Environment Canada has added a lichen monitoring method to its Ecological Monitoring and Assessment Network (EMAN) set of ecosystem monitoring protocols.

Lichens are primitive organisms that grow on the bark of trees. Different species have varying levels of tolerance to air pollution - primarily sulphur dioxide - but also nitrogen oxides, particulate matter, and ground-level ozone. Identifying whether or not key lichen species are on trees in your neighbourhood offers a clue to local air quality.

There are over 3,600 different species of lichens in North America. Using the EMAN lichen protocol, citizens survey 15-20 easily identifiable arboreal lichens ranging from tolerant to very intolerant of air pollution. A 2004 study in Hamilton showed a higher diversity and abundance of lichens on trees near the periphery of the city than downtown. Lichen deserts were identified in some areas, suggesting air quality concerns that require further investigation.

Environment Canada encourages Canadians to get involved with community-based monitoring as a meaningful way to learn about environmental changes and to work together to track and respond to sustainability issues.

For more information on community based monitoring and how to get involved, visit the EMAN website.