Air Pollution Tolerance Index (APTI) Assessment in Tree Species of Coimbatore Urban City, Tamil Nadu, India

Aims: Forest restoration in urbanized and polluted cities is paving the way for mitigation of climate change by reducing the air pollutants level and carbon content level in atmosphere. So, the study was conducted at Coimbatore urban city, Tamil Nadu by using twenty five tree species to know their air pollution tolerance index (APTI) level.

Study Design: The sample procedure used for assessing the APTI was stratified random sampling.

Place and Duration of Study: The leaf sample was collected from different zones of Coimbatore urban city and the sample analysis was carried out in Department of Silviculture, Forest College and Research Institute, Mettupalayam, Tamil Nadu between August 2015-April 2017.

Methodology: Five zones namely residential, industrial, commercial, heavy traffic and control zone were identified from Coimbatore city for estimating the air pollution tolerance index (APTI). In order to assess the air pollution tolerance index of tree species, the biochemical parameters like ascorbic acid content, total chlorophyll content, leaf extract pH and relative water content (RWC) were estimated.

Results: Among the 25 tree species tested, Thespesia populnea recorded highest APTI of 16.07, 15.76, 14.63 and 14.37 in heavy traffic zone, industrial zone, control zone and residential zone respectively. In commercial zone, Pongamia pinnata accounted highest APTI value of 13.96. On contrary, the lowest level of APTI was registered by Michelia champaca in industrial zone (10.21), Peltophorum pterocarpum in heavy traffic zone (10.93), Spathodea campanulata in residential zone (11.11) and Albizia saman in commercial zone (11.46).

Conclusion: On an overall, Thespesia populnea and Pongamia pinnata were performed well with highest APTI and they can be used for controlling the air pollution level in urban cities.