Although such ecosystems are fragile, this study shows that the anthropogenic damages inflicted on the
mangrove forests of West Africa can be reversed over a relatively short time period if environmental
conditions are favorable. The mangrove ecosystem of the microtidal Somone Estuary, Senegal, has
undergone extreme changes during the last century. The area occupied by mangrove forest was estimated
with a diachronic study by GIS for the period 1946e2006. Between 1946 and 1978, 85% of the area
was progressively replaced by unvegetated mudflats in the intertidal zones and by barren area in the
supratidal zones. Until 1990, this was mainly a result of traditional wood harvesting. The impact was
exacerbated by the closing off of the estuary to the sea (1967e1969 and 1987) and by an extended
drought (1970 onwards), which resulted in a lack of renewal of water, hypersalinization and acidification.
The main factors controlling mangrove evolution in the Somone ecosystem, however, are anthropogenic.
Until 1990, traditional wood cutting (for wood and oyster harvesting) was practiced by the local population.
Between 1978 and 1989, a small area occupied by the mangroves was stabilized. Since 1992,
a modification of mangrove logging and a new reforestation policy resulted in an exponential increase of
mangrove area progressively replacing intertidal mudflats. Such success in the restoration of the
ecosystem reforestation is supported by favorable environmental conditions: tidal flooding, groundwater
influence, rainfall during the wet season, low net accretion rate of about 0.2e0.3 cmyear1, and a ban on
the cutting of mangrove wood. The rate of mangrove loss from 1946 to 1978 was 44,000 m2 year1, but
this has been offset by restoration efforts resulting in an increase in mangrove area from 1992 to 2006 of
63,000 m2 year