Monier M. Abd El-Ghani

SOIL–VEGETATION RELATIONSHIPS IN A COASTAL DESERT PLAIN OF SOUTHERN SINAI, EGYPT

Abstract The present study provides an analysis of soil, vegetation types as well as structure and species distribution in 19 sites in El-Qaa plain along the Gulf of Suez (south Sinai, Egypt), and focuses on the environmental factors that control the species distribution. A total of 203 species belonging to 39 families of the vascular plants are recorded. Asteraceae, Fabaceae, Chenopodiaceae and Poaceae are the largest families. Grasses constitute only 9% of the recorded species, while the woody perennials (shrubs and sub-shrubs) are highly dominated (46%). Therophytes and chamaephytes are the most frequent, denoting a typical desert life-form spectrum. Floristic composition in the different geomorphologic landscape units showed differences in species richness. The highest mean species richness of 19.7±1.7 is recorded in the wadi channels. The lowest species richness values are recorded in the coastal shore and playas (6.0±1.4) and in the alluvial fans (mean of 8.4±1.6 species). Chorological analysis revealed that 46% of the studied species are uniregional, being native to the Saharo-Arabian region. On the other hand, about 50% of the recorded species are biregional and pluriregional, extending their distribution all over the Saharo-Arabian, Sudano-Zambezian, Irano-Turanian and Mediterranean regions. Classification of the vegetation is analysed using two-way indicator species analysis (TWINSPAN) techniques resulted in the recognition of five vegetation groups, each of definite vegetation and soil characters, and could be linked to a specific geomorphologic unit. Capparis spinosa var. spinosa occupied the terraces, Cornulaca monacantha, Convolvulus lanatus and Deverra tortuosa inhabited the alluvial plains, Launaea nudicaulis and Artemisia judaica characterized the wadi channels, Acacia tortilis subsp. raddiana and Leptadenia pyrotechnica characterized the alluvial fans and Tamarix nilotica, Zygophyllum album and Nitraria retusa on the playas and the coastal shore. Ordination techniques as detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) are used to examine the relationship between the vegetation and studied soil parameters. Nine soil variables are included: electrical conductivity, pH, calcium carbonate, gypsum, organic matter, gravel, fine soil fractions and soil saturation percentage. Analysis with DCA gave results similar to CCA, suggesting that there is a relatively high correspondence between vegetation and soil factors. DCA axis 1 showed significant positive correlation with CaCO3, pH, soil saturation and organic matter, and interpreted as a calcium carbonate—soil saturation gradient. DCA axis 2 showed significant correlation with pH, gypsum and electric conductivity, and interpreted as an electric conductivity—gypsum gradient. Application of CCA indicated that soil surface sediment, CaCO3, soil saturation, pH and organic matter are the main operating edaphic gradients in the area. These gradients are related closely to the first three canonical axes, and accounted for 67% of the species–environment relationship among the sites.

Plant species distribution and spatial habitat heterogeneity in the landscape of urbanizing desert ecosystems in Egypt.

Information on the urban flora and vegetation in the industrial new cities in Egypt are insufficient and far from complete. For this reason, this study was undertaken as the first attempt to fill this gap of knowledge. For two successive years (2004 and 2005), a reconnaissance survey was conducted in four new industrial cities: 6th October, El-Sadat, Burg El-Arab and 10th Ramadan; aiming at: (1) recognizing the floristic composition and vegetation structure of each of the studied cities; (2) identifying the main urban habitats dominating the studied cities; (3) comparing the vegetation of the urban habitats at the boundaries of each city, where desert soil merges gradually with the agricultural land, with that at its centre (purely agricultural land); and (4) analyzing, quantitatively, the vegetation groups (plant communities) that characterize the urban habitats. A total of 189 permanent stands in the four cities were selected to represent the apparent variation in the different habitats. These stands were distributed as follows: 49 in 6th October, 37 in El-Sadat, 45 in Burg El-Arab, and 58 in 10th Ramadan. Altogether, 305 species of the vascular plants constituted the main synanthropic flora and the total number of species varied from 171 in Burg El-Arab, 157 in 10th Ramadan, 144 in Sadat and 132 to 6th October. The largest families that formed the main bulk of the recorded flora were Gramineae, Compositae, Leguminosae, followed by Euphorbiaceae, Chenopodiaceae, Cruciferae, Cyperaceae, Umbelliferae and Solanaceae. Five main urban habitats (from inner city toward outskirts) were distinguished: lawns, home gardens, public gardens, waste lands and desert outskirts. The most species-rich habitat was the waste lands (172 species), while the total number of species varied from 104 in the lawns and 113 home gardens, to 123 in the desert and 133 in the public gardens. Generally, the recorded synanthropic flora within the five main urban habitats can be classified into: (1) cultivated plant species that included ornamentals, hedges, shade plants, fodder plants, vegetables and fruits; (2) canal banks, salinized areas and wetland plants; (3) xerophytic plants of the outskirting desert; and (4) weeds of arable lands. Application of multivariate analyses techniques to 4 floristic data matrices yielded 22 TWINSPAN vegetation groups in the cities, and 26 in the five habitats, clearly separated along the first two axes of DCA.

Composition of and changes in the spontaneous flora of Feiran Oasis, S Sinai, Egypt, in the last 60 years

Abstract Abd El-Ghani, M. M. & Fahmy, A. G.: Composition of and changes in the spontaneous flora of Feiran Oasis, S Sinai, Egypt, in the last 60 years. — Willdenowia 28: 123–134. 1998. — ISSN 0511-9618. Based on investigations of the spontaneous flora of Feiran Oasis in 1995 and 1996, 70 taxa of vascular plants, 49 dicots and 21 monocots, are listed, of which 33 taxa are recorded for the first time from the oasis. This inventory is compared with herbarium collections and published records of investigations made in the 1930s and 1960s. Considerable changes in the composition of the spontaneous flora of Feiran Oasis in the last 60 years are ascertained and reasons are discussed.

The Deserts of China

This chapter provides features of environmental factors and phytogeographical divisions for desert vegetation in China. There are three kinds of desert vegetation in China: semi-desert, true desert, and extremely arid desert. The desert vegetation is distributed on different land forms with diversified soil feature, extending in NW China with mean annual precipitation less than 200 mm. Dominant species in the desert vegetation in China include eight life forms.

Vegetation and Environment

This chapter provides an overview of desert flora and plant communities. The vegetation-environment relationships were explained with two case studies, true desert in the Jungar Basin and extremely arid desert in the Anxi Extremely Arid Desert National Nature Reserve. There are 610 species in the desert of China, which can be classified into Central Asian element and Inner Asian element. The plant communities are abundant caused by diversified topography and soil features.

The Inland Eastern Desert of Egypt

The inland part of the Eastern Desert of Egypt forms an ecosystem with characteristic habitats: (1) rocky surface, (2) erosion pavement, (3) gravel desert, (4) slopes, (5) cliffs, and (6) desert wadi, which represents a drainage system collecting water from extensive catchment area. The geographic position of the mountainous range along the Red Sea coast is very conspicuous. The flora and vegetation of the Gebel Elba mountainous group is much richer than that of the other coastal mountain, where the Palaearctic and Afrotropical regions meet. The species composition of the Gebel Elba National Park was greatly influenced by disturbances such as severe cutting of trees and shrubs either for domestic fuel or charcoal production and browsing. In terms of classification and ordination, the vegetation and environment in northern wadis and southern wadis in four transects representing three different types of desert running from the Nile Valley to the Red Sea coast were investigated. Based on the current status of flora of the Eastern Desert, a biogeographical analysis and phytogeographical divisions of the were re-assessed.

The Coastal Desert of Egypt

The coastal deserts in Egypt are found along the Mediterranean (east and west), the Red Sea, and the Gulfs of Suez and Aqaba in Sinai Peninsula. The variations in their floristic composition and vegetation structure are varied considerably. The association between the landform units and their floristic features showed significant differences. In the meanwhile, the biological spectrum and chorological analyses of the flora exhibited a general trend in both dominance and structure. Climatic variations, especially rainfall, between the different geographical areas play a profound role in the species distribution patterns. The relationships between the vegetation and the prevailing environmental characteristics indicated the importance of certain soil factors such as coarse and fine sediments, moisture content, electrical conductivity, pH, and organic matter. The distance from the sea and altitude were other significant factors in delimiting species distribution.

The Sinai Desert

The Sinai Peninsula is currently recognized as one of the central regions for biodiversity in the Middle East by the World Conservation Union. It is rich both in the number of species and the high percentage of endemics. The roughness in geomorphology leads to differentiation of enormous number of microhabitats and landforms which resulted in relatively high diversity in ecosystems and flora. The most conspicuous inhabited oasis in south Sinai is Feiran Oasis which is considered as the largest receiving amounts of runoff water from the drainage system of Wadi Feiran. The small size of Feiran Oasis, the limited water resources, the rapid development due to increased touristic and population pressures, as well as the present serious socio-economic situation may cause the destruction of the remaining natural habitats in the near future. Recently, it is subjected to severe destruction and dryness of a great deal of its characteristic date palm orchards habitat. Out of the 33 species which recorded for the first time from Feiran Oasis, 13 were invading xerophytes, growing in fields and orchards, and behaving as field weeds. Floristic analysis, species distribution, and soil–vegetation correlations in Wadi Solaf, W. El-Akhdar, and W. Romana (as inland wadis) were compared to W. Kid (a coastal wadi). In the eastern sector of Central Sinai, plant communities and vegetation analysis were performed along four tracks (unpaved and unaccessible roads): Nekhel–Al-Qasimia, Al-Qasimia–Al-Kuntella, Al-Kuntella–Al-Thamad, and Nekhel–Al-Malha.

The Deserts of Pakistan

Pakistan is a subtropical country spread over an area of 79.6 million hectares (mha) lying between 24° and 37° N and 61° and 75° E. Most of the area is semiarid to arid, extending over 70 mha (87.94% of its land mass), receiving 250 mm annual rainfall. The deserts of Pakistan cover 11 mha (13.82%) of the land situated in the central and southeastern regions. These areas are broadly separated and are located between 100 and 1000 m above sea level. These deserts are monsoon in type, referring to a wind system marked with seasonal fluctuation in response to temperature variations between continents and oceans. The southeast-directed winds of the Arabian Sea supply heavy summer rains. The aridity is characteristic of a desert, with erratic rainfall occurring in clusters. The most dominant and frequent tree species in the desert habitat include Acacia senegal, Acacia nilotica, Azadirachta indica, Capparis decidua, Prosopis cineraria, Salvadora oleoides, Tamarix aphylla, and Tecomella undulata, with Prosopis cineraria being the most dominant and frequent. Among shrubs, Acacia jacquemontii, Aerva javanica, Calotropis procera, Calligonum polygonoides, Dipterygium glaucum, Euphorbia caducifolia, Fagonia indica, Haloxylon salicornicum, Leptadenia pyrotechnica, and Crotalaria burhia are dominant. Ephemerals are an important component of the desert habitat, here represented mostly by Boerhavia procumbens, Convolvulus prostratus, Gisekia pharnaceoides, Heliotropium strigosum, Indigofera argentea, Indigofera cordifolia, Indigofera linifolia, Limeum indicum, Mollugo cerviana, Senna ialica, and Tephrosia purpurea. Grasses are very prominent inhabitants in deserts, including Aristida spp., Cenchrus biflorus, Cenchrus ciliaris, Eragrostis spp., Panicum turgidum, Pennisetum divisum, Saccharum spontaneum, and Stipagrostis plumosa. Abutilon bidentatum, Abutilon pakistanicum, Alysicarpus monilifer, Alysicarpus tetragonolobus, Caralluma edulis, Cenchrus prieurii, Commiphora wightii, Convolvulus scindicus, Gisekia pharnacioides, Ephedra ciliata, Gynandropsis gynandra, Monsonia heliotropioides, Rhynchosia schimperi, and Tecomella undulata are some of the threatened species that are used by the inhabitants to meet their various socioeconomic needs. Pragmatic conservation measures are required to protect such habitats, because they represent threatened or rare and endemic species that are of economic importance to the local communities and thus are used unsustainably.

Arid Deserts of the World: Origin, Distribution, and Features

It is not easy to define the word ‘desert’. Botanicall, deserts could be defined as areas with little rainfall, and sparse vegetation made up of special plants having particular characteristics that enable them to avoid, resist, or tolerate harsh environments. Four major categories of derts are known: (1) subtropical deserts, (2) cool coastal deserts, (3) cold winter deserts, and (4) polar desert. Most arid deserts are found near the equator because of the plentiful daylight the location offers.The types of vegetation coincide with the pattern of the water resources othe habitat. As their diversity in landforms, soils, fauna, flora, water balances, and human activities, no particular definition of arid environments can be derived.However, the one binding element to all arid regions is aridity.