Plant Biodiversity in the southern Region of Jeddah in Kingdom of Saudi Arabia

The present study aims at assessing plant biodiversity in the study area located in the southern province of Jeddah in the ALkmrh region which is suffering from drought and lack of rain. Thirty sites have been selected. In the field study, the perennial plant species was recorded in winter (2006) in selected location beside the practical analysis of soil in such locations. In each of the selected sites plant species were identified. Twenty five perennial plant species were recorded which were belonging to twenty two genera and fourteen plant family. The selected sites in the study area were classified to communities according to dominant plant species and according to the quantitative measures (relative and absolute density, frequency, and cover) and also according to the importance values of these perennial plant species in each of the selected location. The present study recognized seven plant communities in the study area in which species richness ranged from( 2-19) perennial species Some species diversity indices were applied in the present study including species richness index(S),Simpson,n index of dominance (D), species evenness indices E1 and E5. Rank abundance plots were also applied in each of the selected locations in order to predict the pattern species abundance distribution in the location. Soil samples were collected from the selected locations for practical analysis of soil texture, gravel percent, organic matter and soil acidity (pH) and electric conductivity (EC) which was expressed as the total salts present in the soil extract. In addition, some mineral elements were measured in the collected soil samples such as sodium, potassium, calcium, magnesium. The present study reveals that most soils in the selected locations were sandy to loamy sandy soil, organic matter were generally low in content, and gravel percent were high in some locations, low or absent in others. Soils in the study area might be considered as slightly alkaline in all the selected locations, with low salinity. Some statistical analysis tests were applied in the present study, of which spearman rank correlation was examined between species diversity indices and soil factors. The most important or significant correlation was found between soil acidity (pH) of soil extract and species diversity indices in studied locations. A significant correlation was also noticed between sodium element in the soils and some species diversity indices in the selected locations in the present study.