Ecological Study on Zygophyllum coccineum L. in Coastal and Inland Desert of Egypt

Zygophyllum coccineum is very common plant in the limestone wadies and plains of the Eastern (Arabian) desert of Egypt and shows wide soil range. The present study provides an analysis of floristic composition and vegetation types of Z. coccineum at 60 sites in coastal and inland desert of Egypt, emphasizing the environmental factors that affect species distribution. A total of 79 species of the vascular plants (39 perennials, one biennial and 39 annuals) belonging to 63 genera and related to 24 families. Asteraceae, Chenopodiaceae, Poaceae, Cruciferae and Zygophyllaceae are the largest families. Therophytes and chmaephytes are the most frequent, indicating a typical desert life-form spectrum. Chorological analysis of the study area revealed that 40.51% of the total species are Mediterranean taxa and 30.38% is Monoregional Saharo-Sindian. After application of the TWINSPAN and DCA, four groups (A-D) were identified and they were named after the characteristic species. Each group occupied a distinct type of habitats. Z. coccineum is assigned as dominant species in groups A and B or indicator species in groups C and D. Sodium, magnesium, SAR, PAR, EC and pH were the most effective soil factors on the spatial distribution of plants Original Research Article El-Amier et al.; JAERI, 6(4): 1-17, 2016; Article no.JAERI.22640 2 which showed high significant correlations with the first and second axes of CCA ordination diagram.


INTRODUCTION
Zygophyllaceae (Caltrop family) is a family with approximately 25 genera and 240 species adapted to semi desert and Mediterranean climates [1]. Species belonging to this genus represent a group of succulent plants that are drought resistant and/or salt tolerant, living under severe, dry climatic conditions. The abundance of species related to this genus could be attributed to their high tolerance to environmental stresses in addition to their unpalatability. The growth and distribution of Zygophyllum species are attributed to their dependence on the chemical nature of the soil of their habitats [2].
Zygophyllum coccineum is the most widespread Zygophyllum species in Egypt and Saudi Arabia, where it occupies diverse habitats and shows wide soil range. The plant is very common in the limestone wadies and plains of the Eastern (Arabian) desert and tolerant of saline soils. It is a small perennial herb with fleshy leaves and somewhat whitish flowers of saline and sandy habitats near the sea. Its flowering time is starting from October to November [3].
The Egyptian deserts are classified ecologically into: coastal and inland deserts. The coastal deserts are associated with and affected by the Mediterranean, Red Sea and the two Gulfs of Sinai. The inland deserts are those far from the effects of the seas including the oases [4]. The Deltaic Mediterranean coast of Egypt comprises four main habitats: salt marshes, sand formations, reed swamps and fertile noncultivated lands [5].
The desert vegetation in Egypt is the most important and characteristic type of natural plant life. It is mainly formed of xerophytic shrubs and sub-shrubs. The Egyptian desert is one of the most arid parts of the world characterized by arid and/or extreme arid climate. The perennial plant cover forms the permanent framework of the desert vegetation and is the best indicator of the habitat conditions [4].

Studied Areas
The Deltaic Mediterranean coastal land of Egypt extends from Abu-Quir (in the west, Long. 32°19' E) to Port-Said (in the east Long.31°19' E) with a length of about 180 km, and with a width in a N-S direction for about 15 km from the coast [20,4]. On the other hand, Cairo-Suez desert road is located in the northern part of the Eastern Desert of Egypt (Galalah Desert) extends for about 130 Km long. This locality represents the natural xeric habitat which is mainly inhabited by xerophytic vegetation. The gravel desert is one of the most characteristic features of this road.
According to the map of the world distribution of arid regions, the climate of the whole stretch of the Mediterranean coastal desert is, generally, less arid than the remaining southern parts of Egypt [21]. The climatic conditions are warm summers (20-31°C) and mild winters (10-20°C). Relative humidity ranges from 76% to 74% in January and 83% to 75% in July. On the other hand, the climate of the Red Sea coastal land of Egypt is arid. Temperature is high and ranges between 14 and 21.7°C in winter and 23.1-46.1°C in summer. Relative humidity ranges from 43% in summer to 65% in winter. The mean annual rainfall ranges from 25 mm in Suez to 3.4 mm in Qusseir [4].

Estimation of Species Abundance
Sixty stands (10×10 m) were selected in coastal (Deltaic Mediterranean coast) and inlands desert (Cairo-Suez desert road) of Egypt. These stands were chosen to cover different habitat types supporting the growth of Z. coccineum. The density of each plant species was measured by counting the number of individuals of the species within randomly stands [22]. The plant cover of each species in the surveyed stands was measured by using the line intercept method [23]. Relative values of density and cover were calculated and estimate of its importance value (IV=200) for each plant species in each stand. The description and classification of life-forms in the present study were carried out according to Raunkiaer [24]. The nomenclature and identification of the recorded species were done according to Boulos [25].

Laboratory Analysis
For physical and chemical analysis, one composite soil sample was collected from each stand (profile 0-50 cm). Soil texture, soil porosity, water-holding capacity, oxidizable organic carbon, calcium carbonates, chlorides, sulphats, carbonates and bicarbonates were determined according to Piper [26], Jackson [27] and Pierce et al. [28]. Electrical -pH meter with glass electrode was used to determine the soil reaction. Conductivity was expressed as µmhos/cm and measured by YSI Incorporated Model 33 conductivity meter. Concentrations of the cations Na + and K + was estimated using Flame photometer [29]. Ca ++ and Mg ++ were determined by using atomic absorption spectrophotometer (A Perkin-Elemer, Model 2380, USA). Sodium adsorption ratio (SAR) and potassium adsorption ratio (PAR) were calculated according to McKell and Goodin [30].

Multivariate Analysis
Two trends of multivariate analysis were applied in the present study namely classification and ordination. The classification technique was the Two Way Indicator Species Analysis (TWINSPAN) described by Hill et al. [31], while the ordination technique was the Canonical Correspondence Analysis (CCA) described by ter Braak [32].

Statistical Analyses
One-way analysis of variance (ANOVA) was applied to assess the significance of variation in the environmental variables with equal replication using the COSTAT program.

Floristic Composition
The vegetation structure in the study area is relatively simple, in which the species have to withstand the harsh environmental conditions. This it can be reflected by the presence of several highly adapted and drought-resistant species. The floristic diversity of the study area included 79 species of the vascular plants (39 perennials, one biennial and 39 annuals) belonging to 63 genera and related to 24 families indicating the predominance of perennials. The highest number of species (60 species; 29 perennials, one biennial and 30 annuals) is recorded in the inland desert habitat which is represented by about 75.94% of the total recorded species, while the costal desert habitat is represented by 35 species or about 44.30% (18 perennials and 17 annuals).
The percentage of the life span in the current study varied in two locations of the study area. In the Deltaic Mediterranean coast and North Galalah desert, The dominance of perennials may be related to the nature of the habitat types in the present study in which the reproductive capacity, ecological, morphological and genetic plasticity are the limiting factors [33,34]. On the other hand, the predominance of annuals can be attributed to time of study (March -May 2014) and short life cycle that enables them to resist the instability of the harsh condition [33,35].
The species composition of the studied area in the Nile Delta coast and Galalah desert varied considerably from those of the western Mediterranean coast. This may be attributed mainly to the differences in the nature of soil sediments. The floristic elements of the western Mediterranean coastal belt enjoy better climatic conditions than those of the other parts of Egypt [4].
The dominance of therophytes over the other life forms seems to be a response to Mediterranean climate, topography variation and biotic influence [40]. The highest values of hemicryptophytes and chamaephytes may be attributed to the ability of species to resist sand accumulation, grazing, drought and salinity [41]. The dominance of interregional species (bi pluri-regionals) over mono-regional ones is referred to the presence of interzonal habitats, such as anthropogenic or hydro The dominance of interregional species (bi-and regional ones is referred to the presence of interzonal habitats, such as anthropogenic or hydro-, halo-and psammophilous sites [42]. In addition to, dominance of Saharo-Sindian chorotypes, either pure or penetrated into other regions reflect the effect of both Mediterranean and Saharo-Sindian chorotypes in the vegetation of the study area. Similar results were repo in other studies e.g. Galal and Fawzy [36]; Abd EL-Ghani et al. [38] and El [11,39].

Plant life form spectra in the coastal and inland desert spectrum diagram of the coastal and inland desert
, 2016; Article no. JAERI.22640 . In addition to, the Sindian chorotypes, either pure or penetrated into other regions reflect the effect of both Mediterranean and Sindian chorotypes in the vegetation Similar results were reported in other studies e.g. Galal and Fawzy [36]; . [38] and El-Amier et al.

Classification of Vegetation
Application of TWINSPAN classification based on the importance values of 79 plant species recorded in 60 sampled stands representing the costal desert and inland desert habitat led to the recognition of four vegetation groups (Fig. 2), the vegetational composition of these groups are presented in Table 2.

Group (A): Zygophyllum coccinum group
This group was the least diversified (24 species) among the recognized groups with 7 stands dominated by Z. coccinum. Stands of this group were found on soil rich in its sand, organic carbon and sulphates and lowest levels of silt, calcium carbonate, EC and cations (  (Table 3).

Group (B): Zygophyllum coccinum group
This is the largest group (22 stands) of the studied communities. Thirty three species were recorded in this group. The soil of this group was characterized by the highest electrical conductivity, anions and cations (  Table 2). The other indicator species in this group is Anabasis articulata.  Table 2). The indicator species in this group are Chenopodium murale and Launaea nudicaulis.

Group (D): Haloxylon salicornicum group
This group comprised 32 species recorded from 17 stands. The stands of this group characterized by soil with the highest levels of sand and silt fractions, porosity, calcium carbonate and moderates levels of electrical conductivity, chlorides, sulphates and cations ( The desert vegetation in Egypt is the most important and characteristic type of natural plant life. The perennial plant cover forms the permanent framework of the desert vegetation and is the best indicator of the habitat conditions. The identified vegetation groups in the current study were more or less similar with those investigated by Zahran et al. [6], Abd El-Ghani [45], Abd El-Ghani et al. [38], Salama et al. [17,43] and El-Amier et al. [11,39,44].

Ordination of Sampled Stands
It is clearly that the vegetation groups yielded by TWINSPAN classification are markedly distinguishable and having obvious pattern of segregation on the ordination planes. All the vegetation groups in two different habitats are located on the positive sides of the first and second axes.
As shown in Fig. 3, groups A and B dominated by Z. coccinum that separated at left side of the DCA, where group A at the lower part and group B at the upper part. In addition these two groups are superimposed. On the other hand and group C is co-dominated also by Haloxylon salicornicum and Z. coccinum separated at upper part of right side of DCA. Finally, group D is dominated by Haloxylon salicornicum separated at lower part of right side the DCA diagram. The obtained results concerning the DCA ordination in the present investigation were in agreement with the studies carried out by Deweeb [46], Khorshied [47] and Ramez [48].

Soil-vegetation Relationships
The relationship between vegetation and soil variables is indicated on the ordination diagram produced by Canonical Correspondence Analysis (CCA) of the biplot of species-soil factors Fig. 6. It is clear that, sodium, magnesium, SAR, PAR, EC and pH were the most effective soil factors which showed high significant correlations with the first and second axes of CCA ordination diagram.   . Similar results are more or less comparable with those recorded in some other habitats [6,45,49,18].

CONCLUSION
The present study provides an analysis of floristic composition and vegetation structure of Z. coccineum community in coastal and inland desert of Egypt to help in management and conservation of these natural resources. Z. coccineum is the most famous Zygophyllum species in Egypt and Saudi Arabia. It shows wide soil range and occupies diverse habitats. Therefore, the conservation of natural habitats of this desert is vital importance. The recorded 79 plant species in the present study can play a vital role in the economic and medicinal purposes. Hence, the Egyptian desert need for judicious utilization and sustainable development.