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Changes in Biodiversity-Mechanism of Succession

Class 8
May 22, 2023


Nature has the ability to restore these forests that have been devastated.

Ecological succession is the process of returning such barren lands to forests with ecosystems.

There are two stages in an ecological succession: Primary and Secondary.

Primary and secondary succession have been identified as two distinct types of succession.

Primary succession occurs in essentially lifeless—areas where the soil is incapable of supporting life due to factors such as lava flows, newly formed sand dunes, or glacier-retreated rocks.

Primary succession

Secondary succession happens when a previously existing community is destroyed, characterized by smaller-scale disturbances that do not completely wipe all life and nutrients from the environment.

Secondary succession

The entire process of ecological succession is complex and is completed in a series of steps that build on one another.

In 1916, Frederic Clements introduced the sequential phase of ecological succession for the first time.

Frederic Clements


The process of succession is completed through a series of sequential phases that are as follows: –


Nudation is establishing a bare area devoid of any life in preparation for the entrance of new species. Nudation can be caused by a variety of factors, including:


Topographic: Due to soil erosion, landslides, volcanic activity, and other factors, the present community may perish.

Climatic: Storms, fires, colds, and droughts may cause the present community to be destroyed.

Biotic: Anthropogenic activities such as forest damage, grassland devastation, and so on may also devastate the community.

Autotrophic organisms that use organic stuff live in the newly developed area. The ecosystem has been prepared for the arrival of new species. Lichens, for example, secrete acids that aid in the degradation of rock into soil.

Land slide


Dispersal of seeds by the wind

ECESIS (Establishment): After arriving in a new region, the process of effective species establishment due to acclimatizing to the local conditions is known as ecesis. After seeds or propagules germinate in plants, seedlings grow, and adults begin to reproduce; only a few can do so under such primitive conditions, and hence most of them perish. If the plants can sexually produce in the given area, the ecesis is termed complete. The species’ individual becomes established in the area due to ecesis.

Plants establishment

AGGREGATION: When a species is successfully established through reproduction, the number of individuals in the species grows and stays close to each other. Compared to the earlier phases, a more significant number of individuals of a species have gathered in a specific location.

Aggregation of deer

COMPETITION and CO-ACTION: When a high number of members of a species congregate in a small area, competition (interspecific and intraspecific) emerges. The main areas of competition are space and nourishment. Individuals in a species have varied effects on each other’s lives, referred to as co-action. As a result of competition and cooperation, fit individuals survive while unfit ones are eliminated from the ecosystem. Only species with a large reproductive capacity and ecological amplitude can survive.

Intraspecific competition
Interspecific competition


A response is a technique for altering the environment through the effect of live creatures present in it. Changes in soil, water, light, temperature, and a variety of other environmental elements result from the reaction. As a result of this, the environment has changed, making it unfit for the existing community, which will eventually be replaced by another (Seral community). Others will quickly replace such communities. The term’ sere’ refers to the entire cycle of communities that return to one another in a given location (sera). Seral communities or seral stages are the several communities that contribute sere.

Pond succession or sere

A: Emergent plant life, B: Sediment, C: Emergent plants grow inwards, sediment accretes,

D: Emergent and terrestrial plants, E: Sediment fills pond, terrestrial plants take over,

F: Trees grow


Finally, the final terminal community reaches a point in the process when it is more or less stabilized for a more extended period of time and can maintain its equilibrium with the local climate. This final community is known as the climax community, and the stage is known as the climax stage. It describes a group of plants, animals, and fungi that have reached a stable condition as a result of ecological succession in the development of vegetation in a given area over time.

The climate of the region determines the climax community. Forest, grassland, and coral reef are examples of climax communities. The term “climax” was coined by Clement to designate the ideal terminus of succession. The climax community is in balance with its surroundings, representing a constant state of species composition, community structure, and energy flow.

Climax community
Ecological succession
Changes in Biodiversity - Mechanism of Succession


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