Q.i) Name the pioneer species on a bare rock.
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Start your 14-day free trial to unlock the full solution →On bare rock the pioneers are lichens; by weathering the rock and adding humus they build soil for later plants; the final, stable climax community on land is a forest.
This question describes primary ecological succession (xerarch succession) on bare rock:
i) Pioneer species: the first organisms to colonise a bare rock are lichens (a symbiosis of fungus and alga), because they can survive with almost no soil.
ii) How they help the next vegetation: Lichens secrete organic acids that chemically weather and dissolve the rock surface; their growth and death add organic matter (humus). This slowly produces a thin layer of soil, which can then hold water and support the next colonisers — first mosses, then herbs, grasses, shrubs and finally trees. Each stage further deepens and enriches the soil for the next.
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