41. NCERT Exemplar XXIII

 

Lichens are called pioneer colonisers of bare rock because they are the first to inhabit a rocky surface and help in the formation of soil. The lichens grow on the surface of rocks. While growing, they release certain saltsrelease certain acids release certain bases that corrode the surface of rocks to form a thin layer of soil. This surface is now available for the growth of other landsplantsgrass like mosses, etc., which cause the rock to break up further. The whole process of weathering rocks involving living organisms is called microbial weatheringbiological weatheringgeographic weathering.