Vegetation cover composition and seed bank study of beach sand dunes in Karkurah coastal area, east of Libya.

Resumo

The present work was carried out in the coastal sand dunes along the beach of Karkurah area, about 100 km south west of Benghazi, during (January to August 2008), in order to study the relationships between vegetation and environmental factors. Vegetation and soil were sampled in 40 quadrats representing the physiographic variation and different habitat types in the study area. The chemical and physical characteristics of soils were determined for 8 samples and there were significant differences in soil variables like pH, Mg, Na, k, soil texture. Density, constancy and mean cover for each 26 perennial species were calculated. 75 plant species identified, belonging to 34 families, and 68 genera, and deposited at Botany department herbarium, Faculty of science, University of Benghazi. The constancy of perennial species showed the dominance for Retama raetam, Nitraria retusa, Ammophila australis,Lycium schweinfurtii,Ononis natrix. The life form determined, and the most common Therophytes constituted (48%), Chamaephytes (29.3%), Phanerophytes (13.3%) and Cryptophytes (9.3%).Species richness was calculated as average number of species per number of quadrats, and the value was (1733/40) = (43.3), The Simpson index value was (0.85). Total numberof seeds in all quadrats was (5536 seeds/m²), the highest number was (323 seeds/m²) in the quadrat which was located on stabilized sand dunes, while the lowest number of seeds was (53 seeds/m²) quadrat was located on dunes facing the sea. The enhanced anthropogenic pressure was in form of quarrying activities , collection of medicinal plants, agriculture, and over grazing are imposing a serious threat to the diversity in the area in the near future.