Phytogeography of Saudi Arabia
Abdulatif H. Al-Nafie
Department of Geography, Faculty of Social Sciences, Imam Muhammad Ibn Saud Islamic University,
P.O. Box 5760, Riyadh, 11432, Saudi Arabia,
E-Mail: AALNAFIE@Gmail.com
Saudi Journal of Biological Sciences Vol. 15, No (1) June, 2008:
Abstract
This paper presents the phytogeography of Saudi Arabia and examines its phytogeographic location within the complex plant geographical regions of the Middle East. It reviews and discuses works have that been published so far by plant geographers and biogeographers on the phytogeographical regions of Southwest Asia and Northeast Africa, and determines the location of Saudi Arabia within it. The delimitation of the frontiers between plant-regions in Saudi Arabia, especially the south western part, which has always created some difficulties for biogeographers as well as phytogeographers who have studied the region.
Key words: Phytogeography, Saharo-Arabian, Sudano-Zambezian, Nubo-Sindian Afromontane, Saudi Arabia.
Introduction
Saudi Arabia appears to have been overlooked and neglected by many biogeographers and plant geographers, though it is a very significant region for both. The importance of the phytogeography of Saudi Arabia is the result of its location at the meeting point of two continents and two or three major plant geographic regions. Its land plays a great role as an avenue by which plant species could penetrate and are exchanged between these continents and regions. However, unfortunately, most of Saudi Arabia’s lands have been regarded by many scientists, as well as non-professionals, as a ‘lifeless’ environment.
The main purpose of this paper is to examine the phytogeographic location of Saudi Arabia within the complex plant geographical regions of the Middle East. It should be indicated that it is premature to conduct quantitative study, since the checklists of the flora of countries of the Arabian Peninsula are far from complete, and the distribution as well as range of many plant species are uncertain in many neighbouring regions.
The delineation of phytogeographic regions of Saudi Arabia in this paper will follow the traditional phytogeographical hierarchy and will be based mainly on environmental characteristics as well as taxa that dominate various areas of the country.
Conclusion
After reviewing Floras and checklists of Saudi Arabia, and based on the presence and absence of representative plant elements of different plant regions presented in its Flora as well as literature on the phytogeography of the Middle East, and according to the environmental setting of Saudi Arabia, it can be concluded that:
-It is almost impossible to draw a solid line between different plant regions in Saudi Arabia, since species of each region penetrate to the other, where the environmental factors are similar.
-The greater part of Saudi Arabia, especially its interior and northern parts, should be included in the East Saharo-Arabian Subregion which is a part of the Saharo-Arabian (Zohary, 1973), or the Arabian regional subzone within Saharo-Sindian regional zone (White and Leonard, 1991), (Figure 7).
-The Nubo-Sindian Province which is a part of the Sudanian Region (Zohary, 1973) or Nubo-Sindian local centre of endemism belonging to the Saharo-Sindian regional zone (White and Leonard, 1991) stretches in Saudi
Arabia over a narrow strip along the Red Sea coast north of Makkah as well as along Arabian Gulf coast.
-The Eritreo-Arabian Province which is also a part of the Sudanian Region (Zohary, 1973) or the Somalia-Masai regional centre of endemism (White and Leonard, 1991) stretches over a narrow strip along the Red Sea coast south of Makkah (Tihama plain) and below 1800m on As Sarawat Mountains (Alfarhan, 1999).
-Mountains higher than 1800m above sea level should be considered as an impoverished outlier of Afromontane archipelago-like regional centre of endemism (White and Leonard, 1991). The dominant species in this area are Juniperus procera and several evergreen shrubs.
-Some wetter slopes and peaks of As Sarawat mountains over 2800m above sea level form isolated small islands of very impoverished Afroalpine plants with a very low number of species so that it can be included in Afromontane archipelago-like regional centre of endemism.
Finally, more phytogeographical and environmental studies to delimit boundaries of different plant regions in Saudi Arabia precisely and accurately are called for.
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