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

Abstract

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.

Keywords: biodiversity; coastal habitat; mangrove grass; phenotypic plasticity; salt marshes.

Figure 1

Floristic composition of the surveyed region. (A) Represented families, (B) life forms, and (C) chorotype spectra. SA-AR: Saharo-Arabian, SU: Sudian, AF: African, ME: Mediterranean, IR-TU: Irano-Turanian, EU-SI: Euro-Siberian, PL-T: Plurireginalbor-trop, SU-ZA: Sudano-Zambezian, SUB-T: Subtropical-Tropical, SA-South-American, NT-Neotropical, AM-American.

Figure 2

Detrended correspondence analysis (DCA) ordination of the studied locations (■) based on the importance value of dominant, co-dominant, and important species (●) recorded from each location. Ael lag: Aeluropus lagopoides, Tam nil: Tamarix nilotica, Jun rig: Juncus rigidus, Lyc sha: Lycium shawii, Pho dac: Phoenix dactlifera, Phr aus: Phragmites australis, Sal eur: Salicornia europaea, Sua aeg: Suaeda aegyptiaca, Zyg alb: Zygophyllum album, Cre cre: Cressa cretica, Cyp con: Cyperus conglomeratus, Zyg sim: Zygophyllum simplex, Aer jav: Aerva javanica, Pan rep: Panicum repens, Sau mon: Suaeda monoica, Rha str: Rhazya stricta.

Figure 3

Hierarchical clustering of different studied locations based on the importance values of the recorded plant species (n = 48).

Figure 4

Canonical correspondence analysis (CCA) showing the correlation between the soil variables and dominant and important species representing the studied locations. Aca ger: Acacia gerrardii, Ael lag: Aeluropus lagopoides, Zyg coc: Zygophyllum coccineum, Sua aeg: Suaeda aegyptiaca, Zyg alb: Zygophyllum album, Tam nil: T. nilotica, Jun rig: Juncus rigidus, Rha str: Rhazya stricta, Phr aus: Phragmites australis, Cre cre: Cressa cretica, Lyc sha: Lycium shawii, Sal eur: Salicornia europaea, Pho dac: Phoenix dactlifera, Pan rep: Panicum repens, Cyp con: Cyperus conglomeratus, Aer jav: Aerva javanica, Zyg sim: Zygophyllum simplex. OM: organic matter, EC: electrical conductivity.

Figure 5

Pearson’s correlation heatmap between the soil variables and the dominant, co-dominant, and important associated plant species within the studied locations. EC: electrical conductivity, OM: organic matter, and MC: moisture content.

Figure 6

The populations of Aeluropus lagopoides (L.) Thwaites in different locations of Saudi Arabia (a–c), and different morphological growth forms (d–i). AP: Aeluropus patch, FMA: full mature Aeluropus patch, Cu: culm, GI: globose inflorescence, St: stolon.

Figure 7

Map of Saudi Arabia showing the different locations of sampled Aeluropus lagopoides communities. Qareenah (Qar), Qaseem (Qas), Salwa (Sal), Jouf (Jou), and Jizan (Jiz).