Tuesday, November 29, 2022

What Is Succession In Biology

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Classic Perspectives Of Succession

Ecological Succession: A-level biology. Primary & secondary succession & each seral stage explained

Succession is one of the longest-studied ecological concepts. Henry Cowles was the first ecologist to thoroughly characterize successional patterns, which he did in his classic 1899 study of sand dunes along the shores of Lake Michigan . Cowles described the chronosequence of vegetation along sand dunes, moving from bare sand beach, to grasslands, to mature forests. A chronosequence is a space-for-time substitution, where ecologists can predict temporal patterns of vegetation based on a snapshot of an area gradient representing different ages of succession .

While the concept of a climax community is still viable today, the super-organism concept was opposed by another ecologist, Henry Gleason. Gleason argued that communities were individualistic that is, communities were only the fortuitous assembly of species, and that there was no such thing as a climax state for ecosystems. Gleason recognized that the environment, and species movements, had an important role in regulating species assemblages, and that community changes were not nearly as predictable as Clements had proposed . While Gleasons ideas were not well received by scientists in the 1920s, his recognition of the random aspects of community assembly are appreciated today by community ecologists interested in neutral models of biodiversity .

Ecological Succession: Important Types And 3 Mechanisms

Change is the only constant in the universe and the environment is not an exception so is ecological succession. The environment has been dynamic over the life history of the Earth due to several factors like:

  • Change in climatic and physiographic factors.
  • The activities of individuals of the communities.
  • These factors bring out specific changes in the dominance of the existing community. Which in turn sooner or later replaced by another community at the same place. This process continues and successive communities develop one after another over the period at the same area until the final community again becomes more or less stable for some time.

    This occurrence of a relatively different sequence of the community over some time in the same area is known as ecological succession. Each phase of ecological succession is called as Sere or seral stages. The initial sere was known as Pioneer seral stage.

    While due to disturbance by the community from the later seral stage it may acquire an earlier seral stage this is relatively rare in occurrence as generally community moves towards the climax.

    Primary Succession And Pioneer Species

    Primary succession occurs when new land is formed or rock is exposed for example, following the eruption of volcanoes, such as those on the Big Island of Hawaii. As lava flows into the ocean, new land is continually being formed. On the Big Island, approximately 32 acres of land are added each year. First, weathering and other natural forces break down the substrate enough for the establishment of certain hearty plants and lichens with few soil requirements, known as pioneer species. These species help to further break down the mineral-rich lava into soil where other, less-hardy species will grow, eventually replacing the pioneer species. In addition, as these early species grow and die, they add to an ever-growing layer of decomposing organic material, contributing to soil formation. Over time, the area will reach an equilibrium state with a set of organisms quite different from the pioneer species.

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    Types Of Ecological Succession

    Ecological succession progresses through primary and secondary succession. Eventually succession ceases, and the resulting, stable community is called a climax community. Even so, various factors can shift an ecological community into succession again.

    Primary succession: This is a type of ecological succession that begins essentially on a blank slate. A new habitat forms either from a volcanic eruption flow or from glacial retreat, where there is new bare rock or glacial till. The resulting exposed substrate contains no soil or vegetation.

    Once soil is made, new species called pioneer species move in. Over time, the landscape is altered by additional species that affect shade and other factors.

    Secondary succession: An established community undergoes secondary succession due to a disturbance caused by natural disasters such as wildfires, tornadoes or hurricanes.

    Human influences such as foresting, farming and development also lead to secondary succession. After the event, the community species are reestablished.

    Changes In The Environment During Succession

    primary succession
  • At each stage in succession, there are certain species that gradually change the local environment so that it becomes more suitable for other species that have not yet colonised the new land
  • For example, pioneer species change the abiotic conditions so that they are less hostile to new colonising species
  • Often, these new colonising species then change the environment in such a way that it becomes less suitable for the previous species
  • Examples of a Changing Environment During Succession

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    What Is Ecological Succession

    Ecological succession is the process by which natural communities replace one another over time. For example, when an old farm field in the midwestern U.S. is abandoned and left alone for many years, it gradually becomes a meadow, then a few bushes grow, and eventually, trees completely fill in the field, producing a forest.

    Each plant community creates conditions that subsequently allow different plant communities to thrive. For example, early colonizers like grasses might add nutrients to the soil, whereas later ones like shrubs and trees might create cover and shade. Succession stops temporarily when a climax community forms such communities remain in relative equilibrium until a disturbance restarts the succession process.

    In this video from the National Park Service, Tim Watkins and Robert Boyd explore the Indiana Dunes, learning about its history as an important case study for the development of ecological succession theory.

    Understanding how succession happens in a variety of ecosystemsand what kinds of disturbances and time spans lead to the formation of different plant and animal communitiesis important for scientists who want to understand ecosystem dynamics and effectively protect or restore natural communities.

    For example, many natural communities in North America have adapted to periodic disturbances from wildfires: This can help maintain prairie or savanna communities that depend on open habitat and nutrient cycling that might occur as a result of fire.

    Key Takeaways: Primary Succession

    • Succession describes the changes in the composition of an ecological community over time.
    • Primary succession is the initial colonization of living things in a previously lifeless area.
    • In contrast, secondary succession is the re-colonization of a region after a significant disturbance.
    • The end result of succession is the establishment of a climax community.
    • Primary succession requires much more time than secondary succession.

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    Definition Of Biological Succession

    The term biological succession refers to the progression an ecosystem follows as it changes over time. Scientists refer to individual stages of an ecosystems growth as seral stages, and they refer to the entire process of succession as a sere. Biological succession is a natural process that occurs in all of Earths ecosystems.

    What Is Primary Succession

    Ecological succession | Ecology | Khan Academy

    Primary succession occurs when new species gradually colonise a newly exposed or formed terrain. New terrain can be formed in many ways.

    New rock surfaces can be formed by cooling magma from volcanic eruptions. The ocean floor or the bed of a river can be revealed when the water level drops. Even seemingly barren places like deserts and rocky coasts can also be sites of primary succession as long as new species are slowly colonising them.

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    References And Recommended Reading

    Bazzaz, F. A. Physiologicalecology of plant succession. Annual Review of Ecology and Systematics10, 351-371 .

    Chapin, F. S., Walker, L. R. et al. Mechanisms of primary successionfollowing deglaciation at Glacier Bay, Alaska. Ecological Monographs64,149-175 .

    Clements, F. E. Nature andstructure of the climax. Journal of Ecology24, 252-84 .

    Connell, J. H. & Slayter, R. O. Mechanisms ofsuccession in natural communities and their role in community stability andorganization. American Naturalist111, 1119-1144 .

    Cooper,W. S. The recent ecological history of Glacier Bay, Alaska: thepresent vegetation cycle. Ecology 4, 223-246 .

    Cowles, H. C. The ecologicalrelations of the vegetation on the sand dunes of Lake Michigan. Botanical Gazette27, 95-117, 167-202, 281-308, 361-391 .

    Gleason,H. A. The individualistic concept of the plant association. Bulletinof the Torrey Botanical Club 53,7-26 .

    Grime, J. P. Plant strategies and vegetation processes.New York, NY: John Wiley and Sons, 1979.

    Horn, H.S. The ecology of secondarysuccession. Annual Review of Ecology andSystematics 5, 25-37 .

    Hubbell, S. P. The Unified Neutral Theory ofBiodiversity and Biogeography. Princeton, NJ: Princeton University Press,2001.

    Huston, M. & Smith, T. Plant succession- life history andcompetition. American Naturalist130,168-198 .

    Keever, C. Causes of succession onold fields of the Piedmont, North Carolina. EcologicalMonographs20,229-250 .

    Odum, E.P. The Strategy of Ecosystem Development. Science164, 262-270 .

    What Are Primary And Secondary Ecological Succession

    There are two major types of ecological succession: primary succession and secondary succession.

    Primary succession happens when a new patch of land is created or exposed for the first time. This can happen, for example, when lava cools and creates new rocks, or when a glacier retreats and exposes rocks without any soil. During primary succession, organisms must start from scratch. First, lichens might attach themselves to rocks, and a few small plants able to live without much soil might appear. These are known as pioneer species.

    Gradually, the decomposition of those plants contributes to soil formation, and more and larger plants begin to colonize the area. Eventually, enough soil forms and enough nutrients become available such that a climax community, like a forest, is formed. If the site is disturbed after this point, secondary succession occurs.

    Secondary succession happens when a climax community or intermediate community is impacted by a disturbance. This restarts the cycle of succession, but not back to the beginningsoil and nutrients are still present.

    For example, after a forest fire that kills all the mature trees on a particular landscape, grasses might grow, followed by shrubs and a variety of tree species, until eventually the community that existed before the fire is present again.

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    Ecological Succession Of Coral Reefs

    Small coral polyps colonize the rocks. These polyps grow and divide to form coral colonies. The shape of the coral reefs attracts small fish and crustaceans that are food for the larger fish. Thus, a fully functional coral reef exists.

    To know more about what is ecological succession and its types, keep visiting BYJUS website or download BYJUS app for further reference.

    Additional Sources Of Information On Succession

    secondary succession

    Here are some general sources on succession that provide a good introduction to the topic.

    Barbour, M. G., J. H. Burk, and W. D. Pitts 1987. Terrestrial Plant Ecology. The Benjamin Cummings Publishing Company Inc. Menlo Park, California. 634 pages.

    Glenn-Lewin, D. C., R. K. Peet, and T. T. Veblen 1992. Plant Succession: Theory and Prediction. Chapman and Hall, London. 352 pages.

    Luken,J.O. 1990. Directing ecological succession. Chapman and Hall, New York. 251 pages.

    Morin, P. J. 1999. Community Ecology. Blackwell Science, Massachusetts. 424 pages.

    Niering,W. A. 1987. Vegetation dynamics in relation to plant community management. Conserv. Biol. 1, 287-295.

    Ricklefs, R. E. 1990. Ecology. W. H. Freeman and Company, New York. 896 pages.

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    I Facilitation Mechanisms Of Succession

    Facilitation is one of the mechanisms of succession where earlier organisms exploit the habitat and act as a Pioneer species. They are most capable of occupying and establishing on the site. Hence this initial species at a given successional stage make the environment more suitable for the lateral successional stage.

    Example:

    Lepraria , Pamelia , and Usnea are lichens that act as Pioneer species and break down rock into soil, also plays an important role in symbiotic nitrogen fixation and make the soil more fertile for organisms in the next ecological succession stage.

    Succession: Meaning Types And Causes

    In this article we will discuss about:- 1. Meaning of Succession 2. Sequences of Succession 3. Types 4. Causes 5. Examples 6. Species Diversity.

    Meaning of Succession:

    Most communities appear to be stable and unchangeable. However, when observed over a large period of time, they seem to be in a constant state of flux, where organisms die out and their place is taken up by other organisms. Energy and nutrients also take their course in the community.

    The changes in the community occur very slowly if it is not disturbed. But when forest fire, deforestation and other disturbances occur, the habitat gets disturbed and the community rebuilds itself. The pioneer species gets replaced by other species and another community establishes itself.

    Often swamps remaining under water for hundreds of years would turn into shallow lakes. The reverse can also occur, that is, when shallow lake dries out it is invaded by Taxodium and gets converted into a swamp land.

    Such continuous, unidirectional, sequential change in species composition of a natural community initiated by disturbance is called succession. Succession is often taken to mean changes in plant alone. Subsequently, other organisms associated with the vegetation types also change. The concept of vegetation succession was proposed by Frederic E. Clements in 1916.

    Sequences of Succession:

    Types of Succession:

    A. Classification based on water relationship:

    B. Classification of seres according to their origin:

    Micro-sere:

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    Management Of Succession In Conservation

  • Human activities often prevent or interrupt the process of succession
  • As a result, this stops a climax community from developing. For example:
  • If leftalone, a grassy field would eventually develop into an area of shrubs and trees due to the process of succession. However, regular mowing prevents these larger, more woody plants from establishing themselves, so succession can’t occur
  • Similarly, in areas where livestock such as sheep, horses or cattle are kept, succession is halted by the grazing activity of these animals, which eat any new plant shoots trying to grow. Again, grasses are the main plant species that can remain established in these areas
  • Managing Succession

    • Conservation involves the protection and management of ecosystems
    • In conservation terms, preventing an area from reaching its climax community can sometimes be a goodthing
    • This is because ecosystems at the intermediate stages of succession, where small plants, grasses, ferns or shrubs are present, often hold a distinct diversity of plant species that would no longer exist if the climax community was reached
    • These diverse plant species also provide food and habitat for a high diversity of animal species, some of which may also be of conservation importance
  • As a result, some conservation projects require the deliberate, artificial prevention of succession in order to preserve an ecosystem in its current stage of succession. For example:
  • This would mean losing these important species
  • Preventing Succession

    What Are The Types Of Succession In Biology

    Primary succession occurs on | 12 | ECOSYSTEM | BIOLOGY | NCERT FINGERTIPS | Doubtnut

    Species within biotic communities rise and fall in a remarkably orderly and predictable fashion through the process of ecological succession. The first plants to colonize an area are called pioneers they pave the way for other species. The destiny of a species is intrinsically bound to environmental conditions. Succession is ongoing because dominant species can alter the environment in ways that optimize growing conditions for competitors. Succession also occurs after habitat destruction. A biome that achieves long-standing stability is considered a climax community.

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    Community Reversion To Succession

    A climax community can, however, be reverted to a successional stages from new disturbances and environmental conditions. And if those disturbances are repeated, forest succession may not reach the point of a climax community.

    Climate change, natural events such as forest fire, agriculture and deforestation cause this reversion. This sort of disturbance can lead to removal of key species in the community, and potentially extinction. Invasive species can induce a similar disruptive effect. Repeated, large disturbances favor homogeneous plant species and therefore decrease biodiversity.

    Localized disturbances like tree falls from wind storms or animal damage to plants can also revert a community to succession. As climate change affects glacial melt, more areas will be exposed over time, leading to primary succession again.

    B Causes Of Plant Succession

    In a habitat, the main cause of succession is climatic. It is the climate producing the bare area due to change in the climatic condition.

    As a result, initiation of a sere begins. There are also some other agencies like destruction of vegetation by fire, land-slide, flood, etc. responsible for the starting of succession in vegetation.

    When the vegetation of a primary succession is destroyed by anyone or all of the abovementioned factors, then secondary succession is set up. Sometimes, a succession after its development or initiation, may be deflected from its normal course by some disturbing factors like biotic agencies, fire, flood etc. Then it is called deflected succession.

    Soil condition is another cause of shaping the nature of plant community in a seral habitat, change from one type of community to another is largely dependent on soil condition.

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    Examples Of Pioneer Species

    Pioneer species tend to be fast-growing and sun-loving. Some examples of pioneer species include birches, aspens, grasses, wildflowers, fireweed and yellow dryas.

    Examples of plants in primary succession in Alaska include shrubs and small trees like willows and alders, and occasionally actinorhizal plants that can help fix bacteria at the roots. Fertile soil results, leading to larger trees like Sitka spruce. As organisms die, they add organic matter to the soil as well.

    In the drylands of Hawaii, originally new volcanic substrate played host to pioneer plant species such as the shrub Dodonaea viscosa and the grass Eragrostis atropioides. Over time, taller tress such as Myoporum sandwicense and Sophora chrysophylla moved in.

    Interestingly, primary succession takes place more quickly on ropy, pahoehoe lava substrates, possibly because of water flow into cracks where new plants can take root.

    Changes In Animal Life

    Changing Ecosystems

    Succession theory was developed primarily by botanists. The study of succession applied to whole ecosystems initiated in the writings of Ramon Margalef, while Eugene Odum‘s publication of The Strategy of Ecosystem Development is considered its formal starting point.

    Animal life also exhibits changes with changing communities. In the lichen stage fauna is sparse. It comprises a few mites, ants and spiders living in cracks and crevices. The fauna undergoes a qualitative increase during the herb grass stage. The animals found during this stage include nematodes, insects larvae, ants, spiders, mites, etc. The animal population increases and diversifies with the development of the forest climax community. The fauna consists of invertebrates like slugs, snails, worms, millipedes, centipedes, ants, bugs and vertebrates such as squirrels, foxes, mice, moles, snakes, various birds, salamanders and frogs.

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