Story last updated at 11/11/2009 - 11:53 am
I'm excited about lichen! Southeast Alaska's forests and bogs are home to hundreds of different kinds of lichen. They grow on the ground, on rocks, on decaying trees and all over living trees, right up to the top limbs, appearing in vastly different shapes, colors and sizes.
It is incredible that so many completely different looking organisms can all be called lichen. Some are very tiny, some are green and frilly, others grow like a crust or hang in long strands on tall trees-the list goes on. When you go out there with identification book in hand, there seem to be an overwhelming abundance of curious specimens to figure out. One by one, they can be revealed.
Lichen is rather unique in that it exists as a combination of two or more organisms that cooperate to their mutual benefit-they are a symbiosis of a fungus plus an algae or a cyanobacteria (or both). To simplify, the fungus receives food which is produced by the algae through photosynthesis and in turn, the fungus provides a protective habitat for the algae. Very impressive actually.
Lichen have different tricks up their sleeves to assure their continuation and several different ways to reproduce. They are ever-so-clever at surviving drought, extreme temperatures and life in marginal habitats like on rocks or up in the forest canopy. Some lichen increase soil fertility for other plants by turning nitrogen from the air into nutrients the plants can use.
Wildlife rely on lichen for food, nesting materials, shelter and sometimes to conceal themselves. The Sitka black-tailed deer can't conceal themselves with lichen but are grateful when the wind blows witch's hair lichen off the trees, especially if they are standing in deep snow and food is scarce. Flying squirrel, caribou, mountain goat and the Yunnan snub-nosed monkey reportedly eat various lichens.
My recent interest in lichens was inspired by a fascinating book that a friend loaned me. In "The Wild Trees" by Richard Preston, amazing, tree-climbing scientists find some of the same lichen high up in the redwood trees of California and Oregon that we find here in Southeast Alaska. High in the treetops they found many plants including moss, fern and lichen-a wonderful, fragile world in the sky. There's much more to this book than I have begun to mention and I definitely recommend it. If only I had the nerve to climb almost 400 feet up a tree!
One of those lichen we have in common with the redwood forest is often called old man's beard-the hair-like Dolichousnea longissima. Most books and Web sites that I checked still refer to it as Usnea longissima, but according to Wikipedia the name was changed in 2004. Old habits are hard to break. Some people call it Methuselah's beard.
One good place to find old man's beard is around a muskeg where many trees will be draped with the greenish beard-like, hairy shapes. An estuary is also a pretty reliable place to look for Old man's beard as well as a similar lichen referred to as witch's hair (Alectoria sarmentosa). The difference between the two is mainly that old man's beard has an obvious central cord running down its length while witch's hair has no central cord. Old man's beard, along with apparently most lichen, are said to contain antibiotics.
Once you find old man's beard and witch's hair, you will have started your "New Lichens I Have Found" list. Those two lichens are good starters for identification, being rather obvious the way they hang all over the trees.
But the list has just begun. Many more lichen await scrutiny! I for one, am lichen it!