Assessing the Cooling and Air Pollution Tolerance among Urban Tree Species in a Tropical Climate

Abstract

We present the results of classifying plants at species level that can tolerate air pollution, provide cooling, and simultaneously survive and thrive in urban environments. For this purpose, we estimated the air pollution tolerance index (APTI) and anticipated performance index (API) of several species growing in a park located in central Bangkok, Thailand. The cooling effect was quantified by calculating the reduction in soil and air temperatures. Melaleuca quinquenervia (Cav.) S.T. Blake, Albizia saman (Jacq.) Merr., Chukrasia tabularis A. Juss. had the highest API score and were able to substantially reduce the temperature and were in a group of highly recommended species which also included other species like A. saman, C. tabularis, Tabebuia rosea (Bertol.) Bertero ex A. DC., Dalbergia cochinchinensis Pierre etc. Species from both evergreen and deciduous habitat were able to provide ambient cooling but were vulnerable to air pollution and included Elaeocarpus grandifloras Sm. and Bauhinia purpurea L. However, there were other species which had a high air pollution tolerance but failed to provide adequate cooling, such as Hopea odorata Roxb. and Millingtonia hortensis L.f. The results would be of interest to urban greenspace landscapers in such climates while selecting suitable species that can provide multiple ecosystem services ranging from air pollution tolerance to temperature reduction without reducing plant vitality.

Air Pollution Mitigation Potential of Dominant Landscape Plants of an Urban Ecosystem (Lahore City) of Pakistan: An Air Pollution Tolerance Index (APTI) Assessment

“…Total 21 species were selected to determine the air and soil temperature reduction, APTI And API. Among these species it was observed that species of both deciduous and evergreen habitat were good at providing the cooling effect, but they showed variable results in their tolerance potential of air pollution [31]. By considering the ever-increasing ambient pollution levels and the most polluted city of the world (Lahore), this research work was executed to calculate the APTI value of various landscape plant species, so the tolerant plant species would be suggested to plant in urban developing areas for mitigating air pollution while plant species sensitive to pollutants would be utilized as bio-indicators in highly polluted areas [32].…”