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Elevationally restricted floral elements of the Asir Mountains, Saudi Arabia
Journal ofArid Environments (1984) 7, 35-41
Elevationally restricted floral elements of the Asir Mountains, Saudi Arabia H. A. Abulfatih * Accepted 18 February 1983 The region of Asir, located in the south-west of Saudi Arabia, consists of a series of mountains which extend in a north-south direction. The complexity of the plant communities on these mountains is related to the variations in topography, elevation, moisture, and temperature. Along an elevation gradient between Agabat Thila'a (1300 m) and Al Soudah (2740 m) various plant assemblages were encountered in different habitats.
Introduction
The Asir Mountains, which are located in the south-west of Saudi Arabia, support vegetation which is particularly rich in species and varied in community types. A little work has been done on the flora of this area (Mandaville, 1965; Migahid, 1978; Nader, 1982). Papers concerning the ecology, vegetation and flora of the Asir region have been published by the author. These comprise a quantitative analysis of trees and shrubs of the highlands of Asir (Abulfatih, 1979), the distribution of the aquatic plants of Abha Lake (Abulfatih & Al-Khalili, 1979) the vegetation types of the Dalaghan National Park (Abulfatih, 1981a) and the wild plants of Abha (Abulfatih 1981b). The relations of plant communities to elevational gradients and trends in community composition and structure are described here. This study reveals the complex vegetation patterns in relation to topography, elevation, moisture, temperature and soil along an elevation gradient between Agabat Thila'a and Al Soudah mountains. Method
The study was conducted along a 40 km road between 1300 and 2740 m above sea level (Fig. 1). Because of the relatively large areas included, and the diversity of habitats, three major sites in which the vegetation types were most distinctive, were investigated. These sites were Agabat Thila'a (1300 m), Abha (2200 m), and Al Soudah (2740 m). Each was subdivided into topographic units which were described and their species composition recorded and evaluated. When listing the plants in each topographic unit those of limited range were recorded separately. Species which did not show a clear range of distribution were recorded in more than one topographic unit. Plants were observed and collected continuously over a period of 4 years between 1977 and 1981. Identification was made possible by the help of Miss Dorothy Hillcoat of t~e Bri.tish Museum (Natural History) and by reference to Migahid's (1978) Flora ofSaudi Arabia.
* College of Education, Abha, P.O. Box 932. Saudi Arabia. 0140-1963/84/010035 + 07 $03.00/0
©
1984 Academic Press Inc. (London) Limited
36
H. A. ABULFATIH 19°, - - _ - - - - - - - - - - - - - - - - - . - - - - - - - . ,
Khamis Mushayt
•
N
® 1\ U
17°30
o•
5 10
,.
.
City
Village Rood TT Escarpment 0
-
20
30
.,
40
50 km
.
42°
43°
Figure 1. A map shows Asir Area in the south-west of Saudi Arabia. Vegetation distribution along elevationgradient wasevaluated at Al Soudah, Abha, and AqabatThila'a.
Climate Because of the scarcity of the climatic records for Agabat Thila'a (15 km south of Abha) and Al Soudah (30 km west of Abha), air temperatures and rainfall at these places were estimated from the records of meteorological stations at Sabya (about 150 km south of Abha, at sea level), and at Abha. Calculations were based on the correlation between elevation and mean maximum air temperature, mean minimum air temperature, and mean annual rainfall (Table I). The climatic conditions at Agabat Thila'a are characterized by less rain and higher temperatures. Conditions are affected mainly by the terrain and elevation. Valleys, slopes and ridges create a mosaic of micro-climates. Because of its intermediate elevation, Abha receives moderate precipitation and its air temperature is somewhat lower than Agabat Thila'a. As a result of its higher elevation, Al Soudah is cooler and experiences more rain and fog. Afternoon cloud cover is common throughout the year: freezing is frequent at night during December and January. Geology According to Brown (1972) the area belongs primarily to the Pre-Cambrian and Cambrian Intrusive periods which are composed of the following formations. (i) Metamorphosed sedimentary rocks, volcanic rocks and greenstone, showing lineaments; also including
ELEVA TIONALLY RESTRICTED FLORAL ELEMENTS
Table 1.
37
Climatic data for Agabat Thila'a, Abha and Ai Soudah. Average of3 years betuieen /977 and /979
Climatic data Average annual rainfall (mm) Mean maximum air temperature (OC) Mean minimum air temperature (OC)· Mean maximum relative humidity Mean minimum relative humidity
Agabat Thila'a (1300 m) (estimated)
Abha (2200 m)
Al Soudah (2740 m) (estimated)
280
392
640
28.0
22.3
18.5
18.0
13.3
10.0
83 29
units younger than some of the granitoides related to the Hiiaz orogeny. (ii) Basement gneiss, in part remobilized during Late Pre-Cambrian Najd orogenies; may include younger amphibolites. (iii) Late tectonic calc-alkalinegranitic rocks (6~SO million years). Results Site I (Agabat Thila'a)
The area is characterized by dry mountains, ridges, slopes and valleys. It drops sharply southward and westward to the lowlands of Asir (Tihamat Asir) and eventually to the Red Sea. It is divided topographically into three types: west facing slopes, permanently wet sites and seasonally dry wadis. The area receives an immense amount of water from the surrounding mountains during the monsoon rains. This causes destruction to roads, bridges, farms and properties, as occurred in February 1982. The rain does not remain for long, flowing rapidly to the lowlands and the Red Sea. The soils are of sand, gravel or rock. Vegetation is sparse: the cover ranges between 10 and 20 per cent. Common plants are listed in Table 2. Site II (Abha)
Abha is situated in a hilly area which drops gradually to the east. The landscape is featured by rolling lands, rocky hills, permanently wet sites, and seasonally dry wadis. Rocky hills are characterized by large boulders. Abha Lake is man-made. A major wadi, Wadi Abha, runs through the city from west to east. It receives a fair amount of water during the monsoon rains. The soil is sandy to loamy mixed with small sized rocks. Vegetation is sparse and plant cover ranges between 20 and 30 per cent. Site III (Al Soudah)
The Al Soudah area descends gradually eastward and drops sharply westwards to the lowlands of Asir (Tihamat Asir). Large parts of Al Soudah are terraced and cultivated. The
38
H. A. ABULFATIH
Table 2. Plantdistribution along anelevation gradient ontheAsirMountains. Common plants ofAgabat Thila'a (1300 m), Abha (2200 mY, andAl Soudah (2740 m)are listed. Eachsite isdivided into a number of topographic units. Thefirst comprises westfacing slopes (2), permanently wet sites (4), and seasonally dry wadis (5). The second site comprises rolling land (1), rocky hills (3), permanently wet sites (4), and seasonally dry wadis (5). The third site is divided into rolling lands (1), west facing slopes (2), and permanently wetsites (4) Site, elevationand topographic units Agabat Thila'a Abha Al Soudah (1300m) (2200 m) (2740 m) Growth form, family and species Trees Cupressaceae, Juniperus procera Leguminosae, Acacia sp. Moraceae, Ficus palmata Ficussalicifolia Shrubs Asclepiadaceae, Calotropis procera Compositae, Euryops arabicus Psiadiaarabica Ephedraceae, Ephedra sp. Euphorbiaceae, Clutia lanceolata Ricinuscommunis Guttiferae, Hypericum chrysostrictum Liliaceae, Dracaena sp. Polygonaceae, Rumex nervosus Resedaceae, Ochradenus baccatus Rosaceae, Rosa abyssinica Sapindaceae, Dodonaea viscosa Solanaceae, Lyciumshawii Solanumincanum Solanumnigrum Withania somnifera Tamaricaceae, Tamarix sp. Herbaceous plants Acanthaceae, Barleria acanthoides Blepharis ciliaris Hypoestes verticillaris Amaran thaceae, Aervajavanica Aerva lanata Asclepiadaceae, Pergularia damia Periploca aphylla Boraginaginaceae, Alkanna orientalis Cynoglossum lanceolatum Echiumarabica Heliotropium cineraseus Heliotropium longiflorum Campanulaceae, Campanula edulis Caryophyllaceae, Dianthus desertii Silenesc hweinfurthij Commilinaceae, Commelina forsskalei Compositae, Achillea arabica Centaurea maxima
2
4
5
+
3
+
+
+
+ +
4
5
+
+
2
+
+
+
+
+
+ +
+ + +
+
+
+ +
+
+
+
+
+
+ +
+
+ + +
+
+
+
+
+
+
+ +
+
4
+
+
+
+
39
ELEVATIONALLY RESTRICTED FLORAL ELEMENTS
TableZ.
Continued Site, elevation and topographic units Agabat Thila'a Abha AlSoudah (1300 m) (2200 m) (2740 m)
Growth form, family and species
2
4
Centaurea schimpen Cirsium vulgare Echinops sp. Francoeria crispa Onopordon ambiguum Verbisina encelioides Xanthium spinosum Cucurbitaceae, Citrullus colocynthis Cyperaceae, Cyperus rotundus S cirpus inclinatus Euphorbiaceae, Euphorbia cyparissiodes Euphorbia granulata Gentianaceae, Swertia engleri Gramineae, Phragmitis australis Tetrapogon villosus + + Juncaceae, J uncus punctorus Juncus rigidus Labiatae, Lavandula dentata Lavandula pubescens Marrubium vulgare Micromeria trijida Nepetadeflersiana Otostegia fruticosa Plectanthus arabicus Salvia merjamie Leguminosae, Astragalus fatmensis Indigophera arabica + Indigophera spinose Liliaceae, Asphodelus jistulosa Asphodelis nitis + Malvaceae, Abutilon sp. + Hibiscus deflersii + Hibiscus vitifolius Nyctaginaceae, Commicarpus plumbagineus Oxalidaceae, Oxalis sp, Papaveraceae, Argemone mexicana Plantaginaceae, Plantago cylindrica Primulaceae, Anagalisarvensis Ranunculaceae, Ranunculus multiligatus + Resedaceae, Resedasphenoclioides Scrophulariaceae, Verbascum nubicum Veronica anagallis aguatica Solanaceae, Daturastramonium Thymelaeaceae, Gnidiasomalensis Typhaceae, Typha domingensis Urticaceae, Forsskalea tenacissima Succulents Aizoaceae, Aizoon cananens Delosperma abyssinica
5
5
4
3
2
4
+
+ + +
+
+
+ + +
+ + +
+
+
+
+
+
+
+
+
+ +
+
+ + +
+
+ +
+
+
+
+
+
+ +
+ +
+ +
+
+ + +
+
+
40
H. A. ABULFATIH
Table 2.
Continued Site, elevation and topographic units Agabat Thila'a Abha Al Soudah (1300 m) (2200 m) (2740 m)
Growth form, family and species
Apocynaceae, Adeniumobesum Asc1epiadaceae, Caralluma
retrospiciens Caralluma sinaica Cactaceae, Opuntiaficus-indica Compositae, Kleiniaodora Crassulaceae, Kalanchoe sp. Umbilicus ropustris Liliaceae, Aloa sp. Dipcadierythraeum Vitidaceae, Cissus quadrangularis Cissus rotundifolia
2
4
5
2
4
+
+ +
+
+
+ +
+
+ +
Parasites Loranthaceae, Loranthus regularis Viscum sp.
5
+
+
+
4
3
+ +
Ferns Ceterach officinarum Cheilanthes fragrans
+ +
Lichen ( rsnea articulata
+
natural vegetation is dominated by juniper trees. Vegetation differs in the following topograpic categories: rolling lands, west facing slopes, and permanently wet sites (ponds and streams). The soil is rocky and of various depths and textures ranging from sand to sandy loam and of various shades of brown. Exposed rocks are usually dark brown because they contain iron oxide. Vegetation cover ranges between 20 and 60 per cent. Conclusion The complexity of the plant assemblages in the region of Asir is attributed to variations in moisture, temperature and topography. The plants are of desert, temperate and tropical origin, because the region lies between Asia and Africa next to the Arabian desert, and in contact with the Mediterranean mountains northward and with the subtropical mountains of Yemen to the south. The vegetation changes drastically along elevation gradients. Four wild species of trees were encountered. At Agabat Thila'a (1300 m) Ficus salicifolia grows in warm microhabitats along wadis. Ficus palmata grows in crevices between large boulders in Abha (2200 m). Acacia spp. grow sparsely at Agabat Thila'a and in Abha forming 4-5 per cent crown cover. At Al Soudah (2740 m) Juniperus procera trees contribute 12 per cent crown cover. In addition, a few introduced tree species are grown successfully in Abha, These include Cupressus sempennrens forma horizontalis and forma pyramidalis (Cupressaceae) and Eucalyptus rostrata (Myrtaceae). Among the common plants there are also 17 shrubs, 65 herbaceous plants, 13 succulents, two parasites (on Acacia sp. trees), two ferns, and an epiphytic lichen (on Juniperus procera).
ELEYATIO!\:ALLY RESTRICTED FLORAL ELEMENTS
41
References Abulfatih, H. A. (1979). Vegetation of higher elevation of Asir, Saudi Arabia. Proceedings oftheSaudi Biological Society, 3: 139-148. Abulfatih, H. A. & Al-Khalili, A. D. (1979). Biological survey of Abha Lake. Journal of the Saudi Arabian Natural HistorySociety, 25: 17-22. Abulfatih, H. A. (l981a). Plant ecology of Dalaghan National Park, Asir Province, Saudi Arabia. Proceedings ofthe Saudi BiologicalSociety; 5: 131-141. Abulfatih, H. A. (1981b). Wild plants of Abha and its surroundings. Proceedings of the Saudi Biological Society, 5: 143-159. Brown, G. F. (1972). Tectonic map of the Arabian Peninsula. Saudi Arabian Director General of Mineral Resources, Arabian Peninsula Map AP-2. Mandaville, J. P. (1965). A contribution to the flora of Asir, Southern Arabia. Coconut Grove, Miami Field Research Publications, 4: 1-13. Migahid, A. M. (1978). Flora ofSaudi Arabia. Riyadh: Riyadh University Publications. 939 pp. Nader, A. H. (1982). First records of flora from the highlands of Asir, Kingdom of Saudi Arabia. Senchenbcrgiana biologica, 62 (1981): (4/6),405-412.
Elevationally restricted floral elements of the Asir Mountains, Saudi Arabia H. A. Abulfatih * Accepted 18 February 1983 The region of Asir, located in the south-west of Saudi Arabia, consists of a series of mountains which extend in a north-south direction. The complexity of the plant communities on these mountains is related to the variations in topography, elevation, moisture, and temperature. Along an elevation gradient between Agabat Thila'a (1300 m) and Al Soudah (2740 m) various plant assemblages were encountered in different habitats.
Introduction
The Asir Mountains, which are located in the south-west of Saudi Arabia, support vegetation which is particularly rich in species and varied in community types. A little work has been done on the flora of this area (Mandaville, 1965; Migahid, 1978; Nader, 1982). Papers concerning the ecology, vegetation and flora of the Asir region have been published by the author. These comprise a quantitative analysis of trees and shrubs of the highlands of Asir (Abulfatih, 1979), the distribution of the aquatic plants of Abha Lake (Abulfatih & Al-Khalili, 1979) the vegetation types of the Dalaghan National Park (Abulfatih, 1981a) and the wild plants of Abha (Abulfatih 1981b). The relations of plant communities to elevational gradients and trends in community composition and structure are described here. This study reveals the complex vegetation patterns in relation to topography, elevation, moisture, temperature and soil along an elevation gradient between Agabat Thila'a and Al Soudah mountains. Method
The study was conducted along a 40 km road between 1300 and 2740 m above sea level (Fig. 1). Because of the relatively large areas included, and the diversity of habitats, three major sites in which the vegetation types were most distinctive, were investigated. These sites were Agabat Thila'a (1300 m), Abha (2200 m), and Al Soudah (2740 m). Each was subdivided into topographic units which were described and their species composition recorded and evaluated. When listing the plants in each topographic unit those of limited range were recorded separately. Species which did not show a clear range of distribution were recorded in more than one topographic unit. Plants were observed and collected continuously over a period of 4 years between 1977 and 1981. Identification was made possible by the help of Miss Dorothy Hillcoat of t~e Bri.tish Museum (Natural History) and by reference to Migahid's (1978) Flora ofSaudi Arabia.
* College of Education, Abha, P.O. Box 932. Saudi Arabia. 0140-1963/84/010035 + 07 $03.00/0
©
1984 Academic Press Inc. (London) Limited
36
H. A. ABULFATIH 19°, - - _ - - - - - - - - - - - - - - - - - . - - - - - - - . ,
Khamis Mushayt
•
N
® 1\ U
17°30
o•
5 10
,.
.
City
Village Rood TT Escarpment 0
-
20
30
.,
40
50 km
.
42°
43°
Figure 1. A map shows Asir Area in the south-west of Saudi Arabia. Vegetation distribution along elevationgradient wasevaluated at Al Soudah, Abha, and AqabatThila'a.
Climate Because of the scarcity of the climatic records for Agabat Thila'a (15 km south of Abha) and Al Soudah (30 km west of Abha), air temperatures and rainfall at these places were estimated from the records of meteorological stations at Sabya (about 150 km south of Abha, at sea level), and at Abha. Calculations were based on the correlation between elevation and mean maximum air temperature, mean minimum air temperature, and mean annual rainfall (Table I). The climatic conditions at Agabat Thila'a are characterized by less rain and higher temperatures. Conditions are affected mainly by the terrain and elevation. Valleys, slopes and ridges create a mosaic of micro-climates. Because of its intermediate elevation, Abha receives moderate precipitation and its air temperature is somewhat lower than Agabat Thila'a. As a result of its higher elevation, Al Soudah is cooler and experiences more rain and fog. Afternoon cloud cover is common throughout the year: freezing is frequent at night during December and January. Geology According to Brown (1972) the area belongs primarily to the Pre-Cambrian and Cambrian Intrusive periods which are composed of the following formations. (i) Metamorphosed sedimentary rocks, volcanic rocks and greenstone, showing lineaments; also including
ELEVA TIONALLY RESTRICTED FLORAL ELEMENTS
Table 1.
37
Climatic data for Agabat Thila'a, Abha and Ai Soudah. Average of3 years betuieen /977 and /979
Climatic data Average annual rainfall (mm) Mean maximum air temperature (OC) Mean minimum air temperature (OC)· Mean maximum relative humidity Mean minimum relative humidity
Agabat Thila'a (1300 m) (estimated)
Abha (2200 m)
Al Soudah (2740 m) (estimated)
280
392
640
28.0
22.3
18.5
18.0
13.3
10.0
83 29
units younger than some of the granitoides related to the Hiiaz orogeny. (ii) Basement gneiss, in part remobilized during Late Pre-Cambrian Najd orogenies; may include younger amphibolites. (iii) Late tectonic calc-alkalinegranitic rocks (6~SO million years). Results Site I (Agabat Thila'a)
The area is characterized by dry mountains, ridges, slopes and valleys. It drops sharply southward and westward to the lowlands of Asir (Tihamat Asir) and eventually to the Red Sea. It is divided topographically into three types: west facing slopes, permanently wet sites and seasonally dry wadis. The area receives an immense amount of water from the surrounding mountains during the monsoon rains. This causes destruction to roads, bridges, farms and properties, as occurred in February 1982. The rain does not remain for long, flowing rapidly to the lowlands and the Red Sea. The soils are of sand, gravel or rock. Vegetation is sparse: the cover ranges between 10 and 20 per cent. Common plants are listed in Table 2. Site II (Abha)
Abha is situated in a hilly area which drops gradually to the east. The landscape is featured by rolling lands, rocky hills, permanently wet sites, and seasonally dry wadis. Rocky hills are characterized by large boulders. Abha Lake is man-made. A major wadi, Wadi Abha, runs through the city from west to east. It receives a fair amount of water during the monsoon rains. The soil is sandy to loamy mixed with small sized rocks. Vegetation is sparse and plant cover ranges between 20 and 30 per cent. Site III (Al Soudah)
The Al Soudah area descends gradually eastward and drops sharply westwards to the lowlands of Asir (Tihamat Asir). Large parts of Al Soudah are terraced and cultivated. The
38
H. A. ABULFATIH
Table 2. Plantdistribution along anelevation gradient ontheAsirMountains. Common plants ofAgabat Thila'a (1300 m), Abha (2200 mY, andAl Soudah (2740 m)are listed. Eachsite isdivided into a number of topographic units. Thefirst comprises westfacing slopes (2), permanently wet sites (4), and seasonally dry wadis (5). The second site comprises rolling land (1), rocky hills (3), permanently wet sites (4), and seasonally dry wadis (5). The third site is divided into rolling lands (1), west facing slopes (2), and permanently wetsites (4) Site, elevationand topographic units Agabat Thila'a Abha Al Soudah (1300m) (2200 m) (2740 m) Growth form, family and species Trees Cupressaceae, Juniperus procera Leguminosae, Acacia sp. Moraceae, Ficus palmata Ficussalicifolia Shrubs Asclepiadaceae, Calotropis procera Compositae, Euryops arabicus Psiadiaarabica Ephedraceae, Ephedra sp. Euphorbiaceae, Clutia lanceolata Ricinuscommunis Guttiferae, Hypericum chrysostrictum Liliaceae, Dracaena sp. Polygonaceae, Rumex nervosus Resedaceae, Ochradenus baccatus Rosaceae, Rosa abyssinica Sapindaceae, Dodonaea viscosa Solanaceae, Lyciumshawii Solanumincanum Solanumnigrum Withania somnifera Tamaricaceae, Tamarix sp. Herbaceous plants Acanthaceae, Barleria acanthoides Blepharis ciliaris Hypoestes verticillaris Amaran thaceae, Aervajavanica Aerva lanata Asclepiadaceae, Pergularia damia Periploca aphylla Boraginaginaceae, Alkanna orientalis Cynoglossum lanceolatum Echiumarabica Heliotropium cineraseus Heliotropium longiflorum Campanulaceae, Campanula edulis Caryophyllaceae, Dianthus desertii Silenesc hweinfurthij Commilinaceae, Commelina forsskalei Compositae, Achillea arabica Centaurea maxima
2
4
5
+
3
+
+
+
+ +
4
5
+
+
2
+
+
+
+
+
+ +
+ + +
+
+
+ +
+
+
+
+
+
+ +
+
+ + +
+
+
+
+
+
+
+ +
+
4
+
+
+
+
39
ELEVATIONALLY RESTRICTED FLORAL ELEMENTS
TableZ.
Continued Site, elevation and topographic units Agabat Thila'a Abha AlSoudah (1300 m) (2200 m) (2740 m)
Growth form, family and species
2
4
Centaurea schimpen Cirsium vulgare Echinops sp. Francoeria crispa Onopordon ambiguum Verbisina encelioides Xanthium spinosum Cucurbitaceae, Citrullus colocynthis Cyperaceae, Cyperus rotundus S cirpus inclinatus Euphorbiaceae, Euphorbia cyparissiodes Euphorbia granulata Gentianaceae, Swertia engleri Gramineae, Phragmitis australis Tetrapogon villosus + + Juncaceae, J uncus punctorus Juncus rigidus Labiatae, Lavandula dentata Lavandula pubescens Marrubium vulgare Micromeria trijida Nepetadeflersiana Otostegia fruticosa Plectanthus arabicus Salvia merjamie Leguminosae, Astragalus fatmensis Indigophera arabica + Indigophera spinose Liliaceae, Asphodelus jistulosa Asphodelis nitis + Malvaceae, Abutilon sp. + Hibiscus deflersii + Hibiscus vitifolius Nyctaginaceae, Commicarpus plumbagineus Oxalidaceae, Oxalis sp, Papaveraceae, Argemone mexicana Plantaginaceae, Plantago cylindrica Primulaceae, Anagalisarvensis Ranunculaceae, Ranunculus multiligatus + Resedaceae, Resedasphenoclioides Scrophulariaceae, Verbascum nubicum Veronica anagallis aguatica Solanaceae, Daturastramonium Thymelaeaceae, Gnidiasomalensis Typhaceae, Typha domingensis Urticaceae, Forsskalea tenacissima Succulents Aizoaceae, Aizoon cananens Delosperma abyssinica
5
5
4
3
2
4
+
+ + +
+
+
+ + +
+ + +
+
+
+
+
+
+
+
+
+ +
+
+ + +
+
+ +
+
+
+
+
+
+ +
+ +
+ +
+
+ + +
+
+
40
H. A. ABULFATIH
Table 2.
Continued Site, elevation and topographic units Agabat Thila'a Abha Al Soudah (1300 m) (2200 m) (2740 m)
Growth form, family and species
Apocynaceae, Adeniumobesum Asc1epiadaceae, Caralluma
retrospiciens Caralluma sinaica Cactaceae, Opuntiaficus-indica Compositae, Kleiniaodora Crassulaceae, Kalanchoe sp. Umbilicus ropustris Liliaceae, Aloa sp. Dipcadierythraeum Vitidaceae, Cissus quadrangularis Cissus rotundifolia
2
4
5
2
4
+
+ +
+
+
+ +
+
+ +
Parasites Loranthaceae, Loranthus regularis Viscum sp.
5
+
+
+
4
3
+ +
Ferns Ceterach officinarum Cheilanthes fragrans
+ +
Lichen ( rsnea articulata
+
natural vegetation is dominated by juniper trees. Vegetation differs in the following topograpic categories: rolling lands, west facing slopes, and permanently wet sites (ponds and streams). The soil is rocky and of various depths and textures ranging from sand to sandy loam and of various shades of brown. Exposed rocks are usually dark brown because they contain iron oxide. Vegetation cover ranges between 20 and 60 per cent. Conclusion The complexity of the plant assemblages in the region of Asir is attributed to variations in moisture, temperature and topography. The plants are of desert, temperate and tropical origin, because the region lies between Asia and Africa next to the Arabian desert, and in contact with the Mediterranean mountains northward and with the subtropical mountains of Yemen to the south. The vegetation changes drastically along elevation gradients. Four wild species of trees were encountered. At Agabat Thila'a (1300 m) Ficus salicifolia grows in warm microhabitats along wadis. Ficus palmata grows in crevices between large boulders in Abha (2200 m). Acacia spp. grow sparsely at Agabat Thila'a and in Abha forming 4-5 per cent crown cover. At Al Soudah (2740 m) Juniperus procera trees contribute 12 per cent crown cover. In addition, a few introduced tree species are grown successfully in Abha, These include Cupressus sempennrens forma horizontalis and forma pyramidalis (Cupressaceae) and Eucalyptus rostrata (Myrtaceae). Among the common plants there are also 17 shrubs, 65 herbaceous plants, 13 succulents, two parasites (on Acacia sp. trees), two ferns, and an epiphytic lichen (on Juniperus procera).
ELEYATIO!\:ALLY RESTRICTED FLORAL ELEMENTS
41
References Abulfatih, H. A. (1979). Vegetation of higher elevation of Asir, Saudi Arabia. Proceedings oftheSaudi Biological Society, 3: 139-148. Abulfatih, H. A. & Al-Khalili, A. D. (1979). Biological survey of Abha Lake. Journal of the Saudi Arabian Natural HistorySociety, 25: 17-22. Abulfatih, H. A. (l981a). Plant ecology of Dalaghan National Park, Asir Province, Saudi Arabia. Proceedings ofthe Saudi BiologicalSociety; 5: 131-141. Abulfatih, H. A. (1981b). Wild plants of Abha and its surroundings. Proceedings of the Saudi Biological Society, 5: 143-159. Brown, G. F. (1972). Tectonic map of the Arabian Peninsula. Saudi Arabian Director General of Mineral Resources, Arabian Peninsula Map AP-2. Mandaville, J. P. (1965). A contribution to the flora of Asir, Southern Arabia. Coconut Grove, Miami Field Research Publications, 4: 1-13. Migahid, A. M. (1978). Flora ofSaudi Arabia. Riyadh: Riyadh University Publications. 939 pp. Nader, A. H. (1982). First records of flora from the highlands of Asir, Kingdom of Saudi Arabia. Senchenbcrgiana biologica, 62 (1981): (4/6),405-412.