Saudi Journal of Biological Sciences (2014) xxx, xxx–xxx King Saud University Saudi Journal of Biological Sciences www.ksu.edu.sa www.sciencedirect.com ORIGINAL ARTICLE Floristic diversity and vegetation analysis of Wadi Arar: A typical desert Wadi of the Northern Border region of Saudi Arabia Ahmed K. Osman a,b,*, Faraj Al-Ghamdi a,c,1, Abdulhakim Bawadekji a,d,2 a Biology Department, Faculty of Science, Northern Border University, Arar, Saudi Arabia b Botany Department, Faculty of Science, South Valley University, Qena, Egypt c Botany and Microbiology Department, College of Science, King Abd El-Aziz University, Jeddah, Saudi Arabia d Horticulture Department, Faculty of Agriculture, University of Aleppo, Syria Received 8 July 2013; revised 28 January 2014; accepted 5 February 2014 KEYWORDS Abstract Wadi Arar in the Northern border region of Saudi Arabia is one of the most important Kingdom of Saudi Arabia; Wadis of the Kingdom. The present study provides an analysis of vegetation types, life forms, as Northern border region; well as floristic categories and species distribution. A total of 196 species representing 31 families Floristic survey; of vascular plants were recorded. Compositae, Gramineae and Leguminosae were the most com- Flora; mon families. Therophytes and chamaephytes are the most frequent life forms, indicating typical Wadi Arar; desert spectrum vegetation. The distribution of these species in the different sectors of the Wadi Floristic diversity as well as the phytochoria for the recorded species is provided. Ninety-one species (46.5%) are typ- ical bi-regional. Furthermore, about 105 species (53.5%) are mono- or pluriregional taxa. The high- est number of species (136 or 69.5%) was recorded for annual plants, while the lowest number of species (60% or 30.5%) was recorded for perennial, short perennial or annual to biennial species. ª 2014 Production and hosting by Elsevier B.V. on behalf of King Saud University. 1. Introduction * Corresponding author at: Biology Department, Faculty of Science, Northern Border University, Arar, Saudi Arabia. Tel.: +966 The Kingdom of Saudi Arabia is a huge arid land with an area 0547190808/+20 1005811378. of about 2,250,000 km2 covering the major part of the Arabian E-mail addresses: [email protected], osman_a_2000@yahoo. Peninsula, characterized by different ecosystems and diversity com (A.K. Osman), [email protected], [email protected]. sa of plant species (Abdel Khalik et al., 2013). (F. Al-Ghamdi), [email protected] (A. Bawadekji). 1 Tel.: +966 0503688021/0553786932. The topography of Saudi Arabia, as well as that of Arabian 2 Tel.: +966 0557528348. Peninsula, is an ancient massif in which geologic structure Peer review under responsibility of King Saud University. developed concurrently with the Alps (Country Profile: Saudi Arabia, 2006). The climate in Saudi Arabia differs greatly be- tween the coast and the interior. High humidity coupled with more moderate temperatures is prevalent along the coast, Production and hosting by Elsevier 1319-562X ª 2014 Production and hosting by Elsevier B.V. on behalf of King Saud University. http://dx.doi.org/10.1016/j.sjbs.2014.02.001 Please cite this article in press as: Osman, A.K. et al., Floristic diversity and vegetation analysis of Wadi Arar: A typical desert Wadi of the North- ern Border region of Saudi Arabia. Saudi Journal of Biological Sciences (2014), http://dx.doi.org/10.1016/j.sjbs.2014.02.001 2 A.K. Osman et al. whereas aridity and extreme temperatures characterize the over, the vegetation types, life forms and floristic categories interior (Country Profile: Saudi Arabia, 2006). of the collected species were taken into consideration. For fu- Saudi Arabia has not permanent rivers or lakes; however ture reference, voucher herbarium specimens of different plant ‘‘Wadis’’ are frequent along the country. The word ‘‘Wadi’’ samples were pressed and deposited in the herbarium of Col- in this article will be used to designate a non permanent river, lege of Sciences in Arar (Northern Border University). whose runoff is dependent on rain. It frequently happened, but for decades Wadis have been completely inactive. In the dry 2. The study area lands, Wadis represent one of the most prominent desert land- forms, which exhibit physiographic irregularities that lead to The area of the present study is located in the Northern region parallel variations in plant species distribution (Kassas and of Saudi Arabia (30° 550 1300 N, 41° 00 300 E). Wadi Arar (Wadi Girgis, 1964). Wadi ‘‘Arar’’ is considered one of the most of the Anizah tribe) is one of the main Wadis which existed in important Wadis in the northern region. the northeast of Saudi Arabia (Fig. 1). It covers an area of about The flora of Saudi Arabia is one of the richest biodiversities 9500 km square and extends next to Arar city. According to the in the Arabian Peninsula and comprises very important genetic Worldwide Bioclimatic Classification System (http:// resources of crops and medicinal plants (Atiqur Rahman et al., www.globalbioclimatics.org), this region falls within the Medi- 2004). The components of this flora are admixture of Asia, terranean desertic continental climate. This area is dry zone, Africa and Mediterranean regions’ plants. According to Col- characterized by hot, arid, desert climate and an average annual lenete (1999), this flora comprises 2250 species belonging to temperature of 21.5 °C(Fig. 2). Precipitation is scanty, with an 835 genera and about 142 families. 147 species are classified average annual of 20.2 mm, which usually falls during the win- as ‘‘endemic’’, 721 species as ‘‘endangered’’ and about 22 spe- ter months, the extreme rainfall occurring in January and May cies are believed as completely extinct (Collenete, 1999). with more than 90 mm (http://www.globalbioclimatics.org). The number of wild species occurring in a square kilometer area of Saudi Arabia is less significant, especially in areas such 3. Materials and methods as central, eastern and northern regions. Areas along the northwestern and southwestern regions are densely vegetated and contain the highest number of species. Approximately This study was performed in Wadi Arar from November 2011 70% of the country’s floristic species are reported in these to April 2013 during active plant growth period, when most areas. Endemism in Saudi Arabia is relatively insignificant in species were expected to be present. The wild vegetations were comparison with some of the neighboring countries such as sampled in 25 localities including the different Wadi tributar- Yemen and Oman. ies; in each locality, the present species were recorded. Saudi Arabia contains 97 trees, 564 shrubs and about 1620 The collected plant specimens were identified and named herbs, which cover, respectively, 4.25%, 24.73% and 71.02% according to Collenette (1999), Cope (1985), Mighaid (1996), of higher plant diversity of the country (http://www.plant- and Chaudhary (1999–2001). They are deposited in the Her- diversityofsaudiarabia.info/index.htm). barium of Biology Department, College of Sciences, Northern Wild plants of Saudi Arabia were studied by many authors Border University. (Chaudhary, 1999–2001; Chaudhary and Al-Jowaid, 1999; Life forms of species were determined depending upon the Collenette, 1999; Migahid, 1996; Miller and Cope, 1996)as location of the regenerative buds and the shed parts during the general floral studies. Furthermore, many authors have studied unfavorable season (Raunkier, 1934). The floristic categories more limited areas in the course of floral and taxonomical revi- of the investigated species were made to assign the registered sion of some genera (Aleem, 1979; Batanouny and Ismail, species to world geographical groups according to Wickens 1985; Fayed and Zayed, 1989; El Karemy and Zayed, 1992; (1978) and Zohary (1973). Hajar et al., 1998; Hegazy et al., 1998; Al Wadie, 2002; Al-Tur- ki and Al-Qlayan, 2003; Atiqur Rahman et al., 2004; Alfarhan 4. Results et al., 2005; Mosallam, 2007; Alshammari and Sharawy, 2010; El-Ghanem et al., 2010; Al-Sodany et al., 2011; Alatar et al., Table 1 shows the plant species recorded in different surveyed 2012; Alsherif et al., 2012; Farrag, 2012; Gomaa, 2012; Ihsa- sectors of Wadi Arar. The list includes 196 species belonging to nullah, 2012; Waly et al., 2012 and Abdel Khalik et al., 2013). 31 families of phanerogams. Their generic representation is The distribution of life form is closely related to topography quite variable. However, one family is represented by more and landform (Kassas and Girgis, 1965; Zohary, 1973; Orshan, than 29 genera (Compositae), another by 19 genera (Grami- 1986; Fakhireh et al., 2012). In Wadis, the composition of life neae); the third, most represented family carries about 14 gen- forms expresses a typical desert flora, the majority of species era (Cruciferae). Five families are represented by four to eight being therophytes and chamaephytes. Vegetation of Wadis in genera (Caryophyllaceae and Leguminosae with 8 genera; general is not constant; it varies from year to year, depending Umbelliferae with 7 genera; and Zygophyllaceae with 4 gen- upon the moisture level (Siddiqui and Al-Harbi, 1995). The era). Furthermore, eight families showed less number of genera establishment, growth, regeneration and distribution of the (2 to 3 genera) and 15 families are represented by a single plant communities in the Wadis are controlled by many factors, genus (Table 1). such as geographical position, physiographic features and hu- From the standpoint of species richness within the de- man impacts (Shaltout and El-Sheikh, 2003; Ku¨rschner and scribed families of the region, only one family exceeded 30 spe- Neef, 2011; Alatar et al., 2012; Korkmaz and Ozcelik, 2013). cies (Compositae: 48), one family was represented by 26 species The current study includes survey and identification of the (Gramineae), the third family contained 22 species (Legumino- wild plants growing in the Wadi Arar and the surrounding sae), two families had more than 10 species (Caryophyllaceae: sites in the Northern border region of Saudi Arabia.