Lichen: Air Quality Bioindicator


Today I prepared an exam for my students on environmental monitoring and the coverage of the said exam is about biological indicators or the use of organisms as predictors of alterations or changes in the environment.

There are different kinds of biological monitoring in assessment of the environment. For air quality, lichens are used to predict the changes or the concentrations of pollutants in the atmosphere. A lichen represents a symbiotic relationship between an algae and fungus. They normally appear like green or white patches in the barks of the trees. You have to look closer to notice the branches and leaves of the mini forest.


Different Kinds of Lichens (Photo from

The colors and shades of a lichen indicate the concentration of pollutants in the air. There are species sensitive to sulfur dioxide and there are species that can tolerate a certain amount of nitrous oxide. Generally, none of them can tolerate longer exposure to SOx and NOx and it may be difficult to spot a lichen in an urban setting.


 One of the common lichens found in Sabang,Barangay Cabayugan, Puerto Princesa City

A year ago, I brought my class to Sabang area which serves as the portal to the Underground River National Park. I taught them how to measure and map lichens. The field trip was just to let the students experience first hand how to use biological indicators in the assessment of air quality.


The students during their field exposure.

Everything about the environment are very interesting and as an instructor, I still learn every time I take my students out in the field.


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