Question

Name the pioneer species on a bare rock. How do they help in establishing the next type of vegetation? Mention the type of climax community that will ultimately get established.

Answer 1

Ecological succession refers to the series of the natural development of ecological communities in a place until a climax community that doesn’t develop further is created. These ecological communities are a cluster of potentially interacting species living in the same area.

Complete answer:
Lichen is the pioneer species found on a bare rock. They are involved in xerarch succession. This ecological succession takes place in dry habitats such as deserts, dunes, etc. The plants that grow in xerarch succession are known as xerophytes. The various stage involved in xerarch succession are:
Crustose lichen stage: Crustose lichens are Graphis, Rhizocarpons are resistant to grow on bare rocks as an external protective layer by sticking to them. They are thick and can tolerate extreme heat and dry conditions and desiccation. They produce acidic substances resulting in the corrosion of rocks and the formation of a thin layer of soil. The lichens that are dead and decaying add humus to the soil making it habitable for the growth of other lichens.
Foliose and fruticose lichen stage: these lichens are small leaves and stem-like structures. They are grown on the soil on which the previous lichens have shed humus. These lichens increase the moisture content of the soil for mosses to grow.
Moss stage: Moss replaces lichens when the soil is suitable for their growth. Soil accumulates as its roots penetrate deep into the soil and add humus and moisture content.
Herb stage: Due to the presence of humus and moisture in the soil, small herbs start to germinate.
Shrub stage: the death of herbs adds more humus to the soil which results in the growth of shrubs. Shrubs like Zizyphus and Rubus grow and penetrate deeper into the soil.
Tree stage: Trees began to grow after increased moisture and humus content in the soil. The environmental change also plays a vital factor in the development of the tree stage.
Climax community: the climax community for xerarch succession is the forest stage that consists of many trees.

Note:
The structural and functional unit of an environment is referred to as the ecosystem. An ecosystem comprises both the biotic and abiotic substances residing together in a biome. In an ecosystem, all the present organisms interact with one another and with the neighboring surroundings.