Question

Starting from a bare rock or a site of volcanic eruption, trace the organisms that participate in the process of succession.

Answer 1

The ecological succession that begins from bare rock or volcanic rock surfaces is a type of series, the sequence of development stages of an ecological community that starts from the pioneers to the climax stage. Each step of the series has particular types of organisms that grow due to the environment and the nutrients available.

Complete answer:
-Starting from bare rock or sites of volcanic eruptions, particular organisms participate and drive a succession known as the lithosere.
-Lichen species are the pioneer species of lithospheres as they tolerate low-nutrient areas and extreme climates. Crustose lichens first colonize rocks. The organic acid that leaches into the rocks is produced by them. They also absorb moisture from the atmosphere. After death, their thalli decomposes and helps in the formation of soil along with the weathering caused due to extreme climate conditions.
-Foliose lichen follows next. They absorb more water and accumulate more soil, leading to the formation of a fine soil layer on rocks. Further absorption and accumulation of dust and soil occur, with their death leading to the decomposition of thalli into the rock, causing more soil formation. This leads to moss growth.
-Mosses are moisture-loving organisms rich in organic and inorganic compounds. They further penetrate rocks and accumulate soil particles. These create more favorable conditions and attract the growth of herbs or hardy annual grasses like Aristida.
-The decomposition of annual grasses leads to the growth of perennial grasses, whose roots penetrate deep down the rock, secrete organic acids, and further promote the process of weathering. The moisture and fertile soil causes the aridity to subside, which leads to the growth of bacterial and fungal populations.
-This leads to the growth of shrub populations like the Physocarpus species that promote the formation of densely packed and organic soil, thus diminishing the growth of grasses. The root size is also relatively large, thus increasing the penetration and furthering the weathering of the rocks.
- This among shrubs leads to the growth of trees. The kind of trees depends on the soil composition. The leaf litter and decaying roots from dying and dead plants enrich the soil.
- The final climax stage where an equilibrium is reached between the environment and the biotic community.
-An intermediate stage is called sere that is found in a plant or ecological succession. When the structure of species of the ecological community change over a period of time, the process is called Ecological succession.
-Hydrosere, psammosere, and xerosere are other examples of series.

Note:
-The equilibrium of a lithosphere that is the climax community is marked by fast-growing trees such as birch and then by slower-growing but larger trees like oak. This is the moment where plant succession does not go any further.
- Occasionally, a phenomenon known as disclimax may occur, where an intervention eliminates most of the lifeforms in the areas and causes a loss of the climax community.