ABSTRACT
The current research was carried out in Wadi Elkor, one of the Sarawat Mountains regions, which is a special location from an environmental standpoint and one of the only places in Saudi Arabia where a range of Palaearctic flora co-exists with Afrotropical species. The study aimed to determine the floristic composition as well as the effects of slope aspect and elevation on species, life forms, and phytogeographical elements distribution. The study area is located in Wadi Elkor, a valley in the Sarawat Mountains that cuts off the Al-Hada escarpment, 47 km southeast of Makkah City, Saudi Arabia. We conducted the research at three different locations, each with a different elevation and slope aspect. Based on floristic composition, Ward classification moreover Jaccard comparisons were performed. A total of 189 species was discovered, divided into 131 genera and 43 families. The current study identified Argyrolobium rarum Dumme as a new vascular plant in Saudi Arabia's terrestrial flora. In the current study, the Gramineae, Leguminosae, and Compositae families contributed 29% of the total plant species, whereas 14 families were represented by one species each. Solanum was the most numerous genus, with seven species, followed by Acacia and Pulicaria, each with six species, while Commicarpos and Euphorbia, each with four species. At an elevation of 1060 m above sea level, the north facing slope had the most plants, genera, and families. Therophytes had the most species, accounting for 44%, followed by Chamaephytes, which accounted for 26%. Hemicryptophytes accounted for 12% of the total, while phanerophytes accounted for 10%. In the studied area, the bioregional Saharo-Sindian and Sudano-Zambesian groups were the most well-represented (41%). The floristic composition, as well as the distribution of life forms and phytogeographical components, were found to be significantly affected by the elevation and slope aspects. The study showed that slope aspect and elevation both affected the distribution of plant species, with elevation being the most influential of the two variables.
ABSTRACT
Saudi Arabia has no permanent lakes or rivers but has wet meadows, which are desert wetlands temporarily formed due to the seasonal rainfall. This work investigates the environmental variables' impact on the vegetation pattern in the desert-wetland ecosystem in Taif highlands. Forty-one stands were randomly selected representing three main habitats (wet meadows, slopes, and terraces) to study their floristic features and vegetation analysis. A total of 142 species were recorded belonging to 111 genera and 45 families in the desert wetlands of Taif Province. About 64.1% were natural plants, while 25.4% were segetal weeds, 7.7% were aquatic plants, and 2.8% were plants that escaped from cultivation. Therophytes dominated over the other life forms, and mono-regional taxa were the dominant chorotype. Multivariate analysis of the recorded plants produced eight vegetation groups; four of them (A: Potamogeton nodosus-Nasturtium officinale, B: Lemna gibba-Leptochloa fusca, C: Typha domingensis- Xanthium strumarium and D: Conyza stricta- Cyperus longus) represented the wet meadows, while two (E: Acacia gerrardii- Commicarpus plumbagineus and H: Osteospermum vaillantii- Eragrostis Pilosa) for slopes and other two (F: Argemone ochroleuca-Cyperus rotundus and G: Pulicaria undulata- Solanum incanum) for the desert terraces. The vegetation zonation was clear, which started from real aquatic species in the wet meadows passing through mixed vegetation in the slopes and ended with proper xerophytic vegetation in the terraces. Conyza stricta- Cyperus longus community had the highest species diversity, while that of Potamogeton nodosus-Nasturtium officinale had the lowest. The principal component analysis indicated that HCO3, NO3, Mg, Cl, Ca, and pH values were the most effective soil variable. The presence of several segetal weeds suggests the alteration of the natural status of the desert-wetland ecosystem, and thus the conservation of these natural habitats becomes urgent.
