The screening of plant species is of environmental significance hence their sensitivity as bioindicator as well as their tolerance as biomonitoring agent in air pollution mitigation have been established. The present research was aimed at evaluating the potential response of arboreal epiphytes as bioindicator under ambient condition, with the objective of identifying species that can serve as biomonitoring baseline agent for impact prediction and judgment of air pollution. Classical conventional methods were used to evaluate the susceptibility level of the epiphytes under ambient environmental condition using four established physiobiochemical parameters: leaf extract pH, relative water content, ascorbic acid, and chlorophyll to extrapolate Air Pollution Tolerance Index (APTI) for 8 species. Result revealed three categories of APTI responses: APTI 1-10 = sensitivity; APTI 10.01 – 13 = intermediate and APTI 13.01-16 above = tolerance. The order of responses in sensitivity: Platycerum bifurcatum>Oleandra distenta>Nephrolepis bisserata; intermediate: Nephrolepis undulata>Nephrolepis pumicicola and tolerance: Platycerum stagelephantotis > marattia fraxinea> Platycerum grande were recorded. The order of response indicated P. stagelephantotis with higher APTI (15.19) reflecting higher tolerance level and least APTI (6.46) for N. bisserata indicating sensitivity under ambient condition as baseline against air pollution. Therefore by their level potential responses at the ambient level can be recommended for phytosequestration / mitigation hence the APTI sensitive and tolerant species can serve as bioindicator and biomonitor respectively. Such performance might be very useful in the selection of appropriate epiphytic species that can enhance the expected performance of canopy formation of greenbelt in a changing environmental condition.
Key Words:APTI, Chlorophyll, Ascorbic acid, pH, Relative water content