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blue tier, tasmania: lichens

Random image of Blue Tier lichens

Lichens consist of a symbiotic partnership between an alga (the photobiont component capable of photosynthesis) and a fungus (the mycobiont partner providing a home for the alga as well as contributing the mineral nutrients required for the partnership). OSU has a wonderfully clear presentation of lichens for beginners.

Multiplication is usually vegetative but the fungal component has a spore dispersal mechanism, and presumably a sexual stage as well. From this it stands to reason that at some stage the associated alga cells are capable of surviving independently, at least for a short period, until they form a partnership with the fungus.

Given the close relationship between lichens and fungi it should come as no surprise that some fungi are in fact fruiting bodes of the composite lichen, e.g. the Omphalina genus, and others bear a striking resemblance to common fungi, e.g. Dibaeis arcuata.

Although prolific, lichens do not form a major component of the landscape on the Blue Tier but in the bleak climate of the Artic circle it is the dominant vegetation and provides the main food of caribou and other grazers.

While lichens seem to establish nearly everywhere they possibly can, even on sheer rock faces, one of the better places to view the diversity of foliose lichens is in the myrtle forest near Sun Flats. It is particularly rich because of the high incidence of sunlight on the peripehery of the forest proper.

We have made no great attempt to identify all the lichens found on the Blue Tier - their sheer numbers is rather overwhelming, and beyond our very modest abilities. What we provide here are images of some of the most common and easily identified species as well as a number of unidentified species to showcase the sheer diversity to be found. Literature cited below is highly recommended for anyone interested in persuing the subject further.

For convenience lichens are commonly divided into several categories based on the growth form - this has no bearing on the taxonomic relationship. They are:
crustose - forming thin 'skins' tightly adhering to rocks and vegetation;
foliose - forming leaf-like layers;
fruticose - forming clumps;
byssoid - filamentous.

Literature:
- Kantvilas, G & Jarman, S J, Lichens of Rainforest in Tasmania and South-eastern Australia, CSIRO Publishing, 224 pages, color illustrations, January 1999 ISBN 978 0 642 56802 1

Web:
- Australian National Botanic Gardens has a new section on lichens
- New York Botanical Garden provides a good introduction to the subject and provides a number of useful links
- Australian Biological Resources Study maintains a checklist of lichens but we have not found it particularly useful for beginners.

Page URL: http://www.bluetier.org/nature/lichens.htm

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