Air Pollution Tolerance Index (APTI) and Anticipated Performance Index (API) of plants found in Matara city area, Sri Lanka: An approach for recommending plants for landscaping city areas

This study aims to recommend plant species for urban landscaping based on a biomonitoring study accompanied by comparison of Air Pollution Tolerance Indices (APTI) and Anticipated Performance Indices (API) of five tree species (Mangifera indica, Muntingia calabura, Cassia fistula, Azadirachta indica, Ficus benjamina) and four ornamental species (Bougainvillea spectabilis, Ixora coccinea, Ervatamia coronaria, Nerium indicum) found in Matara city area, Sri lanka. APTI was determined by combining the four biochemical and physiological parameters Relative water content (RWC), Total chlorophyll content (TChl), Ascorbic acid content (AA) and Leaf extract pH using a pre-defined formula. Each parameter of all the species was compared with that of it for the control site, Wellamadama premises of University of Ruhuna. Results suggested that RWC, TChl and pH were lower, and AA was higher for the city area in comparison to control site. APTI varied in the decreasing orders C. fistula (13.09), A. indica (11.23), M. indica (11.12), F. benjamina (10.68), M. calabura (9.12) for tree species and E. coronaria (10.22), I. coccinea (10.20), N. indicum (8.85), B. spectabilis (8.43) for ornamental species. Based on APTI, M. indica, C. fistula, A. indica were intermediately tolerant and other species were sensitive to air pollution. The calculated API values suggest, M. indica is ‘excellent’, C. fistula is ‘very good’, F. benjamina and A. indica are ‘good’ and M. calabura is ‘moderate’ in their suitability to be planted on urban landscape as tree species. API values of the tested ornamental plant species showed that B. spectabilis, I. coccinea, E. coronaria as ‘moderate’ and N. indicum as ‘poor’ for urban landscaping. The overall results highlight the suitability of APTI and API as simple, inexpensive, and convenient methods for recommending plant species for urban areas with sound automobile pollution.