Why the discovery of rare lichen in Kejimkujik is good news for air quality

Researchers have been studying plants and animals in Nova Scotia's Kejimkujik National Park for decades, so it's not often they find something new.

But recently, a type of lichen never before seen in Canada was spotted on a tiny island in the middle of Kejimkujik Lake — just before the publication of a new study examining the growing number of lichen in the park.

The discovery is particularly important because lichens are sensitive to pollution, and serve as a sort of environmental-monitoring station that can help scientists gauge changes in air quality. The upshot for the national park is more lichens suggest better air.

"The lichens themselves were gaining in number over the time, so they're increasing due to what we think is maybe improvements in the air quality," said Matthew Smith, park ecologist at Kejimkujik.

Lichens an 'early warning sign'

He said they've also seen growth over the last decade in lichens that are particularly sensitive to air quality.

"Lichens are an early warning sign. So you can imagine in cities where you see a lot less of those lichens, that's meaning they're not there because they're not able to protect themselves," he said.

"That's showing that the air quality is not great."

"If we look at places like protected areas, like Kejimkujik National Park, if we're not seeing those lichens here, that means we're being impacted by pollution from far away."

Lichens are organisms that grow on trees and rocks and are a combination of algae and fungi working in symbiosis.

Only Parmotrema perforatum found in Canada

Last summer, Smith said park volunteer Alain Belliveau was helping with a project on coastal plain flora when he ventured out to an island on the western side of Kejimkujik Lake that takes about 15 minutes to reach by boat.

As Belliveau was searching the coastline for a certain plant species, he noticed something unusual up in one of the trees.

"He knows his lichens, and he noticed a strange lichen — and it turned out to be this very rare lichen," Smith said.

The samples were sent away to Dr. Troy McMullin at the Canadian Museum of Nature, who was in the process of finalizing his 10-year study on lichens in the park. He identified it as Parmotrema perforatum, or perforated ruffle lichen.

"It turned out this was the only spot in Canada where this lichen has been, for sure has been found, which is pretty exciting," Smith said.

"We've looked around at a couple of other islands in this area and we found it on one close by, but really it hasn't been seen in any other spots in the park, which is pretty amazing because it's a big, showy lichen."

'A special spot for lichens'

In an email, McMullin said many lichen species require narrow or specific environmental conditions to grow.

"If their climate changes, some species will likely disappear. Even subtle changes in moisture or temperature can be detected with lichens," he said.

"Lichens are the canaries in the coal mine for environmental changes."

Smith said the fact the island has been mostly undisturbed for so many years allowed the lichen to flourish there.

"If you have harvesting happen or cutting, then the lichens of course take longer to establish and grow," he said. "So it's a special spot for lichens."

In the last decade, Smith has been part of a team examining 12 monitoring sites for lichen throughout the park.

They use a lichen ladder — a small, metal chain broken into five square sections — to determine the growth and variety of lichens.

"There's seven species in particular that we're tracking, that are easy to identify that we see whether their amount is changing over time," Smith said.

"If a tree has lots of these sensitive lichens, then we're going to score good on our air-quality index."

Smith said this monitoring is something he hopes to see used elsewhere to keep an eye on environmental changes.

"All across Canada this same program could be applied in other national parks and other places they want to monitor the air quality without having a very expensive air-quality station set up," he said.

"It's important to watch."