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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Ecological succession | 1/6 | https://en.wikipedia.org/wiki/Ecological_succession | reference | science, encyclopedia | 2026-05-05T07:17:58.613092+00:00 | kb-cron |
Ecological succession is the process of how species compositions change in an ecological community over time. The two main categories of ecological succession are primary succession and secondary succession. Primary succession occurs after the initial colonization of a newly created habitat with no living organisms. Secondary succession occurs after a disturbance such as fire, habitat destruction, or a natural disaster destroys a pre-existing community. Both consistent patterns and variability are observed in ecological succession. Theories of ecological succession identify different factors that help explain why plant communities change the way they do. Succession was among the first theories advanced in ecology. Ecological succession was first documented in the Indiana Dunes of Northwest Indiana by Henry Chandler Cowles during the late 19th century and remains a main ecological topic of study. Over time, the understanding of succession has changed to include a more complex cyclical model that argues organisms do not have fixed roles or relationships. Ecologists and conservationists have since used the theory of succession to aid in developing ecological restoration strategies.
== Stages of succession ==
=== Mechanisms === In 1916, Frederic Clements published a descriptive theory of succession and advanced it as a general ecological concept. The process of succession occurs over multiple stages.
Nudation refers to a bare area that has little to no life forms or organic matter. In secondary succession, nudation occurs after a disturbance. Migration refers to arrival of propagules. Ecesis involves establishment and initial growth of vegetation. Competition occurs as vegetation becomes well established, grows, and spreads, various species begin to compete for space, light and nutrients. Reaction refers to the phase where autogenic changes such as the buildup of humus affect the habitat, and one plant community replaces another. Stabilization occurs when a supposedly stable climax community forms.
=== Seral community ===
A seral community is an intermediate stage found in an ecosystem advancing towards its climax community. In many cases more than one seral stage evolves until climax conditions are attained. A prisere is a collection of seres making up the development of an area from non-vegetated surfaces to a climax community. Depending on the substratum and climate, different seres are found.
=== Climax community ===
According to classical ecological theory, succession stops when the sere has arrived at an equilibrium or steady state with the physical and biotic environment. Barring major disturbances, it will persist indefinitely. This end point of succession is called climax. The final or stable community in a sere is the climax community or climatic vegetation. It is self-perpetuating and in equilibrium with the physical habitat. There is no net annual accumulation of organic matter in a climax community. The annual production and use of energy is balanced in such a community.
=== Characteristics === The vegetation is tolerant of environmental conditions. It has a wide diversity of species, a well-drained spatial structure, and complex food chains. The climax ecosystem is balanced. There is equilibrium between gross primary production and total respiration, between energy used from sunlight and energy released by decomposition, between uptake of nutrients from the soil and the return of nutrient by litter fall to the soil. Individuals in the climax stage are replaced by others of the same kind. Thus the species composition maintains equilibrium. It is an index of the climate of the area. The life or growth forms indicate the climatic type.
=== Types of climax === Climatic Climax If there is only a single climax and the development of climax community is controlled by the climate of the region, it is termed as climatic climax. For example, the development of Maple-beech climax community over moist soil. Climatic climax is theoretical and develops where physical conditions of the substrate are not so extreme as to modify the effects of the prevailing regional climate. Edaphic Climax When there are more than one climax communities in the region, modified by local conditions of the substrate such as soil moisture, soil nutrients, topography, slope exposure, fire, and animal activity, it is called edaphic climax. Succession ends in an edaphic climax where topography, soil, water, fire, or other disturbances are such that a climatic climax cannot develop. Catastrophic Climax Climax vegetation vulnerable to a catastrophic event such as a wildfire. For example, in California, chaparral vegetation is the final vegetation. The wildfire removes the mature vegetation and decomposers. A rapid development of herbaceous vegetation follows until the shrub dominance is re-established. This is known as catastrophic climax. The ecology of natural disturbance and patch dynamics. Disclimax When a stable community, which is not the climatic or edaphic climax for the given site, is maintained by man or his domestic animals, it is designated as Disclimax (disturbance climax) or anthropogenic subclimax (man-generated). For example, overgrazing by stock may produce a desert community of bushes and cacti where the local climate actually would allow grassland to maintain itself. Subclimax The prolonged stage in succession just preceding the climatic climax is subclimax. Preclimax and Postclimax In certain areas different climax communities develop under similar climatic conditions. If the community has life forms lower than those in the expected climatic climax, it is called preclimax; a community that has life forms higher than those in the expected climatic climax is postclimax. Preclimax strips develop in less moist and hotter areas, whereas Postclimax strands develop in more moist and cooler areas than that of surrounding climate.
=== Theories === There are three schools of interpretations explaining the climax concept: