Ecological Succession Definition, Types, Stages, Diagram

What is Ecological Succession?

An environment creates and balances itself through the course of ecological succession. Ecological succession is a series of changes in an ecosystem over a period of time. The succession may form either formation of new unoccupied regions, such as from flow of lava after a volcanic eruption or a severe landslide, or by some form of disturbance of a community as forest fire, severe windthrow, or logging.

Ecological Succession Definition

It is the process of evolution of a species in a steady and gradual manner in a region over a period of time. It can also be described as the sequence of colonization of species in an ecosystem form a barren region. It is a course of evolution in the species with the development of the biological area over a long run starting from:

Pioneer Species –> Intermediate Species –> Climax Species

Types of Ecological Succession

There are two main types of Ecological Succession. Primary Succession & Secondary Succession:

Primary Succession

It thrives in a region that has no vegetation of any kind and in an area where the soil is unable to nurture a sustained life e.g., sand ridges, uncovered ocean surface, newly formed deltas, lava flow, emerging volcanic islands etc. The stages include pioneer microorganisms, and plants (lichens and mosses). The pioneer organisms through their death and decay alter the habitation by releasing nutrients to the substratum (layers of rock/soil). The new condition of the region becomes more suitable for the development of intermediate species such as – grasses, shrubs shade-intolerant trees (such as Pine) and further development of the Climax community including shade-tolerant trees (such as oak).

Secondary Succession

It occurs when the preexisting mature or intermediate community in a region has been partially or completely wiped out due to disturbance caused by natural events such as severe floods, droughts, forest fires, or storms or by human interventions such as deforestation, agriculture, overgrazing, etc. As some of the sediments from the previous community is already present, the development of the secondary succession is relatively faster than the primary community. And with the passage of time forest community develops.

Stages of Ecological Succession

The mixing of species and habitat during the process of ecological succession go through 5 stages:

Causes of Ecological Succession

Initial Causes: They are responsible for the destruction of existing habitats. It occurs due to the following factors Climatic Factors – Factors such as wind, fire, erosion, natural disaster etc. The Biotic Factors include – competition between organisms for existence.

Continuous Causes: It is also called ecesis. It includes process as competition, migration, aggregation etc. It results in a series of changes in the soil structure as – changes in soil pH, accumulation of organic matter, changes in soil nutrients etc.

Ecological Succession in Ecosystem

Ecological succession is essential for the healthy growth and development of the ecosystem as it initiates the colonization and diversification of a new region and the recolonization of a region that has been wiped out due to natural and anthropogenic causes.

Ecological Succession and Stability of Ecosystem: Succession occurs in a series of stages which leads to the establishment of a stable and final community. The final stable community of plants is called the Climax community.

Ecological Succession and Diversity in Ecosystem: Ecological Succession provides diversity as well as depth to a biotic community in an ecosystem. As succession is the gateway of evolution without which life cannot grow or progress.

Ecological Succession Helps Maintaining Equilibrium in Ecosystem:  A community goes through stages of ecological succession until it reaches equilibrium. When a community reaches the climax stage of succession the composition of the community becomes stable thus any small changes or disturbances will be counterbalanced by other changes to restore the original stage.

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