Scientists have learned to use this variability as an indicator of the air quality of any given site. If change of substrate of the lichens as well as their general appearance is interpreted correctly a good picture of the air pollution situation is already available. Biological Indices Using Lichens As Biological Indicators Of Even with the similar zones set up in this experiment Punctelia rudecta showed indicative values for one zone but not for the other two. . The most indicative lichen Punctelia rudecta has been described as fairly tolerant of pollution Brodo 608. These oxides are the result of burning fossil fuels vehicle exhaust emissions and intensive agricultural practices. So botanists can use lichen species as air quality indicators. Because lichens have no roots or protective surface they cannot filter what they absorb so whatever is in the air is taken straight inside. In polluted areas or in areas where pollu...