How lichens act as pollution indicator?
Lichens act as a very reliable pollution indicator. These are released into the air as a byproduct when fossil fuels are burned, and can be detected. The amount of lichens in the air therefore, indicates the pollution levels.
lichens are sensitive to sulfur dioxide, they are biological indicators. The cleaner the air the more lichens will grow. Therefore if there are houses right by a road, if you look on the roof there would be less lichens as there would be more sulfur dioxide in the air because of pollution. Hope this helps By Troy Flynn
The hardy lichens are useful bioindicators for air pollution, espeially sulfur dioxide pollution, since they derive their water and essential nutrients mainly from the atmosphere rather than from the soil. It also helps that they are able to react to air pollutants all year round. Compared with most physical/chemical monitors, they are inexpensive to use in evaluating air pollution.
Many beneficial processes and products are derived from them, such as decomposition, nitrogen fixation, food, medicinal, fabric dyes, and alcoholic fermentation. Lichens and mosses are often used as bio monitors or indicator species of air pollution (since non vascular plants are very sensitive to air pollution as you may know), such as that caused by sulfur dioxide. Hope that helps.