An area of bare ground, either on land or under water, hardly remains that way for a long time. This area in course of time becomes colonized by a variety of species which will occupy the bare ground. The occupation of this bare ground changes the environment which results in the development of new organisms. 

      With time, bigger or stronger species of organisms begin to appear and at the same time the original species are wiped out. As more species of organisms continue to appear in the habitat, it will come to a time when a stable community called climax community will be formed.