Lichens of the Carp Barrens

By Colin Freebury

Out for a walk on New Year’s Day, 2006, I happened to notice some tiny mushrooms on the side of a tree along Riverside Drive. 

Curious as to what they were, I called the mushroom identification number at Agriculture Canada. There I learned that they were probably a species known as Mycena meliigena. Anticipating my next question, I was quickly advised that if I wanted to know about the lichens in the picture, I had best contact Ernie Brodo at the Museum of Nature. And that was the start of my involvement with the fascinating world of lichens.

So, for the uninitiated, what are lichens? Lichens are fungi that include a photosynthetic partner, which can be a green alga or a cyanobacterium, or both, depending on the species. Basically, the fungal partner (mycobiont) provides the structure of the organism, while the photosynthetic partner (photobiont) provides the nutritional energy necessary for life. The mycobiont also provides protection from the harmful effects of ultra-violet rays on the photobiont. 

Lichens are not plants, although some species might be seen to resemble leafy plants, and were consequently once referred to as plants. 

Being able to produce their own food, as long as they can access sunlight and some form of moisture, enables lichens to grow in almost every part of the world, from tropics to polar regions, from deserts to mountains. Few species are found in urban or industrial areas, however, as lichens are very sensitive to air pollution. In this regard, the presence and abundance of lichens have been used as indicators of the effects of measures to improve air quality.

For more on lichen biology, see What is a Lichen? at the British Lichen Society web page, or Lichen at Wikipedia.

Lichens Found on the Carp Barrens

I first became aware of the Carp Hills in 2011 when I was invited to participate in a local bioblitz. I soon discovered an impressive assortment of lichens within an area just 100 m or so on either side of Thomas A. Dolan Parkway near what is now the western entrance to the Carp Barrens Trail. During the bioblitz and several subsequent visits, I’ve managed to develop a list of 84 species. Photos of several of these are available for viewing at the Carp Hills BioInventory project on iNaturalist at Carp Barrens Trail lichen photos, Freebury.

For a complete set of lichen photos from the Carp Hills, see Lichens in Carp Hills BioInventory.

The abundance of lichens on the Barrens is likely due to the amount of open space and sunlight; the number of beaver ponds, streams and swamps in the area; and the wide variety of micro-habitats, including both exposed and shaded rocks, various species of trees, and soil and plant detritus. And, to top it off, relatively clean air! Lichen heaven, one might say.

Winter hikers might have noticed certain lichens on tree bark or exposed rocks and wondered how they survive. The answer has to do with the fact that lichens are quick to dehydrate and, thus, once the cold weather arrives, they don’t contain water that would turn into destructive ice crystals. They are just as quick to rehydrate and get growing again once the immediate air temperature rises above freezing. This cycle can occur over the course of a day, say in the spring.

Photosynthesis (making sugars) is highest at cool temperatures, and respiration (using up sugars) is highest at warm temperatures, so lichens actually grow faster in early spring and late fall than they do in summer.

In our area most lichens grow only a few millimeters a year. This leads to the question of how to protect lichens from damage due to foot or wheeled traffic? We’ve all seen how certain erect, pale species of Cladonia that grow over rock and soil along parts of the Trail have been trampled into fragments. And while these species can regenerate from fragments, they won’t if the fragments are continually disturbed and then blown or washed away. Eventually such areas become widened into bare rock and patches of bare, packed soil, after which there is likely no possibility of regeneration of the lichens or, for that matter, plants like the Pink lady’s slipper in the photo below.

Visiting the Barrens this fall after an absence of several years, I’ve been impressed with the work that the volunteers with the Friends of the Carp Hills have done to establish well-marked trails and put-up cautionary signage. And I’ve been pleased to see that hikers and bikers appear to follow the rules. I even had one biker remind me to stay on the trail! (I had wandered a bit to examine a lichen.) So that’s promising.

I haven’t found any lichens on the Barrens that one wouldn’t expect to find elsewhere in similar environments, for instance in parts of Gatineau Park and Algonquin Park. For me, what stands out about the lichen population on the Barrens is the diversity of species in a relatively small area, which, I remind you, is now within the boundaries of the nation’s capital city!

The Star-tipped reindeer lichen is not only pretty to look at; it is known as an “ecologically important species that forms continuous mats over large areas of the ground in boreal regions around the circumpolar north. The species is a preferred food source of reindeer and caribou during the winter months, and it has an important role in regulating nutrient cycling and soil microbiological communities.”(Wikipedia). The last part of that statement is a good start to a reply to a question I am sometimes asked: ‘very interesting about mutualism and all that, but what are lichens good for?’

Identifying Lichens

Lichens can be identified by their appearance (e.g., morphology, attachment structures; colour); reproductive means (e.g., spores, granules or pieces comprised of fungal hyphae and a photobiont); obligate substrates (e.g., types of tree bark, acidic or calcareous rock, soil); chemistry; and phylogenetics. Four common grouping of lichens based on growth form are as follows:

Foliose lichens have a discernable upper and lower surface. They adhere to their substrate loosely.

Note the bluish or grayish colour, which indicates that the photobiont in this species is a cyanobacterium.

The larger species such as the Star-tipped reindeer lichen are relatively easy to identify in the field using a mobile application such as iNaturalist. A hand lens is useful for observing characteristics of a particular specimen that might not show clearly in a photograph. 

The same is true for some smaller, inconspicuous lichens such as the crust-like species that can be seen adhering to rock and bark. But for the large part, to identify them with confidence it is necessary to take samples of these for dissection and study them under a microscope. Guidance and techniques for this can be found in Lichens of North America (I.M. Brodo, 2001) or Lichens of the Ottawa Region (I. M. Brodo, 1988), both of which are available at the Ottawa Public Library.

If I were just getting started, I think I would take pictures with my phone to post on iNaturalist and see what participants in the program suggest for a name. Then I would consult Lichens of North America to check the identification, and perhaps just as interesting, to learn about the species in question: What chemicals does it contain and what function do they perform? Where else is the species found in Canada and throughout the world? What might explain that? Who first named the species? If it now has a different name, why is that and how was that decided? 

In my case, what began as a little question about a tiny mushroom that I happened to see growing on a tree one wintery day, led to something of a second career as an amateur lichenologist (sometimes referred to as an ‘enthusiast’), adventures collecting specimens, particularly in Grasslands National Park, and many new friends. I can’t say that I satisfied my curiosity about lichens, however; instead, as these things do, it keeps growing!

So, keep your eye out for lichens next time you’re on the Carp Barrens Trail. You never know where that might lead.

Another thing about lichens is that they can be fun and challenging to photograph. I enjoyed taking the photos in this article, and they now bring back fond memories of field trips.

About the Names

Here is a list of the scientific equivalents for the vernacular names that appear in the text:

Acknowledgements

I’d like to thank Janet Mason for inviting me to write this article. And I am grateful to Fenja and Ernie Brodo for reviewing the manuscript.

About the author

Colin Freebury was a Research Associate at the Canadian Museum of Nature where he worked on lichens and helped in the herbarium. He contributed to research on the lichens of the Ottawa region, especially Gatineau Park, and of Grasslands National Park, Saskatchewan.