Adaptive responses of trees to industrial pollution: modulation of leaf anatomical, physio-biochemical, and heavy metal accumulation traits in urban biotopes
摘要
Urbanization and industrialization have introduced complex environmental challenges, particularly concerning air pollution caused by industrial emissions. This study evaluates the adaptive responses of Cassia fistula, Pongamia pinnata, Ficus religiosa, and Ficus virens in polluted urban-industrial environments. Data was collected from five urban biotopes, including residential area (control) and industrial zones: crockery (site 1), iron and steel (site 2), sanitary (site 3), and auto parts industries (site 4), on the growth of broadleaved tree species. Different anatomical, physiological, and biochemical traits along with heavy metal accumulation were assessed. Results depicted that epidermal and stomatal densities declined by 40%, with the most severe reductions at site 4 (auto parts industry), where C. fistula showed the highest changes. Heavy metal accumulation was highest at site 4, with F. virens and F. religiosa accumulating maximum Cd (0.43 mg kg⁻1, 0.38 mg kg⁻1) and Cr (3.34 mg kg⁻1, 3.09 mg kg⁻1), while Pb accumulation was highest at site 2. Antioxidative enzyme activity increased under pollution stress, with maximum SOD (371 U mg⁻1 protein) in F. virens at site 4. Air pollution tolerance index (APTI) results identified F. virens (19.33%) and F. religiosa (18.00%) as the most pollution-tolerant species, while C. fistula and P. pinnata were moderate tolerant species. All industrial sites showed some level of pollution severity, however, the most affected site was site 4: the auto parts industry. The results emphasize that F. virens and F. religiosa are the most suitable for afforestation in industrial zones, and the current findings highlight their suitability for urban greening and emphasize their importance in urban forestry planning to mitigate pollution and enhance biodiversity conservation.