A location with luxuriant growth of lichens on the trees indicates that the:

Explanation

Lichens are very sensitive to SO2 and pollution and are completely destroyed at places with the presence of these substances. Therefore, they act as very good indicators of SO 2 and pollution. A location with luxuriant growth of lichens on the trees generally indicates that the air quality in that area is relatively clean and unpolluted. Lichens are highly sensitive to air pollution, including sulfur dioxide (SO2) and other pollutants. When lichens thrive on trees and other surfaces, it suggests that the atmosphere in the area has low levels of air pollutants.