Succession - Community Change
The factors like fire, floods and human interventions affect an ecosystem considerably. They often lead to the depletion or stripping off of original vegetation of an area. The eventual result is the formation of bare ground or area. But this bare area does not remain devoid of life for long. It is rapidly colonised by a variety of species that subsequently modify one or more environmental factors. This modification of the environment may in turn allow additional species to become established. So, a biotic community destroyed by natural or human causes is gradually replaced in a series of changes, until a mature or climax community is reached. The process of community development, through a series of intermediate succession stages leading to climax community is known as seral stage and all such intermediate stages from bare area to climax community are collectively referred as 'seres'.
Succession is a universal process of directional change in vegetation, on an ecological time scale. If said in another way, succession is a progressive series of changes which leads to the establishment of a relatively stable climax community.