I have to say, I love Lichens. Just beautiful, in their many shapes and colours, as well as awesomely adapted to surviving harsh conditions. I was teaching about them as Pioneer Species today in the Lithosere. They live on Bare Rock, an inhospitable environment indeed. The Lichen is a symbiotic relationship between a fungus and an algae. The algae is photosynthetic and hence autotrophic (it synthesises its own food and the fungus benefits as it cannot). The fungus on the other hand, is heterotrophic and specifically performs extra cellular digestion by secreting enzymes onto its substrate. In this instance, the substrate is the Rock which is slowly dissolved, providing some minerals but essentially giving the fungus a purchase. And of course, the algae benefits.
Lichens lend themselves to student projects. Their distribution can be easily investigated using a mini-quadrat and calculating percentage cover. Comparisons could be made between rocks facing north and south, different rocks or different areas, or classically, the effects of pollution as Lichens are well known to be intolerant of sulphur dioxide.Statistical tests such as standard error and 95% confidence limits would be an appropriate way to analyse such data.
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