Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades for example, after a wildfireor even millions of years after a mass extinction.
The community begins with relatively few pioneering plants and animals and develops through increasing complexity until it becomes stable or self-perpetuating as a climax community.
The "engine" of succession, the cause of ecosystem change, is the impact of established species upon their own environments. A consequence of living is the sometimes subtle and sometimes overt alteration of one's own environment.
It is a phenomenon or process by which an ecological community undergoes more or less orderly and predictable changes following a disturbance or the initial colonization of a new habitat. Succession may be initiated either by formation of new, unoccupied habitat, such as from a lava flow or a severe landslideor by some form of disturbance of a community, such as from a firesevere windthrowor logging.
Succession that begins in new habitats, uninfluenced by pre-existing communities is called primary successionwhereas succession that follows disruption of a pre-existing community is called secondary succession. Succession was among the first theories advanced in ecology.
The study of succession remains at the core of ecological science. Ecological succession was first documented in the Indiana Dunes of Northwest Indiana  which led to efforts to preserve the Indiana Dunes. Precursors of the idea of ecological Levels of a mature forest go back to the beginning of the 19th century.
The French naturalist Adolphe Dureau de la Malle was the first to make use of the word succession concerning the vegetation development after forest clear-cutting.
In Henry David Thoreau wrote an address called "The Succession of Forest Trees"  in which he described succession in an oak-pine forest. Henry Chandler Cowlesat the University of Chicagodeveloped a more formal concept of succession. Inspired by studies of Danish dunes by Eugen WarmingCowles studied vegetation development on sand dunes on the shores of Lake Michigan the Indiana Dunes.
He recognized that vegetation on dunes of different ages might be interpreted as different stages of a Levels of a mature forest trend of vegetation development on dunes an approach to the study of vegetation change later termed space-for-time substitution, or chronosequence studies. He first published this work as a paper in the Botanical Gazette in "The ecological relations of the vegetation of the sand dunes of Lake Michigan". In this classic publication and subsequent papers, Levels of a mature forest formulated the idea of primary succession and the notion of a sere —a repeatable sequence of community changes specific to particular environmental circumstances.
From about tohowever, understanding of succession was dominated by the theories of Frederic Clementsa contemporary of Cowles, who held that seres were highly predictable and deterministic and converged on a climatically determined stable climax community regardless of starting conditions.
Clements explicitly analogized the successional development of ecological communities with ontogenetic development of individual organisms, and his model is often referred to as the pseudo-organismic theory of community ecology.