The traits of gray mangrove (Avicennia marina (Forsk.) Vierh.) at different levels of soil salinity were assessed at three sites along the Tubli Bay coastline of Bahrain. Morphophysiological traits include rates of photosynthesis and transpiration, leaf morphology, and leaf pigment content. Results showed that the rates of photosynthesis and transpiration, the intercellular CO 2 concentration, and stomatal conductance were significantly lower (p ≤ 0.05) in the trees of a low salinity site compared to those of high salinity sites. Pairwise correlation between soil electrical conductivity levels and photosynthesis and transpiration rates was very low, implying an adverse effect of low salinity on both processes. However, the dimensions of leaf area and the sclerophylly index were significantly higher (p ≤ 0.05) in the trees grown in low salinity site compared to those in more saline conditions. On the other hand, pigments were significantly lower in leaves of trees grown in low salinity site compared to the other two sites. The pairwise correlation between electrical conductivity values and chlorophyll a, b, and carotenoid was 0.51, 0.52, and 0.57 consecutively at (p <0.0001), implying moderate effect of salinity on leaf pigments. This study illustrates the adverse and positive effects of soil salinity on some traits of gray mangrove in Bahrain, which might be considered in ecosystem rehabilitation along other coastlines of the country.

The influence of mesquite trees (Prosopis juliflora (Swartz) D.C.) on the physicochemical properties of soils and annual understory plants was investigated in the deserted rangelands of Bahrain. Soil properties were measured in the understory and the uncanopied adjacent areas of mesquite trees. Likewise, the number of plant species was assessed in four 1 × 1 m randomly distributed quadrates in the understory and the uncanopied adjacent areas. The results showed that sand particles exceed 96% of soil composition. Soil bulk density at the 0–5 cm soil depth was significantly higher in the understory of trees compared to the uncanopied adjacent areas. However, moisture at a depth of 40–60 cm was significantly higher in the uncanopied adjacent areas. No differences in the pH, EC, K, Na, and Ca were found between understory and the uncanopied areas in all soil depths. Levels of N, P, Mg, and organic matter were significantly higher in the understory of trees compared to the uncanopied adjacent areas. Organic matter was twice the amount in the upper 20 cm of soil layers in the understory of mesquite trees. Species richness did not differ between the understory and the uncanopied areas. Nevertheless, the density of ephemerals in the understory of mesquite trees was higher than the uncanopied areas by 18%. The Shannon-Weaver index of diversity was higher in the uncanopied areas compared to the understory. The study concluded that the canopy effects of mesquite trees on soil vary with depth. Nonetheless, the influence of mesquite on flora could be beneficial for annual understory plants but subject to many operating factors, including density and cover of mesquite trees.

This research was conducted in four sites at Mahazat as-Sayd reserve in Saudi Arabia to determine the optimum habitats' constituents for Asian houbara bustard Chlamydotis macqueenii via assessing abiotic and biotic factors with special reference to vegetation aspects. Vegetative parameters were quantified using combinations of distance and line intercept methods. Acquired data were analyzed using cluster analysis and analysis of variance tests. Results indicated that three of the four plant communities of the study sites were dominated by Acacia tortilis with underground cover composed of lesser species. On the other hand, White Jabal was dominated by scrubs composed mainly of Fagonia indica with sparse Acacia trees. Rumrumiyya site recorded the highest species abundance and vegetative coverage (133%) among the sites. It is concluded that Black Jabal and White Jabal sites are used as nesting and foraging habitats for houbaras, whereas Jabal Khurse is specifically a males' display site. Nevertheless, Rumrumiyya site was used for foraging and shelter. The study confirmed that density and vegetation cover are of prime importance for houbara site selection. However, other factors affecting feeding and behavior of the species must be considered in further studies.

Accumulation of 8 heavy metals (HM), Cr, Cu, Fe, Mn, Mo, Ni, Pb, and Zn, was assessed in the leaves and sediments of gray mangrove (Avicennia marina (Forsk.) Vierh.) at three sites along Tubli Bay using Inductive Coupled Plasma Analyzer. The results showed no significant differences in HM contents in the leaves of mangroves between the sites except for Mo and Zn. HM concentrations (mg L −1 ) in leaves were in the following order: Fe > Zn > Mn > Mo > Cu > Ni > Cr. Significant differences existed between sediment content of Tubli site and the other two sites with regard to Cr, Cu, Pb, and Zn due to direct exposure of the site to wastewater outfalls. A general trend of decline in HM concentrations was noticeable from the top towards deeper sediment layers in all the sites of the study area. Concentration of HM in sediment was in the following order: Fe > Mn > Zn > Cu > Cr > Pb > Ni. HM concentration in sediments far exceeded the amount present in the leaves of the mangrove except for Ni. The amounts of HM in mangrove sediments were comparable to regional findings and fell within known sediment quality guidelines.

A Vegetation survey aimed at the estimation of species and community parameters was conducted for Mangrove assembly along the coasts of Tubli Bay of Bahrain. Satellite imagery (IKONOS) coupled with ground truthing were used to calculate the areas of the Mangrove. Results showed that Mangrove coverage and density at Sanad site were 70% and 1245 tree/ha., respectively. An ecotonic plant community lies aside composed of Mangrove and flood-tolerant species mostly, Halopeplis perfoliata, Halocnemum strobilaceum, Suaeda maritime. Relative coverage of Mangrove within this community was 55%, whereas coverage and density of Arthrocnemum macrostachym were 35% and 8.22 plant/m2, respectively. A plant community composed principally of Arthrocnemum macrostachym and Halocnemum strobilaceum with 72% and 23% coverage respectively is situated behind. Other species such as, Juncus sp., Aeluropus littoralis, Portulaca sp., Suaeda vermiculata, Suaeda sp., Tamarix sp., Sesuvium verrucosum and Phragmites australis with an average coverage of 56% occupy high intertidal areas. The Shannon- Wiener diversity index and Pielou’s evenness index for the assembly at the site scored 2.44 and 0.95, respectively. The average coverage and density of Mangrove at Sitra Site (1) were 63.3% and 1300 per ha., consecutively. Average coverage and density of Arthrocnemum salicornicum reached 55% and 6.75 plants/m2. Other species such as Suaeda maritime, Arthrocnemum salicornicum, Phragmites australis, Juncus sp., Aeluropus littoralis were observed in high intertidal areas. Diversity and evenness indices for the plant community were 1.96 and 0.85, respectively. Mangrove coverage and density at Sitra site (2) were 45% and 959 plant/ha. Coverage and density of Arthrocnemum salicornicum were 23% and 4.12 plants/m2, respectively. Other species such as Arthrocnemum salicornicum, Aeluropus littoralis, Suaeda maritime, Suaeda vermiculata, Suaeda sp., Hammada sp. were present at higher ground. Diversity and evenness indices for the plant community were 1.96 and 0.85, respectively. Similarity index for the sites ranged from 43-87%. The area of Mangrove community in 2010 totaled 55.46 ha, of which Mangrove occupies 31 ha alone. Another 18 ha. were occupied by Mangrove and other species, compared with 52.56 in 2005 where mangrove formed 30 ha alone and shared an area of 15.5 ha. with other species. It is suggested for any management plan for Mangrove community to take into consideration the basic ecology of Mangrove within this integrated ecosystem as well as preventing further reclamation activities in the Bay.