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Autogenic Succession
"Auto-" meaning self or same, and "-genic" meaning producing or causing. Autogenic succession refers to ecological succession driven by biotic factors within an ecosystem and although the mechanisms of autogenic succession have long been debated, the role of living things in shaping the progression of succession was realized early on. Presently, there is more of a consensus that the mechanisms of facilitation, tolerance, and inhibition all contribute to autogenic succession. The concept of succession is most often associated with communities of vegetation and forests, though it is applicable to a broader range of ecosystems.

History of related research
Henry Cowles is attributed with performing some of the foundational work for a model of succession. In his 1899 work on sand dunes he understood plant traits had to be understood for a full understanding of succession. Plants are mentioned as an ecological factor in succession along with the observation that plants of similar traits occurred together through different progression of a plant community.

Later, in 1911, Cowles explicitly states the role of abiotic and biotic factors in succession as well as coining these factors leading to changes in an ecosystem as "biotic successions". A few years after Cowles 1911 paper, Frederick Clements formalized the concept of succession and provided facilitation as the mechanism by which the living components cause succession.

It was not until 1977 that Joseph Connell and Ralph Slatyer provided an overview of the three mechanisms of succession: Facilitation, Tolerance, Inhibition.

A more in-depth history of successional concepts can be found at ecological succession.

Mechanisms and Models
The mechanisms summarized and discussed by Connell and Slatyer described pioneer species as either improving the environment for other colonizers (facilitation), having little effect on suitability (tolerance), or making the environment less suitable for other colonizers (inhibition). The Facilitation, Tolerance, and Inhibition mechanisms can be read about in greater depth at Connell–Slatyer model of ecological succession.

In addition to those three mechanisms of succession, it has been suggested that the biotic factors of a community can act on succession at the species scale as well as community scale. Species scale autogenic succession refers to things such as how fast a plant can grow and thus compete for light, or a plants ability to release chemicals that inhibit germination or seedling success. Community scale mechanisms are things such as the accumulation of organic matter into a humic layer or characteristics of plants that promote fire.

Autogenic succession does not only refer to like organisms (plant-on-plant) creating favourable or unfavourable conditions. As in a typical forest succession, herbivores and microorganisms both play roles in taking a community through stages of succession.

Inhibition:
Johnson grass has been shown to inhibit germination and seedling growth in old-field succession. The leaves, modified stems (rhizomes), and roots of the Johnson grass were shown to release or contain compounds that inhibit the success of seeds trying to establish in the area. Decaying leaves and rhizomes were also shown to inhibit germination and seedling success of other plants. In inhibition not all plants are hindered to the same degree which shapes how the following stage in succession is composed.

Facilitation:
There are many direct and indirect ways in which plant species facilitate the survival of others contributing to a change in community composition and thus succession. For example, Pinus flexilis (limber pine) has been shown to provide shade as well as protection from wind and snow to a select number of species. Other general examples of facilitation include :


 * protection from predators
 * improvement of soil nutrients and chemical composition (i.e salt content and pH)
 * moderating temperature and moisture extremes
 * increasing the benefits from soil microorganisms for other plants

Gophers have also been shown to contribute to autogenic succession. A volcano eruption lead to the primary succession of an area and the digging activity of gophers was able to a create a more suitable habitat for vegetation to colonize. As a result, the new community began with a greater diversity and abundance of plants growing on gopher mounds.

Alternative applications
Although succession and its associated mechanisms are typically reserved for application to plant communities, this has recently been expanded to included things such as microbial communities.

Microbial autogenic succession:

changes in the abundance of similar microbes occur together so that specific traits of the microorganisms such as growth rate, nutrient competition and heat tolerance gave specific species of bacteria advantages at different times. For example, heat resilience provides a mechanism of tolerance and nutrient competition acts as an inhibiting mechanism.