Response of round-leaf ash (Fraxinus rotundifolia Mill.) leaves to urban pollutant gases

Air pollution is one the threatening factors affecting human and plants health in the cities. Since human continuance is closely related with the plants’ survival, different effects of pollution on plants can affect green areas and vegetation management and preservation in urban zones. Therefore, this study was carried out to define the effects of urban pollutant gases (SO2, NO2 and O3) on quantitative characteristics of round-leaf ash (Fraxinus rotundifolia Mill.) in Tehran. The study was carried out in seven municipal districts of Tehran, which were selected to include the wide spectrum of climatic conditions and contrasted levels of air pollution within the city. Quantitative characteristics including leaf area, specific leaf area, wet and dry weight, leaf toughness and thickness and water content percentage were studied by means of correlation analysis and t- test. The correlation results showed that increasing air pollution results in decreasing dry and wet weights and leaf area. Amongst the seven studied districts, the analysis revealed that Azadi and Sorkhehesar areas were associated with significant differences in pollution and non-significant differences in soil and climate. Our study indicated that all of the characteristics are significantly different in two areas. Furthermore, the quantities of all parameters except leaf thickness significantly decreased in more polluted areas.