Assessment of the Sensitivity of Washingtonia and Balanites Trees using Air Pollution Tolerance Index and Anticipated Performance in some Areas of Fezzan, Libya

Abstract

Tree cultivation receives considerable attention due to its role in filtering pollutants, especially in areas which exposed to high levels of various air pollutants, such as urban areas. However, selecting appropriate plant species remains a challenge for decision-makers, raising an important question: Is this tree species sensitive or tolerant to air pollutants? Based on the foregoing, this study aimed to evaluate the Air Pollution Tolerance Index (APTI) and Anticipated Performance Index (API) for Washingtonia robusta and Balanites aegyptiaca trees in three regions of Fezzan in southwestern Libya (Sebha, Brack Al-Shatti, and Tessawa). This was achieved by analyzing four parameters: relative water content, leaf extract pH, total chlorophyll, and ascorbic acid concentration, in addition to evaluating the Anticipated Performance Index. The study results showed that the tolerance index of the studied trees fell into the Immediately Tolerant classification. The results proved that the Washingtonia tree (24.48) was the best tree tolerant to air pollutants in all studied sites, while the tolerance index for Balanites was (18.48). The results of the Anticipated Performance Index (API) confirmed that Balanites performed very well compared to the Washingtonia tree, which showed a better tolerance index than Balanites. This is attributed to the simpler structure of the Washingtonia tree and its lower economic and social importance according to the performance index. From these results, it can be concluded that these two trees can be relied upon for cultivation in cities due to their ability to tolerate air pollutants.