Vertical and Horizontal Distribution of Vegetation ...

Arab Journal ofScientific Research 18 (1) pp 4- 53

Marei Hussain AI-Qahtani

Vertical and Horizontal Distribution of Vegetation Communities and Habitats in Assir Mountains

year Precipitation and atmospheric normally high with the average rainfall ---UHil

400 mm per year Due to the monsoon it is

Abstract Data and reconnaissance surveys showed that from an and geomorphological point of view the research area could be divided horizontally into two distinct plant communities (mountainous plant and semi-desert plant community) and into five plant habitat types namely the toe-slope foot-slope habitat mid-slope habitat shoulder habitat and summit slope habitat The communities and habitat types varied in their environmental features (topography soil conditions and the of animal impacts) and consequently in their composition Although the vegetation in this area is low 11 100 m) it is considered with other areas in Saudi Arabia diversities in density and

were found between slope segments and also between the south-west and north-east parts of the research area The floristic composition and distribution of main plant groups were found to reflect the condition of soil and the topographical variety in Assir Mountains

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UUgtJI wi ~JJ ~4J1 ~fill ~ 4-i)l1

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Ulli -U)l1 lw ) ~ illj t

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Introduction

Arabian

lvarei Hussain Department King Khaled po Box

is located in the southshymiddotj-Arp it encompasses wide

that cover many Africa These

and the

biogeographers such as Alshyand according to the

(193119321

includes the research area within the east Sudanian region

vegetation of the Sudanian by hundreds of genera numerous

and plant communities The main region are open woodland savanna and

Eritrean-Arabian Arabian province in the

peninsula is most complex with its

containing about 225 (Takhtajan 1986 Zohary I

is characterized climatically a with high temperatures in summer

warm temperatures throughout Saudi Arabia Tel Fax E-mail

41

42

distributed through the rainy season and takes place mainly during the spring months (AI-Qahtani 1991) High mountains in the area receive rainfall throughout the year but rainfall reaches its peak in the spring season The subregions in the Arabian peninsula are mainly characterized by temperatures that are high enough to support a tropical vegetation

Within the study area ecologists and phytogeographers have indicated in brief comments that this area is an important part of Saudi Arabia in terms of the magni tude of its vegetation cover Some of these studies have described the vegetation of this area as follows

Brooks amp Mandil (1983) studied the Vegetation Dynamics in Asir Woodlands and reported the following

In Saudi Arabia the greatest number of plant species is found in the highlands of the south and south-west where East African vegetation contributes to the character of the region Fortyshyfour per cent of the flora in southern and southshywestern Arabia represents Sudanian elements found in the altitudinal zonation of the savanna scrub and the montane woodlands

Konig (1988) investigated the Phytogeography of South-western Saudi Arabia and described the vegetation in the study area as follows

The vegetation of the study area is climatically influenced and characterized mainly by forest woodland and xeromorphic woodland communities - in contrast to the central parts of the Arabian peninsula which are dominated by dwarf-shrub communities grassland and deserts

This study amis to investigate and analyse in detail the perennial vegetation of the research area in terms of the morphology ecology and distribution and their relationship with slope habitats Investigation and analysis of the above points is based on data of vegetation slope and soil samples that were collected from 300 quadrats from the research area

Materials and Methods

Sixty transects were selected systematically as profile lines along the eastern slopes of Assir mountains Each transect started from a specific measured point on the lower slope and crossed the facing slope to the edge of the mountains The distance between transects was 5 km Each transect was subdivided into five slope units from the ridge to the toe summit shoulder mid-slope foot-slope and toe-slope These units covered all the

M H Al-Qahlani

physiographic and physiognomic variations of the region Selection of these units which can be seen every where depended on variation of vegetation distribution slope gradient and form with soil uniformity Sample collection sites were established in the centre of each slope unit on each transect According to ecologists and pedologists the best time for gathering samples of soil and vegetation is after rain period which stretches from November until the end of May As a result of this fieldwork was carried out in the period June to August 1999 The point-centred quarter method (Kent amp Coker 1992) which is widely used for the sampling of gradient vegetation in forest and woodland ecosystems as well as in sparsely-vegetated areas was applied at the centre of these units In other words this technique was used to measure investigate and analyse the perennial plants in 300 sites In each site slope factors (slope angle slope gradient and slope length) and vegetation components (height basal diameter basal area crown area absolute density relative covering value number of points with particular species total number of individuals abundance of speciesll 00 m2

absolute dominance absolute frequency relative density relative dominance relative frequency and importance value) were measured and computed and soil samples (soil depth soil moisture texture class pH and organic matter) and plants were collected and analysed This technique has proven to be sufficient and effective in previous investigations of vegetation status and its relationship with slope and soil factors such as Mueller-Dombois amp Ellenberg (1974) Kent amp Coker (1992) Martz (1992) Derose et al (1993) Makhnach (1994) and Simanton et al (1994) Plant species and nomenclature were identified in situ in most of the studied sites by the means of the available scientific references on the flora of Saudi Arabia and its surrounding countries such as Abulfatih (1984 1987) Al-Qahtani (1991 1998) Blatter (1907) and Migahid (1980 1988) The other species were identified via collecting samples from fresh branches and transfer them to the herbarium The all procedures suggested by Tarzi (1984) were applied in the collecting and preparation of soil samples which were analysed according to the procedures that were suggested by soil survey staff (1992) and are applied at laboratories of King Saud University and the National Agriculture and Water Research Centre Saudi Arabia

43 Vertical and Horizontal Distribution

The Study Area

between 41 0

Geologically the Afro-Arabian

contains rolling area is distinguished throughout most year is a decrease in temperature in winter it reach freezing point because this area is by the warm marine wind that this area receives a high rainfall distributed throughout the year with and summer (Al-Qahtani 1998)

S A U D I A bull

showed that from an ecological and ge()mOn)hC)IOIncal point of view the research area

horizontally into two distinct plant plant community and

community) and vertically into namely the toe-slope

foot-slope habitat mid-slope habitat habitat and summit slope habitat The

communities and habitat types varied in environmental features (topography soil

and the of animal impacts) and in their vegetation composition This

what Batanouny (1987) stated and soil properties especially the

attributes and water resources play an role in the distribution of the different

plant communities in the western mountains of Arabian peninsula Analysis and discussion of these

and types are presented below

2- Mountainous Plant Community

A plant community is distributed in topography and climate are widely

the semi-desert plant nrTn bullp of the research

(2000-3130 m

Figure 1Geographical and Regional the Study Area

Results and Discussion

1- Features of Plant Communities and Habitats

The following discussion and plant community whereas quantitative estimates of vegetation structure and pro cera the distribution of the plant communities and habitats in basal diameter cm) crown area the research area They focus particularly on the 14 The plant cover value varies one data collected from the research area and the stand to but than the plant reconnaissance surveys cover plant community

Data analysis and reconnaIssance surveys mean estimation of

44 M H Al-Qahtani

plant cover value was counted to be 494 which desert plant community (24611 00 m2 and 13 21 equals about 11 to 25 respectively) Absolute dominance values indicate

Quantitative analysis of species m the that Juniperus procera (21766 cm21 00 m2) Acacia mountainous plant community covering absolute gerradii (8206 cm2l 00 m2) Acacia negrii (6538

2density relative covering value number of point cm211 00 m2) Dodonaea viscosa (15 cm21 00 m ) and with species total number of individuals abundance Lycium shawii (682 cm2lOO m2) are the most of species absolute dominance absolute frequency dominant in this community Importance values relative density relative dominance relative indicate that Juniperus procera (IV = 6976) Acacia frequency and importance value is presented in negrii (IV = 5593) Acacia gerradii (IV = 544) Table 1 The absolute density and relative covering Lycium shawii (IV = 2834) and Dodonaea viscosa value of perennial species in this community are (IV = 2473) are the important perennial species 301100 m~ and 32 respectively These are whereas the other species recorded in south-western considered high values compared with the absolute mountains are considered to be of less importance density and relative covering value in the semi-

Table 1 Summary of Vegetation Data of Mountainous Plant Community NPS = number of points with 2species TNI = total number of individuals AS = abundance of species in 100 m AD = absolute dominance

(cm2 100 m2) AF = absolute frequency (percent) RDE = relative density RDO = relative dominance RF

= relative frequency IV = importance value and IVR = importance value rank

No of Sampling points = 150 Absolute density (per 100 m) =30 I No of Species samples = 600 Relative Covering Value = 32

No Species NPS TNJ AS AD AF RDE RDO RF IV IVR

Acacia gerradii 38 102 0512 8206 2533 1701 2039 1700 5440 3 2 Acacia negrii 53 119 0597 6538 3533 1984 1625 1984 5593 2 3 Lycium shawii 37 80 0401 682 2467 1332 169 1333 2834 4 4 Lycium barbarum 6 13 0065 060 400 216 015 217 448 9 5 Solanum inc anum 5 7 0035 037 333 116 009 117 242 10 6 Solanum schimperianum 2 4 0020 019 133 066 005 067 138 12 7 Withania soml1lfera 2 0010 013 067 033 003 033 069 18 8 Dodonaea viscosa 31 63 0316 1500 2067 1050 373 1050 2473 5 9 Kleinia odora 22 53 0266 360 1467 884 090 883 1857 7 10 Euryops arabicus 35 59 0296 550 2333 983 137 983 2103 6 II Psiadia arabica 19 27 0136 135 1267 452 034 450 936 8 12 Juniperus procera 30 47 0236 21766 2000 784 5409 783 6976 13 Leptadenia pyrotechnica 3 6 0030 051 200 100 013 100 213 II 14 Calotropis procera 0005 014 067 017 003 017 037 20 15 Periploca aphylla 1 2 0010 026 067 033 006 033 072 17 16 Sageretia thea 3 4 0020 017 200 066 004 067 137 13 17 Rumex netmiddotvosus 2 3 0015 013 133 050 003 050 103 15 18 Reseda sphenocleoidis 3 0015 010 067 050 002 050 102 16 19 Lavandula dentata 0005 006 067 017 001 017 035 21 20 Adenium obesum 1 2 0010 228 067 033 057 033 123 14 21 Cluytia richmdiana 2 2 0010 011 133 033 003 033 069 19

Total 600 301 40242 19601 100 100 100

Source personal field work

3- Semi-Desert Plant Community highlands with the desert regions to the east The soil in this part is relatively deep and alkaline with

The semi -desert plant community IS clearly little organic matter Values of rainfall in the north-evident in the north-east of the research area This east of the research area are too low to support a part of the research area is located between 1000shy perennial vegetation cover (Al- Qahtani 1998) 2000 m altitude and links the south-western However many perennial species have adapted to

45

to be 359 (or 1 recorded in this community are succulent plants which can endure and moisture and

respectively Comparing relative covering value in

Vertical and Horizontal Distribution

Acacia arabica 92 313 1283 6745 6133 5215 17357 5217 12168 2 Acacia gerradii 25 50 0205 5730 1667 833 14745 833 3141 4 3 Acacia negrii 0004 020 067 016 0051 017 038 21 4 Lagonyehium faretum 5 7 0029 026 333 1 18 0067 117 242 11 5 Tephrosia 1 0004 002 067 016 0005 017 034 22 6 shawii 47 93 0381 1113 3133 1549 2864 1550 3385 3 7 Lycium barbarum 8 12 0049 044 533 199 0113 200 410 8 8 Solanum incanum 2 0009 009 067 037 0023 033 072 17 9 Dodonaea viseosa 17 33 0135 319 1133 549 0820 550 1181 6 10 Kleinia odora 14 26 0107 198 933 435 0509 433 919 7 II arabicus 11 11 0046 064 733 187 0165 183 389 9 12 Psiadia arabica 4 8 0033 028 267 134 0072 133 274 10 13 Juniperus procera 15 24 0098 16787 1000 398 4320 400 5118 2 14 2 2 0008 016 133 033 0041 033 070 18 15 procera 3 0012 037 133 049 0095 050 109 15 16 Sageretia thea 3 2 0009 010 200 037 0026 033 073 16 17 Rhamnus 2 4 0016 272 133 065 0700 067 202 12 18 Phoenix 0004 6977 067 016 7954 017 1828 5 19 Ziziphus 0004 363 067 016 0934 01 126 13 20 Rumex nervosus I I 0004 040 067 016 0102 017 043 20 21 Lavandula dentata 2 2 0008 010 L33 033 0026 033 069 19 22 Mentha lavandulacea 2 3 0012 051 133 049 0131 050 112 14

this environmental situation and have ~ntf~rprl are distributed in this region As can be seen Table 2 22 perennial species belonging to 19 and 9 botanical families were rprmiddotrgtrtPf1

desert plant community Phoenix the greatest height (14 m)

basal diameter (149 cm) and the crown area (17679 m2

) in the semi-desert plant Due to the overgrazing that occurs in this zone and the low level of rainfall the plant cover value is very weak in this community According to

the mean estimation plant cover value was

Table 2 Summary of species TNI = total (cm 1 100 m2

) AF = absolute = relative frequency IV

No of Sampling points 150 No of Species samples = 600 No Species NPS TN AS

values in the mountainous plant community it is found that the north-eastern part of

less density and of abundance (128311 00 m) shawii

Acacia gerradii (0205100 viscosa (0135100 m2

) and (0107100 m2) are very common species in western part of the research area dominance values showed that JHIlfnr--nl

(16787 cm21l00 m2) Phoenix

cmllOO ml) Acacia arabica (6745 and Acacia gerradii (5730 cm2100 m2) are dominant in this community Importance have confirmed that Acacia arabica (IV 121 Junipents procera (IV = 5118) Lycium (IV

3358) and Acacia gerradii (IV 3141) are the perennial species

are of comparatively little

Plant Community N PS = number species in 100 ml AD =

RDE = relative RDO

Absolute 100 =246 Relative Covering Value 1321

AD AF RDE RDO RF IV IVR

Total 600 246 38861 17 32 100 100 100 Source work

46

4- Toe-Slope Habitat Type

Toe-slope zones are comprised of stream sides which are one of the characteristic geomorphologic features of the research area These streams are formed of a complex network of the research area and its tributaries The soil of toe-slope zones is formed of materials derived from the suoounding mountains (EI-demerdash amp Zilay 1994) and receives more water from surface flow and flood than elsewhere The results of soil analysis show that these zones have deep soil high moisture and fertility compared with the other habitats in the research area

As listed in Table 3 this habitat is occupied by 21 perennial species These species are Acacia arabica Acacia gerradii Acacia negrii Lycium shawii Lycium barbarum Solanum incanum Solanum schimperianum Withania somnifera Dodonaea viscosa Kleinia odora Euryops arabicus Psiadia arabica Juniperus pracera Leptadenia pyrotechnica Ca10trapis procera Sageretia thea Phoenix dactyliera Ziziphus spinashychristi Rumex nervosus Lavandula dentata and Mentha lavandulacea Mean height (233 m) basal diameter (1543 cm) and crown area (1640 m2

) of the perennial species recorded in this habitat indicate that the plants of this habitat are characterised by large size compared with the other habitats in the research area (Figures 2 amp 3) Abundance values of species indicate that the most common species in this habitat are Acacia arabica

M H Al-Qahtani

(07011 00 m) Acacia gerradii (0581 100 m) Acacia negrii (05411 00 m2) Lycium shawii (04411 00 m) and Juniperus procera (027100 m) The relative covering value of perennial species in the toe-slope habitat (4401) is consistent with the comment made above regarding the large size of the trees and shrubs of this habitat (see fig 4) The absolute density of perennial plants in this habitat is 295100 m This is considered high density compared with the absolute density in the other habitats of the research area Absolute dominance values show that Acacia gerradii (190 55 cm2 100 m) Phoenix dactyliera (17444 cm2 1 00 m2

)

Acacia arabica (7050 cm21 00 m ) Juniperus procera (6115 cm I00 m) and Acacia negrii (5662 cm21 00 m2) are the most dominant in this habitat Importance values indicate that Acacia gerradii (IV = 7222) Acacia arabica (IV = 5967) Acacia negrii (IV = 4643) Lycium shawii (IV =

3142) and Phoenix dactyliera (IV = 3095) are the important perennial species According to the importance value and the rank of importance value Lycium barbarum Solanum incanum Solanum schimperianum Withania somniera Dodonaea viscosa Kleinia odora Euryops arabicus Psiadia arabica Juniperus pracera Leptadenia pyrotechnica Calotropis pro cera Sageretia thea Ziziphus spina-christi Rumex nervosus Lavandula dentata and Menthal lavandulacea are associated with this habitat but are less important than those mentioned above

Table 3 Summary of Vegetation Data of Toe-slope habitat type NPS = number of points with species TNI = total number of individuals AS = abundance of species in 100 m2

AD = absolute dominance (cm2 I 100 m2

) AF = absolute frequency (percent) RDE = relative density RDO = relative dominance RF = relative frequency IV = importance value and IVR = importance value rank

No of Sampling points = 60 Absolute density (per 100 m) =295 No of Species samples = 240 Relative Covering Value = 44 01 No Species NPS TNI AS AD AF RDE RDO RF IV IVR

I Acacia arabica 17 57 070 7050 2833 2372 1220 2375 5967 2 2 Acacia gerradii 20 47 058 19055 33 33 1966 3298 1958 7222 1 3 Acacia negrii 16 44 054 5662 26 67 1830 980 1833 4643 3 4 Lycium shawii 19 36 044 871 3167 1491 151 1500 3142 4 5 Lycium barbarum 3 3 004 036 500 136 006 125 267 11 6 Solanum incanum 2 003 033 167 102 006 083 191 14

7 Solanum schimperianum 1 001 010 167 034 002 042 078 18 8 Withania somnifera 1 2 003 038 167 102 007 083 270 9 9 Dodonaea viscosa 3 5 006 079 500 203 014 208 425 8 10 Kleinia odom 2 2 003 061 333 102 011 083 196 13 11 ELIyops arabicus 4 7 009 160 667 305 028 292 625 7 12 Psiadia arabica 3 3 004 043 500 136 007 125 268 to

47

plant morphology of trees and shmbs are dispersed and stunted

density is 2781 00 m2 and the mean is 107 m The relative covering value of

is also low (2068) Abundance show most common in this are Acacia arabica Acacia gerradii Acacia and Dodonaea viscosa

100 m2 0461100 m2

041100 O 6100 m2

Acacia negrii Acacia arabica (3990 are the

in habitat According to value Acacia arabica (IV = 6844) Acacia (IV 6061) Junipents procera (IV Acacia (IV = 4005) and (3 J are the most important whereas the other species listed in

are considered common


13 10 22 027 6115 1667 915 1058 916 2889 6 14 001 028 167 034 005 042 081 17 15 001 071 167 034 012 042 088 16 16 001 013 167 034 0Q2 042 078 19 17 Phoenix 001 17444 167 034 3019 042 3095 5 18 Ziziphus 001 908 167 034 157 042 233 12 19 Rumex nervosus 001 010 167 034 002 042 078 20 20 Lavandula dentala 001 013 67 034 002 042 078 21 21 Mentha lavandulacea 2 002 077 167 068 013 083 164 15

Total 240 295 57777 8004 100 100 100


Habitat Habitat

Figure 2Mean of the vegetation 3Mean of basal diameter in the habitats in the area cuvu habitats of the area

5- Foot-Slope in deterioration of the The or foot-slope is the greatest slope

area in terms of its area and low 7deg 43 These zones

and mid-slope habitat 13deg Although

zones is somewhat more water from surface flow than

elsewhere are deep and compared the other habitats and the texture class is loamy It is noted that these zones are affected particularly in the northshy

area due to its their accessibility to (AI-Qahtani 1998)

1n terms of 16 perennial foot-slope habitat and are listed botanical species are Acacia

gerradii Acacia negrii Lycium shawli Lycium

incanum Solanum iJUUUintU viscosa Kleinia odora

rrrYnl(l1~ Psiadia arabica Sageretia Rumex nervosus As habitat but with less importance

grazing which

48 M H Al-Qahtani

Table 4 Summary of Vegetation Data of Foot-Slope Habitat Type NPS = number of points with species TNI = total number of individuals AS = abundance of species in 100 m2 AD = absolute dominance (cm2 100 m2) AF = absolute frequency (percent) RDE = relative density RDO = relative dominance RF = relative frequency IV = importance value and IVR = importance value rank

No of Sampling points = 60 Absolute density (per 100 m) =278 No of Species samples = 240 Relative Covering Value = 2068 No Species NPS TNI AS AD AF RDE RDO RF IV IVR

Acacia arabica 18 66 076 39 90 3000 2733 1361 2750 6844 I 2 Acacia gerradii 16 40 046 8033 2667 1654 2741 1666 6061 2 3 Acacia negrii 14 29 034 46 12 23 33 1223 15 74 1208 4005 4 4 Lagonychium farctum 1 001 007 167 035 002 042 079 16 5 Lycium shawii 16 35 041 591 2667 1475 202 1458 3135 5 6 Lycium barbarum I I 001 0 07 167 036 002 042 080 15 7 Solanum incanum 2 1 001 013 333 036 004 042 082 13 8 Solanum schimperianum 001 009 167 036 003 042 081 14 9 Dodonaea viscosa 7 14 016 324 1167 576 111 583 1270 6 10 Kleinia odora 5 10 012 196 833 432 067 417 916 9 II Euryops arabicus 11 13 015 221 1833 540 075 542 1157 7 12 Psiadia arabica 7 11 013 106 1167 468 036 458 962 8 13 Juniperus procera 7 9 011 11073 11 67 396 3779 375 4550 3 14 Sageretia thea 4 4 005 049 667 180 017 167 364 10 15 Rhamnus disperma 2 002 051 167 072 017 083 172 12 16 Rumex nervosus 2 3 003 026 333 108 009 125 242 11

Total 240 278 Source personal field work

6- Mid-Slope Habitat Type

The mid-slopes are very complex zones in terms of topographical structure and botanical composition The mean slope angle of these zones is 13deg 46 and slope forms are mostly straight though in a few places they are concave The soil is shallow and has moderate moisture (238) while the texture class is loamy sand As for vegetation of this habitat 16 perennial species were recorded and listed in Table 5 The body size of plant species in this habitat appear to be small with a mean height basal diameter and crown area of 139 m 860 cm and 507 m 2 respectively Juniperus procera recorded the greatest height (680 m) and the biggest basal diameter (100 cm) whereas Acacia negrii recorded the greatest crown area (78 29 m~ in this habitat The percentage of plant cover value in this habitat was estimated at each sampling point According to Domins scale the mean estimation was computed to be 433 This value equals 11 to 25 Abundance of species indicated that Acacia arabica (086 100 m2) Lycium shawii (0411100 m2) Acacia gerradii (030 100 m2) Dodonaea

2viscosa (0291 00 m ) Kleinia odora (025 100 m 2)

29308 18835 100 100 100

(0 19 100 m2) and Juniperus procera (0181 00 m2) are very common and widespread species in this habitat Psiadia arabica Leptadenia pyrotechnica Lycium barbanlm Solanum incanum Calotropis procera Langonychium arctum Rhamnus disperma and Mentha lavandulacea are considered common associate components Computation of absolute density (2991 00 m2) indicated that the

distance between perennial species is low nevertheless viewing the plants of this habitat from high stands gives the impression that the absolute density is more than 299100 m2

bull Relative covering value (1833) confirmed what was mentioned above that the body sizes of plant species in this habitat are small Absolute dominance values show that Junipenls procera (332 04 cm21 00 m2) Acacia arabica (40 85 cm2100 m2) Acacia gerradii (3795 cm21 00 m2) Acacia negrii (19 20 cm21 00 m2) and Dodonaea viscosa (1251 cm21 00 m2) are the most dominant in this habitat On the other hand the importance values indicate that Juniperus procera (IV = 83 60) Acacia arabica (IV = 6628) Ly cium shawii (IV = 2971) Acacia gerradii (lV = 281 9) and Dodonaea viscosa (IV = 2197) are the

important perennial species in this habitat

Acacia negrii (024 100 m) Euryops arabicus


Table 5 ofVegetation Data of Mid-Slope Habitat Type NPS number with TNI total number of individuals AS abundance of in 100 m2 AD absolute dominance (cm2 100

m2) AF absolute (percent) RDE = relative RDO dominance RF = relative frequency IV importance value and IVR importance No of points = 60 Absolute (per 100 =299

= 240 Relative Value = 1833 NPS TNI AS AD AF RDE RDO RF IV IVR

1 Acacia arabica 20 69 086 4085 3333 2876 877 2875 6628 2 2 Acacia gerradii 10 24 030 3795 1667 1004 815 1000 2819 4 3 Acacia 10 19 024 1920 1667 803 412 792 2007 6 4 Lagonychium faretum 1 001 007 167 033 002 042 077 16 5 shawii 15 33 OA1 IOA5 2500 1371 225 1375 2971 3 6 Lycium barbanlm 2 3 004 050 333 134 011 125 270 12 7 Solanum incanum 2 3 004 039 333 134 008 125 267 ]3

8 Dodonaea viseosa 13 23 029 1251 2167 970 269 958 2197 5 9 Kleinia odora 9 20 025 369 1500 836 079 833 1748 7 10 arabicus 10 15 019 227 1667 636 049 625 1310 8 11 Psiadia arabica 4 6 007 062 667 234 013 250 497 9 12 Juniperus procera 10 15 018 33204 1667 602 7133 625 8360 1 13 pyrotechnica 2 4 005 069 333 167 015 166 348 10 14 procera 2 3 004 066 333 134 014 125 273 11 15 Rhamnus disperma 001 314 167 033 067 OA2 142 14 16 Mentha lavandulaeea 001 050 167 033 011 042 086 15

Total 240 299 Source work

7- Shoulder Slope Habitat Type

Although many researchers in and environmental have not regarded the shoulder slope as an independent unit and distinct habitat such as Martz and ( 1994)

type of

IS a area

other communities it absolute density

00 ml) and the lowest plant diversity 15 species were recorded in the sampling

points of this habitat) The soil habitat is alkaline in general texture is coarse while its mean is very (233) of plant this habitat seem to be The mean of height diameter and crown area of

plants were found to ml respectively

recorded biggest basal greatest crown area (70714 viscosa recorded

Table 6 15 III the

points of covering value of these species was computed to be 2028 and the

46553 18668 100 100 100

mean vegetation cover value of habitat was estimated according to Domins scale to be 403 which about 4 to 10 Abundance (Table 6) that Acacia arabica

Lycium shawii (0391100 Dodonaea viscosa (0281 00 (0241100

Ewyops In

101100 Solanum incanum (00311 00 Leptadenia

pyrotechnica (003100 m2) Cluytia richardiana

(00211 00 Tephrosia apollinia (00 III00 m2)

and dentata (0011 1 00 m2) are considered

common components III this dominance value Juniperus

procera (7481 00 m) viscosa (1912 cmlIOO Acacia 1 cm2J 00 ml) Acacia arabica (1556 00 m2

) and Acacia negrii (l cmll 00 ml) are the most dominate

in this to computing of

shawii (IV and

are the important in this habitat The other

listed in Table 6 are considered but to a much

50 M H Al-Qahtani

Table 6 Summary of Vegetation Data of Shoulder Slope Habitat Type NPS = number of points with species TNI = total number of individuals AS = abundance of species in 100 mZ AD = absolute dominance (cmZ 100 m) AF = absolute frequency (percent) RDE = relative density ROO = relative dominance RF =

relative frequency IV = importance value and IVR = importance value rank


Acacia arabica 18 66 071 1556 30 00 2741 976 2750 6467 1 2 Acacia gerradii 9 22 024 1841 1500 926 1155 917 2998 5 3 Acacia negrii 5 10 01 J 1385 833 425 869 417 1711 7 4 Tephrosia apolinia 1 001 005 167 039 003 042 084 15 5 Lyeiurn shawii 17 36 039 820 2833 1506 514 1500 3520 3 6 Lyeiurn barbarurn 4 9 010 083 667 386 052 375 813 10 7 Solanum ineanurn I 3 003 032 67 116 020 125 261 12 8 Dodonaea viseosa 13 26 028 1912 2167 1081 11 99 1083 3363 4 9 Kleinia odora 9 20 022 349 1500 849 219 833 1901 6 10 Euryops arabicus 8 17 0 18 251 1333 695 157 708 1560 8 II Psiadia arabica 6 10 011 134 ]000 425 084 417 926 9 12 Junipents procera 10 14 015 7481 1667 579 4691 583 5853 2 13 Lepladenia pyroleehniea 2 3 003 061 333 116 038 125 279 11 14 Lavandula denlala 1 001 013 167 039 008 042 089 14 15 Cluylia riehm-diana 2 2 002 023 333 077 015 083 175 13


8- Summit Slope Habitat Type

In general this habitats soil is partly shallow (mean depth = 2088 cm) alkaline (mean pH = 831) and moist (mean moisture = 253) while its texture is coarse (loamy sand) (AI-Qahtani 1998) The botanical formation of the mountain top habitat differs markedly from the other plant habitats in the area under study Although the mean ground plant cover of this habitat is weak (403 according to Domins scale) the absolute density of perennial species is very high (62211 00 mZ) compared with other habitats in the research area (Fig 5) The distance between trees and shrubs is small The greater plant density can be attributed to augmentation of rainfall amount in this habitat particularly in the south-western mountains and to its remoteness from human activities especially from the grazing in the north-east of the research area The vegetation of this habitat gives the appearance of hats covering the mountain peaks especially in the south-western mountains

According to the mean of trees and shrubs height (127 m) basal diameter (759 cm) crown area (376 m2

) and the relative covering value (3838) it is possible to say that the sizes of this habitats species are moderate Acacia arabica recorded the greatest height (6 56 m) and Juniperus procera recorded the

15946 17667 100 100 100

biggest basal diameter (62 cm) whereas Acacia gerradii recorded the greatest crown area (6898 mZ) in this habitat As listed in Table 7 18 perennial species belonging to 10 botanical families and 15 genera were recorded at the tops of slopes Quantitative analysis (Table 7) of the number of points with species total number of individual abundance of species absolute dominance absolute frequency relative density relative dominance relative frequency and importance value gave the following results

According to abundance of species Acacia arabica (142 I 00 mZ

) Lycium shawii (085 I 00 mZ

) Dodonaea viscosa (073 100 mZ) Kleinia odora

(0 7011 00 m2) Acacia gerradii (04911 00 mZ

)

Euryops arabicus (047 100 m2) and Acacia negrii

(04611 00 mZ) are very common species in summit slope habitats whereas Junipents pro cera (02911 00 m2

) Lycium barbarum (02311 00 m2) Lagonychium

Jarctum (01311 00 m2) Psiadia arabica (0 13 100

m2) Reseda sphenocleoidis (008 I 00 m2

) Solanum schimperianum (00511 00 m2) Periploca aphylla (0051100 m2

) Adenium obesum (005 100 m) Sageretia thea (003 I 00 m ) Rhamnus disperma (0 0311 00 mZ)and Lavandula dentata (003 11 00 m ) are considered common associate components Absolute dominance values show that Juniperus procera (20942 cm2100 m2

) Acacia gerradii

51 Verlical alld Horizonlal Dislribulion

00 m2) Acacia (6569 cm21l 00 = 3410) Acacia 3088) Dodonaea

m2) Acacia (4488 cmz 00 and Lycium viscosa (IV = 2692) Kleinia odora (IV = 2457) shawii cm2100 are the most dominant and Acacia negrii 2414) in the mountain

in this habitat Importance values confinned the area under study other perennial the importance of Acacia arabica (IV 5927) In 7 are considered important

procera (IV 5236) shawii in the research area but to a lesser

Table 7 Summary of Data Summit Habitat NPS number of with TNI = total number of individuals abundance of species in 100 m2

AD absolute dominance 100 m2) AF absolute (percent) RDE relative RDO dominance RF relative frequency IV = importance value IVR = importance value

No of Sampling points 60 Absolute (per 100 m) =622 No of samples 240 Relative Value 3838 No Species NPS TNI AS AD AF RDE RDO RF IV IVR

Acacia arabica 19 55 142 6569 3167 2283 1352 2292 5927 2 Acacia gerradii 8 19 049 7325 1333 788 1508 792 3088 4 3 Acacia negrii 9 18 046 4488 1500 740 924 750 2414 7 4 Lagonychium farctum 3 5 013 133 500 209 027 208 444 10 5 Lycium shawii 17 33 085 3247 2833 1367 668 1375 3410 3 6 Lycium barbarum 4 9 023 205 667 370 042 375 787 9 7 Solanum 1 2 005 047 167 080 010 083 173 16 8 Dodonaea viscosa 12 28 073 1707 2000 1174 351 1167 2692 5 9 Kleinia adora 11 27 070 1004 1833 1125 207 1125 2457 6 10 arabicus 12 18 047 487 2000 756 100 750 1606 8 11 Psiadia arabica 3 5 013 099 500 209 021 208 438 11 12 procera 8 I 029 20942 1333 466 4312 458 5236 2 13 Periploca 2 005 130 167 080 027 083 190 15 14 Sageretia thea I 003 021 167 048 004 042 094 18 15 Rhamnus 1 003 943 167 048 194 042 294 13 16 Reseda 3 008 050 167 129 010 125 264 14 17 Lavandula dentata I 003 038 167 048 008 042 098 17 18 Adenium obesum 2 005 1139 167 080 235 083 398 12

Total 240 622 48574 18835 100 100 100 Source work

45 40 35 30 25 20 15 10 5 0-+---shy

Habitat

5 Absolute of perennial In

the botanical habitats in the research area

P-Slope S-Slope M-Slope F-Slope T-Slope

Habitat

4 Relative covering value of perennial vegetation in the research area

52 M H AI-Qahtani

Conclusions

From the foregoing it emerges that the vegetation of the area under study is associated clearly with numerous environmental parameters such as topography altitude soil condition and moisture amount (Alwelaie et al 1993) as well as other climatic and human factors These circumstances and factors influence the distribution establishment growth and regeneration of the plants (Batanouny 1987) and have produced different plant shapes inside the research area (Bloot 1996 EI-Demerdash et al 1994) The following paragraphs summarize the main findings of this research

The composition and distribution of vegetation reflect the conditions ofthe environmental factors in the research area The soil topography and climate of the south-western part (or mountainous plant community) differ widely from those of the semishydesert plant community located in the north-eastern part This is due to the high altitude (2000-3130 m asl) of the former area with its consequences for air temperature and to relatively high rainfall without a prolonged dry period as in the semi-desert plant community The vegetation density in the southshywestern part (3 01 100 m2) is higher than that in the north-eastern part (246 I00 m2) Also the vegetation density in the upper slope segments namely summits and shoulders of slopes (4411100 m2) is higher than that in the lower slope segments namely toes and feet of slopes (287 100 m2)

As mentioned earlier due to the greater precipitation amount on the habitat of peak-slopes the absolute density of this habitat (622100 m2) is more than double the absolute density in any other habitat while the shoulder slope habitat recorded the lowest absolute density (2591 00 m2) The toeshyslope habitat foot-slope habitat and mid-slope habitat also had a relatively low density (2 95 I00 m2 278100 m2 and 299 100 m2 respectively) As can be seen from Fig 4 the relative covering values in the toe-slope habitat (440 I) and peak-slope habitat (3838) are high compared with other habitats The augmentation of relative covering value in these two habitats is imputed mostly to individual sizes in toe-slope habitat and the greater plant density in the peak-slope habitat

The height of plants is one of the important botanical components that comprise the life-form of individuals As said before and as can be noted from Fig 2 the individuals of the toe-slope habitat are characterised by large breadth and height The mean of perennial plant heights in this habitat is 233 m whereas it ranges between 107 to 139 m in the

other habitats One of the main reasons why plants in the toe-slope habitat flourish is the soil conditions the soil is deeper and more moist than in the other habitats These conditions enable the individuals to extend their roots faraway to stabilize themselves and to obtain water In addition the lower elevation and low wind speed in this habitat has allowed the plants to grow more and achieve greater height (Abulfatih 1981 amp Al-Qahtani 1998)

Mean basal diameter again confirmed the distinctiveness of toe slope habitat plants It is considered very high in this habitat (1543 cm) compared with the mean basal diameter in the other habitats Probably the augmentation of mean basal diameter in the toe-slope habitat is related to the concentration in this habitat of Acacia spp which have big stems as well as to availability of other environmental factors such as moisture soil depth and conservation As can be seen from Fig 3 the means of plant basal diameters in the other habitats are moderate to small

From the findings of this research and the review of available literature on the research area and on Saudi Arabia as a whole the following recommendations for the conservation and protection of natural vegetation are summarised and offered belowshy

1- The successful method of conservation (the hema system) that was adopted over a very long period of time by the tribes in the AI-Hejaz and Assir regions to protect the trees shrubs and pastures should be reapplied with some modifications to be appropriate to the present time (eg cancellation of tribal quality)

2- Cutting green trees and shrubs should be prevented completely by enforcement of laws prohibiting it Alternative sources of fuel (eg Gas) should be provided by the Government in the markets If no alternatives are available the inhabitants of Assir mountains will be forced to obtain fuel from Acacia arabica Acacia gerradii Acacia negrii and Juniperus procera

3- Road-building should avoid the areas dense in vegetation Roads could however be established across the valley course sides which are usually bare of vegetation cover

4- Reforestation and planting of trees and shrubs that are well adapted to the environmental conditions of Assir mountains such as Tamarix aphylla Olea europaea and Acacia negrii should be encouraged


References

Abulfatih (198 Plant Ecology of National Asir Province Saudi

of Saudi Biology Society 5 131-141 (1981 Wild Plants of Abha and its

IfC)CeleQllngs of Saudi 5 143-159

Abulfatih (1984) Elevationally Restricted Flora Elements of the Asir Mountains Saudi Arabia 1 ofAsid Environment 7 35-41

(1984) Wild Plants from Abha and its Saudi House for Publication

and Distribution Saudi Arabia Jeddah 125 pp Abulfatih ( Medical Plants from Southshy

west of Saudi Arabia (in Arabic and AI press Khamis Mushayt 153 pp

AI-Aodat M Abdullah A and AI Sheikh A (1985) or- King Saud Publication

326 pp M (1991) Effect of Soil Characteristics

on Morphology of Wood-plant in Wadi Wad Saudi Arabia MA thesis of

Saud 155 pp M (I An Assessment of the

Between the Surface Soil DNn~rtgt Compommts of Slope and in the

Wadi Bishah Basin Saudi Arabia PhD thesis (unpublished) Faculty of Science and Environment Hull 35 pp

AI-Shareef A (1994) Geography of Saudi Asabia (Vol 1 ) (in Arabic) Dar Al Marrikh AI Riyadh Saudi Arabia 383 pp

Choudary and AI Y VC)~ltCllRJ1l of Some Red Sea Islands of the

of Saudi Arabia J of Arid Environments 24 287-296

t n K (1987) Current of Plant in the Asabian Gulf

291-315 (1907) The Flora of Aden 1 of

History ] 7 895-920 (1996) Plants of species in monkey

stomachsOkad No 10946 W amp Mandil Vegetation

in the Asir Woodlands of South-western Saudi Arabia Journal of Arid 6 357-362

Derose R Trustrum and Blaschke P (1993) Post-Deforestation soil loss from steepland hills lopes in Taranaki New Zealand Earth Surface Processes and Landfonns 18 131 144

(1931-1932) Les elements et les groups auxiliaries dans la flora

v 2 Feddes Beih 63 I 201 120 Tafl

(I A essay on Palestinian forests of L ssp itbaburensis (Desc) in and present Beih Botcbl Abt B 51 225-272

EI-Demerdash Hejazy A and (1 Distribution of the Plant Communities in Tihamah Coastal Plains of Jizan Region Saudi Arabia 1 of 112 (2) 141-151

EI-Demerdash M amp Zilay (1994) An introduction to the Plant Ecology of Tihamah Plain

Saudi Arabia Arab Gulf J 12 285-299

and A Practical London 363 pp

Konig (1988) Phytogeography of South-western Saudi Arabia Die Erde 119 75-89

Makhnach (1994) Distribution of Minerals of the Fine-sand fraction in slope soil of Eurasia Soil 26 (8) 57-66

The variation of soil erodibility with in a cultivated Canadian Prairie

landscape Earth Surface Processes and 17 543-556

(I 980a) Natural vC)CLlVIl

(in Asabic)Al Majallah Al (Asabic Journal) 5 32-43

I~nh A (1980b) Natural (in Asabic)AI Journal) 6 40-47

A (1988) Flora of Saudi Arabia 3rd ed Saud Publication AI

Mueller-Dombois D amp (I Aims and Methods of Vef1eUlti John Wiley and New York 547 pp

Schmidt Dj Hadley Dj W Gonzales Coleman R and Brown (1973) Stratigraphy and tectonism of the southern part of the Precambrian shield of Saudi Arabia Dir Gen Mineral Resources Min Bull 8 13 Jeddah

J Renard C and Lane ( distribution of surface rock along catenas in semi-arid Arizona and USA Catena 23 29-42

Soil Survey Staff (I to Soil Soil Management Monograph No 19 ed) Pocahontas Blacksbury Virginia 541 pp

Takhtajan A (986) Floristic Regions of the world (Translated 1 Crovello) of California Los Angeles 208 pp

Tarzi J (I Procedures for Collecting Soil Samples for Different Under the Condition of the English and Ministry Water Directorate of Agricultural Research Al Riyadh Saudi Arabia 50 pp

Zohary M (1973) Geobotanical foundations of the Middle 2 vots Gustav Fischer 244 pp

PCPfPI1 23022000 In revised fonn 1911212000)

42

distributed through the rainy season and takes place mainly during the spring months (AI-Qahtani 1991) High mountains in the area receive rainfall throughout the year but rainfall reaches its peak in the spring season The subregions in the Arabian peninsula are mainly characterized by temperatures that are high enough to support a tropical vegetation

Within the study area ecologists and phytogeographers have indicated in brief comments that this area is an important part of Saudi Arabia in terms of the magni tude of its vegetation cover Some of these studies have described the vegetation of this area as follows

Brooks amp Mandil (1983) studied the Vegetation Dynamics in Asir Woodlands and reported the following

In Saudi Arabia the greatest number of plant species is found in the highlands of the south and south-west where East African vegetation contributes to the character of the region Fortyshyfour per cent of the flora in southern and southshywestern Arabia represents Sudanian elements found in the altitudinal zonation of the savanna scrub and the montane woodlands

Konig (1988) investigated the Phytogeography of South-western Saudi Arabia and described the vegetation in the study area as follows

The vegetation of the study area is climatically influenced and characterized mainly by forest woodland and xeromorphic woodland communities - in contrast to the central parts of the Arabian peninsula which are dominated by dwarf-shrub communities grassland and deserts

This study amis to investigate and analyse in detail the perennial vegetation of the research area in terms of the morphology ecology and distribution and their relationship with slope habitats Investigation and analysis of the above points is based on data of vegetation slope and soil samples that were collected from 300 quadrats from the research area

Materials and Methods

Sixty transects were selected systematically as profile lines along the eastern slopes of Assir mountains Each transect started from a specific measured point on the lower slope and crossed the facing slope to the edge of the mountains The distance between transects was 5 km Each transect was subdivided into five slope units from the ridge to the toe summit shoulder mid-slope foot-slope and toe-slope These units covered all the

M H Al-Qahlani

physiographic and physiognomic variations of the region Selection of these units which can be seen every where depended on variation of vegetation distribution slope gradient and form with soil uniformity Sample collection sites were established in the centre of each slope unit on each transect According to ecologists and pedologists the best time for gathering samples of soil and vegetation is after rain period which stretches from November until the end of May As a result of this fieldwork was carried out in the period June to August 1999 The point-centred quarter method (Kent amp Coker 1992) which is widely used for the sampling of gradient vegetation in forest and woodland ecosystems as well as in sparsely-vegetated areas was applied at the centre of these units In other words this technique was used to measure investigate and analyse the perennial plants in 300 sites In each site slope factors (slope angle slope gradient and slope length) and vegetation components (height basal diameter basal area crown area absolute density relative covering value number of points with particular species total number of individuals abundance of speciesll 00 m2

absolute dominance absolute frequency relative density relative dominance relative frequency and importance value) were measured and computed and soil samples (soil depth soil moisture texture class pH and organic matter) and plants were collected and analysed This technique has proven to be sufficient and effective in previous investigations of vegetation status and its relationship with slope and soil factors such as Mueller-Dombois amp Ellenberg (1974) Kent amp Coker (1992) Martz (1992) Derose et al (1993) Makhnach (1994) and Simanton et al (1994) Plant species and nomenclature were identified in situ in most of the studied sites by the means of the available scientific references on the flora of Saudi Arabia and its surrounding countries such as Abulfatih (1984 1987) Al-Qahtani (1991 1998) Blatter (1907) and Migahid (1980 1988) The other species were identified via collecting samples from fresh branches and transfer them to the herbarium The all procedures suggested by Tarzi (1984) were applied in the collecting and preparation of soil samples which were analysed according to the procedures that were suggested by soil survey staff (1992) and are applied at laboratories of King Saud University and the National Agriculture and Water Research Centre Saudi Arabia


The Study Area

between 41 0



S A U D I A bull














(2000-3130 m






44 M H Al-Qahtani










Total 600 301 40242 19601 100 100 100




45






















RDE = relative RDO




46





M H Al-Qahtani


)









47




100 m2 0461100 m2

041100 O 6100 m2






Total 240 295 57777 8004 100 100 100


Habitat Habitat












grazing which

48 M H Al-Qahtani








29308 18835 100 100 100















type of

IS a area






Table 6 15 III the


46553 18668 100 100 100



Ewyops In









shawii (IV and



50 M H Al-Qahtani










15946 17667 100 100 100






)








) Acacia gerradii











45 40 35 30 25 20 15 10 5 0-+---shy

Habitat




Habitat


52 M H AI-Qahtani

Conclusions













References















































The Study Area

between 41 0



S A U D I A bull














(2000-3130 m






44 M H Al-Qahtani










Total 600 301 40242 19601 100 100 100




45






















RDE = relative RDO




46





M H Al-Qahtani


)









47




100 m2 0461100 m2

041100 O 6100 m2






Total 240 295 57777 8004 100 100 100


Habitat Habitat












grazing which

48 M H Al-Qahtani








29308 18835 100 100 100















type of

IS a area






Table 6 15 III the


46553 18668 100 100 100



Ewyops In









shawii (IV and



50 M H Al-Qahtani










15946 17667 100 100 100






)








) Acacia gerradii











45 40 35 30 25 20 15 10 5 0-+---shy

Habitat




Habitat


52 M H AI-Qahtani

Conclusions













References














































44 M H Al-Qahtani










Total 600 301 40242 19601 100 100 100




45






















RDE = relative RDO




46





M H Al-Qahtani


)









47




100 m2 0461100 m2

041100 O 6100 m2






Total 240 295 57777 8004 100 100 100


Habitat Habitat












grazing which

48 M H Al-Qahtani








29308 18835 100 100 100















type of

IS a area






Table 6 15 III the


46553 18668 100 100 100



Ewyops In









shawii (IV and



50 M H Al-Qahtani










15946 17667 100 100 100






)








) Acacia gerradii











45 40 35 30 25 20 15 10 5 0-+---shy

Habitat




Habitat


52 M H AI-Qahtani

Conclusions













References














































45






















RDE = relative RDO




46





M H Al-Qahtani


)









47




100 m2 0461100 m2

041100 O 6100 m2






Total 240 295 57777 8004 100 100 100


Habitat Habitat












grazing which

48 M H Al-Qahtani








29308 18835 100 100 100















type of

IS a area






Table 6 15 III the


46553 18668 100 100 100



Ewyops In









shawii (IV and



50 M H Al-Qahtani










15946 17667 100 100 100






)








) Acacia gerradii











45 40 35 30 25 20 15 10 5 0-+---shy

Habitat




Habitat


52 M H AI-Qahtani

Conclusions













References














































46





M H Al-Qahtani


)









47




100 m2 0461100 m2

041100 O 6100 m2






Total 240 295 57777 8004 100 100 100


Habitat Habitat












grazing which

48 M H Al-Qahtani








29308 18835 100 100 100















type of

IS a area






Table 6 15 III the


46553 18668 100 100 100



Ewyops In









shawii (IV and



50 M H Al-Qahtani










15946 17667 100 100 100






)








) Acacia gerradii











45 40 35 30 25 20 15 10 5 0-+---shy

Habitat




Habitat


52 M H AI-Qahtani

Conclusions













References














































47




100 m2 0461100 m2

041100 O 6100 m2






Total 240 295 57777 8004 100 100 100


Habitat Habitat












grazing which

48 M H Al-Qahtani








29308 18835 100 100 100















type of

IS a area






Table 6 15 III the


46553 18668 100 100 100



Ewyops In









shawii (IV and



50 M H Al-Qahtani










15946 17667 100 100 100






)








) Acacia gerradii











45 40 35 30 25 20 15 10 5 0-+---shy

Habitat




Habitat


52 M H AI-Qahtani

Conclusions













References














































48 M H Al-Qahtani








29308 18835 100 100 100















type of

IS a area






Table 6 15 III the


46553 18668 100 100 100



Ewyops In









shawii (IV and



50 M H Al-Qahtani










15946 17667 100 100 100






)








) Acacia gerradii











45 40 35 30 25 20 15 10 5 0-+---shy

Habitat




Habitat


52 M H AI-Qahtani

Conclusions













References























































type of

IS a area






Table 6 15 III the


46553 18668 100 100 100



Ewyops In









shawii (IV and



50 M H Al-Qahtani










15946 17667 100 100 100






)








) Acacia gerradii











45 40 35 30 25 20 15 10 5 0-+---shy

Habitat




Habitat


52 M H AI-Qahtani

Conclusions













References














































50 M H Al-Qahtani










15946 17667 100 100 100






)








) Acacia gerradii











45 40 35 30 25 20 15 10 5 0-+---shy

Habitat




Habitat


52 M H AI-Qahtani

Conclusions













References
























































45 40 35 30 25 20 15 10 5 0-+---shy

Habitat




Habitat


52 M H AI-Qahtani

Conclusions













References














































52 M H AI-Qahtani

Conclusions













References















































References














































Vertical and Horizontal Distribution of Vegetation ...

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