Stuff to Like About Lichens

Unidentified Crustose lichen on Quartzite. © Drew Brayshaw

Did you know that we have over 1100 different species of lichens in British Columbia?

Lichens aren’t fungi, moss, or plants. Instead, think of lichens as a set of stellar roommates – a mutualistic relationship where both parties benefit. In most cases, lichens are made up of photosynthetic algae or cyanobacteria living within strands of fungi. They come in hundreds of different shapes, sizes, and colors, and some grow less than 1 millimeter per year.

The fungi make up the bulk of the lichen, and protect the cyanobacteria or algae cells while providing valuable storage for moisture and nutrients. In return, the cyanobacteria or algae produce carbohydrates for the fungi using photosynthesis to break down carbon dioxide from the air. In cases where cyanobacteria is partnered with the fungus – or partners with both algae and fungus in a three-way symbiosis – it also fixes atmospheric nitrogen. Typically, the fungus sandwiches the algae or cyanobacteria (or both!) between layers of fungal strands.

Showing a lichen (Parmelia saxatilis) in cross-section, with the layer of green-algal cells (P) positioned between the protective fungal layers. Fungal segments are divided into the upper cortex layer (UC), medulla layer (M) and lower cortex layer (LC). © Royal Botanical Garden Edinburgh, 2023.

Atmospheric nitrogen is what can be called a “limiting factor”. Imagine a car running out of fuel. It doesn’t matter what shape the car is, what color it is, or who the driver is. If it runs out of fuel, it won’t move. Atmospheric nitrogen is fuel for the production of all types of cells, and with only so much to go around, the speed of cell growth is limited by how much atmospheric nitrogen is available. 

Algae are responsible for approximately half of all photosynthesis on earth, and lichen enables algae to survive in some of the most extreme environments on earth – places they wouldn’t be able to tolerate on their own. They break carbon dioxide down into oxygen, and provide food for all types of creatures. 

Lichen, like wetlands, are excellent sponges, absorbing pollutants from the atmosphere. In this way, they make good bio-indicators, as pollutants can build up in the lichen and be measured to determine how severe the air pollution is in that area. 

Lichens tend to thrive in wetland environments due to the abundance of moisture, the availability of sunlight, and lots of available surface area – like deadwood – for them to grow on. It isn’t uncommon to see several different species of lichen growing on the same rock or log.

Next time you’re out, see how many different types of lichen you can count! For more information on identifying your local lichens, check out Local Lichens of South Coastal BC by Capital Regional District on our Other Resources page!

You really want to talk about wetland stewardship don't you? Why not share your opinion on this Blog entry...

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s