The Mangroves of the East of Madagascar: Ecological Potentials and Pressures

Abstract

With 213,000 ha of remaining mangroves in 2016, Madagascar has about 4260 ha of mangrove on its Eastern coast. The purpose of this article is to provide essential data on the spatial distribution of this ecosystem of Eastern Madagascar, its ecological potentials and the pressures on its resources. Five Eastern Mangrove sites were selected, from South to North, because of their accessibility and their spatial position: Foulpointe, Sainte Marie, Manompana, Mananara Nord and Rigny. Eastern mangroves regenerate quite well, with a regeneration rate of over 500%. Their height and basal area range respectively between 1.7 -12 m and 7 -42 m 2 ·ha −1 . The aboveground biomass perfacies can go up to 47 t·ha −1 , or even more, at the level of the large homogeneous mangrove of Mananara and Rigny (>70 t·ha −1 ), whereas this one does not exceed 10 -20 t·ha −1 in the sporadic mangroves of Foulpointe and Manompana. The carbon sequestration capacity of the aboveground biomass is estimated at more than 5 -20 t·ha −1 , along a South-North gradient, equivalent to a minimum sequestration potential of 21,300 to 85,200 t for the whole East. Despite these ecological potentials and the low annual clearance rates observed for some sites, this ecosystem is subject to anthropogenic pressures linked to urbanization, timber harvesting and irrational exploitation of fishery resources.

Combining Traditional Ecological Knowledge and Scientific Observations to Support Mangrove Restoration in Madagascar

“…However, the density of the plantation in the BdA was lower compared with the highest number of trees per hectare recorded within the tall, mature stands of trees Rhizophora mucronata dominated, recorded in Mahajamba, 4900 ± 1500 trees/ha −1 [48], and within the highest density recorded within intact, tall and mature stands dominated by Rhizophora mucronata recorded in Ambaro-Ambanja bays, 4719 ± 1133 trees/ha −1 [38]. Additionally, this is lower compared with the highest density of mature trees recorded on the eastern coast of Madagascar, 7960 tree/ha −1 [50].…”