Leaf length may determine particulate matter retention efficiency in trees and shrubs species: a case study in Faisalabad city

Abstract

Globally, climate change has been a serious concerned especially in case of air pollution particularly fine particles termed as particulate matter (PM). Vehicle emissions, industrial chimneys, open waste burning, dust from building sites, and unpaved roads are the primary sources of PM. Although vegetation has been found to be effective in by filtering out PM from the atmosphere, however, PM removal efficiency varies from one specie to another. To fill this research gap the study focused on compering the PM retention efficacy of five native broad-leaf tree species and five native shrub species commonly found in Faisalabad city, Pakistan. Leaf morphology along with leaf orientation was also evidenced as they play a vital role in modifying the PM retention efficiency. The location for the experiment was carefully selected depending on the occurrence of the selected tree species within a 3±0.5 km radius. The high traffic site was selected for this experiment Club Road, Civil Lines (31°42'N 73°08'E). Findings have shown that among trees, Ficus benghalensisdemonstrated the highest PM retention ability (5.61g/m²), whereas Lantana camara emerged as the most efficient shrub (6.27g/m²), significantly exceeding all other species analyzed. Morphological and architectural features such as leaf length, leaf width and petiole length (19.6 cm, 10.7 cm, 4.6 cm, respectively) and twig-petiole and petiole-blade angle (108°, 222.6°) was also found highest in Ficus benghalensis. Furthermore, leaf length and leaf width was found positive correlated with PM retention across tree species. Therefore, it can be concluded that increased PM retention efficiency in Ficus benghalensis was related to larger leaf size and horizontal leaf orientation. This study contributes significantly selecting tree for urban environment however, further research including other species can be valuable before improving urban greenery in a heavily polluted, industrial city like Faisalabad.