Horn of Africa
ID
529
Author(s)
Ashley Brown and Michele Thieme, Countries Reviewer(s)
Djibouti
Ethiopia
Somalia
Major Habitat Type
Xeric freshwaters and endorheic (closed) basins
Drainages flowing into
The northern mountains drain primarily to the north toward the Gulf of Aden and to the southeast where several wadis cut through the plateau and flow to the Indian Ocean (Hughes & Hughes 1992).
Main rivers to other water bodies
From north to south, the major drainages flowing into the Indian Ocean from the interior plateau, include the ephemeral Jaceyl, Dhuudo, and Nugaal rivers. Among the many small, ephemeral drainages into the
Description
Boundaries
The temporary rivers, wadis, and sinkholes of the Horn ecoregion support a depauperate freshwater fauna adapted to fluctuating environmental conditions. The ecoregion corresponds to the xeric Horn of Africa, the most easterly portion of the continent covering the northern portion of
Topography
A mountain chain runs parallel to the Gulf of Aden, reaching the highest point in Somalia on Shimbiris Mountain at 2,416 m (WWF and IUCN 1994). The land slopes down from this northern ridge to an interior plateau at about 600 to1,000 m above sea level in the central portion of the ecoregion. The low-lying coastal plain covers a narrow strip along the
Freshwater habitats
Nearly all water bodies within this arid ecoregion are ephemeral. In the valley of the Nugaal River, there are several tugs (a temporary watercourse that spreads across flat land) and bullehs (endorheic depressions) (Hughes & Hughes 1992). Along the tip of the Horn there are also pans, springs, and pools in many of the small northern wadis that discharge to the
Terrestrial habitats
Most of the ecoregion is covered with barren desert or sparsely vegetated mixed scrub and grassland. The vegetation of the ecoregion is primarily deciduous shrub or bushland inland, with grassy scrublands on the coast. The most common tree species belong to the deciduous genera Acacia and Commiphora. The understory consists of shrubby herbs less than one meter high, such as Acalypha, Barleria, and Aerva. At lower elevations where rainfall is less consistent, vegetation becomes semi-desert scrubland. Around sinkholes in the interior limestone country and near tugs and bullehs, Acacia tortilis grows in association with Commiphora spp. (Hughes & Hughes 1992). Thickets of dense vegetation often indicate surface or sub-surface water. Evergreen and semi-evergreen scrub grows in the mountains, and Afro-montane vegetation including juniper forest grows at the highest elevations (Hughes & Hughes 1992).
Description of endemic fishes
The monotypic Somalian blind barb (Barbopsis devecchii), the only ecoregional endemic, lives in caves of the ecoregion.
Justification for delineation
This ecoregion is defined by the xeric Horn of Africa and is characterized by a depauperate and poorly known aquatic fauna.
Level of taxonomic exploration
Poor
References
- FishBase (2001) \Search FishBase\ "<"http://www.fishbase.org/search.cfm ">" (2001)
- Hughes, R. H.;Hughes, J. S. (1992). "A directory of African wetlands" Gland, Switzerland, Nairobi, Kenya, and Cambridge, UK: IUCN, UNEP, and WCMC.