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ENLARGE
Raini Rippy
Now that the leaves are dropping, you might have noticed something else attached to tree trunks and branches. You might have decorated your face with some of it when you were younger. The green, fuzzy stuff is most likely moss, but what about the rest of it? Those would be lichens.
What exactly are lichens? In simplest terms, they consist of a fungus and an alga growing together. Lichens can be found from the tropics to the poles. They can grow on rocks, soil, trees, metal, glass, cloth, and plastic, to name a few places. While they grow best where the temperatures are moderate and there is plenty of light and moisture, lichens are often the dominant form of “vegetation” in harsh environments, such as high mountain peaks, the Arctic and Antarctic regions and some deserts. Lichens typically grow slowly, some as little as 0.5 millimeters per year! It’s estimated that some alpine-arctic lichens may be 1,000 to 4,500 years old.
People often assume that lichens are parasites that injure trees, but this is not true. Heavy lichen colonization is more common on slow-growing trees than on fast-growing trees simply because the fast-growing trees shed bark (and the lichens attached to it) more frequently. Unhealthy trees have less foliage and typically grow slowly, allowing lichens to accumulate. This makes lichens stand out on many dying trees, but they are not the actual cause of decline. During the winter months lichens are more evident when deciduous trees are bare. You don’t have to go far to spot them — just look out your window!
Lichens acquire water from the air and precipitation, absorbing up to 300 percent of their weight in water, which may explain how they can withstand droughty conditions for several months. Some lichens bind soil particles together, helping to stabilize the soil, while others can even colonize bare rock.
For thousands of years, lichens have been used as a source of dyes. They are also used in perfumes, soaps, and deodorants. A few groups of indigenous peoples used lichens to make a type of pudding or taffy. Some also used lichens to poison arrowheads. It’s believed a number of lichens possess antibiotic properties, and a few chemicals produced by lichens are actually used in medications. Lichens are also important sources of food, shelter, and nesting materials for wildlife.
One of the more important uses of lichens is monitoring air quality. They are very sensitive to air pollution, which is one reason you don’t find many lichens in cities. The U.S. Forest Service and the National Park Service are using lichens in their environmental monitoring programs. In fact, lichens were even used to monitor radioactive material deposition after the Chernobyl nuclear incident. Good air quality and appropriate habitat will be necessary to maintain lichen diversity.
Though truly beautiful and worth admiring, they are more than “natural” decorations. Next time you see lichens, think about their important role in the environment and take a closer look.
What exactly are lichens? In simplest terms, they consist of a fungus and an alga growing together. Lichens can be found from the tropics to the poles. They can grow on rocks, soil, trees, metal, glass, cloth, and plastic, to name a few places. While they grow best where the temperatures are moderate and there is plenty of light and moisture, lichens are often the dominant form of “vegetation” in harsh environments, such as high mountain peaks, the Arctic and Antarctic regions and some deserts. Lichens typically grow slowly, some as little as 0.5 millimeters per year! It’s estimated that some alpine-arctic lichens may be 1,000 to 4,500 years old.
People often assume that lichens are parasites that injure trees, but this is not true. Heavy lichen colonization is more common on slow-growing trees than on fast-growing trees simply because the fast-growing trees shed bark (and the lichens attached to it) more frequently. Unhealthy trees have less foliage and typically grow slowly, allowing lichens to accumulate. This makes lichens stand out on many dying trees, but they are not the actual cause of decline. During the winter months lichens are more evident when deciduous trees are bare. You don’t have to go far to spot them — just look out your window!
Lichens acquire water from the air and precipitation, absorbing up to 300 percent of their weight in water, which may explain how they can withstand droughty conditions for several months. Some lichens bind soil particles together, helping to stabilize the soil, while others can even colonize bare rock.
For thousands of years, lichens have been used as a source of dyes. They are also used in perfumes, soaps, and deodorants. A few groups of indigenous peoples used lichens to make a type of pudding or taffy. Some also used lichens to poison arrowheads. It’s believed a number of lichens possess antibiotic properties, and a few chemicals produced by lichens are actually used in medications. Lichens are also important sources of food, shelter, and nesting materials for wildlife.
One of the more important uses of lichens is monitoring air quality. They are very sensitive to air pollution, which is one reason you don’t find many lichens in cities. The U.S. Forest Service and the National Park Service are using lichens in their environmental monitoring programs. In fact, lichens were even used to monitor radioactive material deposition after the Chernobyl nuclear incident. Good air quality and appropriate habitat will be necessary to maintain lichen diversity.
Though truly beautiful and worth admiring, they are more than “natural” decorations. Next time you see lichens, think about their important role in the environment and take a closer look.
Raini Rippy is an Extension forester for OSU Extension Service in Douglas County. She can be reached by e-mail at raini.rippy@oregonstate.edu or at (541) 672-4461.
