Question

ecological succession

Answer 1

Ecological succession is the slow natural changes that take place in an area. There are usually two types of succession. There is primary - this is when new species begin to colonize an area, usually Lichen. Secondary succession is the "rebuilding" after a devastation, or something of the sort. Moreover, it already has a foundation, whereas primary succession must start from scratch. Either way, both successions take place until it reaches a climax community. :)

Answer 2

http://en.wikipedia.org/wiki/Ecological_succession