What is a Lichen?
Lichens are composite, symbiotic organisms made up from members of as many as three kingdoms. Fungi, algae and sometimes bacteria.
The dominant partner (not all experts agree) is a fungus. Fungi are incapable of making their own food. They usually provide for themselves as parasites or decomposers. Some fungi join with bacteria or algae to form lichen.
“Lichens are fungi that have discovered agriculture”— lichenologist Trevor Goward.
The lichen fungi (kingdom Fungi) cultivate partners that manufacture food by photosynthesis. Sometimes the partners are algae (kingdom Protista), other times cyanobacteria (kingdom Monera). Some enterprising fungi exploit both at once. The bacteria/algae manufacture food, the fungi create a structure for both to live in and the fungi are in control of reproduction. Many fungi in lichens are unable to live without their partners but some fungi can be found both as individual life forms and as lichens when joined with partners from other kingdoms.
Even this description is in question at the present time. Lichen are so complex that scientists are continually finding new functions and relationships that do not fit prior understanding of what a lichen is or does. Check back with us for updates on this frontier.
Lichen reproduce by several methods.
*One is a small piece of the lichen breaks off and scatters.
*Some lichen make spores of the fungal part that are released to the wind. These need to find the right bacteria or algae partner to start life again as a lichen.
*Some make tiny non sexual packets of material that break away from the main body and start a new organism.
Why Study Lichens?
Lichen are a pioneer species that colonize places hard for other life to live in; rock, bark, bone even metal and plastic. They are able to survive in extreme conditions of heat, cold and dryness, regaining function within hours when exposed to moisture and more moderate temperatures.
- Pollution Monitors: Lichen are “like little sponges, taking up everything in the air”, are extremely sensitive to air pollution and so are early indicators of bad air quality. Lichen need very clean environments, a stable place that doesn’t decompose or move quickly, and occasional moisture. Cyanobacteria can take nitrogen gas from the air and turn it into biologically usable compounds, so lichens with these partners make major contributions to soil fertility. Lichen grow extremely slowly, about 1mm/year.
- Chemists: They create over 500 chemicals that humans know about. From dye to animal and human food and medicine (possibly half of all lichens have antibiotic properties), geological dating to air quality monitoring lichen have many uses for humans as well as are possibly essential in the web of life everywhere on the planet.
- Food Producers:We are interested in lichens because they are a critical part of life for almost every category of life- microbes, insects, birds, rodents, large and small mammals, trees and other plants and humans too. Even though the use or interaction with lichen may be occasional or a small percentage of another creature’s life it may be critical for survival. The loss of lichen in every part of the world is one of the reasons many other plants and animals are disappearing. Here in the Kickapoo Valley Reserve we hope learning about lichen will improve our understanding of the world we depend on and therefore improve our ability to care for the living systems that support our lives.
This observation reflects our reasons for learning about lichens and illustrates the global import of this life form:
In a striking example from northern Sweden, birds, invertebrates, lichens were all found to be functionally connected and all were impacted by forestry practices. (Pettersson, et. al, 1995)
The authors state that, “Natural forests had greater invertebrate diversity than managed forests and nearly five times as many invertebrates per branch…The number and biomass of invertebrates were related to the number of lichens, even after controlling for sampling location and branch size. Other studies have implicated forestry in the decline of non-migratory passerine birds in northern Europe through the destruction and fragmentation of forests, but ourstudy indicates that it may also reduce foraging habitat quality through a reduction in lichen abundance.” It might be reasonable to postulate similar effects in North America.
There are three basic lichen forms that may be found in the Kickapoo Valley Reserve:
Crustose lichen are integrated into the strata they live on so tightly they cannot be removed intact. They are flat usually having only an upper surface.
Foliose lichen are leaf like and have lobes, are loosely attached to their substrate, have rhizomes and usually an upper and lower side.
Fruticose lichen are usually round in cross section and often look like little shrubs or masses of strands. They grow upward or hang in long strands.
We welcome anyone to participate in the Lichen Survey as it develops and progresses in the future. We have currently collected samples from 5 sites in the KVR, we are in the process of developing a kit where you can learn to identify at least 2 lichens at each site and report your findings. Please contact us anytime and join us.