Ecological Succession

Ecological succession is the gradual and predictable change in the species composition of a given area over time — a spatial pattern that unfolds through time, with time itself being the crucial variable. An area is initially occupied by pioneer species; as time passes, species diversity increases and gives way to progressively more complex organisms, until a stable climax community is eventually reached that does not evolve further as long as the environment remains unchanged. The process of succession itself proceeds through a sequence of steps: nudation (an area being laid bare), invasion (arrival of species), ecesis (their successful establishment), aggregation (increase in their numbers), competition and co-action (interaction between the establishing species), and finally reaction and stabilization. During succession, populations of some species become more numerous while others decline or disappear altogether. The complete sequence of communities that successively replace one another in a given area is called a sere, and each individual transitional community within that sequence is called a seral community; through the successive seral stages, species diversity, total number of organisms, and total biomass all tend to increase. …