Plant Communities and Floristic Composition of the Vegetation of Wadi Al-Assiuty and Wadi Habib in the Eastern Desert, Egypt

Torrential rains (in January 2011) that have swept a limited area in the Eastern Desert, facing Assiut Province (Upper Egypt), resulted in enriching the vegetation in Wadi Al-Assiuty and its tributary Wadi Habib. Vegetation survey carried out shortly after this event (in May) revealed the prevalence of annuals which are hardly recognizable in such usually dry habitats. The normally scarce perennial vegetation has flourished. A total of 66 plant species, 33 perennials and 33 annuals, belonging to 53 genera from 22 different families were recorded. Therophytes are the predominant life form (50%) followed by chamaephytes (21%), phanerophytes (15%), hemicryptophytes (11%) and geophytes (3%). Chorological analysis revealed that Saharo-Arabian (81.8%) constitute the main bulk of the total flora of the studied area. The majority of the perennial species behave similarly to each other in their phenology, and usually perennials sprout at the end of February, become leafy in March, flower in April and produce fruits between April and July. The investigation revealed that the wadis studied are potential shelters of four vegetation groups. Twenty two of the recorded species (33.3%) are omnipresent and had a dominant degree of occurrence (Q-value ≥ 0.2). The highest among others were Zilla spinosa and Zygophyllum coccineum which recorded in 86% and 88% respectively of the studied stands and spread their dominancy all over the Eastern Desert of Egypt.


Introduction Introduction Introduction Introduction
The Eastern Desert of Egypt extends between the Nile Valley and the Red Sea. It is traversed by numerous canyonlike depressions (wadis) running to the Red Sea or to the Nile Valley. Wadi Al-Assiuty is one of the most notable features of the Egyptian Eastern Desert. It is the largest and greatest dry valley which runs in Sahara desert for a distance of about 115 km. Its width varies from 5 to 25 km. Although this wadi is generally dry all over the year, some seasonal rainfall is experienced in winter time, which may occasionally become torrential in autumn and spring times.
The main trunk of wadi Al-Assiuty has an east-west orientation extending between latitude 27°10' and 27°20' N. Its tributaries cover an area between longitudes 31°16' and 31°50' E ( Fig. 1). The main wadis, which debouch their water in wadi Al-Assiuty are: wadi Hubara, wadi Qird El-Farr from north and wadi Marahil, wadi Habib from the south (Said, 1962;Abu Al-Izz, 1971). Due to the variety of chances of water feeding of the tributaries of Wadi Al-Assiuty originating in the mountain range of Red Sea and pouring their flood waters into its principle channels, difference in floral characteristics and vegetation composition are something expectable. Kassas and Girgis (1972) studied the ecology of Wadi Al-Assiuty among other wadis in the region between latitude 27°30 ' and 25°30' N. Abd El-Wahab (1963) studied the Autecology of Leptadenia pyrotechnica in wadi Al-Assiuty. Migahid et al. (1972) and Batanouny (1973) investigated Eco-Phsiological characters of desert plants in Wadi Al-Assiuty. El-Khatib (1993) studied the ecophysiology and palynology of the vegetation of wadi Al-Assiuty and Wadi Qena based on recent floristic investigations by the author.
Phenological studies provide information on functional rhythms of plants and plant communities (Ralhan et al., 1985). Moreover, various phenological events may be timed to biotic and/or abiotic environmental conditions (Estabrook et al., 1982;Lee, 1971). It was also reported by Nilsen (1981) that desert plants exhibit phenologies that are closely related to moisture availability and temperature, as well as photoperiod and nutrient input (Abdel-Razik, 1980). The phenological cycles may represent physiological and morphological adaptations by species to utilize resources (Kemp and Gardetto, 1982;Salama et al., 2012).
In last decades, Wadi Al-Assiuty was affected by human activities including; cultivation of the deltaic part, the intensive collection of plant species for its values (medicinal, fuel, fiber etc.), establishment of new Assiut city, new high ways, farms and others. These activities affect the natural flora and changing the distribution of plants in Wadi Al-Assiuty. This means great changes in the distribution, species richness and extinction of the floristic composition of Wadi Al-Assiuty.
Torrential rains (in January 2011) that had suddenly swept a limited area in the Eastern Desert facing Assiut Province (Upper Egypt) resulted in enriching the vegetation of some extremely dry wadis at this location. This leads to the prevalence of annuals and the flourishing of the scarced perennial vegetation (El-Sharkawi et al., 1982 a, b;Salama et al., 2013). It is worthy to mention that the last torrent sudden in this wadi was at 1994. This reflects the high aridity in the studied wadis.
Such an event was the inspiration to carry out this study with the aim of recognizing the potential of natural vegetation in the wadis as a result of an unexpected water supply. The plant communities and its associated species were investigated. This study deals with analyses of floristic composition, life forms, phenology, chorological spectrum, and analyses the vegetation inhabiting the deltaic part and the principal channel of Wadi Al-Assiuty and Wadi Habib.

Materials and methods Materials and methods Materials and methods Materials and methods
Wadi Al-Assiuty is easily traversable by vehicle. The study was carried on two successive years: 2011-2012. The studied stands were randomly chosen at locations where considerable vegetation cover was encountered. Based on presence/absence of each species, 50 stands were studied in the deltaic part, and along the main trunk of the Wadi Al-Assiuty and Wadi Habib, and geo-referenced using GPS technique (Fig. 1). Meteorological data obtained from the Assiut University station at Assiut, through the last ten years (2003 to 2012) showed the temperature is regular in its seasonality. The average lowest minimum temperature through the last ten years is 8 °C recorded in January and the average highest maximum temperature is 39 °C recorded in June. The highest mean relative humidity in the study area is 50% recorded in December and the lowest mean is 24% recorded in May.
Ten species were selected randomly to study their phenological characteristics through one year, from January 2012 to December 2012. The species were Acacia niotica, Acacia raddiana, Calotropis procera, Datura innoxia, Leptadenia pyrotechnica, Ochradinus baccatus, Tamarix aphylla, Tamarix nilotica, Zizyphus spina-christi and Zygophyllum coccineum. Four phenophases were distinguished: vegetative, flowering, fruiting and seed dispersal and were recorded monthly. The recorded species are classified according to their life forms (Hassib, 1951;Raunkiaer, 1937). The number of species within each life form is expressed as a percentage of the total number of species in the study area. Plant specimens collected were identified and deposited at the herbarium of the Botany Department of Assiut University. Identifications were done according to Täckholm (1974) and Boulos (1995Boulos ( , 1999Boulos ( , 2000. Duplicates were checked for identification and deposited at the Cairo University Herbarium. Analysis of phytogeographical ranges was carried out according to Zohary (1966Zohary ( , 1972Zohary ( , 1973, Abd El-Ghani (1981) and Hassan (1987). A floristic data matrix of 50 stands and 66 species was subjected to classification by cluster analysis of the program Community Analysis Package (CAP) version 1.2 (Henderson and Seaby, 1999) using squared Euclidean distance dissimilarity matrix with minimum variance (also called Ward's method) as agglomeration criterion (Orlóci, 1978).
Results and discussion Results and discussion Results and discussion Results and discussion

Floristic composition
The floristic composition of the species showed that 66 plant species were recorded in Wadi El-Assiuty and Wadi Habib. They include 33 perennials and 33 annuals, belonging to 53 genera from 22 different families (Tab. 1). The largest family was Asteraceae, which included 11 genera and 14 species. Six of them were perennials and the others were annuals (Tab. 1). The second family was Chenopodiaceae with six genera and eight species. Four of them were annuals and four were perennials. Brassicaceae, Boraginaceae and Zygophyllaceae had the same number of the recorded species (five for each). Family Brassicaceae included one perennial and four annuals. Family Boraginaceae have two perennial and three annuals. Family Zygophyllaceae included four perennials and one annual. Two genera and four species were recorded for family Fabaceae. Three of them were annuals and one was perennial. Four species were recorded as members of the Poaceae family. They were included in four genera. All of them were perennials except Avena sterilis, which was annual. For each of the Malvaceae, Polygonaceae, Resedaceae, Solanaceae, Mimosaceae, Tamaricaceae families two (for each) species were recorded. One genera belonged to family Tamaricaceae, was represented by two perennial species, Tamarix aphylla and Tamarix nilotica. One genera belonged to Mimosaceae family represented by two perennial species: Acacia nilotica and Acacia tortilis. The other families were represented by only one species, each. The largest genera were: Astragalus, Fagonia and Pulicaria, which include three species. Six genera, represented by two species: Launaea, Bassia, Helliotropium, Chenopodium, Acacia and Zygophyllum. Other genera were represented by one species, each (Tab. 1).  Fig. 2 shows the life forms of the recorded plant species according to Raunkiaer (1937). The total number of species in the study area was 66, which belong to five different life forms. Therophytes (50%) constitute the largest number of species (33 species). Chamaephytes had 21% including 14 species. Phanerophytes have 10 species represent about 15% of the flora. Hemicryptophytes represent about 7 % of the flora including 11 species. Geophytes (3%) are represented by two species; Cynodon dactylon and Panicum turgidum.

Chorological affinities
Results of the total chorological analysis of the surveyed flora presented in Fig. 2 revealed that 28 species belonging to monoregional region representing 42.4% of the total recorded species. There were 26 species recorded as Saharo-Arabian species (39%); while Hibiscus trionum belonging to Irano-Turanian region (2%) and Ammi majus belonging to Mediterranian region (2%). A total of 28 species are biregional elements representing 42.4% of the recorded species. It comprises the following four regions as followes: nine species belonging to the Saharo-Arabian, Sudano-Zambezian regions representing 14% of the recorded species. Mediterranian, Irano-Turanian regions, represented by five species, formed 8 % of the recorded species. Ten species, belonging to the Saharo-Arabian, Irano-Turanian regions represented 15% of the recorded species. Four species belonging to the Saharo-Arabian, Mediterranian region consist 6% of the recorded species. A total of five species (7.6% of the recorded species) are Pluri-regional taxa of wide geographical range. They were as follows: Centaurea calcitrapa, Imperata cylinderica, Matthiola longipetala, Tamarix aphyllaand Tamarix nilotica. Cynodon dactlyon is the only species representing pantropic floristic region. Four species were recorded as cosmopolitan taxa comprising 6.1% of the recorded species.

Species distribution pattern
Data of Tab. 1 revealed that four of the recorded species are omnipresent. Zygophyllum coccineum has presence value equal 88% and recorded in 44 studied stands in the study area. Zilla spinosa was recorded in 43 stands of 50 studied stands giving presence value 86%. Calligonum polygonoides has presence value 74% and recorded in 37 stands. Cornulaca monacantha was recorded in 35 stands giving presence value 70%.On the other hand, Matthiola longipetala, Atriplex halimus and Cotula cinarea showed the highest presence estimated among annuals (P=68%, 60% and 56%) respectively. Matthiola longipetala appeared in 34 stands, where Atriplex halimus appeared in 30 stands and Cotula cinarea was detected in 28 stands. Artemisia judaica and Eremobium aegyptiacum appeared in 27 stands giving P=54%. Diplotaxis acris and Tamarix nilotica recorded in 26 stands (P=52%). Fagonia arabica and Bassia indica presented in 23 stands (P=46%). 33 species or about 50% of the total recorded species are perennials, demonstrated a constant degree of constancy, while the other 33 species, 50% of the total recorded species, are annuals most of them recorded after 2011 rainfall. The presence of Tamarix aphylla, Tamarix nilotica, Salsola imbricata and Atriplex halimus refers to salinization.

Phenological pattern
As shown in Fig. 3, Acacia nilotica started the vegetative growth from July to October. Flowering is in October to December period. The plant began fruiting in January to `May. In about six months from January to June, Tamarix aphylla completes its vegetative growth. Flowering occurs in two months; July and August. Fruiting takes two months also; September and October. Finally seed dispersal occurs in November and December. Tamarix nilotica grows vegetatively from March to August. Flowering occurs in two months from September to October. Fruiting occurs in two months; November and December, seed dispersal in January and February. Zizyphus spina-christi grows vegetative from August to September. Flowering starts in October to mid of November. Fruiting starts in late of November to May. Seed dispersal occurs in June and July. Zygophyllum coccineum starts its vegetative growth from August to December. Flowering occurs from January to March. Fruiting takes two months, from April to May. Seed dispersal occurs after fruiting and lasts to July.
Vegetation structure (Classification of vegetation) Application of classification using cluster analysis to the floristic data of Wadi El-Assuity yielded four vegetation groups (Fig. 4). Most of the groups (A) and (B) stands were confined to the main trunk of Wadi El-Assuity, while those of groups (C) and (D)    The present study comprises an ecological survey in Wadi Al-Assiuty and its tributary Wadi Habib in the Eastern Desert of Egypt. The impact of extreme aridity and the scanty rains in Wadi Al-Assiuty and its tributaries is quite clear from the poverty of species encountered. The plant species collected from the study area of Wadi Al-Assiuty included 66 species, 33 perennials and 33 annuals, belonging to 53 genera from 22 different families. Most of the collected annuals were recorded after 2011 rainfalls. The largest family was Asteraceae which represented by 14 species (21.2% of the recorded species), followed by family Chenopodiaceae which represented by eight species (12.1%). It may be noted that the deltaic part of Wadi Al-Assiuty and a great part of its main course are parts of a great bay fringing the Nile Valley. The near of underground water reservoir from the surface in this area, at depth 2-5 m (Kassas and Girgis, 1972) is obviously an important source of water for plants with deep roots (perennials).
Results of the total chorological analysis of the surveyed flora (Fig. 2) revealed that 28 species (42.4% of the total flora) are mono-regional, of which 26 species (39.4%) are native to the Saharo-Arabian chorotype. Cosmopolitan ranked second with 3.1%. About 50% of the recorded species are 33 bioregional and pluri-regional, extending their distribution all over the Saharo-ArabianSudano-Zambezian, Irano-Turanian and Mediterranean regions. The Saharo-Arabian chorotype (bi-and pluri-), part of the Saharo-Arabian region, constitutes 34.8% and 7.6%, respectively, of the recorded species (total 81.8%) and it forms the major component of the floristic composition of this study. These results coincide with Hassan (1987), Sheded (1992) and Fossati et al. (1998).
The phenological events of perennials are fairly constant regardless of the rainfall. This is because these plants depend on a permanent source of the underground water. The majority of perennial species behave similarly to each other in their phenology. Usually perennials sprouted in the end of the month of February and become leafy in March, flowered in April and produced fruits between April and July (Abd El-Rahman and Batanouny, 1959;El-Adawy, 2001;Salama et al., 2013).
In their detailed study on the plant communities in the vicinity of this study area, El-Sharkawi et al. (1982a) described three major community types. The first included Zilla spinosa, Zygophyllum coccineum, Schouwia thebaica, Zygophyllum simplex, Cotula cinerea, Salsola baryosma, Pulicaria undulata, Tribulus pentandrus, and Launaea capitata. Certainly, the identified vegetation group B belongs to these community type. Kassas and Girgis (1972) stated that the plant growth in WAdi Al-Assiuty and Wadi Habib differes in obvious relations to the size of the catchment area. They recognized also Zilla spinosa, Zygophyllum coccineum, and Leptadenia pyrotechnica community types among other communities recorded in the studied wadis.