On the autecology of some endangered plants, Sinai Peninsula

Abstract

Sinai Peninsula is considered one of globally significant arid and semi-arid zone ecosystems capturing high inter-specific endemism in an arid environment, particularly in the mountainous region of Saint Katherine's Protectorate. Vegetation of north Sinai is characterized by sparseness of plant cover, limited number of dominant and associated species, paucity of trees, and high percentage of rare and very rare species. Although southern Sinai is characterized by sparse vegetation that occurs everywhere, the mountainous region of southern Sinai probably contains a greater biodiversity in Egypt. Environmental conditions and different types of human impacts including urbanization, agriculture, mining and quarrying, over collection, and overcutting of woody species have a significant influence on diversity and distribution of threatened, endemic, and medicinal plants in Sinai Peninsula. The current study was carried out at four wadis; Om-Thomaila and El-Mea'gef in Gebel Halal in the north-central part of Sinai Peninsula and Al-Arbae'en and Tala'a wadis in Saint Katherine region in the south of Sinai Peninsula. The study area is the home of 71 species, belonging to 60 genera and 26 families. Eight of the recorded species (target species) are of medicinal value, endemic and endangered plants (Anarrhinum pubescens Fresen., Chiliadenus montanus (Vahl) Brullo., Juniperus phoenicea L., Nepeta septemcrenata Benth., Origanum isthmicum Danin., Origanum syriacum subsp. sinaicum (Boiss.) Greater & Burdet., Phlomis aurea Decene. and Thymus decussatus Benth. Regarding the number of species within each family, the abundant families were Asteraceae which has the highest contribution to the total Summary 239 number of the recorded species (comprising thirteen species with ratio 18.3%), followed by Lamiaceae comprising twelve species with ratio 17%, Zygophyllaceae comprising six species with ratio 8.5% and each of Brassicaeae, Chenopodiaceae, Fabaceae and Solanaceae comprising four species with ratio 5.6%. Chamaephytes (Ch) were the abundant life-form in the study area and represented by 47 species of about 66.19%, followed by Therophytes (12.67%), Hemicryptophytes (8.45%), Phanerophytes (7.04%), and finally Geophytes (5.63%). Considering the global floristic distribution, the monoregional elements recorded the highest species number among the four classes of chorotypes especially Saharo-Arabian chorotype which increased northward and contain 32 species (69.6%), the biregional elements contained 11 species (21.6%) and the pluriregional elements attained the lowest species number among the four classes of chorotypes. It include four species (8%) located at the south wadis only. The phytosociological study of these wadis was based on the analysis of vegetation in 37 stands using Braun-Blanquet technique. In north Sinai application of the Two-Way Indicator Species Analysis (TWINSPAN) to the data set of cover estimated of 47 species in 18 stands resulted in agglomerating of four major groups at the cut level two of this classification. Application of the detrended correspondence analysis (DECORANA) indicated reasonable segregation among these vegetation groups. Chiliadenus montanus is the dominant species of groups A, B and C, while Juniperus phoenicea is the dominant species of group D. The ordination diagram produced by CCA indicated that the most important correlation of environmental variables correlated with species distribution in north Sinai wadis are elevation, chloride content, pH value, gravels, CO3 -2,HCO3 -, content and major cations (Na+ and K+). Summary 240 In south Sinai, application of the Two-Way Indicator Species Analysis (TWINSPAN) to the data set of cover estimated of 52 species in 19 stands resulted in agglomerating of four major groups at the cut level three of this classification. Application of the detrended correspondence analysis (DECORANA) indicated reasonable segregation among these vegetation groups. Dominant species are Stachys aegyptiaca for group A, Achillea fragrentissma for group B, Fagonia glutinosa for group C and Verbascum sinaticum for group D. The ordination diagram produced by CCA indicated that the most important environmental variables correlated with species distribution in south Sinai (St. Katherine) are elevation, SO4 -2 content, major cation (K+, Ca++and Mg++) content, pH value, HCO3 - , Cl-, and fine sand. Geographic Information System (GIS) played an important role in analysis, management and extract of spatial variation for different habitats by using simple information collected from filed, this will give a great analysis just by using such programs. GIS capable of presenting a colored map that allows the visualization of the spatial pattern of the phenomenon. Contribution of (GIS) in vegetation data analysis of eight endangered species in north and south Sinai indicated that presence of Juniperus phoenicea (at north) is restricted to locations of high elevation, although low densities of Juniperus phoenicea but it records high coverage values (87 %) due to its nature (shrubby) compared with other species. Origanum isthmicum (at north) shows the lowest values of coverage (4.1%) if compared with the other species, it was recorded in wadi Om-Thomaila only. Cover and density of Chiliadenus montanus records very low values in the studied wadis of St. Katherine, south Sinai if compared with the studied wadis in Gebel Halal north Sinai. Thymus decussatus recorded only in wadi Al-Arbae´en and its presence is restricted to locations of high elevation.