Types of Ecological Succession with Examples

Ecological Succession is the gradual process by which ecosystems change and develop over time. Nothing remains the same and habitats are constantly changing.

Ecological Succession Definition

Stages of Ecological Succession

Primary Succession

Pioneer Community

Climax community

Secondary Succession

Other prominent types of Ecological Succession

Ecological Succession Definition

Ecological Succession is the gradual process by which ecosystems change and develop over time. Nothing remains the same and habitats are constantly changing.

It is the observed process of change in the species structure of an ecological community over time. Within any community some species may become less abundant over some time interval, or they may even vanish from the ecosystem altogether. Similarly, over some time interval, other species within the community may become more abundant, or new species may even invade into the community from adjacent ecosystems.

This observed change over time in ‘what is living’ in a particular ecosystem is Ecological Succession.

Ecological Succession may also occur when the conditions of an environment suddenly and drastically change. A forest fires, wind storms, and human activities like agriculture all greatly alter the conditions of an environment. These massive forces may also destroy species and thus alter the dynamics of the ecological community triggering a scramble for dominance among the species still present. The rise and fall of numerous species within our various communities illustrate two types of motive forces of succession: the impact of an established species to change a site’s environmental conditions, and the impact of large external forces to suddenly alter the environmental nature of a site.

The “engine” of succession, the cause of ecosystem change, is the impact of established species on their own environments. The original environment may have been optimal for the first species of plant or animal, but the newly altered environment is often optimal for some other species of plant or animal. Under the changed conditions of the environment, the previously dominant species may fail and another species may become ascendant.

Stages of Ecological Succession

Ecological Succession proceeds through various stages, starting from Pioneer Community to Climax stage. Each such stage is called sere or seral community. 

As seral community is an intermediate stage found in ecological succession in an ecosystem advancing towards its climax community. In many cases, more than one seral stage evolves until climax conditions are attained. A pri-sere is a collection of seres making up the development of an area from non vegetated surfaces to a climax community. A seral community is the name given to each group of plants within the succession. 

Ecological succession breaks down into three fundamental phases: Primary Succession, Secondary Succession and a Climax Community.

Primary Succession

It occurs when organisms colonise an area devoid of life, usually after a catastrophic natural event that leaves the land barren. Often the first organisms to take hold are algae, fungi and simple plants such as lichens and mosses. Over time a thin layer of soil builds up so that more advanced plants, such as grasses and ferns, can take root. Along with the successful colonisation of plants come animals, insects, birds and small invertebrates.

One example of primary succession is the pioneer communities that begin to inhabit a newly created lava bed, where life cannot exist until the rock surface cools to a moderate temperature.

Primary Succession It occurs when organisms colonise an area devoid of life, usually after a catastrophic natural event that leaves the land barren.

Pioneer Community

It is a group of organisms that invade a new area in the process of Ecological Succession. These organisms are typically plants, animals and fungi. They are the first to move into a new habitat and often make the habitat more hospitable for future inhabitants. The pioneers through their death and decay leave patches of organic matter in which small animals can live. Organic debris accumulates in pockets and crevices, providing soil in which seeds can become lodged and grow. As the community of organisms continues to develop, it becomes more diverse and competition increases, but at the same time new niche opportunities develop. The pioneer species disappear as the habitat conditions change and invasion of new species progresses, leading to the replacement of the preceding community.

Pioneer Community is a group of organisms that invade a new area in the process of Ecological Succession.

Climax community

The culminating stage in the succession is the establishment of a stable community in the area, which is known as the climax community. That is, the final stage of ecological succession is the formation of the climax community. Climax communities are relatively stable and can vary widely in a given region. Some of the features of the climax community are: the vegetation of this region is tolerant to the environmental conditions. The species diversity is large and the food chains of these species are complex and with spatial structure. It is a balanced ecosystem. There is also equilibrium between the nutrients taken in from the soil and the return of the nutrients to the soil by litter fall. The individual organisms in the climax ecosystem are replaced by other organisms of the same kind. Thus it maintains species equilibrium.

The culminating stage in the succession is the establishment of a stable community in the area, which is known as the climax community.

Secondary Succession

Secondary Succession happens when an established community is replaced by a different set of plants and animals. Most ecological changes occur as secondary succession. In fact, most biological communities are in a continual state of secondary succession. Secondary succession is gradual, always moving toward the climax community. It occurs when an area that has previously had an ecological community community is so disturbed or changed that the original community was destroyed and a new community moves in.

Such successions are comparatively more rapid. This is more common than primary succession, and is often the result of natural disasters such as fires, floods, and winds, as well as human interface such as logging and clear-cutting. It starts from previously built-up substrata with already existing living matter. This type of succession starts in a given area where the conditions for life are favourable because of the fact that the area was occupied earlier by well developed community. For example- succession in an abandoned crop field.

Other prominent types of Ecological Succession

Autotrophic Succession

Autotrophic Succession is characterised by early and continued dominance of autotrophic organisms like green plants. It begins in a predominantly inorganic environment and the energy flow is maintained indefinitely.

Allogenic Succession

In Allogenic Succession, the replacement of the existing community is caused largely by any other external condition and not by the existing organisms.

Autogenic Succession

Autogenic Succession refers to that type when the community itself, as a result of its reactions with the environment, modifies its own environment and thus causing its own replacement by new communities.