Model Question and Answers for APSC | Describe ecological succession? Discuss key features and significance of primary and secondary succession with examples.

Ans: Ecological succession refers to the gradual and predictable changes that occur in an ecosystem over time as it progresses through different stages of development. It is a process of natural change in the structure and composition of plant and animal communities in response to changes in the physical environment. There are two main types of ecological succession: primary succession and secondary succession.

Primary Succession: Primary succession occurs on newly formed or exposed surfaces where no soil or organisms previously existed, such as on bare rock, volcanic island or in areas where glaciers have retreated. The key features of primary succession are:

• Pioneer Species: The first organisms to colonize the area are usually lichens and mosses that are able to grow in harsh conditions with little or no soil.

• Soil Formation: As the pioneer species grow, they begin to change the physical environment by breaking down rock and creating soil. This allows other, more complex organisms to move in.

• Successional Stages: Primary succession typically progresses through several stages, each characterized by different dominant plant species, until a stable climax community is reached.

One example of primary succession is the formation of a new volcanic island. As lava cools and solidifies, it creates a barren, lifeless environment. Over time, wind and water bring in seeds and spores, and lichens and mosses begin to grow, breaking down the rock and creating soil. This process continues until a stable community of plants, animals, and microbes is established.

Secondary succession: Secondary succession occurs on preexisting soil after a disturbance such as fire, flood, or human activities has removed or altered the existing community. The key features of secondary succession are:

• Regeneration Of Vegetation: After the disturbance, remaining plants, seeds, and spores in the soil regenerate the vegetation.

• Rapid Growth Of Pioneer Species: Pioneer species that are adapted to disturbed environments grow quickly and compete for resources.

One example of secondary succession is the regrowth of a forest after a fire. After a fire, the remaining trees, seeds, and spores in the soil begin to regenerate the forest. Fast-growing pioneer species, such as grasses and shrubs, grow quickly and compete for resources. Over time, the pioneer species are replaced by larger trees, until a stable forest ecosystem is established.

The Significance Of Primary And Secondary Succession:

• The significance of both primary and secondary succession is that they help to maintain biodiversity and the health of ecosystems.

• They allow for the colonization of new environments, the regeneration of damaged ecosystems, and the development of stable and diverse communities of plants, animals, and microbes.

• Understanding the process of ecological succession is important for understanding the impacts of human activities on the environment

Understanding ecological succession is essential for managing and restoring ecosystems and can have practical implications for human activities such as land management and ecological restoration.