroves play an essential role in West Africa’s coastal fisheries, which contribute $400 million annually to the regional economy (USAID, 2014). In spite of these important roles, mangroves are experiencing deforestation and are a heavily threatened ecosystem throughout the region. Mangroves are found in 10 of the 17 countries of West Africa, from Senegal to Nigeria. Some very small stands of mangroves can also be found in Mauritania and Togo, but their extent was too small to be mapped at the scale of this project. Nigeria contains the most extensive mangrove ecosystem of any country in West Africa, comprising nearly 50 percent of the total mangroves of the region. About 18 percent of the area identified as mangrove falls within designated national and international protected areas. However, only a small number of the designated protected areas are actively managed (Corcoran, Ravilious, and Skuja, 2007). In some places, mangroves grow as far as 100 km inland, due to strong tidal influences on rivers such as The Gambia and the Casamance rivers in Senegal, the Gêba River in Guinea-Bissau, and the Niger Delta in Nigeria (Corcoran, Ravilious, and Skuja, 2007). Similarly, where there are strong riverine influences into the ocean, islands affected by freshwater influxes provide an environment for mangrove growth, like in the Bijagos Archipelago of Guinea Bissau (AFROL, 2002).

Graph Mangroves
Mangrove area in West Africa by country in 1975, 2000, and 2013 (in sq km)

The overall regional trend from 1975 to 2013 indicates a decline in mangrove area of 4.8 percent, a net loss of 984 sq km. Nigeria had the greatest loss of mangroves between 1975 and 2013 (432 sq km), followed by Senegal and Guinea-Bissau (288 sq km and 220 sq km, respectively). Ten additional countries also show a decrease, but four countries — Ghana, Côte d’Ivoire, Liberia, and Sierra Leone — appear to have either no change or an overall increase in mangrove area over the 38-year period. Encouragingly, following reforestation efforts, Guinea, The Gambia, and Senegal show a gain of mangrove cover from 2000 to 2013.

West Africa’s coastlines have some of the highest and most rapidly growing populations. Many communities rely on mangrove wood as a primary fuel source for curing fish and other purposes, and urban expansion and intensifying demands for charcoal, fuel wood, and land for agriculture are growing drivers of mangrove deforestation and degradation (USAID, 2014). These factors — combined with rising sea levels, erosion from extreme weather, and more intense storm surges — represent significant and growing threats to mangroves (Corcoran, Ravilious, and Skuja, 2007).

Since the 2000s, large-scale reforestation campaigns have been initiated and operated by non-governmental organizations operating in Senegal (e.g., IUCN, Oceanium). Results have been spectacular: between 2006 and 2013, 140 sq km of mangrove forests were replanted, mostly in Casamance, but also along Senegal’s Saloum Region (Cormier-Salem and Panfili, 2016). The pair of high-resolution images above shows successful mangrove restoration along the Koular Bolon estuary in the commune of Keur Saloum in Senegal.
Mangrove 2004
Download high resolution image (11 MB)

 

Mangrove 2014
Download high resolution image (12 MB)

 

At the regional scale, efforts have increased to save mangrove forests from further destruction. Many national governments have passed legislation and signed international conventions, including the Convention on Climate Change, the Convention on Biodiversity, the Convention on International Trade in Endangered Species, the Convention on Ozone Layer and the Ramsar Convention on the Conservation of Wetlands (Wetlands International, 2012). Mangrove restoration efforts have been conducted in almost all the coastal nations along the Gulf of Guinea to help communities restore and better manage their mangroves.