Abstract
Haloxylon persicum is a desert shrub with economic and ecological importance for arid zones in Saudi Arabia. It has a vital role in the protection of Unaizah and Buraidah, two large cities, and their surrounding from the dangerous mobile sand dunes and without it, the area could be covered by these dunes in a few years. The current study aims to analyze the floristic, vegetation structure and size structure of H. persicum. Eighteen stands were selected along the north and south of the study area with 20 m(2) each. At each stand, the vegetation inventory including plant species abundance percentage and size structure for H. persicum were estimated. Three plant associations; H. persicum-Plantago boissieri, H. persicum-Stipagrostis plumose and H. persicum were identified. Analysis of H. persicum size structure frequency was skewed towards medium size classes in all populations and the early life stages such as juvenile and the seedling recruitment was extremely limited. These results indicated that the populations of H. persicum are threatened by aridity and human impacts. Therefore, efforts are required to minimize uncontrolled exploitation. Finally, in situ and ex situ conservation of H. persicum populations are strongly recommended.