Scientists view old-growth forests through lichens to understand value

Two Canadian biologists say there is more to old-growth forests than just trees, and lichens can be used to assess their value.

Troy McMullin, a lichenologist at the Canadian Museum of Nature, says defining forests by the age of the trees is an oversimplification because it overlooks the importance of biodiversity in those habitats.

He says lichens are like the canaries in the coal mine because they're sensitive to the smallest of changes including pollution, humidity or the amount of light being received, which makes them strong indicators of the environment.

He says more lichen in forests is associated with more biodiversity.

Yolanda Wiersma, a landscape ecologist at Memorial University of Newfoundland, says lichen are not just an important food source for caribou, insects and slugs, but birds use it to build their nests because of its disinfectant properties.

The scientists note that these fungi are already being used to assess old-growth value in parts of Europe, and want to start by building a list of lichen seen in forests in North America.