Time for Nature

Learning about lichens

March 5, 2007

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Gwaii Haanas National Park Reserve and Haida Heritage Site

Why study lichens ? According to Irwin Brodo, lichens are not only beautiful; they are also extremely interesting. Dr. Brodo, recently retired from the Canadian Museum of Nature, has been studying lichens in the islands of Haida Gwaii, British Columbia since 1967. He is cataloguing the incredibly rich variety of lichens found there, including some that form vivid bands of color on the shores of Gwaii Haanas National Park Reserve and Haida Heritage Site .

Bands of color

Dr. Irwin Brodo (in beard) worked with Parks Canada's Norm Sloan to study lichen zonation on the coastal rocks of Gwaii Haanas.
© Parks Canada, Fenja Brodo

Every species from pine tree to cactus to lichen has its own habitat depending on what it needs and what it can tolerate in its environment. In Gwaii Haanas, factors such as exposure to waves, immersion in salt water and amount of sunlight determine where particular lichen species will grow on coastal rocks. Differences in these habitat factors result in distinctly colored bands or zones on the shore, each zone characterized by certain species.

At the water's edge, lichens appear sparsely among the barnacles and rockweed. Farther from the water, the rocks are less frequently submerged or splashed. Here, the "sea tar lichen" and other black species of Verrucaria crowd in to create a dense, dark band.

Still farther from the sea, where there is only salt spray, the black band gives way to gray, gray-brown and orange species, including the "fire-dot lichens," Caloplaca. Then nearing the upper edge of the beach, the "volcano lichen," Coccotrema maritimum forms a vivid white band that is a distinctive feature of the Haida Gwaii coast.

Lichens like no others

The occurrence of different colored lichen species causes the zonation evident in this picture. The white lichen is Coccotrema , and the black lichen is mostly Verrucaria maura .
© Sylvia & Stephen Sharnoff

Dr. Brodo has found some 580 lichen species in Haida Gwaii including at least 25 that had never been named. More than a dozen are found only in Haida Gwaii and nearby areas.

Distant relatives

Some of the species are "disjuncts." They are found here and in other locations as far away as Europe or Asia but nowhere in between. How could this be?

During the last ice age, parts of Haida Gwaii, Europe and Asia were ice-free refugia. Lichens, which were once widely distributed, likely survived only in the refugia as isolated populations

Did they hitch a ride?

Dr. Brodo suggests that continental drift is another possible reason for the disjunct populations. The lichens of the white zone are closely related to species found in South America. Possibly lichens hitched a ride on a continental plate that broke away from Peru and began travelling northward some 230 million years ago, eventually arriving where Haida Gwaii lies today.

More than pretty colored rocks

This photo shows patches of the yellow and tan Caloplaca litoricola lichen growing over or next to the black Verrucaria maura
© Sylvia & Stephen Sharnoff

For Dr. Brodo, lichens do not simply decorate the rocks. They are living things that help turn rock into soil and provide food for other creatures. "To overlook lichens is to deny yourself an enriching experience. An appreciation of the natural world is the first step in protecting it," says Dr. Brodo.

Parks Canada managers agree. Getting to know the lichens and other small organisms is vital to managing Gwaii Haanas and maintaining its ecological integrity.

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