Population structure and dynamics of the endemic species Phlomis aurea Decne in different habitats in southern Sinai Peninsula, Egypt

Phlomis aurea Decne is a rare and endangered species inhabiting high altitudes at southern Sinai Peninsula, Egypt. The present study investigated the population structure of P. aurea  , in terms of size distribution, height, diameter, density, frequency and cover at its favourable habitats, and attempted to assess the effect of different habitats, which reflect the elevation gradients, on sizes distribution and density of occurrences of the study species. Sixty five stands (each of 25 × 25 m) were sampled to represent most variations among PP. aurea populations in four main habitats (basins, mountain slopes, gorges and wadi beds). P. aurea   in basins had the highest plant frequency, cover, plant diameter and height, size index, leaf length and width, leaves, branches, flowers, inflorescences and inflorescence length, while slope population had the lowest. Population in gorges and wadi beds had the highest height to diameter ratio, while in basin and slope had the lowest. Plants in gorges had the highest density, followed by those in basins, wadi beds and slopes. The size structures in the gorges and basins approximated the normal distribution; while that of the slope population approximated the positively skewed distribution. The plant cover was positively correlated with silt, clay, Ca, altitude, CaCO3, fine sand and HCO33; while it was negatively correlated with soil pH and Mg. In addition, plant cover response along soil salinity (EC) gradient approximated normal distribution. This study may help in planning for conserving this endemic species and we recommend, as a priority, to increase the area of the protected areas at mid- to high altitude in the Southern Sinai to grant further protection in zones with the highest density of endemics.