List out the beneficial aspects of lichens.

Explanation

(a) Lichens secrete organic acids like oxalic acid which corrodes the rock surface and helps in weathering of rocks, thus acting as pioneers in Xerosere.
(b) Usnic acid produced from lichens show antibiotic properties.
( c) Lichens are sensitive to air pollutants especially to sulphur-di-oxide. Therefore, they are considered as pollution indicators.
(d) The dye present in litmus paper used as acid base indicator in the laboratories is obtained from Roccella montagnei.
(e ) Cladonia rangiferina (Reindeer moss) is used as food for animals living in Tundra regions.