Succession (idea)

In an environmental sense:

Succession is the gradual change in the species that occupy a given area, with some species invading and becoming more numerous while others decline and disappear.
Succession is caused by a change in one or ore abiotic or biotic factors that benefits some species at the expense of others.
Succession is also the gradual change in plant life, from grass to hard wood forrests. The species tend to follow this kind of succession.