Using trees as urban heat island reduction tool in Enugu city Nigeria based on their air pollution tolerance index

The Study examined the air pollution tolerance indices (APTI) of five plant species around Enugu urban area. Four physiological and biological parameters including leaf relative water content (RWC), ascorbic acid (AA) content, total leaf chlorophyll (TCh), and leaf extract pH were used to develop an APTI. The vegetation monitoring in terms of its APTI acts as a ‘Bioindicator’ of air pollution and can be incorporated into assessment studies for selecting trees for urban heat island (UHI) mitigation strategy. The result of the APTI showed order of tolerance as Anacarduim occidentale (22.20), Pinus spp (22.35), Catalpa burgei (22.57), Mangifera indica (23.37), and Psiduim guajava (24.15). A comparative analysis was also done between the shedding ability of these trees and their APTI. The result showed that the best tree that provides both shed and high air pollution tolerance appeared in that order: Psiduim guajava, Magifera indica, Catalpa burgei, Pinus spp and Anacarduim occidentale. The results of such studies are therefore handy for future planning, and as well provide tolerant species for landscape and urban heat island mitigation.