With sparkling mountain streams, forests drenched in mist and incredible
high-altitude agricultural terracing, this afrotropical ecoregion is one of the
most fascinating and unusual in Arabia. Plant diversity and endemism are very
high here, with over 2,000 plant species and about 170 endemics. The woodlands
are rich in animal life, sheltering approximately 34 mammal species, 245 bird
species, 41 reptile species and 7 amphibian species. Overgrazing, erosion of
poorly maintained agricultural terraces, deforestation and hunting are the
major threats here. It is situated in the southwest Arabian highlands above
2,000 m and includes part of the Asir Mountains of Saudi Arabia and most of the
western highlands of Yemen. In the west, a steep escarpment drops to the
Tihamah plain on the Red Sea coast. To the east is a high plateau, with the
mountains then sloping more gently to the inner desert regions and sands of the
Rub’al-Khali (Empty Quarter). The escarpment mountains are the principal
topographic feature here; they run in a north-south direction, parallel to and
overlooking the Red Sea. The rugged mountainous landscape contains several
peaks over 3,000m, including Jebal Sudah. The Asir Mountain chain is the
highest land in the Arabian Peninsula, which tilts from west to east. East of
the mountains the land slopes gradually to the Arabian Gulf. The mountains are
composed mainly of sedimentary rocks such as limestones, sandstones and shales
that are of Jurassic, Cretaceous and lower Tertiary ages. These overlie a
basement complex of Pre-Cambrian granitic igneous rocks. The climate of the
region varies considerably depending on altitude, aspect and season. The
highlands receive variable rainfall caused by the southwest monsoon, which
brings damp oceanic winds. A tradition of high-mountain agriculture spanning
two thousand years has produced a spectacular terraced landscape on the steep
mountain slopes. However, this has eliminated much of the forest and woodland
cover and only scattered patches of woodland now survive. In Saudi Arabia, the
vegetation of the Asir Mountains has remained largely intact, although the
situation is deteriorating. In some places the vegetation shows a distinct
zonation, with an evergreen forest or scrub above about 2,000m and largely
Afroalpine vegetation above 2,500m. At these higher altitudes a lush cloud
forest exists, including Juniperus procera, usually festooned with the lichen
Usnea articulata, the woody shrub Euryops arabicus and Lavandular on the north
facing slopes. On the more barren south facing slopes, Aloe sabae and Euphorbia
are common. The flora of southwest Arabia has strong affinities with parts of
Africa, particularly East Africa. Juniperus procera, found above 2,500m in the
Asir Mountains, is also very abundant in and characteristic of the East African
highlands. There, it is a dominant plant in some montane or subalpine
vegetation units and is well known in Eritrea, Somalia, Ethiopia, Kenya and
Tanzania at almost the same altitudes.
 |
| Juniper |