Science of the Seasons: Liking lichen — Ground cover colors fall views

By Dr. David Wartinbee, for the Redoubt Reporter

Photos courtesy of Dr. David Wartinbee. Lichen growth in an alpine meadow appears light green against the darker green foliage. These lichen patches are food for caribou during the winter months.

Each fall we head out to some secret places to pick low-bush cranberries. They are actually lingonberries, but who cares when you are mixing that sweet sauce with your Thanksgiving turkey?

This weekend we spent several hours walking and crawling through moist hummocks of sphagnum that are laced with the tiny plants that produce the treasured berries. We picked a gallon of berries before midday and considered it a successful excursion. They will be washed and frozen until it’s time to make sauce or put them in various muffins.

While out harvesting, I kept finding something else to pick at my attention — various forms of lichens, and there seemed to be a new growth form just about every time I turned around.

I seem to have lichens on the brain lately. Last weekend I noticed many bright-orange lichens on rocks around Skilak Lake. Back a few weeks, I had been so taken by the diverse colors of lichens on rocks above tree line that I took pictures hoping to capture their beautiful patterns. And friends in Wasilla, who raise reindeer, just returned from a trip to collect lichens as a winter treat for their animals.

Lichens are beautiful and useful, but what, exactly, are they? Lichens are a

This leafy lichen is in the genus Peltigera and is common in our area. It is also fed upon by caribou in the winter.

combination of a fungal organism and either cyanobacteria (photosynthetic bacteria) or green algae. These organisms are the classic example of a symbiotic relationship. In this situation, both organisms benefit by the relationship, since the fungal hyphae provide protection, moisture and nutrients for the algae, while the algae provide sugars on which the fungus feeds. Since lichens have been around for a long time, some have referred to the lichen fungi as being the very first farmers.

While this situation is described as mutualism, these associations are mostly obligatory for survival of the fungal members of the team. If fungal spores germinate and they do not find a photosynthetic symbiont, they will probably perish. To assure the fungal members have their needed algal or cyanobacteria counterpart, many lichens produce soredia. These minute packets of a few cells contain both fungal cells and a few algal or cyanobacteria cells that are dispersed by wind or water. When they are carried into a suitable habitat, they develop into new lichen.

Recent research using DNA analysis has shown that there are more than one species of fungus in most lichens. The additional species are not well known, and even their role seems to be cloudy. These extra species have been called “lurkers,” which tends to give the impression they are not the best of neighbors. Perhaps this is justified, since, in several cases, these extra fungi are apparently parasitic. There are more questions than answers about the multiple fungal species being together in lichens.

Along with multiple species of fungi, some lichens contain multiple species of

This image shows a lichen called crowned pixie cups in the genus Cladonia.

photosynthetic team members. In some Peltigera species, with large, green, leafy lobes, the tiny dark dots on the surface are masses of cyanobacteria, while the rest of the lichen is green due to the presence of green algae.

Lichens are abundant in most habitats and have become an important member of the ecological community. Is Alaska, the primary winter food for caribou is a number of lichens. Caribou can smell the white fruticose (like miniature white bushes) lichens below the snow surface and will dig for them throughout the winter. It is well documented that mountain goats and blacktail deer frequently feed on various lichens, too. A variety of birds and squirrels use lichens to line their nests. In the winter months, squirrels use their nest material as a food source, too. Even our pesky slugs feed on a variety of lichens.

Native populations around the world have used lichens for a wide multitude of

This image shows a white fruticose lichen that is a favorite of caribou.

uses. The uses are probably as diverse as the growth forms. Several colors for yarns and clothing come from soaking the yarn with specific lichens. The beautiful yellow colors found on Chilkat Tlingit blankets come from wolf lichen. This bright-yellow lichen (Letharia vulpine) is considered poisonous, but elders also used it as a medicine for a variety of ailments. Even today, some lichens are harvested and used in the perfume manufacturing industry. Apparently the lichens provide an “earthy” component to various fragrances.

The growth form of lichens is amazingly diverse on the Kenai Peninsula. Large patches of bright-green, leafy lichens can be found in moist areas with spruce trees overhead. Note that the part of the lichen that is facing sunlight is green while the portion in the shadows is almost white, since algae would not survive there.

Hanging from those spruce trees can be long masses of hairlike strands, which are a lichen sometimes called “witch’s hair.” A moist rotting log can be covered with small growths of “pixie cups” that look like miniature, light-green golf tees. Examining the surface of rocks and boulders can reveal even more multicolored lichens on the surface. These encrusted lichens are able to survive long periods of drought and can quickly rehydrate and grow when conditions improve.

Wherever you happen to be, whether wandering the woods, lakeshores or even intertidal areas, keep an eye out for these amazing symbiotic relationships between fungi, algae and cyanobacteria.

David Wartinbee, Ph.D, J.D., is a biology professor at Kenai Peninsula College’s Kenai River Campus. He is writing a series of columns on the ecology of the Kenai River and Cook Inlet watershed.

 

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