Explain the changes in biotic community on the rocks?

The lichen stage is the pioneer stage on rock. The lichens are wind born which settle on the wet surfaces made of rock. This process happens after the rain occurs. They have rhizoids. The crustose lichens are the first one to develop out of all the lichens. They have the ability to tolerate the extreme conditions including the desiccation. The carbonic acids and lichen acids are secreted by the lichens. They corrode the surface of rock and liberate the minerals. These are required for the growth of lichen planus. The corrosion leads to depression in the rock. These are filled by the wind borne soil particles along with the organic matter. This helps in the facilitation of large lichens which are known as the foliose lichens. It includes the parmelia. They increase the rock shading as it leads to bigger depressions and can aggregate the soil particles and organic matter. They have the ability to kill the smaller lichens known as the crustose lichens. It includes the tortula. This stage is followed by the moss stage. The foliose lichens allow the moss to settle easily on the rocks. The mosses are large in size and occur in groups. They have the rhizoid which helps in the penetration in rocks. They replace the lichens. They aggregate soil and the organic matter. The substratum remains wet for most of the time. The rock starts breaking which allows more mosses to settle over there. This stage is followed by the annual grass stage. The surface formed by mosses remains wet and allow the grasses to grow over there. The germination of seed also occurs. It includes the poa and eleusine. The grasses grow for some time as long as the moisture is present. Their roots penetrate deeper in the rocks. It increases the moisture and soil. The soil helps in the growth of the grasses. The soil starts accumulating. This stage is followed by the perennial grass stage. The increase in the moisture and soil leads to the replacement of annual grasses by perennial grasses. They have the runners and rhizomes. They help in the spreading of grass. It includes the heteropogan. The moisture, shade and soil attract many animals for the perennial vegetation. This stage is followed by the shrub stage. The xerophytes shrubs have seeds and rhizomes. They occur in the area occupied by the perennial grass. It includes the rubus and caparis. They are larger in size. Their roots are longer and lead to the cracks in the rock. They help in the soil formation. They provide shade and moisture to the area. They invite the tress and many animals. This stage is followed by the climax community. The shrubs are replaced by the tress. They can be light or hard. The moist content and the shade increase as the number of plants increases. The climate plays a crucial role in the development of climax community. It is also referred as a climatic climax community. They are mainly rain forests which occur in the tropical area. A deciduous forest occurs in the temperate area. The area with the less rainfall has grasslands. These replace the shrubs and trees.