This paper presents an assessment of changes in Avicennia marina population along the Egyptian coasts of the Red Sea. A retrospective analysis of the mangrove cover and distribution was carried out. The populations in Sharm El-Bahary and wadi El-Gimal lack at least one or more volume class stages, while all volume classes are represented in the last two populations occurring in wadi Al-Qu’lan and Sharm El-Madfa’a. The relationships between the individual diameter and canopy volume of A. marina population are simply linear. Strong correlation coefficients are obtained (r
2=0.92) for the population of Sharm El-Bahry and the weak correlation coefficients are obtained (r
2=0.63) for the population of wadi El-Gimal. On the other hand, the relationships between the individual heights and canopy volume of A. marina population are simply linear. Strong correlation coefficients are obtained (r
2=0.72) for the population of Sharm El-Bahry and the weak correlation coefficients are obtained (r
2=0.46) for the population of wadi El-Gimal. All growth performance of A. marina species differ significantly at the four localities except the circumference. The comparison of soil characteristics A. marina populations in the four study localities showed significant variations in all variables except the silt content and SO4.
his study investigated the soil seed bank composition and standing vegetation over five different microhabitats (terraces, springs, wadi bed, saltmarshes and sand dunes) of a coastal ecosystem along the North Western Coast of Egypt. The floristic composition and diversity of the soil seed bank, as well as its similarity with the standing vegetation varied among wadi microhabitats. Such variation could be attributed to differences in disturbance intensity among microhabitats and variation of soil factors along the micro topographic gradient. Sand dunes showed the highest species richness and size of soil seed bank, followed by wadi bed and then terraces. Moreover, the diversity index of the seed bank and its similarity with standing vegetation were significantly greater in salt marshes, followed by the terraces and the lowest in wadi bed. The species richness of seed banks was increased in the sand dunes than the other ones. Annual/perennial ratio and species richness of the standing vegetation were high terraces in comparison with the other microhabitat.
Shawky R., 2018: Effect of edaphic factors on vegetation zonation in some littoral and inland salt marshes of Egypt. - Botanica, 24(2): 202-210. The segregation of a few dominant plant species into distinctive zones is characteristic of salt marshes. Vegetation zonation was investigated in the littoral salt marshes (South Marsa Alam region) and the inland salt marshes (Wadi El-Natrun region) of Egypt. Twenty taxa belonging to 18 genera and 11 families were recorded and classified into two sets at the two studied sites and subdivided into four groups by TWINSPAN, according to a relevance value: group A) co-dominated by Juncus acutus and Juncus rigidus; B) - dominated by Aeluropus lagopoides; C, D) - Limonium axillare. The analysis of species diversity in the inland salt marshes as well as the Shannon and the Simpson indices showed the highest species richness compared to that in the littoral salt marshes. The soil of the inland salt marshes was characterized by high percentages of silt, clay, also the soluble anion SO4-2was the highest. While the most effective factor in the littoral salt marshes was EC, sand fractions, moisture content, soluble cations as Na+, Ca+2, soluble anions as Cl-, organic matter and CaCO3. The proximity matrix between the two types of salt marshes indicated that they were different, except for the stands of Juncus rigidus, the elucidation distance was the smallest and they were similar together.
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