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.


Cleanest and Greenest City: Puerto Princesa

Have you ever been to Palawan? I hope you did because it is such a nice place to visit. Aside from having top tourist destinations, the proper waste disposal is another thing that is worth noting for. It has been the culture in the province since the implementation of the Oplan Linis Program in 1992. The strict implementation resulted to minimized trash in the streets, thus, a clean and green city.

The successful implementation of the program not only improved the waste disposal of the city, but it also changed the behaviour and attitude of the residents as well. Even the younger generations are disciplined and aware as to where to dispose candy wrappers properly. Trash bins are positioned in every corner of the city to ensure easy access for residents and easier collection by the waste management too.

00(Photo from

At young age, it is imperative to educate the children on the importance of the environment in general. This reminds me of our accountability in taking care of our natural resources as mentioned in the seven (7) environmental principles listed below:

1. Nature Knows Best.
2. All forms of life are important
3. Everything is connected to everything else
4. Everything changes
5. Everything must go somewhere
6. Ours is a finite earth
7. Nature is beautiful and we are stewards of God’s creation.

Let me also end this article by quoting one of Mahatma Gandhi’s which says,