The process of succcssion involves the following steps:
This is a process by which a bare area is created. The reasons behind the creation of a bare area may be topographic (soil erosion, landslide, volcanic activity); climatic (glaciers, storms, frost, fire etc.), or biotic (anthropogenic activities like industrialisation, agriculture, etc.).
This is the process in which new specics reach and establish themselves in the bare areas. There are three substages of invasion.
This is the entry of propagules like seeds or spores by agents like air or water into the new area.
Once the propagules reach the new area, they germinate as they are to survive in the new environment. Most plants fail to survive. The process of successfully es- tablishing in the new envi- ronment is called ecesis. The first species that establishes itself is called the pioneer.
Increase in the number of individuals after ecesis is called aggregation.
(iii) Competition and coaction:
There is always a competition among or within the species for nutrition and space. Due to competition, there is coaction in which one influences the other leading to survival of the fittest.
The organisms that have established themselves and are competing for nutrition and space influence the environment and bring in a change in the sur- roundings. Such a process is called reaction. Reaction causes a change or destruction of one community and establishment of another. Each such stage that appears due to reaction is called serai stage.
(v) Stabilisation or climax:
It is the final stage in which the community that has developed is not replaced and is called the climax community.
A climax community, according to Clements (1916) shows three characteristics- unity, stability and phylogenetic relationship.