Characteristics, Types and Causes of Ecological Succession
Characteristic of Ecological Succession:
- It is a systematic process which involves change in species structure.
- The changes are directional and take place as a function of time.
- The succession occurs due to the changes in physical environment and population of species.
- The changes are predictable. The process of succession is self-going, stake and biologically feasible.
- The change also occur due to population explosion of the species,
Types of Ecological Succession:
There are two types of ecological succession: - Primary Succession:
It is characterised as initial stage of development of an ecosystem which begins with the creation of a community on such a location which was previously unoccupied by living organism. E.g., Formation of certain type of forests of dried lava. - Secondary Succession:
It is characterised as a stage of reestablishment of an ecosystem which existed earlier but was destroyed due to some natural calamities like fire, flood, etc. Such re-establishment occurs due to the presence of seeds and organic matte’ of biological community in soil. E.g., Vegetation grows once again which was destroyed due to flood.
Causes of Ecological Succession:
Following are the causes of ecological succession: - Initial Causes:
Causes those are responsible for the destruction existing habitat. Such occurrences happen due to the following factors:
(a) Climatic Factor:
Such as wind, deposits, erosion, fire etc.
(b) Biotic Factor:
Such as various activity of organisms. - Continuing Causes:
Causes those are responsible for changes in population shifting features of an area. Such factors are:
(a) Migration for safety against outside aggregation.
(b) Migration due to industrialization and urbanization.
(c) As a reactionary step against local problems.
(d) Feeling of competition - Stabilising Cause:
Causes which bring stability to the communities. Such factors are:
(a) Fertility of land
(b) Climatic condition of the area
(c) Abundance of availability of minerals etc.
Ecological Succession in Our Environmental: Causes, Types And General Process of Succession!
Communities are never stable, but dynamic, changing more or less regularly over time and space. They are never found permanently in complete balance with their component species or with the physical environment.
Variations in climatic and physiographic factors and the activities of the species of the communities themselves bring about marked changes in the dominants of the existing community, which is thus sooner or later replaced by another community at the same place.
This process continues and successive communities develop one after another over the same area, until the terminal final community again becomes more or less stable for a period of time. This occurrence of relatively definite sequence of communities over a period of time in the same area is known as ecological succession.
Hult (1885) is said to have used for the first time the term succession for the orderly changes in communities. Clements (1916) while studying plant communities defined succession as the natural process by which the same locality becomes successively colonised by different groups or communities of plants. Odum (1971) preferred to call this orderly process as ecosystem development rather than the more often known ecological succession. He defined ecosystem development in terms of the following three parameters:
(i) It is an orderly process of community development that involves changes in species structure and community processes with time, it is reasonably directional and therefore, predictable.
(ii)It results from modification of the physical environment by the community, that is, succession is community controlled.
(iii) It culminates in a stabilised ecosystem in which maximum biomass and symbiotic function between organisms are maintained per unit of “available energy flow.”
Causes of Succession:
Since succession is a series of complex processes, it is natural that there may not be a single cause for this. Generally, there are three types of causes. - Initial or initiating causes:
These are climatic as well as biotic. The former includes factors, such as erosion and deposits, wind, fire, etc. and the latter includes the various activities of organisms. These causes produce the bare areas or destroy the existing populations in an area. - Ecesis or continuing causes:
These are the processes as migration, ecesis, aggregation, competition, reaction, etc. which cause successive waves of populations as a result of changes, chiefly in the edaphic features of the area. - Stabilising causes:
These cause the stabilisation of the community.
Basic Types of Succession: - Primary succession:
In any of the basic environments viz., terrestrial, fresh water, marine, one type of succession is primary succession which starts from the primitive substratum, where there was no previously any sort of living matter. The first group of organisms establishing there are known as the pioneers, primary colonisers or primary community. - Secondary succession:
It starts from previously built up substrata with already existing living matter. The action of any external force, as a sudden change in climatic factors, biotic intervention, fire etc. causes the existing community to disappear. Thus, area becomes devoid of living matter but its substratum, instead of primitive, is built up. - Autogenic succession:
After the succession has begun, in most of the cases, it is the community itself which, as a result of its reactions with the environment, modifies its own environment and thus causing its own replacement by new communities. This course of succession is known as autogenic succession. Casus – Biotec components - Allogenic succession:
In some cases, the replacement of the existing community is caused largely by any other external condition and not by the existing organism. Such a course is referred to as allogenic succession. Causes Volcano Drought Flood - Autotrophic succession:
It 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. There is gradual increase in the organic matter content supported by energy flow. Autotroph means plat when it starts dominate hetrophic bodies - Heterotrophic succession:
It is characterised by early dominance of heterotrophs, such as bacteria, actinomycetes, fungi and animals. It begins in a predominantly organic environment, and there is a progressive decline in the energy content.
Heterophic bacteria fungi small animals
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