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| Many boreal forest spruce sport old man's beard lichens, which caribou find very tasty. Photo by MNR's Stan Vasiliauskas. |
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| Lichens are among the most durable organisms on Earth, able to thrive in the most windswept and frigid climates, such as the rocky shoreline of Lake Superior. |
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While lichens are fascinating and common, they are not well studied. Not much is known about how forestry activities affect them.
OFRI research scientist Wayne Bell first fielded questions about how sensitive lichens are to forestry herbicides in the mid-1990s. “A quick literature search revealed limited information, and I recognized a gap that needed to be addressed,” he recalls.
With funding from the Forest Ecosystem Science Co-op, Bell worked with University of Guelph graduate student Troy McMullin and professor Steven Newmaster to install just such a study in northern Ontario.
According to Bell, their results indicate that lichens range from tolerant to very sensitive to herbicides and that richly branched lichens are most susceptible.
EACOM biologist Kandyd Szuba notes, “This excellent study, conducted in semi-mature conifer stands with little hardwood competition, sheds new light on why and how herbicides affect lichens. One caution is that these types of stands would not normally be targeted for spraying, so more information is needed on how lichens would respond in more operational conditions. Another area of interest is how lichen recovery in sprayed stands compares with their recovery after natural disturbance such as fire.”
Bell agrees that previous research shows that competing hardwoods could capture some of the herbicide before it hits the ground—and the lichens—in operational settings and that more research on lichen susceptibility to herbicides in various conditions is warranted.
Want to read more?
The effects of triclopyr and glyphosate on lichens (order PDF)
Did you know...? Facts about lichens
- Lichens are primitive plant-like organisms that are part algae and part fungi or cyanobacteria. Scientists call them symbiotic, meaning they are made up of two different organisms that exist and grow together for mutual benefit.
- Lichens are very common in Ontario, growing on tree bark and branches, rocks, cliff faces, bare ground, shingles, buildings, and even the shells of tortoises.
- They can be quite beautiful when draping down in long clumps from the branches of black spruce trees or decorating rock faces with patches of red, yellow, and green. The British soldier lichen is actually cute, looking like a tiny troop of red soldiers marching along a rotting log.
- Lichens do not have roots, stems, flowers, or leaves, but the alga part of them does photosynthesize (use sunlight to produce energy for growth and reproduction).
- These remarkable organisms thrive in a wider range of climates than either algae or fungi do alone, from very hot, dry places to coldest Antarctica. And they can dry out without dying and revive when it rains.
- They can also photosynthesize when the temperature is well below freezing, giving them an edge over regular plants in cold climates like Ontario’s.
- Many wild animals like to eat lichens, including caribou. Birds use lichens for nesting material, and insects and snails use them for food and shelter. Lichens also absorb nutrients from the air (they help fix nitrogen, for example), and they produce acids that help to break down rock to form soil.
- Throughout history, people have used lichens for food, dye, clothing, decoration, medicines, and other products. But do your homework before collecting any lichens—some are poisonous.
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| A single rotting log can have many types of lichens growing on it, including the delightfully-named British soldier lichen, known for its bright red colour. Lichens help break down old logs, renewing the forest. And many types of wildlife depend on lichens; they are a primary food source for caribou, and flying squirrels use them to line their nests. Lichens are a commercial crop in Scandinavia, where they are ground and used to thicken soups and desserts. |
