KCET 2015 Biology Solved Paper

The species that invade a bare area are called pioneer species. In Xerarch, i.e., succession in dry areas, lichens are pioneer species. Lichens secrete acids to dissolve rocks, help in weathering and soil formation and begin the ecological succession. Primary succession takes a very long time. In primary succession in water, i.e., hydrarch, the pioneers are the small phytoplanktons. The spores of these organisms reach the water body through wind or animals.