Abstract
Wadi Othylan is one of the most important protected areas in the central region of Saudi Arabia supporting a high level of plant diversity. The current study aims to examine the vegetation and floristic diversity of wadi Othylan protected area and the relation between such diversity and soil characteristics. A total of 78 plant species belonging to 69 genera distributed among 27 families were collected from the studied stands. TWINSPAN, and detrended correspondence analysis (DCA) analyses classified the plant cover data into the following four plant communities: VG I: Fagonia bruguieri-Haloxylon salicornicum, VG II: Acacia ehrenbergiana-Echinops spinosissima, VG III: Acacia ehrenbergiana-Acacia gerardii and VG IV: Acacia ehrenbergiana-Calotropis procera. Plant species present in wadi Othylan may be an indicator for the low human impact on this area. A significant variation in soil texture, pH, EC and organic matter and mineral contents were observed which was correlated with different vegetation groups.