Today, one of the most pressing issues confronting the civilized and modern world is air pollution.Particulate matter (PM) is a well-known pollutant that contributes signi cantly to urban air pollution and has numerous short-and long-term adverse effects on human health. One method of reducing air pollution is to create green spaces, mainly green walls, as a short-term solution. The current study investigated the ability of nine plant species to reduce tra c-related PM using a green wall system installed along a busy road in Mashhad, Iran. The main aims were (1) estimate the tolerance level of plant species on green walls to air pollution using the Air pollution tolerance index (APTI); (2) assess the PM capture on the leaves of green wall species using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) analysis and accumulation of heavy metals using Inductively Coupled Plasma (ICP); (3) select the most tolerance species for reducing air pollution using Anticipated Performance Index (API). The plants' APTI values ranged from 5 to 12. The highest APTI value was found in Carpobrotus edulis and Rosmarinus o cinalis, while Kochia Prostrata had the lowest. Among the APTI constituents, leaf water content (R 2 = 0.29) and ascorbic acid (R 2 = 0.33) had a positive effect on APTI. According to SEM analysis, many PM were adsorbed on the adaxial and abaxial leaf surfaces, as well as near the stomata of Lavandula angustifolia, C. edulis, Vinca minor, and Hylotelephium sp. Based on EDX analysis, carbon and oxygen formed the highest amount (more than 60%) of metals detected in the elemental composition of PM deposited on the leaves of all species. The Sedum re exum had the highest Cr, Fe, Pb, and As accumulation. The concentrations of all heavy metals studied in green wall plants were higher than in the control sample. Furthermore, the C. edulis is the best plant for planting in industrial, urban areas of the city based on APTI, biological, economic, and social characteristics. It concludes that the use of green walls composed primarily of plants with small leaves can signi cantly adsorb PM and accumulation of heavy metal.

Today, one of the most pressing issues confronting the civilized and modern world is air pollution. Particulate matter (PM) is a well-known pollutant that contributes significantly to urban air pollution and has numerous short- and long-term adverse effects on human health. One method of reducing air pollution is to create green spaces, mainly green walls, as a short-term solution. The current study investigated the ability of nine plant species to reduce traffic-related PM using a green wall system installed along a busy road in Mashhad, Iran. The main aims were (1) estimate the tolerance level of plant species on green walls to air pollution using the Air pollution tolerance index (APTI); (2) assess the PM capture on the leaves of green wall species using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) analysis and accumulation of heavy metals using Inductively Coupled Plasma (ICP); (3) select the most tolerance species for reducing air pollution using Anticipated Performance Index (API). The plants' APTI values ranged from 5 to 12. The highest APTI value was found in Carpobrotus edulis and Rosmarinus officinalis, while Kochia Prostrata had the lowest. Among the APTI constituents, leaf water content (R2 = 0.29) and ascorbic acid (R2 = 0.33) had a positive effect on APTI. According to SEM analysis, many PM were adsorbed on the adaxial and abaxial leaf surfaces, as well as near the stomata of Lavandula angustifolia, C. edulis, Vinca minor, and Hylotelephium sp. Based on EDX analysis, carbon and oxygen formed the highest amount (more than 60%) of metals detected in the elemental composition of PM deposited on the leaves of all species. The Sedum reflexum had the highest Cr, Fe, Pb, and As accumulation. The concentrations of all heavy metals studied in green wall plants were higher than in the control sample. Furthermore, the C. edulis is the best plant for planting in industrial, urban areas of the city based on APTI, biological, economic, and social characteristics. It concludes that the use of green walls composed primarily of plants with small leaves can significantly adsorb PM and accumulation of heavy metal.

Aridity and intensive grazing have been confirmed to affect the facilitative effects of dryland shrubs. However, their combined effects on plant-plant interactions have rarely been tested. To test how these two factors affect relations between plants, we analyzed 144 plots (under shrub canopy vs. open areas) at 12 sampling areas established in the conditions of two grazing regimes (high grazing vs. low grazing intensity) and two different climatic regions (arid vs. semi-arid) in northeastern Iran. A dominant shrub, Artemisia kopetdaghensis, was selected as the model species. Further, we studied changes in plant life strategies along the combined grazing and aridity stress gradients. We used relative interaction indices to test the outcomes of plant-plant interactions, calculated for species richness, Shannon diversity and species abundances. Then we compared them using linear mixed-effect models (LMM). The indicator species analysis was used to identify species typical for the under-canopy of shrub and for the adjacent open areas. The combination of stress factors affected the type and intensity of plant-plant interactions and plant life strategies (CSR) of the indicator species. Artemisia kopetdaghensis showed the highest facilitation effect under the most intensive stress conditions (high aridity/high grazing), which turned into competition under the low stress conditions (low aridity/low grazing). In the arid region, the canopy of shrub protected ruderal annual forbs and grasses with SR and R-strategy, respectively, in both high (high aridity/high grazing) and low grazing intensity (high aridity/low grazing). In the semi-arid region and high grazing intensity (low aridity/high grazing), the shrubs protected perennial forbs with C-strategy. Our FINDINGS highlight the importance of context-dependent shrub management in the restoration of vegetation damaged by intensive grazing.

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Experiments were conducted to investigate the ability of two species of Salicornia persica and Salicornia perspolitana to extract heavy metals, including aluminum, iron, and copper. In this study, manure and biochar were applied to improve performance. The two species of S. persica and S. perspolitana were grown outdoor in experimental pots. The effect of experimental treatments including manure and biochar on the two species was investigated. The results showed that biochar significantly influenced (P < 0.05) the accumulation of heavy metals in both S. persica and S. perspolitana. In biochar treatment, the values of heavy metals in roots and shoots were found to be 3327 mg/kg, 109.17 mg/kg for aluminum, 3527 mg/kg and 142.17 mg/kg for iron, and 73.93 mg/kg and 11.90 mg/kg for copper, respectively. In the manure treatment, the values of heavy metals in the roots and shoots were reported as 3993 mg/kg and 119.29 mg/kg for aluminum, 5542 mg/kg and 179.17 mg/kg for iron, and 78.67 mg/kg and 12.74 mg/kg for copper, respectively. In general, our findings showed that using biochar and manure in the soil allowed heavy metals to be stabilized, which reduced heavy metal accumulation in both S. persica and S. perspolitana. Heavy metal accumulation was higher in S. perspolitana than in S. persica.