**2.3 Sudanian penetration region**

This ecozone extends from southern Jordan near Aqaba Gulf along Wadi Araba reaching the southern part of the Jordan Valley near Dayr Alla northward. It also extends to southeastern Jordan near Wadi Ram, the largest sandstone mountain formation and granite mountains to the east. Altitudes range from 400 m bls around the Dead Sea area to as high as 1734 m asl for Jabal Ram mountain. Precipitation is of less than 50 mm annually. Two species of Acacia occur in this region in varying densities, *Acacia raddiana* and *Acacia tortilis*. *Tamarix* spp. and *Ziziphus spina-christi* are also found along wadi beds. A variety of shrubs, *Anabasis articulata*, *Gymnocarpos decandrum*, *Haloxylon persicum*, and *Lycium* sp. are abundant. The soil is mostly sandy for most of the region, interrupted with some rocky areas [20].

## **2.4 Saharo-Arabian region**

This region constitutes the largest biogeographical region, covering about 70% of Jordan. It spreads to the east bordering the Irano-Turanian region from the west and the Sudanian Penetration region from the southwest. *Haloxylon persicum*, *Hammada scoparia*, and *Ochradenus baccatus* are the typical sand dune vegetation. *Achillea fragrantissima*, *Artemisia herba-alba*, and *Astragalus* sp. are usually associated with wadi beds, and in certain areas east of Ma'an, few scattered *Acacia tortilis* are also found. The soil is mostly gravel, sandy Hamada, saline, and sandy. Altitude ranges from 100 m to 800 m asl, with annual rainfall not exceeding 50 mm. Azraq Oasis, one of the most important nature reserves in Jordan, is located in the middle of the eastern desert [20].
