What is the biological importance of lichens

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1 + 1 = 1: The lichens
It has only been known for a little over a hundred years that lichens are not independent organisms, but rather represent a close community (symbiosis) of fungus and algae. In a symbiosis, both partners benefit from each other: the chlorophyll-free fungus, which itself is not able to produce organic substances (sugar, starch, etc.) from inorganic raw materials (such as carbon dioxide and water), is turned by the algae, which enables photosynthesis is supplied with these substances. The fungus supports and fixes the algae with its tissue and gives the whole lichen a hold on its base. Only he can absorb water and minerals from the environment, which in turn benefits the algae.

Occurrence of lichens
According to the external shape, a distinction is made between crusty, leaf and bush lichens. The crusty lichens form thin, crusty thalli on the base (the substrate). In leaf lichens, leaf-like parts of the bearing rise from the substrate. This is even more pronounced in the case of the shrub lichen, and extensive parts of the camp are round and long in the shape of a stalk.
Lichen can colonize a wide variety of substrates. They are found on the ground and rock as well as epiphytically on other plants, mostly on the bark of deciduous and coniferous trees. Lichen is the first to colonize bare rubble and rock corridors as well as poor soils and thus enable higher plants to settle. Lime-dwelling lichen species contribute to the weathering of the rock, which they are able to loosen with their lichen substances.
Lichen can be found in all climate zones on earth. They also invade extreme zones such as arctic tundra and desert as an outpost of plant life. The most abundant growth of lichen, however, is found in humid and rainy areas, where a constant supply of moisture is guaranteed, because lichens are not able to store water.

Use of lichen
Lichen has long been used for a wide variety of purposes:

  • In general, lichens are of no importance for human nutrition; in many cases they served more as emergency food. Only in Japan is the lichen Umbilicaria esculenta - a species that grows on vertical cliffs - still eaten as a delicacy.
  • The edible Lecanora esculenta is a ground lichen in the steppe countries of North Africa and Asia. It is often blown together in large piles by the steppe wind and is still used today as fodder.
  • The Icelandic moss (Cetraria islandica) is a ground lichen that is used as a medicinal plant. A cough suppressant can be obtained from it.
  • Litmus lichens (Roccella spec.) Provide a dye that is important for chemical investigations. Their home is mainly the east coast of India and the coastal areas of the southern Atlantic.
  • The reindeer lichen (Cladonia rangiferina) is often the only food the reindeer eat during the long winter in the polar regions. This type of lichen is also found in temperate regions, especially in dry pine forests. They or similar species are often used as little trees or bushes for model railways under the name "moss".
  • Oak moss (Evernia prunastri) is characterized by its own distinctive odor and is therefore used as a fragrance in perfume production.

Some standard works on lichens such as

Henssen and Jahns (1974): An Introduction to Lichen Studies
Comprehensive information on the history of lichenology, the composition and formation of lichens, their economic importance, structure and metabolism, growth and reproduction, ecology and distribution, classification and taxonomy;

Masuch (1993): Biology of Lichen.
Also offers a comprehensive overview - with practical tips! - on the topics "What are lichens?", Lichen determination, structure of lichen, lichen symbiosis, metabolism, reproduction and reproduction, lichen growth, lichen chemistry. Ecology and taxonomy;

as well as various pages on the Internet, including:
http://ocid.nacse.org/lichenland
Behind it are funny and informative pages on lichen biology.

http://fschumm.de/index.html
The mathematician and physicist Felix Schumm invites you to his lichen gallery. Microscopic preparations of lichens are his specialty.


And…

In the middle of the 19th century, especially in England and France, it was observed that especially the species of lichen that lived on trees withdrew from cities and industrial areas due to air pollution (Grindon, 1858; Nylander, 1866). Many species have already died out here or are threatened with extinction. Above all, the environmental conditions in urban agglomerations have had an unfavorable effect, as lichens are very sensitive to air pollution. In addition, the climatic conditions in these areas are less favorable for the lichens: The air humidity and temperature are on average lower here than in the surrounding area. The centers of large cities were therefore not infrequently downright “lichen deserts”. Since then, many studies have been carried out around the world in which lichens were specifically used to determine air quality and environmental pollution. They thus serve as lThe same "measuring instruments" (bio-indicators).



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