Lichen are one of those organisms that don’t get much love. I learned to appreciate them during my final year research project when a group of us set out to inventory a nature reserve near Sutton to see if inexperienced people could be trained to identify them and be included in biological assessments. I haven’t looked at them the same since. Often mistook as moss, they are actually a symbiosis (partnership but unclear who really benefits) of a photosynthetic component, like algae or cyanobacteria, and a fungi. The fungi uses the algae to produce food from sunlight while supporting itself to a substrate, like rocks or trees, and extracts minerals. They are among the toughest organisms known, surviving in harsh conditions of the Arctic, deserts, exposed rock and even Mars! They come in lots of different shapes: flat crustose or branched-off fruticose, even leafy foliose, among others!
The rationale behind the project was that lichens are indicators of ecological health and air pollutants. Forest fragmentation, composition and age affect what kinds of lichen can grow and where. Also, high lichen diversity often corroborates with high diversity of other organisms like spiders and birds. Metrics like these are vital in assessing properties for potential conservation value. In the Eastern Townships, the presence of Pseudavernia cladonia is useful to assess how climate warming is progressing. This species only grows at certain altitudes, above the transition from leaf-bearing trees to mature fir forests. Warmer temperatures have pushed up the transition between the forests, pushing suitable P. cladonia habitat upwards as well. Lastly, presence of lichens have been used to indicate air pollution levels in urban areas because they are susceptible to heavy metals. A study released in 1970, in Montreal, showed that lichen diversity decreased in areas downwind from point sources, like factories. The presence of some lichen in relation the absence of others indicate what kind of metals are carried in the air.
It was a fun project and left me with some great memories and friendships. There is a great diversity to them and hope you’re liking the lichen! See if you can spot the lichen on the first picture.
Now for some older, close-ups. Unfortunately, I lost the ability to identify them by sight.
The last two pictures are from a visit to a local cemetery. My sister was interested in the genealogy. I was interested in the lichens on the tombstones.
- “The canaries of the fungal world” (wildlifecorrespondentmhp.wordpress.com)
- I’m Lichen What I’m Seeing! (sullde01.wordpress.com)