Lichens – a practical partnership
|Lichens on the forest floor|
Lichens are great indicators of clear, unpolluted air. In Scotland we are most used to seeing lichens grow on trees, smothering inland forest branches like grey-green beards. Sometimes we’ll notice lichen on stones, too, creating a chequerboard effect of colours and patterns.
But Culbin’s lichens are very different: because of the low levels of vital nutrients in Culbin’s soil, they have carpeted the ancient shingle ridges and more recent paths of Culbin with clumps and tussocks of lace-like Cladonia lichens, free from competition with larger, nutrient-loving plants.
In the arctic tundra, these Cladonia lichens provide a meagre meal for reindeer, but at Culbin, while here and there you may see tussocks uprooted, it is more likely to be incidental damage by a badger looking for tasty woodland insects or by birds looking for nesting material than a sign of it being eaten.
So what is a lichen?
Each lichen is actually made up of two different organisms, a fungus and an alga, sometimes with helpful blue-green algae as part of the mixture too.
The alga uses energy from sunlight (photosynthesis) to combine molecules of air and water to create carbohydrates to feed the fungus. In return, the fungus provides the algae with a protected place to live; it shelters its algae from ultra-violet light, it stops the algae drying out in times of drought, and it protects it from drowning in extremely wet weather. This beneficial partnership is called symbiosis.
Some of the special lichens in Culbin like a little bit of disturbance, but others don’t. Please help protect these special species by not trampling on them and keeping to the paths wherever possible.
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