IMPORTANCE OF LICHEN

Lichen have both harmful and useful aspects in nature-

A. USEFUL ASPECTS :

(a) Role in Ecology : Lichen are ecological importance for the following aspects-

Pioneer colonizers- Lichens are said to be the pioneers in establishing vagetation on bare rocky area. They are the first members to colonize the barren Rocky area. During development they bring about the disintegration of rock stones by forming acids, e.g., oxalic acid , carbonic acid etc. Thus ,they play an important role in nature in the formation of soil ( a pehomenone is called pedogenesis).

Pollution Detector- Lichens are very sensitive to atmospheric Pollutants such as sulphur dioxide. They are unable to grow in towns, cities and around industrial sites such as oil refineries and brickworks. So, the Lichens can be used as reliable biological indicators of pollution. By studying Lichens on trees, a qualitative scale has been devised for estimation of mean SO2 level in a given season. The Lichens are used as pollition monitors.

(b) Food and Fooder- The lichen serve as important source of food for invertebrates. A large number of animals for example , mites, caterpillars, termites, snails, slugs etc. feed partly or completely on Lichens. Lichens as food have also been used by man during families. They are rich in polysaccharide, certain enzymes and some vitamins.

Cetraria islandica is taken as food in Sweden. Norway, Scandinavian countries , Iceland etc. Lecanora esculenta is used as food in Israel and Umbilicara esculenta in Japan. Species of parmelia are used as curry powder in India. In France the Lichens are used in confectionery for making chocolates and pastries.

Cladonia rangiferina is the main food for reindeer in polar countries. Cetraria islandica is also used as Fooder- for horses. Species of Stereocaulon are also used as fooder.

(c) Source of Medicine- Since very early times the Lichens are used to cure jaundice, fever , diarrhoea and various skin diseases.

Various Lichens are of great medicinal.

A yellow substance usnic acid is obtained from species of Usnea and Cladonia. It is a broad spectrum antibiotic and is used in the treatment of various infections. It is effective against gram positive bacteria. Some lichen compounds e.g., lichenin, isolichenin have anti tumour properties.

Protolichesterenic acid, a compound obtained from some Lichens , is used in preparation anti cancer drugs . Erythrin obtained from Roccella montagnei is used to cure angina.

Source wikipedia

(d) Role in industry- Lichen is used in various types of industries-

Tanning and dyeing- Some Lichens are used in leathers industries. Cetraria islandica and Lobaria pulmortaria show the astringents propety. This astringents substance is extracted from the thallus and is used in tannin industry.

Cosmetics and perfumes- Lichens like Evernia , Ramalina, Pseudorina are reported to have perfumed volatile oils. Due to the aromatic substances present in the thallus, the Lichens are used in the preparation of various cosmetic article, perfumery goods , dhoop, Hawan samagries etc.

Brewing and Distillation- Some species of lichen for exampl, Cetraria islandica contain carbohydrates in the form of lichenin. In Sweden and Russia alcohal is produced from these lichen. These lichen are also used in confectionery.

Minerals- Lichens such as Lecanora esculenta is found in lime stone desrts yields large amount of calcium oxalate crystals. These are 60% of it's dry weight.

Natural products- Lichen are known to produce over 550 natural products. Some important natural products are-

Source wikipedia

(e) Poison from Lichen- Some lichen are poisonous due to presence of various substance in them.

Source Wikipedia

B. HARMFUL ASPECTS :

Lichens growing on young fruit trees and sandal trees are harmful to the plant.

During hot season some species of lichen become so dry and anflammable that they often help in spreading forest fire.
Some Lichens act as allergens.
The commercial value of glass and marble stone is reduced because of itching of their surface by Lichens.