Assessment of coastal salt marsh plants on the Arabian Gulf region

Floristic diversity and vegetation of the az Zakhnuniyah Island, Arabian Gulf, Saudi Arabia

Islands are broadly recognized as hotspots of ecology, biological and geophysical diversity with unique plant species. The present study aimed to address the floristic composition in the Az Zakhnuniyah Island along the Arabian Gulf of Saudi Arabia. A total of 21 quadrats, of 100 m² each were sampled, and both relative density and cover were determined. Classification (Agglomerative Hierarchical Clustering {AHC} and ordination [Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA)] were applied to identify vegetation clusters and their correlation to the underlying soil factors. Fifty plant species belonging to 21 families were recorded. Amaranthaceae (22.9%), Poaceae (12.5%), Asteraceae and Zygophyllaceae (8.33% each) were the largest represented families. Therophytes and chamaephytes were the most represented life-forms, indicating saline-desert vegetation. Most of the surveyed plant species are used for medicinal purposes and grazing. AHC and DCA allowed identifying three vegetation clusters within three distinct habitats: cluster (A): Halopeplis perfoliata- Suaeda vermiculata in wet salt-marsh habitat, cluster (B): Limonium axillare- Zygophyllum mandaville in sabkha, and cluster (C): Heliotropium bacciferum- Panicum turgidum in sand dune habitat within the island. The CCA results imply strong relationships between floristic composition and salinity measures (CaCO₃, electric conductivity, Mg⁺², Na⁺, K⁺, Cl^- and SO₄) and soil texture. The current vegetation pattern in Zakhnuniyah Island reflects a salinity gradient with variations in soil texture. Knowledge of the floristic composition and its correlation to the environmental factors within islands should guide future conservation strategy and management efforts.

Vegetation Composition of the Halophytic Grass Aeluropus lagopoides Communities within Coastal and Inland Sabkhas of Saudi Arabia

Sabkhas are unique, highly saline ecosystems, where specially adapted plants can grow. Aeluropus lagopoides (L.) Thwaites is a halophytic forage plant growing in salt marsh habitats of inland and coastal sabkhas of Saudi Arabia. The present study provides an analysis of vegetation composition and distribution of the A. lagopoides community in five different regions within Saudi Arabia, emphasizing the environmental factors that affect species distribution. The floristic survey revealed the presence of 48 species, belonging to 26 families. Poaceae, Chenopodiaceae, Mimosaceae, Zygophyllaceae, and Asteraceae are the largest families (50% of total species). Phanerophyte, followed by chamaephytes, are the most frequent forms, indicating a typical saline desert life-form spectrum. The vegetation analysis revealed the dominance of A. lagopoides in all locations, where it was the most dominant species in Qareenah, Qaseem, and Salwa locations, and the second most dominant species in Jouf and Jizan locations. The flourishment of this halophytic grass within a wide soil range in sabkhas revealed its adaptability to the harsh environment, which could be ascribed to its structural adaptations and modifications, as well as the phenotypic plasticity. The Qareenah and Qaseem locations attained the highest species richness and evenness, while the Jizan location was the least diverse. Within the studied locations, other highly salt-tolerant species were determined with high abundances, such as Suaeda aegyptiaca (Hasselq.) Zohary, Zygophyllum album L.f., Tamarix nilotica (Ehrenb.) Bunge, Cressa cretica L., and Salicornia europaea L. The soil analysis showed a significant variation for all parameters among the studied locations, except for pH, chloride, and clay content. The Qaseem location revealed the highest values of most soil parameters, while the Jizan location showed the lowest. The canonical correspondence analysis (CCA) showed that the community structure and diversity are mainly affected by the soil salinity and moisture. Due to the economic potentialities of A. lagopoides as a forage plant and sand stabilizer, the conservation of its habitats is of vital importance. In addition, this grass could be integrated as a promising forage candidate that can be planted in saline-affected areas, even in the summer dry season.