الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The vegetation of Suluga and Gezel PA represents relicts of the original Nubian Riverain Vegetation, a semi-arid scrub and grassland, which have successfully survived up to the present, particularly after the construction of the Aswan old and High Dams. 112 species, representing 23 orders, 37 families and 90 genera; 29 families are Dicotyledonoae (78.4 %) with 76 species, and 8 families are Monocotyledonous (21.6%) with 36 species (32.1 %). In accordance to flora of the studied islands as a whole, 64 annuals (57.1%) and 48 perennials (42.9%).With regards to most represented families are Poaceae has the highest contribution to the total flora (24 species: 21.4%), followed by Fabaceae (17 species15.2%), Asteraceae (12 species: 10.7%). The vegetation life form spectrum of Suluga and Gezel islands reflects a typical desert flora, the greater part of species are therophytes and phanerophytes (70.5%). The phytogeographical analysis revealed that the Palaeotropical have the highest contribution (26 species: 23.2%) followed by the Cosmopolitan (19 species: 17%) and Pantropical (18 species: 16.1%). The monoregional represented by (22 species: 19.6%). The bi-regional chorotype was represented by 21 species (18.8% of the total flora). Pluriregional represented by 6 species (5.4%). Species richness, Shannon-Weiner H, and Margalef indices measurements indicated that shoreline and islands banks are the most diverse habitat. + 28 species (+20 %) were lost or may be extremely very rare within 40 years. This could be due to severe environmental conditions, climate changes and Human interface in the present study area. Six woody vegetation and their size class distributions index (SCDs) was carried out in order to clarify their relationship with factors affecting the survival of individuals in each population and to give an idea about the stability and decline of these populations. SCDs of Tamarix nilotica, Acacia seyal and Faidherbia albida, Populations exhibit a more or less inverse- J- shaped or positively skewed size frequency distribution, which may represent rapidly growing population with high reproductive capacity. Many species, particularly large trees, have few young individuals and therefore at SCDs that deviate from the reverse-J shape SCD characterizing species with abundant and constant rejuvenation. Acacia laeta, Acacia tortilis subsp. raddiana and Acacia nilotica have a tendency towards a J- shaped distribution or negatively skewed distribution. Both shapes of distribution characterize a declining species; because the population has a large proportion of larger individuals than smaller ones. The sparcity of small individuals indicates week regeneration due to hyper-aridity and low fertility. The spatial overlay indicated also that 67.3 % of the larger individuals mapped in 2020 were present in 2000s, 79.3% of the total survived individuals and detected on imagery of 2020. Within 20 years the sparse and dense vegetation decrease by 4.5 ha (16.0%), the non-vegetation area also increased by 3 ha (13.3%) and the cultivated area increased by 1.8 ha (26.9%) that can be interpreted as a result of climate changes and human interference such as fires, this came in NDVI indicated Parallel results (-0.1 - 0.7 in the past and (-0.18 - 0.85) in the present. long term analysis indicated that 15.5 % of vegetation were lost and 16.0% cover lost due to climate changes and Human interface which put the study area under risk of desertification and land degradation and the need for more conservation efforts.