Figs. 2 and 5 illustrate the regression in back mangrove forests
between 1951 and 2000. On the 2000 map, only some patches of A.
marina and Rh. mucronata are recorded, as they can survive in the
environmental conditions of Zone B (Fig. 5). Between 1951 and
2000, about 768 ha of mangrove, i.e. 38% of the original area
disappeared in this zone. In 2000, 60% of the remaining forest
consisted of Avicennia, with 35% being a mixed Avicennia/
Rhizophora forest. The previous mangrove forest was probably
replaced by tannes. These changes in mangrove stand structure, i.e.
decreasing but persistence of pure Avicennia stands, rarefaction or
disappearance of other species, could have been caused by salinity