Scholarly article on topic 'Effect of the recent land use on the plant diversity and community structure of Omayed Biosphere Reserve, Egypt'

Effect of the recent land use on the plant diversity and community structure of Omayed Biosphere Reserve, Egypt Academic research paper on "Biological sciences"

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{"El-Omayed Biosphere Reserve" / "Alien species" / "Species diversity" / Vegetation / Habitat}

Abstract of research paper on Biological sciences, author of scientific article — Dalia A. Ahmed, Manal Fawzy, Nouran M. Saeed, Mohamed A. Awad

Abstract The present study aims at describing and analysing the floristic composition and vegetation types, as well as determining the effect of recent land uses on the vegetation structure. It aims also at identifying the alien plants species and elucidating the impact of these species on the plant diversity and community structure of the study area. One hundred and ninety stands were selected monthly for this study, 145 species were recorded (69 perennials and 76 annuals) related to 83 genera, 40 families in 9 identified habitats in El-Omayed Biosphere Reserve (coastal sand dunes, salt marshes, saline depression, non-saline depression, inland ridges, inland plateau, irrigation canals, road sides and cultivated lands). Therophytes were the most represented life form. Three habitat groups resulted after the application of TWINSPAN and DCA as classification and ordination techniques: 2 represented the natural habitats and one represented the urban and cultivated habitats. Group I represented coastal dunes and salt marshes GII: saline depressions, non-saline depressions, inland plateau and inland ridges and GIII: irrigation canals, road sides and cultivated lands. Coastal dunes had the highest species richness ( α -diversity), followed by cultivated lands, while inland plateau had the lowest; but saline depressions had the highest species turnover ( β -diversity). Non-saline depressions had the highest relative evenness, while saline depressions had the highest relative concentration of dominance. Coastal dunes had highest values of calcium carbonates and calcium ions, and salt marshes had the highest salinity, pH, potassium and sodium contents, but cultivated lands had the highest values of silt, clay and organic matter. The diagram resulting from CCA showed an influence of most soil variables, except nitrogen, calcium and potassium. Twenty two species were recorded for the first time in the study area. The recent land use (overgrazing, wood cutting and collecting, construction of summer resorts and irrigation canals and agricultures) led to the emergence of new invasive species, which may severely affect the plant diversity and community structure of this hot spot of biodiversity in Egypt.

Academic research paper on topic "Effect of the recent land use on the plant diversity and community structure of Omayed Biosphere Reserve, Egypt"

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Global Ecology and Conservation

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Original research article

Effect of the recent land use on the plant diversity and community structure of Omayed Biosphere Reserve, Egypt

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Dalia A. Ahmeda'*, Manal Fawzyb, Nouran M. Saeedb, Mohamed A. Awad

a Botany Department, Faculty of Science, Tanta University, Tanta, Egypt b Department of Environmental Sciences, Faculty of Science, Alexandria University, Egypt

article info

Article history:

Received 13 May 2015

Received in revised form 14 May 2015

Accepted 15 May 2015

Available online 23 May 2015

Keywords:

El-Omayed Biosphere Reserve

Alien species

Species diversity

Vegetation

Habitat

abstract

The present study aims at describing and analysing the floristic composition and vegetation types, as well as determining the effect of recent land uses on the vegetation structure. It aims also at identifying the alien plants species and elucidating the impact of these species on the plant diversity and community structure of the study area. One hundred and ninety stands were selected monthly for this study, 145 species were recorded (69 perennials and 76 annuals) related to 83 genera, 40 families in 9 identified habitats in El-Omayed Biosphere Reserve (coastal sand dunes, salt marshes, saline depression, nonsaline depression, inland ridges, inland plateau, irrigation canals, road sides and cultivated lands). Therophytes were the most represented life form. Three habitat groups resulted after the application ofTWINSPAN and DCAas classification and ordination techniques: 2 represented the natural habitats and one represented the urban and cultivated habitats. Group I represented coastal dunes and salt marshes GII: saline depressions, non-saline depressions, inland plateau and inland ridges and GIII: irrigation canals, road sides and cultivated lands. Coastal dunes had the highest species richness (a-diversity), followed by cultivated lands, while inland plateau had the lowest; but saline depressions had the highest species turnover (ft-diversity). Non-saline depressions had the highest relative evenness, while saline depressions had the highest relative concentration of dominance. Coastal dunes had highest values of calcium carbonates and calcium ions, and salt marshes had the highest salinity, pH, potassium and sodium contents, but cultivated lands had the highest values of silt, clay and organic matter. The diagram resulting from CCA showed an influence of most soil variables, except nitrogen, calcium and potassium. Twenty two species were recorded for the first time in the study area. The recent land use (overgrazing, wood cutting and collecting, construction of summer resorts and irrigation canals and agricultures) led to the emergence of new invasive species, which may severely affect the plant diversity and community structure of this hot spot of biodiversity in Egypt. © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC

BY license (http://creativecommons.org/licenses/by/4.0/).

1. Introduction

In semi-arid Mediterranean ecosystems, the scarce and irregular rainfall, long dry and hot summer, and man-mediated degradative activities may synergistically act as driving-forces for the promotion of the desertification process (Azcon-Aguilar et al., 2003). Degradation of natural plant communities, in terms of population structure, successional patterns or

* Corresponding author. Tel.: +20 1223712092.

E-mail addresses: dalia.ahmed@science.tanta.edu.eg, drnada158@gmail.com, drnada158@yahoo.com (D.A. Ahmed).

http://dx.doi.org/10.1016/j.gecco.2015.05.005

2351-9894/© 2015 The Authors. Published by Elsevier B.V. This is an open access article underthe CC BY license (http://creativecommons.org/licenses/by/ 4.0/).

species diversity, is known to occur concomitantly with the degradation of physico-chemical and biological soil properties (Requena et al.,2001).

Alien plants species are species that are introduced as a consequence of human activities to new geographic areas, where they become established and then proliferate and spread, to the detriment of human interests and natural systems. These impacts are not all negative and alien plant species bring both costs and benefits to local people. Costs are incurred if the alien species inhibit the effective functioning of the local social and ecological systems, such as when alien species become weeds within agricultural systems, inhibit vital ecosystem functions or affect animal or human health (Pimentel et al., 2001). Apart from alien species threat to biodiversity and ecosystem services, alien species have a significant socio-economic impact, they reduce yields from agriculture, forestry and fisheries, decrease water availability, cause costly land degradation, block transport routes and contribute to the spread of disease (Garcia-Llorente et al., 2008).

Man-made habitats, as in reclaimed desert lands, represent species-rich environments (Wittig, 2002) due to habitat heterogeneity, frequent and diverse disturbances creating mosaics of different successional stages, and immigration of alien species (Pysek et al., 2002). This human interference causes the invasive species to replace the wild species in these reclaimed areas (Baessler and Klotz, 2006), which are considered to be transitional habitats between the old cultivated land and desert. The invasive species in the new agricultural lands cause serious problems that require attention to be paid to the negative impacts of plant invasions on ecosystems and gene pools (Hegazy et al., 1999).

El-Omayed Biosphere Reserve (OBR) is the only protected area in the northwestern Mediterranean coast. It joined the world network of biosphere reserve in 1981 and was declared as a protected area by Prime Minister Decree in 1986. Being a biosphere reserve, the area is expected to serve as a site for sustainable development of natural resources by rationalizing ecotourism, rangeland management, propagating multipurpose woody species, and promoting local industries. It also has an important function in long-term ecological monitoring.

El-Omayed Biosphere Reserve (OBR) was a representative area of the northern Mediterranean coast of Egypt which has a variety of development and conservation activities. The pressure of land use, coupled with a severe environment and uncertainly of rainfall, has resulted in an advanced stage of desertification. Studies on the distribution of plant species and communities in the different habitats has been reported by Migahid et al. (1971), Ayyad (1976), Abdel-Razik (1976), (Shaltout, 1983, 1985), Abdel-Razik et al. (1984), Kamal (1988), Shaltout and Ayyad (1994), Ayyad and Fakhry (1996), Shaltout and Al-Sodany (2002). Moreover, it was subjected to many human-induced disturbances (the construction of irrigation canals and roads, the construction of tourist resorts on the coastal ridge, the implementation of rain-fed plantations, quarrying activities inside the reserve). These impacts may directly result in the introduction and establishment of alien plant species affecting the vegetation structure and biodiversity.

The present study aims at describing and analysing the floristic composition and vegetation types, as well as determining the effect of recent land uses on the vegetation structure. It aims also at identifying the alien plants species and elucidating the impact of these species on the plant diversity and community structure of the study area.

2. Material and methods

2.1. Study area

OBR is located in the western Mediterranean coastal region of Egypt, at 80 km west of Alexandria (29° 00'-29° 18' E and 30° 52'-20° 38' N). It extends about 30 km along the Mediterranean coast from west El-Hammam to El-Alamein with a width of 23.5 km to the south. Its landscape is differentiated into a northern coastal plain and a southern plateau. The coastal plain is characterized by alternating ridges and depressions running parallel to the coast in an east-west direction. This physiographic variation distinguishes seven types of habitats, (coastal sand dunes, saline depressions, non-saline depressions, inland ridges, inland plateau, inland siliceous deposits, and rain-fed farms), each with its characteristic flora and vegetation. In the non-saline depressions, man-made rain-fed fig and watermelon plantations are common in addition to grazing, intensive quarrying and irrigated land agriculture which is another potential activity that is introduced due to the extension of an irrigation canal from the Nile delta to the region and intensive establishment of resorts on the coastal dunes (Ghabbour, 2012).

Surface soil layers were loose and subject to active erosion and deposition creating micro-topographic variations, but below 25 cm, soils are often compact (El-Kady, 1993). The climate of this region belongs to the warm coastal desert climate; mean air temperatures varied from 13.6 to 27.2 ° C, the warmest summer month (August) has a mean temperature less than 30 ° C, and the coldest winter month (January) has a mean temperature above 10 ° C. Mean air relative humidity varied from 56% to 87%. The rainy season begins during the second half of October and extends to the first half of May. Mean annual precipitation is 120 mm, recorded at an elevation of 10 m. Occasional short rainstorms occur mainly in winter. The ratio of annual precipitation to annual evaporation is between 0.03 and 0.2 (Agwa and Al-Sodany, 2003).

In the last few years, the study area had witnessed stresses on water resources that had led to undesirable consequences related to both its quantity and quality. Recently established summer tourism resorts along the coastal area have damaged the important freshwater aquifer (dune sand accumulation) near the coast. In addition, groundwater pollution either by salt-water intrusion or by sewage from septic tanks or landfills (from the resorts) had been noticed in some areas. The desert ecosystems were exposed to both natural (aridity and soil surface erosion) and human induced impacts (overgrazing,

Fig. 1. Distribution of sampled stands in Omayed Biosphere Reserve, Egypt, 2011 (map was prepared using Google Earth Program).

woodcutting, soil salinization, and the introduction or expansion of agro-forestry systems with multiple land-use to develop tourism, wildlife, hunting and sports) which either act in isolation or in combination with each other (Ahmed, 2009).

2.2. Floristic analysis

One-hundred and ninety stands (each of about 20 x 20 m) were sampled monthly to represent the variation in the vegetation of different habitats of the study area, during spring 2010 to spring 2011 (Fig. 1). These stands distributed as follow: 15 in coastal sand dunes, 12 in salt marshes, 35 in saline depressions, 20 in non-saline depressions, 18 in inland ridges, 25 in inland plateau, 50 in cultivated lands (10 in peach fields, 2 in vine, 14 in apple, 3 in water melon, 8 in Fig, 12 in tomato and 1 in Lemon), 9 in irrigation canals and 6 in road sides. In each stand, floristic records were carried out based on the presence/absence of species, relative cover (by line intercept method: relative cover of spp A = total distance of spp A/sum of distance of all species along line x 100). Identification and nomenclature were according to, Boulos (1999, 2000, 2002, 2005, 2009). Life forms of the recorded species were identified following the system of Raunkiaer (1937). The actual and relative number of species belonging to each life form (i.e. biological spectrum) were calculated. Endemics, which are usually rare and restricted to rather small geographical regions, were gathered from Boulos (2009). Voucher specimens of the recorded species were deposited in Tanta University and Alexandria University Herbaria.

2.3. Soil analysis

Three soil samples were collected from each stand as profiles of 0-50 cm, sieved by a 2-mm sieve to remove gravel and debris. Soil texture was determined by Bouyoucos hydrometer method. Organic matter was determined as the loss-on-ignition at 450 ° C, which gives satisfactory results for a wide range of soils. Determination of calcium carbonate was carried out using Bernard's calcimeter. Soil water extracts of 1:5 were prepared for the determination of soil salinity (EC) using conductivity meter and soil reaction (pH) using pH meter (model Jenway 3020).

For the determination of available nutrients of P, K, Ca, Na and Mg, extracts of 5 gm air-dried soil samples were prepared using 2.5% v/v glacial acetic acid. The digested solution for the determination of total nitrogen was prepared using MicroKjeldahl apparatus. Flame photometer (Model 410) was used for K, Ca and Na analyses. On the other hand, Molybdenum blue and Indo-phenol blue methods were applied for determination of P and N, respectively using the spectrophotometer at wave length 700 nm in case of P and 660 nm in case of N. The Mg analysis was done using Shimadzu Atomic Absorption/Flame Emission Spectrophotometer. All these procedures are outlined Allen et al. (1986).

Hydrophytes (2.1%) Phanerophytes (4.1%) Parasite (0.7%)

Geophytes - Helophytes (8.7%)

Hemicryptophytes (11.0%)

Therophytes (54.5%)

Chamaephytes (19.3%)

Fig. 2. Life form spectrum of the species recorded in Omayed Biosphere Reserve.

2.4. Statistical analysis

Two trends of multivariate analysis were applied in the present study: two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA) as classification and ordination techniques, respectively (Hill, 1979a,b). The relationship between the habitat and soil characteristics was determined by Canonical Correspondence Analysis (CCA) (ter Braak, 1987). Species richness (alpha-diversity) for vegetation groups was calculated as the average number of species per stand, while species turnover (beta-diversity) was calculated as the ratio between the total number of species recorded in certain vegetation group and its alpha-diversity (Whittaker, 1972). Relative evenness or equitability of the importance value of species Shannon-Wiener index was expressed as H1 = ^S= 1 Pi log Pi, where s is the total number of species and Pi is the relative importance value (i.e. relative cover) of the species. The relative concentration of dominance is expressed by Simpson's index: D = 1/C and C = ^S= 1 Pi2. The significance of variation in soil characters was assessed using one-way analysis of variance (ANOVA-1) (SPSS, 2006).

Nine main habitats were recognized in OBR: 1—coastal sand dunes, 2—salt marshes 3—saline depressions 4—non-saline depressions, 5—inland ridges 6—inland plateau, 7—irrigation canals, 8—road sides and 9—cultivated lands (include peach, vine, apple, water melon, fig, tomato and lemon). One hundred and forty-five species were recorded in the study area (Appendix), (69 perennials and 76 annuals) related to 83 genera, 40 families. Asteraceae had the highest contribution (18.6% of the total species), followed by Poaceae (12.4%) and Chenopodiaceae (9.7%).

The life form spectrum of the recorded species showed the predominance of therophytes (79 species = 51.3% of the total species), followed by chamaephytes (28 species = 19.3%) and hemicryptophytes (16 species = 11.0%) (Fig. 2). One endemic species (Anthemis microsperma Boiss. & Kotschy) and two near-endemics: Carthamus glaucus M. Bieb. (Egypt and Libya) and Plantago crypsoides Boiss (Egypt and Palestine authority) were recorded.

The application of TWINSPAN classification on the floristic composition of the nine habitats identified in the study area led to distinguish 3 habitat groups at the second level. These groups were segregated along the ordination plane of the first and second axes of DCA (Fig. 3(a) and (b)). Two groups represented the natural habitats (GI: coastal dunes and salt marshes and GII: saline depressions, non-saline depressions, inland plateau and inland ridges) and 1 group represented urban and cultivated habitats (GII: irrigation canals, road sides and cultivated lands) (Table 1). Group I dominated by Ammophila arenaria, Hyoseris radiata subsp. graeca, Arthrocnemum macrostachyum and Suaeda vera, GII dominated by Limoniastrum monopetalum, Anabasis articulata, Bassia indica, Lycium shawii, Thymelaea hirsuta and Aegilops kotschyi and GIII dominated by Setaria verticillata, Chenopodium album, Cyperus rotundus, Polypogon monspeliensis and Malva parviflora (Table 1). Coastal dunes had the highest species richness (a-diversity) (20.3 species stand-1), followed by cultivated lands (13.8 species stand-1), while inland plateau had the lowest (3.5 species stand-1); but saline depressions had the highest species turnover (ft-diversity) (5.3), while road sides had the lowest (1.9) (Table 2). In addition, non-saline depressions had the highest relative evenness (3.2), while saline depressions had the lowest (1.7). On the other hand, saline depressions had the highest relative concentration of dominance (0.21), while cultivated lands had the lowest (0.05) (Table 2).

3.2. Soil characters

Most of soil characters are significantly affected except sand, silt, phosphorous and nitrogen (Table 3). Coastal dunes dominated by Ammophila arenaria (L.) Link and Hyoseris radiata L. subsp. graeca Halacsy had highest values of calcium

3. Results

3.1. Vegetation

I II m

Coastal dunes Saline depressions Irrigation canals Salt marshes Non-saline depressions Road sides

Inland ridges Cultivated lands Inland plateaus

(a) Habitat classification (TWINSPAN).

■I 250

Natural habitats / Urban and A RO

cultivated habitats

IP VGII ! VGm

VGI [cF-s NSI /

4SD V \ IR / w

300 400 First axis (Eigen value = 0.8204)

(b) Habitat ordination (DCA).

Fig. 3. Classification (A) and ordination (B) of the 9 habitats in Omayed Biosphere Reserve. CD: coastal dunes, SM: salt marshes, IP: inland plateau, NS: non-saline depressions, SD: saline depressions, IR: inland ridges, IC: irrigation canals, RO: road sides and CL: cultivated lands.

Table 1

Characteristics of the 3 habitat groups derived after the application of TWINSPAN on the floristic composition of 9 habitats which identified in Omayed Biosphere Reserve. Habitats are coded as: CD: coastal dunes, SM: salt marshes, SD: saline depressions, NS: non-saline depressions, IP: inland plateau, IR: inland ridges, IC: irrigation canals, RO: road sides and CL: cultivated lands. P: presence percentage and RC: relative cover.

VG Habitat No. of stands No. of species First dominant P RC Second dominant P RC

Natural habitats

I CD 15 43 Ammophila arenaria 100 6.2 Hyoseris radiata subsp. graeca 100 2.7

SM 12 21 Arthrocnemum macrostachyum 58.3 2.5 Suaeda vera 50 8.9

SD 35 50 Limoniastrum monopetalum 65.7 7.4 Anabasis articulata 45.7 12.0

II NS 11 IP 20 29 Bassia indica 100 10 Lycium shawii 90 12.6

25 8 Anabasis articulata 96 60.6 Thymelaea hirsuta 68 27.3

IR 18 38 Anabasis articulata 66.7 34.6 Aegilops kotschyi 66.7 3.0

Urban and cultivated habitats

IC 9 23 Setaria verticillata 100 2.4 Polypogon monspeliensis 85.7 13.2

III Cl 50 33 Chenopodium album 100 22.5 Malva parviflora 80 10.5

RO 6 20 Cyperus rotundus 100 4.7 Polypogon monspeliensis 75 11.3

Table 2

Variation in some diversity indices calculated forthe 9 habitats identified in Omayed Biosphere Reserve. The maximum and minimum values are underlined.

Habitat Species richness Species turnover Shannon index Simpson index

Coastal dunes 20.3 2.1 2.7 0.07

Salt marshes 6.2 3.4 1.8 0.18

Saline depression 9.5 5.3 1.7 0.21

Non-saline depressions 11.5 2.5 3.2 0.06

Inland ridges 10.5 3.6 2.4 0.12

Inland plateau 3.5 2.5 3.1 0.06

Irrigation canals 11. 2.1 2.0 0.14

Cultivated lands 13.8 2.4 3.1 0.05

Road sides 10.5 1.9 1.9 0.16

carbonates (6.2%) and calcium ions (2.6 mg 100 gm-1), while had the lowest of phosphorous and nitrogen contents (for each 0.02 mg 100 gm-1), salt marshes (Arthrocnemum macrostachyum (Moric.) K. Koch and Suaeda vera Forssk. ex J. F. Gmel.) had the highest salinity (6.3 ^S/cm), pH (9.9), potassium (1.1 mg 100 gm-1) and sodium (0.71 mg 100 gm-1) contents, saline depressions Limoniastrum monopetalum (L.) Boiss. and Anabasis articulata (Forssk.) Moq. had the highest values of phosphorous (0.6 mg 100 gm-1) and nitrogen (0.51 mg 100 gm-1) contents, but the lowest percentage of clay (5.7), inland ridges (Anabasis articulata (Forssk.) Moq. and Aegilops kotschyi Boiss.) had the lowest values of calcium carbonates (3.3%), pH (7.7), magnesium (0.12 mg 100 gm-1) and potassium (0.03 mg 100 gm-1) contents, inland plateau (Anabasis articulata (Forssk.) Moq. and Thymelaea hirsuta (L.) Endl.) had the highest value of magnesium (1 mg 100 gm-1), irrigation canals had the highest values of sand (90.1%), while the lowest of silt (2.3%), calcium (0.45 mg 100 gm-1) and sodium (0.04 mg 100 gm-1), cultivated lands (Chenopodium album L. and Malva parviflora L.) had the highest values of silt (20.9%), clay (44.7%) and organic matter (21%), but the lowest of sand (40.3%) and salinity (1.1 ^S/cm) and road sides (Cyperus rotundus L. var. rotundus and Polypogon monspeliensis (L.) Desf.) had the lowest values of organic matter contents (1.5%) (Table 3).

Table 3

Mean of the soil characteristics of the 9 habitats identified in Omayed Biosphere Reserve. The minimum and maximum values are underlined. The F-values are indicated. CD: coastal dunes, SM: salt marshes, SD: saline depressions, NS: non-saline depressions, IP: inland plateau, IR: inland ridges, IC: irrigation canals, CL: cultivated lands and RO: road sides.

Soil character Habitat F-value

G I GII GIII

CD SM SD NS IR IP IC CL RO

Sand 84.1 85.2 82.3 78.3 77.3 79.7 90.1 40.3 89.6 1.53ns

Silt 7.2 7.5 12.0 11.0 11.0 10.0 2.3 20.9 3.2 1.69ns

Clay % 8.7 7.3 5.7 10.7 11.7 10.3 7.6 44.7 7.2 1.15*

CaCO3 6.2 4.5 5.3 3.5 3.3 4.2 5.7 3.9 4.6 4.21*

OM 2.5 5.4 7.5 4.1 9.4 2.3 3.2 21.0 1.5 4.41**

PH 8.2 9.9 8.4 7.5 7.7 8.7 9.1 7.8 8.6 1.67*

EC (^S/cm) 6.0 6.3 4.5 4.6 3.2 4.4 5.9 1.1 2.8 3.65**

P 0.02 0.15 0.60 0.46 0.14 0.12 0.31 0.7 0.22 1.45ns

N 0.02 0.15 0.51 0.06 0.21 0.12 0.11 0.4 0.1 1.43ns

Ca+2 Mg+2 mg100g-1 2.6 1.35 0.55 0.7 0.7 0.65 0.45 0.55 0.6 2.96**

0.35 0.80 0.125 0.125 0.12 1.00 0.15 0.6 0.49 5.55**

K+ 0.2 1.1 0.09 0.01 0.03 0.6 0.1 0.55 0.06 2.65*

Na+ 0.1 0.71 0.31 0.28 0.20 0.22 0.04 0.125 0.06 3.69***

ns = not significant (i.e. P > 0.05). * P < 0.05. " P < 0.01. ■" P < 0.001.

Fig. 4. CCA biplot of the habitats (represented by triangles) and the soil characters (represented by arrows) in Omayed Biosphere Reserve. The habitats were coded as follow: CD: coastal dunes, SM: salt marshes, SD: saline depressions, NS: non-saline depressions, IP: inland plateau, IR: inland ridges, IC: irrigation canals, Cl: cultivated lands and RO: road sides.

3.3. Habitat-soil relationship

The soil-habitat relationship resulted from the application of CCA indicated that organic matter, sodium, calcium carbonate, magnesium, pH and salinity (EC) were the most influence variables. Cultivated lands vegetation was highly affected by organic matter contents, while coastal dunes and irrigation canals vegetation affected by salinity (EC) magnesium and calcium carbonate contents (Fig. 4).

3.4. Alien species

In present study 22 species (15.2% of total species recorded in OBR) were recorded for the first time in the study area. Most of alien species were recorded in cultivated lands (17 species = 77.3% of total alien species), followed by irrigation canals (15 species = 68.2%) and road sides (14 species = 63.6%), while the lowest number of alien species were recorded in saline depressions and inland plateau each had 4 species (18.2%) (Table 4). Natural plant species was decreased and replaced by alien species; aliens species in road sides represented 70% of its floral composition, followed by irrigation canals (65.2%) and cultivated lands (51.5%); while it was less represented in saline depressions (8%) (Table 4).

Table 4

Presence of alien species recorded in different habitats which identified in Omayed Biosphere Reserve. Habitat is coded as: CD: coastal dunes, SM: salt marshes, SD: saline depressions, NS: non-saline depressions, IR: inland ridges, IP: inland plateau, IC: irrigation canals, RO: road sides and Cl: cultivated

lands.

Alien species Habitat Total

Natural Urban CL

CD SM SD NS IR IP IC RO

Plantago coronopus ... * * * 6

Eryngium creticum * .... 5

Fagonia glutinosa . . . . . 5

Launaea nudicaulis . . . . .5

Matricaria chamomilla L. . . . . . 5

Plantago lagopus . . . . . 5

Pseudognaphalium Luteo-album . . ... 5

Bassia indica . . . . 4

Dactyloctenium aegyptiacum . . . . 4

Ranunculus sceleratus . . . . 4

Cenchrusincertus ... 3

Enarthrocarpus lyratus ... 3

Foeniculum vulgare ... 3

Reseda pruinosa . . . 3

Setaria verticillata ... 3

Spergularia rubra ... 3

Suaeda maritima . . . 3

Trigonella hamosa ... 3

Chenopodium album . 1

Lemna gibba . 1

Portulaca oleracea . 1

Potamogeton crispus . 1

Total 6 6 4 5 5 4 15 14 17 22

Alien/natural species (%) 14 28.5 8 17.2 13.2 50 65.2 70 51.5 15.2

4. Discussion

One hundred and forty-five species belonging to 83 genera and 40 families were recorded in the OBR. This number represents 14.9% of the flora of western Mediterranean desert of Egypt, 22 of these species were recently recorded in the study area (Migahid et al., 1971; Ayyad, 1976; Abdel-Razik, 1976; Ayyad and Ammar, 1974; Ayyad and El-Ghareeb, 1982; Shaltout, 1983; Abdel-Razik et al., 1984; Kamal, 1988; Shaltout and Ayyad, 1994; Ayyad and Fakhry, 1996; Shaltout and Al-Sodany, 2002; Ahmed, 2009). Asteraceae had the highest contribution to the flora of OBR in agreement with the study of Shaltout and Al-Sodany (2002) and Agwa and Al-Sodany (2003), which indicated that Asteraceae is most common in the arid and semi arid regions of the subtropical and lower temperate latitudes.

The life form spectra provide information, which may help in assessing the response of vegetation to the variation in the environmental factors (Ayyad and El-Ghareeb, 1982). Raunkiaer (1937) designated the Mediterranean climate as a ''thero-phyte climate type'' because of the high percentage of this life form (>50% of the total species) in several Mediterranean floras (Raven, 1971). The present study reported that therophytes had the highest contribution followed by chamaephytes and hemicryptophytes. The dominance of therophytes seems to be a response to the hot-dry climate, topographic variation and biotic influence (Heneidy and Bidak, 2001). The short life cycles of field crops, in addition to the adverse climatic conditions, moisture deficiency and substrate instability probably lead to the frequent occurrence of therophytes during the favourable seasons (Ayyad, 1983). Also, Wang et al. (2002) and Da Costa et al. (2007) reported that therophytes were the most dominant life form in arid and semi-arid areas. Therophytes are well adapted to mild moist winters and dry summers, and often account for 40%-50% of the species present in the Mediterranean region. Cryptophytes are also well adapted to the Mediterranean climate, where their under-ground parts (e.g. bulbs, corms or rhizomes) stay dormant during summer, and produce vegetative and reproductive above-ground organs during winter and spring (Heneidy and Bidak, 2001).

Application of TWINSPAN classification technique on the sampled stands in the present study resulted in 3 habitat groups: 2 groups characterized the natural habitats and one characterized the urban and cultivated habitats. In present study coastal dunes dominated by Ammophila arenaria, salt marshes byArthrocnemum macrostachyum, saline depression and inland ridges by Anabasis articulata, non-saline depression by Bassia indica and inland plateau Thymelaea hirsuta and this agrees with that reported by Ayyad (1973, 1976); Ayyad and Ammar (1974); Ayyad and El-Ghareeb (1982); Shaltout and Al-Sodany (2002); Ahmed (2009). Heneidy and Bidak (2004) reported that communities that represent salt marshes were less diverse than other communities, while communities that extend their occurrence in coastal sand dunes, saline depressions and inland ridges had the highest diversity, these finding agrees with the result of present study. Ghabbour (1984), reported that with increasing human interferences through agricultural practices and more intensive land use, there was a reduction in diversity, due to the higher density of the cultivated plants, over those of another natural plants, so in present study the

less diverse of communities that represent non-saline depression and inland plateau could be interpreted in the view that the clearance of non-saline depression for crop cultivations and overgrazing in inland plateaus.

Ghabbour (2012), reported that all soils in the OBR area were considered to be very young and immature, and highly influenced by the geological and geomorphological conditions of their formation. The chemical analysis of these soils indicated that they were characterized by low salt content. Organic matter and total nitrogen contents were relatively higher in the cultivated soils than in un manipulated areas, calcium carbonate was generally very high in the coastal areas; these finding agrees with the results of the present study. As indicated by CCA organic matter, Na, CaCO3, Mg, pH and salinity (electrical conductivity) contribute significantly to the distribution of plant species and plant communities in the study area. This finding had been reported by (Abd El-Ghani and Amer, 2003; Hegazy et al., 2004; SUMAMAD, 2014; Salama et al., 2014). Abd El-Ghani (1998) indicated that organic matter played an important role as a key element in soil fertility, and distribution of plant species. CaCO3 and salinity were one of the effective factors that control the growth of plant vegetation (Agwa and Al-Sodany, 2003; Zahran and Willis, 2009).

Alien species (invasive species) differ temporally, in their mode of introduction, and in the degree of their establishment in various artificial, semi-natural or natural sources (Simpson, 1932; Drar, 1952; El-Hadidi and Kosinova, 1971; Tackholm and Boulos, 1974; Hejny and Kosinova, 1977). Twenty two species were recorded for the first time in the study area; as result of excessive human impact (summer resorts, overgrazing, wood cutting, construction of irrigation canal, agricultures... etc.), which cause the introduction of many new species and decreasing of native plant species. (Shaltout and Al-Sodany, 2002), recorded that 4 species (Cynodon dactylon, Aster squamatus, Artemisia monosperma and Potamogeton pectinatus) had begun to invade the OBR as a result of recent human impact. After the extension of a supplementary irrigation canal from the Nile, the extent of irrigated areas of Omayed had increased to about 8%. After being sedentary, together with population growth, overuse of water resources, overgrazing and uprooting of indigenous vegetation, climate change, and other political and social forces, there had been an increased pressure on land resources that affected its performance and provision of goods and services (Ghabbour, 2012).

Bassia indica was native to south and east India, introduced into Egypt in 1945 as a promising fodder plant to fill a gap in the ranges of the north western coastal strip of Egypt, then it began to invade the Nile Delta and other related regions of the Nile valley (Drar, 1952; Draz, 1954; Shaltout and El-Beheiry, 1997,2000; Shaltout et al., 2010), and in recent it was very common in the study area. Cenchrus incertus may become weedy or invasive in some regions or habitats and may displace desirable vegetation if not properly managed, it was from flora of Nile region (Shaltout et al., 2010).

Many of the alien species (chenopodium album, Dactyloctenium aegyptiacum, Enarthrocarpus lyratus Foeniculum vulgare, Pseudognaphalium Luteo-album, Launaea nudicaulis, Matricaria recutita, Portulaca oleracea, Ranunculus sceleratus, Setaria verticillata and Trigonella hamosa) recorded in the present study were common segetal and ruderal weeds in the Nile Delta (Shaltout et al., 2010), due to the chang of the land use in the study area (e.g. the establishment of summer resorts and gardens around them and agriculture), lead to the appearance of a sporadic weed flora, while most of the species of the original plant cover disappear. Before the first weeding, a lot of desert species (Ebenus armitagei, Gagea fibrosa, Hordeum spontaneum, Salsola tetragona, Prasium majus, Euphorbia hierosolymitana Althaea ludwigii and Lobularia arabica) were still in the gardens, after continuing the human impact (e.g. cleaning, ploughing, etc.) many of them were completely eliminated. In contrast to typical weeds, desert species lack the possibility to persist after this new land use system. The transported soil from the agriculture land of the Nile Delta to raise gardens acted as a seed bank of weeds, and this phenomenon is not restricted to the study area only, but extend to different area as in Red Sea area (Sheded and Shaltout, 1998; Sheded and Turki, 2005). The stratification of a transferred soil, however, occurred accidentally or periodically on the original one, leads to arising of new soils (neopedon), and previously unknown species often appear, and the old species, in buried layers of soils, live in the form of diaspores in anabiosis (Sheded et al., 2014).

Understanding the factors affecting the diversity and distribution of plant communities will provide guidance for the conservation of biodiversity and restoration of degenerated vegetation in the study area. The biodiversity is threatened because of intensive anthropogenic pressures which lead to habitat degradation, removal of plant cover from vast areas and some plant species becoming rare. Activities which represent a threat to the area include: overgrazing, uncontrolled mass tourism activities, cultivation of crops, and intensive collection of plants for economic purposes.

5. Conclusion

In the course of this study, it can be concluded that the natural plant species suffer from population decline, limited regeneration and replacement by invasive weeds as result of extensive human impact. Thus, damage of the coastal dunes and ridges for constructing the summer resorts along the Mediterranean coast should be stopped and the different human activities should be controlled. In conclusion, the recent land uses had significant impact on the plant diversity and community structure in OBR; the present study helps in focusing the attention towards the management and conservation of plant diversity in OBR.

Appendix

Floristic features of the recorded species in the OBR, Egypt. Ph: phanerophytes, Th: therophytes, Ch: chamaephytes, Gh: geophytes-helophytes, Hm: hemicryptophytes, Pa: parasites and Hy: hydrophytes. Habitats are coded as: CD: coastal dunes,

SM: salt marshes, SD: saline depressions, ND: non-saline depressions, IR: inland ridges, IP: Inland plateau, CL: cultivated lands, IC: Irrigation canals and RO: road sides.

Species Family Life form Habitat

Adonis dentata Delile Ranunculaceae Th CD, ND,IR, IP, IC,RO

Aegilops kotschyi Boiss. Poaceae Th IR

Allium roseum L. var. tourneauxii Boiss. Alliaceae Gh CD

Althaea ludwigii L. Malvaceae Th CL, IR, RO

Ammophila arenaria (L.) Link Poaceae Gh CD

Anabasis articulata (Forssk.) Moq. Chenopodiaceae Ch SD, ND, IR, IP

Anacyclus monanthos (L.) Thell. subsp. monanthos Asteraceae Th CD, SM. SD, IR

Anthemis microsperma Boiss. & Kotschy Asteraceae Th SM, IR

Arnebia decumbens (Vent.) Coss. & Kralik Boraginaceae Th ND

Artemisia monosperma Delile Asteraceae Ch SD, ND, CL, IC, RO

Arthrocnemum macrostachyum (Moric.) K. Koch Chenopodiaceae Ch SM

Asparagus aphyllus L. Asparagaceae Gh ND

Asparagus stipularis Forssk. Asparagaceae Gh ND, IR

Asphodelus aestivus Brot. Asphodelaceae Gh ND, IR

Astragalus annularis Forssk. Fabaceae Th SD, IR

Astragalus spinosus (Forssk.) Muschl. Fabaceae Ch SD

Atractylis cancellata L. Asteraceae Th ND

Atractylis carduus (Forssk.) C. Chr. var. glabrescens Asteraceae Hm ND, IR, CL

(Boiss.) Täckh. & Boulos

Atriplex halimus L. Chenopodiaceae Ph SM, SD

Bassia indica(Wight) A.J. Scott Chenopodiaceae Th ND

Bassia muricata(L.) Asch. Chenopodiaceae Th CD

Brachypodium distachyum (L.) P. Beauv. Poaceae Th CL

Brassica tournefortii Gouan Brassicaceae Th CL

Bromus rubens L. Poaceae Th CL

Calendula arvensis L. Asteraceae Th CD, IR

Carduncellus eriocephalus Boiss. Asteraceae Th CD, SD, ND, IR, CL

Carduus getulus Pomel Asteraceae Th SM, SD

Carthamus glaucus M. Bieb. subsp. alexandrinus Asteraceae Th SM

(Boiss. & Heldr.) Hanelt

Cenchrus echinatus L. Poaceae Th CL, IC

Cenchrus incertus M. A. Curtis Poaceae Th CL

Centaurea calcitrapa L. Asteraceae Ch SD, IR, CL, IC, RO

Centaurea pumilio L. Asteraceae Th CD, IR

Chenopodium album L. Chenopodiaceae Th CL, IC

Chenopodium murale L. Chenopodiaceae Th CL

Cichorium endivia L. subsp. divaricatum (Schousb.) Asteraceae Th CL

P.D. Sell

Convolvulus arvensis L. Convolvulaceae Hm CL, IC, RO

Convolvulus lanatus Vahl Convolvulaceae Ph ND, IR, CL

Crucianella maritima L. Rubiaceae Ch CD, SD

Cutandia dichotoma (Forssk.) Batt. & Trab. Poaceae Th SD

Cutandia memphitica (Spreng.) Benth. Poaceae Th SD

Cynanchum acutum L. Asclepiadaceae Ph IC

Cynodon dactylon (L.) Pers. Poaceae Gh IC, RO

Cyperus rotundus L. var. rotundus Cyperaceae Gh CL, IC, RO

Dactyloctenium aegyptium (L.) Willd. Poaceae Th CL

Deverra tortuosa (Desf.) DC. Umbelliferae Ch SM, SD, ND, IR

Echinops spinosus L. Asteraceae Hm SD, IR, CL

Echiochilon fruticosum Desf. Boraginaceae Ch CD, SM, SD, IR

Echium angustifoliumMill. subsp. sericeum (Vahl) Boraginaceae Ch CD

Emex spinosa (L.) Compd. Polygonaceae Th CL

Enarthrocarpus lyratus(Forssk.) DC. Brassicaceae Th CL, IC, RO

Erodium crassifolium L' Hér. Geraniaceae Hm SD, IR

Species Family Life form Habitat

Erodium laciniatum (Cav.) Willd. subsp. Geraniaceae Th IR

pulverulentum (Boiss.) Batt.

Erodium neuradifolium Delile ex Godr. Geraniaceae Th CD,SD

Eryngium creticum Lam. Umbelliferae Gh RO

Euphorbia paralias L. Euphorbiaceae Hm CD

Fagonia cretica L. Zygophyllaceae Hm IR

Fagonia glutinosa Delile Zygophyllaceae Hm SM, SD, IR

Filago desertorum Pomel Asteraceae Th SM, SD

Foeniculum vulgare Mill. Umbelliferae Hm CL, IC, RO

Pseudognaphalium luteo-album (L.) Hilliard & B. L. Asteraceae Th CD

Gymnocarpos decandrus Forssk. Caryophyllaceae Ch CD, SD

Helianthemum kahiricum Delile Cistaceae Ch CD

Helianthemum stipulatum (Forssk.) C. Chr. Cistaceae Ch CD, SD, IP

Hemiaria hirsuta L. Caryophyllaceae Th SD

Hippocrepis areolata Desv. Fabaceae Th SD

Hordeum murinum L. subsp. leporinum (Link) Poaceae Th IC, RO

Arcang.

Hordeum spontaneum K. Koch Poaceae Th CL, IC, RO

Hyoseris radiata L. subsp. graeca Halácsy Asteraceae Th CD

Ifloga spicata (Forssk.) Sch. Bip. Asteraceae Th CD, SM, SD, ND, IR, IP

Launaea capitata (Spreng.) Dandy Asteraceae Hm CD, SD, RO

Launaea nudicaulis (L.) Hook. f. Asteraceae Hm CD

Lemna gibba L. Lemnaceae Hy IC

Leontodon hispidulus (Delile) Boiss. Asteraceae Th IC, RO

Limoniastrum monopetalum (L.) Boiss. Plumbaginaceae Ch CD, SD

Limonium pruinosum (L.) Chaz. var. pruinosum Plumbaginaceae Hm SD

Limonium tubiflorum (Delile) Kuntze var. tubiflorum Plumbaginaceae Hm SM, SD

Linaria haelava (Forssk.) Delile Scrophulariaceae Th SD

Lobularia arabica (Boiss.) Muschl Brassicaceae Th CD, SM, SD

Lobularia libyca (Viv.) C. F. W. Meissn. Brassicaceae Th CD, IR

Lolium perenne L. Poaceae Th CD, SM, SD

Lotus glaber Mill. Fabaceae Hm IR

Lotus polyphyllos E. D. Clarke Fabaceae Ch CD

Lycium shawii Roem. & Schult. Solanaceae Ph ND

Malva parviflora L. Malvaceae Th SM, SD, ND, IR, IP, CL, IC, RO

Matricaria recutita L. Asteraceae Th IR

Matthiola longipetala (Vent.) DC. subsp. livida Brassicaceae Th CD

(Delile) Maire

M. longipetala (Vent.) DC. subsp. hirta (Cont.) Brassicaceae Th CD

Greuter & Burdet

Medicago laciniata (L.) Mill. var. Brassicaceae Th CL

brachyacanthaBoiss.

Melilotus messanensis (L.) All. Fabaceae Th CL

Mesembryanthemum crystallinum L. Aizoaceae Th SD

Mesembryanthemum nodiflorum L. Aizoaceae Th SD

Moltkiopsis ciliata (Forssk.) I. M.Johnst. Boraginaceae Ch CD

Moricandia nites (Viv.) Durand & Barratte Brassicaceae Ch SD

Neurada procumbens L. Neuradaceae Th SD, IR

Noaea mucronata (Forssk.) Asch. & Schweinf. Chenopodiaceae Ch SD, ND

Ononis vaginalis Vahl Fabaceae Ch CD

Ornithogalum trichophyllum Boiss. & Heldr.in Boiss. Hyacinthaceae Gh ND

Orobanche crenata Forssk. Orobanchaceae Pa IC, RO

Pancratium maritimum L. Amaryllidaceae Gh SD, ND, IP

Parapholis marginata Runem. Poaceae Th SM, SD

Phagnalon rupestre (L.) DC. Asteraceae Th SD

Phlomis floccosa D. Don Labiatae Ch IR

Plantago coronopus L. Plantaginaceae Th SM

Species Family Life Habitat

Plantago crypsoides Boiss Plantaginaceae Th SD

Plantago lagopus L. Plantaginaceae Th CL

Plantago notata Lag. Plantaginaceae Th IR

Plantago ovata Forssk. Plantaginaceae Th CD, ND

Polypogon monspeliensis (L.) Desf. Poaceae Th IC, RO

Portulaca oleracea L. Portulacaceae Th CL

Potamogeton crispus L. PotamogetonaceaeHy IC

Potamogeton pectinatus L. PotamogetonaceaeHy IC

Pseudorlaya pumila (L.) Grande var. pumila Umbelliferae Th CD, IP

Ranunculus sceleratus L. Ranunculaceae Th CL, RO

Reaumuria hirtella Jaub. & Spach Tamaricaceae Ch ND

Reichardia tingitana (L.) Roth Asteraceae Th CD, SD

Reseda decursiva Forssk. Resedaceae Th CD

Reseda pruinosa Delile Resedaceae Th CL

Retama raetam (Forssk.) Webb & Berthel. subsp. Fabaceae Ph CD

raetam

Rostraria pumila (Desf.) Tzvelev. Poaceae Th CL

Rumex pictus Forssk. Polygonaceae Th CD, SM, SD, ND

Rumex vesicarius L. Polygonaceae Th IR

Salsola kali L. Chenopodiaceae Th CL

Salvia aegyptiaca L. Labiatae Hm CD

Salvia lanigera Poir. Labiatae Ch IR

Scabiosa eremophila Boiss. Dipsacaceae Th ND

Schismus barbatus (L.) Thell. Poaceae Th SD, IR

Scorzonera undulata Vahl Asteraceae Gh SD, IR

Senecio glaucus L. subsp. glaucus Asteraceae Th SD

Seriphidium herba-alba (Asso) Sojak Asteraceae Ch IR

Setaria verticillata (L.) P. Beauv. Poaceae Th CL, IC, RO

Sonchus oleraceus L. Asteraceae Th CL

Spergularia marina (L.) Bessler Caryophyllaceae Hm SM, SD, ND, IR

Spergularia diandra (Guss.) Boiss. Caryophyllaceae Th IR

Stipa capensis Thunb. Poaceae Th CD

Stipa lagascae Roem. & Schult. Poaceae Hm CD

Suaeda aegyptiaca (Hasselq.) Zohary Chenopodiaceae Ch ND

Suaeda maritima (L.) Dumort. Chenopodiaceae Th CD

Suaeda pruinosa Lange Chenopodiaceae Ch SD

Suaeda vera Forssk. exJ. F. Gmel. Chenopodiaceae Ch CD, SM

Thymelaea hirsuta (L.) Endl. Thymelaeaceae Ph CD, SM, SD, ND, IR, IP

Thymus capitatus (L.) Link Labiatae Ch SD

Traganum nudatum Delile Chenopodiaceae Ch ND

Trigonella hamosa L. Fabaceae Th CL, IC, RO

Urginea undulata (Desf.) Steinh. Hyacinthaceae Gh ND

Zygophyllum album L. Zygophyllaceae Ch CD, SD

References

Abd El-Ghani, M.M., 1998. Environmental correlates of species distribution in arid desert ecosystems of eastern Egypt. J. Arid Environ. 38, 297-313.

Abd El-Ghani, M.M., Amer, W.M., 2003. Soil-vegetation relationships in a coastal desert plain of southern Sinai Egypt. J. Arid Environ. 55,607-628.

Abdel-Razik, M.S., 1976. A Study on Vegetation Composition, Productivity and Phenology in a Mediterranean Desert Ecosystem. Egypt (M.Sc. Thesis), Faculty of Science, Alexandria University, Egypt, p. 130.

Abdel-Razik, M., Abdel-Aziz, M., Ayyad, M., 1984. Multivariate analysis of vegetational variation in different habitats at Omayed (Egypt). Vegetatio 57, 167-175.

Agwa, H.E., Al-Sodany, Y.M., 2003. Arbuscular-mycorrhizal fungi (Glomales) in Egypt. Ill: Distribution and ecology in some plants in El-Omayed Biosphere Reserve. Egypt. J. Biol. 5,19-26.

Ahmed, D.A., 2009. Current situation of the flora and vegetation of the western Mediterranean Desert of Egypt (Ph.D. Thesis), Tanta University, Tanta, Egypt, p. 234.

Allen, S.E., Grimshaw, H.M., Parkinson, J.A., Quarmby, C., Roberts, J.D., 1986. In: Moore, P.D., Chapman, S.B. (Eds.), Methods in Plant Ecology, 2nd ed. Blackwell Scientific Publications, Oxford, pp. 411-466.

Ayyad, M.A., 1973. Vegetation and environment of the western Mediterranean coastal land of Egypt: The habitat of sand-dunes. J. Ecol. 61,509-523.

Ayyad, M.A., 1976. Vegetation and environment of the Western Mediterranean coastal land of Egypt. IV: The habitat of non-saline depressions. J. Ecol. 64, 713-722.

Ayyad, M.A., 1983. Some aspects of land transformation in the Western Mediterranean Desert of Egypt. Adv. Space Res. 8 (2), 19-29.

Ayyad, M.A., Ammar, M.Y., 1974. Vegetation and environment of the western Mediterranean coastal land of Egypt. II. The habitat of inland ridges. J. Ecol. 62,439-456.

Ayyad, M.A., El-Ghareeb, R., 1982. Salt marsh vegetation of the Western Mediterranean desert of Egypt. Vegetatio 49,3-19.

Ayyad, M.A., Fakhry, M., 1996. Plant biodiversity in the Western Mediterranean Desert of Egypt. Verh. Ges. Oekol. 25, 65-76.

Azcón-Aguilar, C., Palenzuela, J., Roldan, A., Bautista, S., Vallejo, R., Barea, J.M., 2003. Analysis of the mycorrhizal potential in the rhizosphere of representative plant species from desertification-threatened Mediterranean shrublands. Appl. Soil Ecol. 14,165-175.

Baessler, C., Klotz, S., 2006. Effects of changes in agricultural land use on landscape structure and arable weed vegetation over the last 50 years. Agric. Ecosys. Environ. 115, 43-50.

Boulos, L., 1999. Flora of Egypt, Vol. I. Azollaceae-Oxalidaceae. Al Hadara Publishing, Cairo, p. 419.

Boulos, L., 2000. Flora of Egypt. Vol. II. Geraniaceae-Boraginaceae. Al Hadara Publishing, Cairo, p. 352.

Boulos, L., 2002. Flora of Egypt. Vol. III. Verbinaceae-Compositae. Al Hadara Publishing, Cairo, p. 373.

Boulos, L., 2005. Flora of Egypt. Vol. IV. Monocotyledons (Alismataceae-Orchidaceae). Al Hadara Publishing, Cairo, p. 617.

Boulos, L., 2009. Flora of Egypt: Checklist, Revised Annotated ed.. Al Hadara Publishing, Cairo, p. 410.

Da Costa, R.C., De Araujo, F.S., Lima-verde, L.W., 2007. Flora and life form spectrum in an area of deciduous thorn woodland (Caatinga) in north-eastern Brazil. J. Arid Environ. 68, 237-247.

Drar, M., 1952. A report on Kochia indica wight in Egypt. Desert Inst. Bull. 2,54-58.

Draz, O., 1954. Some Desert Plants and their Uses in Animal Feeding. In: Publications de l' Institut du Désert d' Egypte, vol. 2. pp. 1-95.

El-Hadidi, M.N., Kosinová, J., 1971. Studies on the weed flora of cultivated land in Egypt: preliminary survey. Mitt. Bot. Staatessamml.—München 10, 354-367.

El-Kady, H.F., 1993. The ruderal vegetation of the Mediterranean desert of Egypt. Feddes Repert. 104,403-415.

Garcia-Llorente, M., Martín-López, B., González, J.A., Alcolo, P., Montes, C., 2008. Social perceptions of the impacts and benefits of invasive alien species: implications for management. Biol. Conserv. 141, 2969-2983.

Ghabbour, S.I., 1984. Effect of agricultural practices on soil fauna in the arid and semiarid regions of Egypt and Libya: A comparison within a variety of habitats. Paper presented at: Scientific Workshop on Impact of Agricultural Management on the Environment in Regional Scale, Kobuleti, Georgia, p. 12.

Ghabbour, S.I., 2012. Potential impacts of climate change on soil fauna: Case of the xero-mediterranean omayed biosphere reserve (OBR) Egypt. Int. J. Environ. Sci. Eng. (IJESE) 3, 71-83.

Hegazy, A.K., Diekmann, M., Ayyad, G., 1999. Impact of plant invasions on ecosystems and native gene pools. In: Hegazy, A.K. (Ed.), Environment 2000 and Beyond. Horus for Computing and Printing, Cairo, pp. 275-310.

Hegazy, A.K., Fahmy, G.M., Ali, M.I., Gomaa, N.H., 2004. Vegetation diversity in natural and agro-ecosystems of arid lands. Community Ecol. 5, 163-176.

Hejny, S., Kosinová, J., 1977. Contribution to Synanthropic Vegetation of Cairo. In: Publications From Cairo University Herbarium, 7 and 8. pp. 273-286.

Heneidy, S.Z., Bidak, L.M., 2001. Multipurpose plant species in Bisha, Asir region, south western Saudi Arabia. J. KingSaud Univ. 13 (Science: 1 and 2), 11-26.

Heneidy, S.Z., Bidak, L.M., 2004. Potentialuses of plant species of the coastal Mediterranean region Egypt. Pak. J. Biol. Sci. 7 (6), 1010-1023.

Hill, M.O., 1979a. DECORANA-A FORTRAN Program for Detrended Correspondence Analysis and Reciprocal Averaging. Cornell University, Ithaca NY, p. 90.

Hill, M.O., 1979b. TWINSPAN-A FORTRAN Program for Arranging Multivariate Data in an Ordered Two-Way Table by Classification of the Individuals and Attributes. Cornell University, Ithaca, NY, p. 52.

Kamal, S.A., 1988. A Study of Vegetation and Land-Use in the Western Mediterranean Desert of Egypt (Ph.D. Thesis), The Faculty of Science, Alexandria University, Egypt, p. 194.

Migahid, A.M., Batanouny, K.H., Zaki, M.A.F., 1971. Phytosociological and ecological study of a sector in the Mediterranean Coastal Region in Egypt. Vegetatio 23,113-134.

Pimentel, D., McNair, S., Janecka, J., Wightman, J., Simmonds, C., O'Connell, C., Wong, E., Russel, L., Zern, J., Aquino, T., Tsomondo, T., 2001. Economic and environmental threats of alien plant, animal, and microbe invasions. Agric. Ecosyst. Environ. 84,1-20.

Pysek, P., Jarosík, V., Kucera, T., 2002. Patterns of invasion in temperate nature reserves. Biol. Conserv. 104,13-24.

Raunkiaer, C., 1937. Life Forms of Plants and Statistical Plant Geography. Arno Press, New York, p. 620.

Raven, P., 1971. Relationships between Mediterranean floras. In: Davis, P.H., Harper, P.C., Hedge, I.C. (Eds.), Plant Life in South West Asia. Botanical Society of Edinburgh, Edinburgh, pp. 119-134.

Requena, N., Pérez-Solis, E., Azcón-Aguilar, C., Jeffries, P., Barea, J.M., 2001. Management of indigenous plant-microbe symbioses aids restoration of desertified ecosystems. Appl. Environ. Microbiol. 67,495-498.

Salama, F., Abd El-Ghani, M., Gadallah, M., El-Naggar, S., Amro, A., 2014. Variations in vegetation structure, species dominance and plant communities in south of the Eastern Desert-Egypt. Not. Sci. Biol. 6(1), 41-58.

Shaltout, K.H., 1983. An Ecological Study of Thymelaea hirsute (L.) Endl. in Egypt (Ph.D. Thesis, Thesis), Faculty of Science, Tanta University, Egypt, p. 165.

Shaltout, K.H., 1985. On the diversity of the vegetation in the western mediterranean coastal region of Egypt. Proc. Egypt. Bot. Soc. 4,1355-1376. Egypt.

Shaltout, K.H., Al-Sodany, Y.M., 2002. Phytoecology of Omayed Site. Mediterranean West Coast Project. Egyptian Environmental Affairs Agency, Cairo, p. 89.

Shaltout, K.H., Ayyad, M., 1994. Phytosociological Behavior of Thymelaea hirsuta (L.) Endl. in Egypt. Flora 189, 193-199.

Shaltout, K.H., El-Beheiry, M.A., 1997. Phytomass and nutrient status of Kochia indica, a promising fodder plant in Egypt. Flora 192,39-45.

Shaltout, K.H., El-Beheiry, M.A., 2000. Demography of Bassia indica in the Nile Delta region Egypt. Flora 195, 392-397.

Shaltout, K.H., Sharaf El-Din, A., Ahmed, D.A., 2010. Plant Life in the Nile Delta. Tanta University Press, Tanta, Egypt, p. 243.

Sheded, M.G., Hamed, S.T., Badry, M.O., 2014. Vegetation analysis of six riverian islands in hyper-arid environments at Qena Governorate (Upper Egypt). Acta Bot. Hung. http://dx.doi.org/10.1556/ABot.56.2014.3-4.15.

Sheded, M.G., Shaltout, K.H., 1998. Weed flora in plantations of recently established tourist resorts along Red Sea coast—Egypt. J. Union of Arab Biol. 5(B), 109-119.

Sheded, M., Turki, Z., 2005. Analysis of plants communities resulting from change of land-use in the natural habitats in Egypt. Flora Mediterr. 15,307-319.

Simpson, N.D., 1932. A Report on the Weed Flora of the Irrigation Channels in Egypt. Ministry of Public Works, Government Press, Cairo, p. 124.

SPSS, 2006. SPSS Base 15.0 User's Guide. SPSS Inc., Chicago.

SUMAMAD (Sustainable Management of Marginal Drylands), 2014. A policy brief based on the Sustainable Management of Marginal Drylands project. The United Nations University 30-31.

Tackholm, V., Boulos, L., 1974. Supplementary Notes to Studients' Flora of Egypt. Publications of Cairo University Herbarium, p. 5.

ter Braak, C.J.F., 1987. The analysis of vegetation-environment relationships by canonical correspondence analysis (CCA). Vegetatio 69,69-77.

Wang, G.H., Zhou, G.S., Yang, L.M., Li, Z.Q., 2002. Distribution, species diversity and life form spectra of plant communities along an altitudinal gradient in the northern slopes of Qilianshan Mountains, Gansu, China. Plant Ecol. 165,169-181.

Whittaker, R.H., 1972. Evolution and measurement of species diversity. Taxon 21, 213-251.

Wittig, R., 2002. Siedlungsvegetation. Eugen Ulmer, Stuttgart (in German).

Zahran, M.A., Willis, A.J., 2009. The Vegetation of Egypt. Springer, Netherlands, p. 437.