Meanwhile, rocks, walls and gravestones are decorated with clusters of green, grey, black, white, orange and pink. As delicate as they look, lichens are amongst the oldest and most durable inhabitants of our land and an invaluable part of our ecosystem. They also tell us much about the quality of the air that our own survival depends upon.
Only a limited number of species of algae can survive being incorporated into a lichen. Conversely, every lichen consists of a different fungus.
Their slow growth rate means that once lost, lichen colonies can take decades to re-form
Even when they grow on the same tree, different lichens will prefer different conditions – some prefer damp areas, while others will be found growing on sunlight branches or very old wood. Whereas many lichens may occur in a wide range of tree habitats some are restricted to specific microhabitats. Even the type of bark, which can change characteristics as the tree grows older, will dictate the types of lichen that can be supported.
Loss of ancient trees and woods can therefore have potentially serious negative consequences for lichen communities, especially rare species. They may even contain species that are internationally threatened by intensive forestry or pressure from development.
Lichens, like many wildflowers, came under the medieval Doctrine of Signatures, which dictated that a plant resembling a part of the body could be used to treat a wide manner of ailments relating to it.
Some lichens are also used in the perfume industry.