Lichens as indicators of forest health in Canada

Canadian forests are naturally dynamic ecosystems, changing species composition and abundance as the ecosystem evolves through succession or reacts to disturbances, such as wind and insects. Pollution and climate change will be the largest stressors to Canada's forests in the future. Their future impact on the health of Canada's forests remains speculative. Lichens have been identified as valuable indicators of forest health; however, there are no comprehensive datasets on which lichens are indicative of forest health in Canada. An analysis of the existing literature reveals a large number of lichens that can be used to monitor levels of various pollutants (general pollution: 51 species; sulphur dioxide: 42 species; photochemicals: 23 species; fluoride: 18 species; heavy metals: 3 species; acid precipitation: 8 species; sulphite: 2 species; nitrate: 2 species). The use of lichens as indicators of climate change is also reported in the literature but, there are insufficient data to monitor the effects of climate change on lichen communities in North America. While various provincial and federal government departments and industries have been monitoring lichen communities across Canada for up to nearly three decades, there exists no standard monitoring protocol for lichens in Canada, which makes comparisons among studies challenging. The development of a standard monitoring protocol would allow integration of the various initiatives into a nationwide lichen monitoring program.