Ecological succession

Ecological succession is the process of change in the species that make up an ecological community over time. The process of succession occurs either after the initial colonization of a newly created habitat, or after a disturbance substantially alters a pre-existing habitat. Succession that begins in new habitats, uninfluenced by pre-existing communities, is called primary succession, whereas succession that follows disruption of a pre-existing community is called secondary succession. Primary succession may happen after a lava flow or the emergence of a new island from the ocean. Surtsey, a volcanic island off the southern coast of Iceland, is an important example of a place where primary succession has been observed. On the other hand, secondary succession happens after disturbance of a community, such as from a fire, severe windthrow, or logging. Succession was among the first theories advanced in ecology. Ecological succession was first documented in the Indiana Dunes of Northwest Indiana and remains an important ecological topic of study. Over time, the understanding of succession has changed from a linear progression to a stable climax state, to a more complex, cyclical model that de-emphasizes the idea of organisms having fixed roles or relationships. Precursors of the idea of ecological succession go back to the beginning of the 19th century. As early as 1742 French naturalist Buffon noted that poplars precede oaks and beeches in the natural evolution of a forest. Buffon was later forced by the theological committee at the University of Paris to recant many of his ideas because they contradicted the biblical narrative of Creation. Swiss geologist Jean-André De)luc and the later French naturalist Adolphe Dureau de la Malle were the first to make use of the word succession concerning the vegetation development after forest clear-cutting. In 1859 Henry David Thoreau wrote an address called "The Succession of Forest Trees" in which he described succession in an oak-pine forest.