Lichens are a bright little highlight amongst the decaying leaves and wood littering the forests around Juneau.
On a recent hike, I stumbled upon what is likely a small example of Cladonia bellidiflora, the toy solider lichen. These lichens are small, yet sport a bright red, berry-like fruiting body that bares a passing resemblance to Betty Boop-inspired lipstick (in fact, a closely related species, Cladonia macilenta, is sometimes known as the lipstick lichen). Toy solider lichens are obviously inspired by the famous red-hatted, tin soldiers of children’s stories, and are sometimes known as matchstick lichens, as well. These lichens stand out against their grayish bodies and the drab browns and blacks of the wood they typically perch upon.
Lichens are an integral part of the ecosystem around Juneau — flashy or not — and represent a fascinating biological partnership. They are actually two semi-independent organisms, a fungus and an alga, living together. The fungal portion is the outside bit, providing the structure of the lichen as a whole — some look like leaves, others like the Cladonia, which often resemble little fairy cups. Trapped inside the fungi are photosynthetic algae or bacteria, often termed “photoautotrophs,” meaning they make their own food (“-autotrophs”) from sunlight (“photo-“). These little guys operate like plants, basically. As a result, the fungi get lunch, and the algae or bacteria get structure and protection from the elements, and sometimes water and nutrients. Together, they don’t need much beyond a surface to attach to, and so you find them in often harsh environments.
But as a result of this peculiar lifestyle, lichens are often quite sensitive to air pollution.
Why is that? Perhaps the most obvious is the lack of roots — the vast majority of the minerals, nutrients and water that are necessary for the partnership to thrive are taken directly from the air. Any pollutants in the atmosphere are therefore felt directly, and so many communities use lichens as bio-indicators of high pollution levels.
Lichens have been around a long time. Some interesting work in China has dated fossils that appear to be lichens to approximately 600 million years ago — not only that, but they were also sea dwelling (in shallow marine areas, to be more precise). By 400 million years ago they had moved on land, and fossil lichens from that period can be found in Scotland. But it’s quite difficult to find lichen fossils in the first place (they do not fossilize well and are often hard to identify) so there is a good chance that those dates will change as paleontologists continue to poke around old rocks and sea beds.
Regardless, the fact that fungi and photoautotrophs teamed up so long ago — long before modern plants like trees got started — and are still around is testament to the hardiness and utility of that relationship.
So next time you see some little lichens in the forest or on the rocks out by the glacier, remember you’re looking at two organisms, not one, working in a partnership that has been going on for a long, long time.
• Brian Buma, Ph.D, is an assistant professor of forest ecosystem ecology with the University of Alaska Southeast.