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The trouble with lichen

Lichen on rocks at Girraween National Park. Photo Mary Gardner

The others continue hiking up to the lookout here at Girraween National Park, while I linger looking at small creatures. We’re in the Granite Belt, a landscape of rocks made of cooled magma only revealed after long erosion on this old continent. One of the prettiest of the small creatures I see is this coral lichen Cladia retipora. It’s also telling of one of the most ancient and subversive lifestyles on this planet.

Coral lichen. Photo Mary Gardner

When this creature was first described by the naturalist Jacques-Julien de Labillardie in 1806, he called it an algae. He was back in Paris classifying a specimen he picked up from Tasmania in 1792. By 1879, Heinrich Anton de Bary, a botanist specialising in fungi, reclassified this as an entirely new creature. This was a lichen, from the Greek leichen ‘what eats around itself’. Professor de Bray also described this fungi and algae partnership, inventing the term symbiosis from the Greek syn- ‘together’ and bios ‘life’.

The coral lichen is a transformation wrought by creatures from two different kingdoms. Why is this political term used at the foundation of biology? Members of the algae kingdom use photosynthesis and are nourished by sunlight. By contrast, members of the kingdom of fungi absorb nourishment through their cell walls and reproduce by casting spores in the wind. In partnership, the algae share sugars and the fungi the minerals collected from rocks and the very air itself. The body of the algae often, but not always, gives colour to the lichen while that of the fungi holds moisture.

The lichens’ capacity to draw nutrients from the air means that in their quest for nitrogen they also collect radiation, heavy metals, lead, sulphur and other industrial pollutants. Biologists can relate this back to changing levels of air pollution. Quantities of pollutants found in dead lichens stored in museums differ from those found in lichens growing today.

Once lichens of one sort or another lived everywhere from one pole to the other. But now fruticose ones, shrubby ones with branches, are often missing from cities and towns. They are also missing in the areas affected by plumes from coal fired energy plants. They are the least resistant to fossil fuel pollution. Even though lead is no longer in vehicle exhaust fumes, it is still in the dust around Sydney. Airborne again, though in smaller quantities, it enters the slow revival of any fruticose lichens.

Foliose lichens, the ones with leafy lobes, are a bit more resistant. The most resistant are the crustose lichens, those flat rings of various colours which live on not only stones in walls and graveyards, but on the bark and even the leaves of different trees.

What lichens truly are is still startling. One apparently global species turns out to be made of one species of fungi with a different species of algae depending which hemisphere it finds itself. Many lichen prove to be made of not only of a species of algae and fungi but of two species of fungi. The second fungi is a single cell type known as yeast.

At Girraween, I find other lichen on the rocks along the waterways. The different bands of colour mark the increasing drought. Their growth varies according to the water levels and how long they are submerged. Some are underwater still.

Little is known about freshwater let alone marine lichen. Some of these may be ‘cross-dressing’ lichen, ones where the algae rather than the fungi is the dominant body structure. Some of the algal partners might be what was called ‘blue-green algae’ but are now classified as cyanobacteria. Yes, another kingdom.

Symbiosis harks back to the origins of life itself. Bacteriologist Lynn Margulis called these living tangles of species holobionts. Across the planet, every variation of symbiosis is under-way. One involves us, whose nutrition and health is linked to algae, yeast and fungi inside our guts. Do we appreciate the full impact of environmental pollutants on each of our necessary companion species?

To see the world of holobionts, of lichen combos, of every plant and animal together with all the microbes that keep them alive, to see ourselves as part of this, is to sense the activities of evolution and creation. Politics? Although the religions of Abraham also refer to ‘The Kingdom’, an alternate translation is ‘The Reign’. The glories of these sovereignties are all around and inside of us. The powers are inscrutable and rational words change into sounds with feelings.

 


One response to “The trouble with lichen”

  1. Len Heggarty says:

    Small creatures linger here, there and everywhere in Girraween National Park and are a wonder to the bush walker’s eye while wandering or trekking up to the lookout.
    The Granite belt is a place of rock and stone that puts the trekker back in the Stone Age and the shapes of huge boulders were shaped back before that in the Ice Age when the granite was magma deep within the Earth and huge expanding forces pushed it to the surface where it rested and cooled.
    Cool streams wander amid and around the rocks and in the rich soil wildflowers bloom with a diversity of plants while lichens cling and grow on the rock because there are harsh winters here.

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