Ecological succession is classified on the basis of various parameters of classification based on time of succession.
(i) Primary succession: This type of succession starts on a substratum where there is no living matter. The living organisms that establish themselves for the first time on such a substratum are called pioneers or primary colonisers. The community thus formed is called primary community.
(ii) Secondary succession: Here the succession starts on a substratum where there was living matter previously, but has disappeared due to some natural calamity.
Classification based on cause:
(i) Autogenic succession: When the organisms of a community modify the environment in such a way that the community itself is replaced by a new one, the succession is called autogenic.
(ii) Aerogenic succession: Here the causative factor behind sue- cession is not the community itself but the physical surrounding.
Classification based on nutritional status:
Autotrophic succession: In this type, the dominant organisms are the autotrophs; and it starts in an inorganic environment.
Heterotrophic succcssion: Here the dominant organisms are heterotrophs; and it starts in an organic environment, where the energy and organic matter gradually decreases.
Classification based on the habitat where succcssion starts: Succession may start in aquatic, xeric, saline, sandy, rocky habitats and -accordingly successions can be classified as hydrosere, xerosere, halosere, psamosere and lithoserc respectively.