Succession is a process by which an ecological community undergoes changes following an initial disturbance. During succession, biotic and abiotic conditions change to create different stages to the development of the whole ecosystem. Pioneer and intermediate communities alter conditions so much so that they promote the growth of new communities that eventually replace them as the ecosystem becomes more mature and stable. Succession is the natural evolution or progression of an ecosystem, and there are just two types: primary or secondary. Primary succession is a natural process where life colonizes new land. Secondary succession is the succession that occurs after the initial process has been disrupted and some plants and animals still exist.