Are the northernmost mangroves of West Africa viable?: a case study in Banc d'Arguin National Park, Mauritania
Dahdouh-Guebas, F.; Koedam, N. (2001). Are the northernmost mangroves of West Africa viable?: a case study in Banc d'Arguin National Park, Mauritania. Hydrobiologia 458(1-3): 241-253. dx.doi.org/10.1023/A:1013126832741
In: Hydrobiologia. Springer: The Hague. ISSN 0018-8158; e-ISSN 1573-5117, more
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| Keywords |
Anatomical structures > Body organs > Plant organs > Leaves
Colonization
Dispersion
Ecosystems
Mangroves
National parks
National parks
Natural populations > Plant populations
Population dynamics
Recreational facilities > Areas > Amenity and recreation areas > Parks > National parks
Reproduction > Sexual reproduction
Reproduction > Vegetative reproduction
Survival
Vegetation cover
Water > Fresh water
Water bodies > Inland waters > Wetlands > Swamps > Mangrove swamps
Avicennia germinans (L.) L. [WoRMS]
Mauritania [Marine Regions]
Marine/Coastal; Brackish water; Fresh water |
| Author keywords |
mangrove; physiognomy; regeneration; predation; biogeography; Mauritania |
| Abstract |
In the Parc National du Banc d'Arguin (P.N.B.A.) in Mauritania, the mangroves of the West-African coast reach their northernmost distribution and comprise exclusively Avicennia germinans. As a biogeographically marginal, monospecific mangal in an area where freshwater availability has decreased over the last decades, concern about the survival of the mangroves has been expressed. As yet, a description was lacking and no data regarding the fitness of A. germinans in the P.N.B.A. were available. The mangrove and associated vegetation nearby Cape Timiris (southern border of the P.N.B.A.) was mapped in January 1998 and described for the adult, young and juvenile vegetation layer, along the lagoon perimeter of about 4 km. Physiognomic aspects of the mangroves were compared with those of a mangrove formation on the tidal island of Eizin further North and with those of the northernmost mangrove system, in Iouik. Four different formations were found (tall trees, wide trees, shrub and sebkha formations) with `trees' as small as 30 cm flowering profusely. There were no site-related differences in leaf morphological characteristics. Propagules were available in large numbers but germinated successfully only where protected from the main Sahara wind currents and from the sun. Experiments to investigate the effects of predation or aridity (air exposure) on germination showed an absence of predator influences and that drought did affect viability of propagules. Release of propagules at the time of spring tides may favour colonisation of new areas. Future management plans can consider the collection and broadcasting of fresh propagules, as well as favouring free play of hydrodynamics (including flooding, breaching of barriers) in the system. Except for inappropriate topographical conditions (mangroves growing in terrestrial locations, with little chance for propagule survival),A. germinans did not show signs of reduced vitality at its biogeographical limit. |
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