As a consequence, the species composition of communities typically does not remain static with time. Apart from the regular fluctuations in species abundance related to seasonal changes, a community may develop progressively with time through a recognizable successional sequence also known as a sere; Fig.
Pioneer populations are replaced by successive colonists along a more or less predictable path toward a relatively stable community. This process of succession results from interactions between different species, and between species and their environment, which govern the sequence and the rate with which species replace each other.
The rate at which succession proceeds depends on the species' life history as well as on the effects species may have on each other and on the environment which supports them.
See also: Ecological community ; Population ecology. The course of ecological succession depends on initial environmental conditions. Primary succession occurs on areas such as volcanic ash, glacial deposits, or bare rock. In such harsh, unstable environments, pioneer colonizing organisms must have wide ranges of ecological tolerance to survive.
In contrast, secondary succession is initiated by disturbance, such as fire, which removes a previous community from an area. Pioneer species are here constrained not by the physical environment but by their ability to enter and exploit the vacant area rapidly.
See also: Fire and disturbance ecology. As succession proceeds, many environmental factors may change through the influence of the community.
Especially in primary succession, this leads to more stable, less severe environments. At the same time interactions between species of plant tend to intensify competition for basic resources such as water, light, space, and nutrients. Successional change results from the normal complex interactions between organism and environment which lead to changes in overall species composition.
Whether succession is promoted by changing environmental factors or competitive interactions, species composition alters in response to availability of niches.
Populations occurring in the community at a point in succession are those able to provide propagules such as seeds to invade the area, being sufficiently tolerant of current environmental conditions, and able to withstand competition from members of other populations present at the same stage Fig.
Species lacking these qualities either become locally extinct or are unable to enter and survive in the community. In some cases, successional sequences may take hundreds of years to complete, and direct observation at a given site is not possible. Adjacent sites may be identified as successively older stages of the same successional sequence, if it is assumed that conditions were similar when each seral stage was initiated. Early stages of succession tend to be relatively rapid, whereas the rates of species turnover and soil changes become slower as the community matures.
Eventually an approximation to the steady state is established with a relatively stable community, the nature of which has aroused considerable debate. Earlier, the so-called climax vegetation was believed to be determined ultimately by regional climate and, given sufficient time, any community in a region would attain this universal condition. This unified concept of succession, the monoclimax hypothesis, implies the ability of organisms progressively to modify their environment until it can support the climatic climax community.
Although plants and animals do sometimes ameliorate environmental conditions, evidence suggests overwhelmingly that succession has a variety of stable end points. Koske, R.
Mycorrhizae and succession in plantings of beachgrass in sand dunes. American Journal of Botany 84 , Sakai, A. The population biology of invasive species. Annual Review 32 , Tilman, G. The resource-ratio hypothesis of succession. Young, T. The ecology of restoration: historical links, emerging issues and unexplored realms. Ecology Letters 8 , Predation, Herbivory, and Parasitism. Characterizing Communities. Species with a Large Impact on Community Structure. Successional Changes in Communities.
Effects of Biogeography on Community Diversity. Community Ecology Introduction. Avian Egg Coloration and Visual Ecology. Causes and Consequences of Biodiversity Declines. Disease Ecology. The Ecology of Avian Brood Parasitism. Elemental Defenses of Plants by Metals.
The Maintenance of Species Diversity. Neutral Theory of Species Diversity. Abiotically-Mediated Direct and Indirect Effects. Biological Stoichiometry. Sampling Biological Communities. Succession: A Closer Look. Dynamics of Predation. Ecological Consequences of Parasitism. Resource Partitioning and Why It Matters. Direct and Indirect Interactions.
Keystone Species. Citation: Emery, S. Nature Education Knowledge 3 10 What do volcanoes, glaciers, sand dunes, storms, agriculture, and fire have in common? They all initiate the process of succession in communities. Aa Aa Aa. The Role of Disturbance. In plant communities, succession begins when an area is made partially or completely devoid of vegetation because of a disturbance.
Disturbances can take many different forms, and can vary in intensity and size. Large, extreme disturbances such as volcanic eruptions or glacier retreat result in very slow succession due to complete mortality of all living individuals in the system, as well as loss of the entire soil complex. This type of succession is often called primary succession, as the soil, as well as all characteristic organisms, needs to re-establish.
Large, low intensity disturbances, such as plowing in conventional agriculture, result in moderate amounts of succession, where species can survive in the soil and quickly recolonize areas after a disturbance. Early successional communities are those that establish themselves relatively quickly after disturbance, while late successional communities are those that establish themselves much later. To learn more about the evolution of amphibians and reptiles, read this tutorial Skip to content Main Navigation Search.
Dictionary Articles Tutorials Biology Forum. Following a wild fire in a forest land, an ecological succession may ensue. Ecosystem Succession If the balance of nature is left untouched, landscapes can change dramatically over time. Community Patterns Learn about community patterns and the ecological factors influencing these patterns.
Indicator Species and Endangered Species Certain species are capable of expressing characteristics indicative of the state of the ecosystem they occupy. Peet, and T. Veblen Plant Succession: Theory and Prediction. Chapman and Hall, London. Vegetation dynamics succession and climax in relation to plant community management. Examples of Succession Succession occurs in all sorts of vegetation.
Additional Sources of Information on Succession Here are some general sources on succession that provide a good introduction to the topic. Directing ecological succession. Chapman and Hall, New York. Morin, P. Community Ecology.
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