 |
| Lithosere |
|
|
| |
| a) Crustose - lichen stage |
| |
| Lichen species like Graphis Rhizocarpon, Rinodina and Lacanora forms the pioneer community in a lithosere, as they can tolerate desiccation. Organic acids produced by lichens corrode the rock surface and release minerals for proper growth of lichens. Wind borne soil particles and organic matter collect in the depressions, which initiates soil formation, leading to the growth of foliose lichens like Parmelia, Physcia etc. |
| |
| Foliose lichen retain more water and accumulate more soil particles, helping in the development of a fine layer of soil on the rock surface. |
| |
| b) Moss stage - Accumulation of soil and humus leads to the growth of mosses such as Polytrichum and Grimmia. Over a period of time, collection of more soil and organic matter favour the growth of moisture loving mosses like Hypnum, Bryum etc. |
| |
| c) Herb stage - Death and decay of mosses produce a mat of organic moss on partially fragmented rock help the germination to seeds of hardy grasses like Eleusin, Aristicla, Poa, etc. Further decomposition of these annual grasses lead to replacement by perennial grasses like Cymbopogon, Heteropogon etc. Some small animals also invade the habitat. |
| |
| d) Shrub stage - Further weathering or rocks and death of herbs make the habitat more suitable for the growth of shrubs like Rhus, Caparis, Zizyphus etc. Since the shrubs are larger in size and their roots penetrate more deeply in the rocky substratum causes more weathering and soil formation. |
| |
| e) Forest stages - Many light demanding, stunted and hardy trees invade the area. Vegetation finally becomes mesophytic. A steady state is reached between the environment and the biotic community. Type of climax community depends upon the climate. |
| |
| For e.g., A rain forest is formed in a moist tropical area, coniferous forest in temperate area, a grassland in area with less rainfall etc. |
| |
 |
| |
 |
| |
