Jeff Green | Sep 11, 2008
Sept 11/08 - Outdoors
Back toHomeOutdoors in the LandO'Lakes - September 11, 2008 Lichens Outdoors in the Land O'Lakes by Lorraine Julien
As you walk on and around the rocks of the Canadian Shield, pay attention to the Lichens that cling to life on the rocks and even some tree trunks, like a carpet made by Mother Nature. In fact, if you happen upon an open, rocky area, and you look closely, you may see lots of different Lichen species. Lichens, as well as fungi and algae, are in a group of plant life all their own. They predate modern plants and go back in time towards the origins of life.
Lichens are the hardiest of all plants, able to survive without water for up to a year and live on nothing but air. When dry, they appear to be dead but they only lie dormant until the next rainfall when they are transformed into a soft, spongy, colourful rug.
The Lichens that form a thin layer on the Canadian Shield are called Crustose Lichens which account for about half of Ontario’s Lichen species. They grow very slowly – less than one mm of growth a year. Within this species, there are many types which grow in various shapes, too numerous to mention here. You may have noticed another type of Crustose Lichen which grows at the waterline, leaving black tracings that mark the high-water point of bodies of water.
They originally formed hundreds of millions of years ago when plant life first moved gradually from the sea onto barren land. Although Lichens have no roots per se, they do stick to bare rock and produce acids that slowly break down stone, creating depressions to anchor themselves more securely.
Lichens are humble little plants that result from a partnership between various species of thread-like fungi and various kinds of algae. They grow in a wide variety of colours according to the species of the partners; resistant to drought, heat and cold, they grow in practically every environment. It’s also a good source of food for many residents of the forest such as moose, deer, flying squirrels, termites, caterpillars, snails, slugs and mites.
Lichens also play an important role in soil making. During changes in temperature, Lichen contract or expand, moving the rock dust they have produced and mixing it with their own wastes to make a thin soil which is slowly enriched as the Lichen partners continue to grow. Eventually, the depth and quality of the soil will sustain mosses, which will release their own organic wastes, further enriching the growing environment. As the build-up continues, conventional fungi colonize the fertile wild gardens provided by the Lichens, and small plants and tree seedlings take root, all of which produce wastes that add to the content of the natural compost. Slowly the soil area grows wider and deeper, and larger plants take root. Finally, trees are able to stand and grow in the good soil that has covered the barren rock.