Air pollution monitoring and green belt assessment of three urban tree species in Erbil City, Iraq

Abstract. Sabr HA, Ali KA. 2025. Air pollution monitoring and green belt assessment of three urban tree species in Erbil City, Iraq. Asian J For 9: 299-311. This study evaluates the tolerance levels of three roadside tree species—Brachychiton populneus, Ligustrum lucidum, and Olea europaea—to air pollution for the establishment of an urban greenbelt in Erbil City, Iraq. The Air Pollution Tolerance Index (APTI) and Anticipated Performance Index (API) were calculated using biochemical and physiological parameters, including leaf area, proline, and total carbohydrate content. Leaf samples were collected from four locations with differing pollution intensities. Results showed that B. populneus had the highest APTI values at Locations 3 and 2, with 12.67±0.33 and 11.67±1.20, respectively, compared to other species. The same species also maintained a pH range from 6.11 to 7.1 across all locations studied. Additionally, L. lucidum exhibited lower percentages of LRWC in less polluted sites. The highest ascorbic acid content was found in B. populneus, measuring 2.76±0.07 mg g-1. No significant differences in total chlorophyll were observed among all species in polluted locations compared to less polluted sites during the study, except for L. lucidum at Location 2. At the same time, a significant increase in total chlorophyll was observed for B. populneus in Location 3 (0.22±0.03 mg g-1). There was a significant positive correlation between APTI and LRWC% (R2=0.89). The findings support the integration of B. populneus, O. europaea, and L. lucidum as primary candidates for urban greenbelt development in Erbil to enhance air quality and ecological sustainability.