Lichens are fungi that live in intimate association
with algae. Lichens are very responsive to environmental
stressors in forests, including changes in forest
structure, air quality, and climate. In Forest
Inventory and Analysis (FIA), we collect data
on epiphytic lichens, those species growing
on trees and shrubs.
Why is the Lichen Indicator Important?
A lichen community is a group of various species
of lichens present at a site. The composition
of an epiphytic lichen community is one of the
best biological indicators of nitrogen and sulfur-based
air pollution in forests. Their sensitivity
results from their total reliance on atmospheric
sources of nutrition. Because lichens are so
sensitive to these pollutants, they are useful
as an early indicator of improving or deteriorating
air quality. Using lichens, we can answer the
- Is regional air quality (specifically nitrogen-
and sulfur-based pollutants) changing over
time? If so, is it improving or deteriorating?
- In what fraction of an area do lichens indicate
the possibility of air pollution impacts
on forest productivity and biodiversity?
Since the effects of air pollutants on trees
can be difficult to separate from other influences
on growth (such as soil variations), epiphytic
lichens provide a clear indication of potential
air quality impacts on total forest productivity.
For more information about the Lichen Indicator view
Lichen Indicator Fact Sheet.