Home ยป What lichens can tell us about climate and pollution | CBC News

What lichens can tell us about climate and pollution | CBC News

Lichens can be observed on tree trunks and branches in Edmonton’s river valley, adorning them with vibrant growths in various shades of yellow, green, grey, and bluish spots.

Lichens are not plants but fungi. They have a symbiotic relationship with their photosynthetic partner, typically algae, which reside within the lichen structure.

Troy McMullin, a lichenologist at the Canadian Museum of Nature in Ottawa, stated that lichens play a crucial role in influencing air quality.

He explained that they can be imagined as tiny sponges, absorbing nutrients and minerals from what is present in the surroundings, including the air.

In essence, they consume the air and if there are any contaminants present in the air, they will also ingest them.

A hand beside a close-up photo of tree bark with lichens visible.
Diane Haughland states that three types of lichens can be found growing on this tree: the orange hooded sunburst, the grey shadow lichen, and the pale green speckled greenshields. This specific assortment of lichens is commonly observed in areas that are exposed, dry, and have good air quality. (Peter Evans/CBC)

Different lichens have different sensitivities to pollution and other environmental conditions, such as humidity. 

Some lichens are able to endure harsh conditions, while others are more delicate and need a pristine environment.

McMullin stated that if you possess knowledge about lichens, you have the ability to personally search for them and enhance your understanding of the environmental conditions in your vicinity.

McMullin explained that one would need to possess knowledge about particular species and actively search for them.

What your local lichen can tell you about the air quality in your neighbourhood

23 hours ago

Duration 2:30

Featured VideoDiane Haughland, a lichen expert, authored the manual on lichens found in Alberta. We accompanied her on a stroll in the river valley to gain insights into various lichen species commonly found in Alberta. Furthermore, we discovered how the presence or absence of these lichens can provide valuable information about the air quality in the area.

Diane Haughland, an expert in studying lichens at the Alberta Biodiversity Monitoring Institute, displayed various lichen species commonly found within the city to CBC Edmonton.

Standing at Irene’s Lookout on Groat Road on the edge of the steep bank of the river valley, not far from the University of Alberta, she examined tree bark covered in yellow lichens, called hooded sunburst, with a few pale green ones over the tree trunk, called speckled greenshield, and a few practically invisible grey ones — shadow lichens. 

According to her, this characteristic is representative of the arid and exposed setting. It suggests that the humidity is likely insufficient for various species found at lower elevations. However, it also indicates that the air quality in this specific area is not extremely poor.

A man and woman standing beside a tree in the river valley.
Haughland showing lichens that cover the trunk of the birch tree growing near the river (Peter Evans/CBC)

“If we were to explore a lichen desert in Edmonton, even within the tree population, these lichens would be exceptionally scarce.”

According to Haughland, the downtown and industrial areas in Edmonton are referred to as “lichen deserts.”

According to Haughland, a wide range of lichens can be observed in the river valley due to its cooler and more humid environment, as well as the presence of a tree canopy that helps filter pollutants.

A close-up photo of a lichen on a tree.
A pelt lichen, found in the river valley. (Peter Evans/CBC)

At Irene’s Lookout, a birch tree near the riverbank was almost completely covered by speckled greenshield lichens, measuring the same size as a two-dollar coin.

According to Haughland, only small patches were allowed at the summit of the hill.

According to Haughland, certain lichens, such as pelt lichens, are exclusively found in the river valley and lawns adjacent to it in Edmonton. They do not occur in any other locations in the city.

She stated that the presence of these organisms indicates that there is sufficient moisture for their growth, photosynthesis, and overall well-being.

Pelt lichens are some of the biggest in Alberta. They are very important for soil health, Haughland said. They help stablize it and retain moisture, keeping the soil moist. 

They also absorb nitrogen from the air and convert it into a form that other organisms can use. 

A woman with a magnifying glass
Diane Haughland is using a magnifying glass to examine a lichen. (Peter Evans/CBC)

She mentioned that the composition, abundance, and size of species can provide valuable insights into the surrounding environment.

Although lichens can flourish in urban environments, cities can present difficulties as habitats for them.

According to McMullin, there comes a time when the air pollution reaches a level that even the toughest lichens cannot tolerate. At this point, they vanish and give rise to areas devoid of lichens, known as lichen deserts.

“He stated that they serve as the early warning signs or indicators since they consume food in the air.”

She stated that lichens serve as a reminder of how crucial forests are for humans during times of climate change.

We are aware that the temperature of our surroundings is increasing, and this is causing additional stress for us. The presence of a tree canopy is advantageous for lichens and humans alike.

Source: cbc.ca