Somali montane xeric
Cal Madow, Somalia - Photograph by Frank Horwood
BIOME: Deserts and Xeric Shrublands
SIZE: 24,000 square miles (62,200 square kilometers) - about the
size of West Virginia
CONSERVATION STATUS: Critical/Endangered
The Somali Montane Xeric Woodland ecoregion runs around the Horn of Africa,
including a number of higher montane areas close to the sea. Although
classified as part of the Somali-Masai regional center of endemism this
area also contains remnant plant species linking it to Mediterranean,
Macaronesian and Afromontane regions. It has served as a refuge for arid
and semi-arid relict elements from these different regions. This ecoregion
includes the highest point in Somalia and has the highest amount of
rainfall in Somalia. At least ten species of plants, and six species of
vertebrate animals are endemic to the ecoregion. The habitats are fairly
intact due to the low human population and the inaccessibility of the
escarpment and plateau areas, but populations of larger mammals have been
greatly reduced by hunting. However, the difficult topography and
long-running political problems mean that much of the region is unexplored
biologically (WWF and IUCN 1994).
Location and General Description
This ecoregion stretches along the coast of Somalia through the regions of
Somaliland and Puntland from the Shimbiris Mountain east of Hargeysa
through the northern mountains of Somalia to Raas Caseyr, covering the
very tip of the Horn of Africa, and continuing some 300 kilometers south
along the Somali coastal plain. Elevations range from sea level to the
summit of Shimbiris at 2,416 m, the highest point in Somalia (WWF and IUCN
1994). There are also extensive coastal plains and sizeable mountain
escarpments with areas higher than 1,500 m. As a result, some authorities
(e.g. Friis 1992) consider these mountain areas to be biogeographic
extensions of the Ethiopian highlands. The climate is hot and dry, with
considerable seasonal temperature variations. Mean temperatures range from
21°C to 30°C in the lowlands to 9°C to 21°C in the mountains. The mean
rainfall of the low-lying areas is less than 200 mm annually, though it is
presumably far greater at higher elevations, and falls mainly during the
winter months. The escarpment near Maydh receives the most rainfall in
Somalia, over 700 mm each year.
Most of the higher mountain areas are composed of limestone and gypsum,
covered with free-draining thin rendzina lithosols that retain little
moisture outside the rainy seasons. Many endemic species are confined to
these areas, such as Reseda sessilifolia that grows on outcrops of gypsum.
The vegetation of this ecoregion varies due to elevation, rainfall, and
soil or rock types. At lower elevations, xerosols and yermosols have
developed, particularly on the lowland coastal plains bordering the Indian
Ocean. Here, there is little to no vegetation in this desert to
semi-desert habitat. In subcoastal areas woody vegetation becomes denser
with dominant species from the genera Acacia, Commiphora, and Boswellia
(WWF and IUCN 1994). Along the sides of the escarpment Macchia-like
evergreen and semi-evergreen scrub occurs with species such as Dracaena
schizantha, Cadia purpea, Buxus hildebrandtii, and Pistacia aethiopica,
while remnants of Juniperus forest grow at higher altitudes on the
mountains (WWF and IUCN 1994, White 1983).
The biological value of the ecoregion is poorly known. Most of the area
has been inaccessible for many years due to political instability in
Somalia, and much of the information that does exist is old and
potentially unreliable. However, it is known that there are over ten
species of endemic plants represented in this ecoregion, including relict
elements of arid and semi-arid groups; for example, four endemic species
of Helianthemum and one endemic species of Thamnosma. Also, the monotypic
genus Renschia is a strict endemic (WWF and IUCN 1994). Both WWF and IUCN
(WWF and IUCN 1994), Friis (1992) and Lovett and Friis (1996) regard this
as a center of endemism for plants. The most endemic-rich zone is the high
montane region, but plant endemics are also found at lower elevations.
There are three strict endemic reptiles, the snakes Spalerosophis
josephscorteccii and Leptotyphlops reticulatus and the lizard Pseuderemias
savagei, with two other reptiles nearly-endemic to the ecoregion. Three
strict endemic birds also occur: the Somali pigeon (Columba oliviae, DD),
the Somali thrush (Turdus ludoviciae, CR), and the Warsangli linnet (Carduelis
johannis, EN), all found in the North Somali mountains endemic bird area (Stattersfield
et al. 1998). Three small mammal species are also considered near-endemics,
Atelerix sclateri, Acomys louisae and Elephantulus revoili. The rare
antelopes beira (Dorcatragus megalotis, VU) and Speke's gazelle (Gazella
spekei, VU) are also found here and in a few other ecoregions in the Horn
of Africa area (East 1999).
The severely threatened Somali thrush and Warsangli linnet are principally
or perhaps wholly confined to juniper forests at higher elevations. More
widely distributed mammal species such as Speke's gazelle (Gazella spekei,
VU), Salt’s dikdik (Madoqua saltiana), beira (Dorcatragus megalotis, VU),
and Soemmerring's gazelle (Gazella soemmerringii, VU) are also threatened
and suffer from over-hunting and from grazing competition with livestock
Due to the longstanding and continued political difficulties in the former
Somalia, there is no accurate information about the habitat within this
ecoregion. It is known that the area of juniper forest has been greatly
reduced and what remains is heavily degraded. At lower elevations and
drier sites, the vegetation may be in better condition because the human
population density is low and the habitats are semi-deserts in many areas.
Previously, small forest patches were principally centered on the higher
elevation areas of the Surud-Ad-Al Madu and Mosca highlands (Friis 1992).
The only protected areas within the ecoregion are a few forest reserves,
of which the most important is Daloh Forest Reserve, an area of montane
Juniperus forest. Because of the past political situation these areas
probably have not been protected for some time.
Types and Severity of Threats
The major threats to the ecoregion are thought to be intensive grazing by
goats and other livestock (including cattle in the mountains), and cutting
of Juniperus trees for timber and fuel wood. Hunting of larger mammals is
also a long-standing problem. The prolonged period of political
instability in the ecoregion may have also resulted in a number of
additional threats, but apart from the breakdown of management authorities
set up to conserve forests and wildlife, these are not well documented.
Justification of Ecoregion Delineation
This ecoregion follows the ‘Somalia-Masai semi-desert grassland and
shrubland’ vegetation unit classified by White (1983). The Somali Montane
Xeric Woodland covers approximately the same area as the North Somali
Mountains Endemic Bird Area (Stattersfield et al. 1998), and includes Cal
Madow (Al Medu), a center of endemism for plants (WWF and IUCN 1994). It
also shares affinities with the Mediterranean, Macaronesian and
Afromontane regions. Modifications to the ecoregion include its extension
further west than Berbera, as well as the inclusion of the littoral region
and an island of montane vegetation at Shimbiris, east of the Harer branch
of the Ethiopian Highlands (WWF 1998). Although White (1983) classifies
this unit with the Ethiopian Highlands, it was considered to be more
similar to the other parts of the Somalian Xeric Woodland ecoregion.
East, R. (comp.) 1999. African Antelope Database 1998. IUCN/SSC Antelope
Specialist Group. ICN, Gland, Switzerland and Cambridge, UK. x + 434 pp.
Friis, I. 1992. Forests and Forest Trees of Northeast Tropical Africa.
HMSO, Kew Bulletin Additional Series XV.
Lovett, J.C., and I. Friis. 1996. Patterns of endemism in the woody flora
of north-east and east Africa. Pp. 582-601. In: L.J.G. van der Maesen et
al. (eds.). The Biodiversity of African Plants. The Netherlands: Kluwer
Stattersfield, A.J., M.J. Crosby, A.J. Long, & D.C. Wege. 1998. Endemic
Bird Areas of the World. Priorities for Biodiversity Conservation.
BirdLife Conservation Series No. 7. BirdLife International, Cambridge, UK.
White, F. 1983. The vegetation of Africa, a descriptive memoir to
accompany the UNESCO/AETFAT/UNSO Vegetation Map of Africa (3 Plates,
Northwestern Africa, Northeastern Africa, and Southern Africa,
1:5,000,000). UNESCO, Paris.
WWF and IUCN. 1994. Centres of plant diversity. A guide and strategy for
their conservation. Volume 1. Europe, Africa, South West Asia and the
Middle East. IUCN Publications Unit, Cambridge, U.K.
WWF. 1998. A conservation assessment of terrestrial ecoregions of Africa:
Draft proceedings of a workshop, Cape Town, South Africa, August 1998.
World Wildlife Fund, Washington, DC, USA.
Prepared by: Chris Magin, Christine Burdette