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ecological succession

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ECOLOGICAL SUCCESSION
BHARATHIYAR UNIVERSITY

Published in: Environment
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ecological succession

  1. 1. ECOLOGICALECOLOGICAL SUCCESSIONSUCCESSION
  2. 2. What is Ecological Succession? • Natural areas are subject to disturbances of many kinds. Humans and natural disturbances such as storms and fires, hurricane, earthquake etc., • Such disturbances have existed so long that animals and plants have adapted to them and benefit from their occurrence
  3. 3. • If fundamental requirements are available for life areas on earth without life are soon filled with living things. • The Ecosystem undergo series of patterns of development called ecological succession. • There are two types of succession – Primary succession – Secondary succession
  4. 4. Primary SuccessionPrimary Succession • The establishment and development of an ecosystem in an area that was previously uninhabited • The establishment and development of an ecosystem in an area that was previously uninhabited Lichens and mosses Grasses And small shrubs Large shrubs and small trees Large trees
  5. 5. Primary Succession • Begins in a place without any soil: »Sides of volcanoes »Landslides »Flooding • First, lichens that do not need soil to survive grow on rocks • Next, mosses grow to hold newly made soil • Known as PIONEER SPECIES
  6. 6. Pioneer Species Lichens break down rock to form soil. Low, growing moss plants trap moisture and prevent soil erosion
  7. 7. Mosses on rocks
  8. 8. Primary Succession • Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces • When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil
  9. 9. • Primary succession can be seen happening on the sidewalks. • If left alone, even NYC would return to a cement filled woodland.
  10. 10. Primary Succession • Simple plants like mosses and ferns can grow in the new soil
  11. 11. Primary Succession • The simple plants die, adding more organic material (nutrients to the soil) • The soil layer thickens, and grasses, wildflowers, and other plants begin to take over
  12. 12. Primary Succession • These plants die, and they add more nutrients to the soil • Shrubs and trees can survive now
  13. 13. Primary Succession • Insects, small birds, and mammals have begun to move into the area • What was once bare rock, now supports a variety of life
  14. 14. SurtseySurtsey • The island of Surtsey formed by volcanic eruption off of the coast of Iceland during the period from 1963 - 1967
  15. 15. Surtsey – Post EruptionSurtsey – Post Eruption
  16. 16. Surtsey TodaySurtsey Today
  17. 17. 6/5/03 M-DCC / PCB 2340C 20 Primary Succession
  18. 18. Secondary Succession • Begins in a place that already has soil and was once the home of living organisms • Occurs faster and has different pioneer species than primary succession • Example: after forest fires
  19. 19. Secondary succession-
  20. 20. Secondary SuccessionSecondary Succession • The recovery of a damaged ecosystem in an area where the soil was left intact • The recovery of a damaged ecosystem in an area where the soil was left intact FireweedFireweed Sequoia seedlingSequoia seedling
  21. 21. Yellowstone National ParkYellowstone National Park 1988 – Devastating forest fires burn much of Yellowstone National Park.
  22. 22. Yellowstone National ParkYellowstone National Park
  23. 23. Yellowstone National ParkYellowstone National Park 1988 – Park map showing areas (1.6 million acres) burned by the series of fires.
  24. 24. 1988 fires – The immediate aftermath.Photo: National Parks Service
  25. 25. • One year after the fires • Note the appearance of fireweed
  26. 26. • Ten years after the fires (1998)
  27. 27. Yellowstone National ParkYellowstone National Park • Twenty years after the fires (2008)
  28. 28. ChernobylChernobyl • In April, 1986, a nuclear power plant in the former USSR experienced a core meltdown and a catastrophic release of radioactivity into the environment.
  29. 29. ChernobylChernobyl • Surrounding towns and villages had to be immediately, permanently abandoned.
  30. 30. Chernobyl – Twenty Years LaterChernobyl – Twenty Years Later Pripyat town square.
  31. 31. Chernobyl – Twenty Years LaterChernobyl – Twenty Years Later Pripyat Soccer Stadium opened in 1986.
  32. 32. Chernobyl – Twenty Years LaterChernobyl – Twenty Years Later A local highway.
  33. 33. Pond Succession
  34. 34. 6/5/03 M-DCC / PCB 2340C 45 The Circle of Life in Secondary Succession
  35. 35. PATTERNS OF SPECIES CHANGE DURING SUCCESSION • THREE PATTERNS OF INTERACTIONS AMONG EARLIER AND LATER SPECIES OF SUCCESSION – Facilitation – Interference – Life history difference CHRONIC PATCHES
  36. 36. 6/5/03 M-DCC / PCB 2340C 47 The Climax Community • A climax community is a mature, stable community that is the final stage of ecological succession. In an ecosystem with a climax community, the conditions continue to be suitable for all the members of the community. • Any particular region has its own set of climax species, which are the plants that are best adapted for the area and will persist after succession has finished, until another disturbance clears the area.
  37. 37. 6/5/03 M-DCC / PCB 2340C 48 These are Climax Communities
  38. 38. 6/5/03 M-DCC / PCB 2340C 49 • Two main physical factors determine the nature of the community that develops in an area. These are temperature and the amount of rainfall. • If we place the amount of rainfall on a graph’s “x” axis, from 0-10, 10-20,and 20-30+ inches and the temperature along the “y” axis from hot, moderate, to cold, the various types of ecosystems will fit into the graph based on the conditions that they require. Temperature Cold Cold desert Tundra Taiga Moderate Temperate forest Grassland Deciduous forest Hot Hot desert Savanna Tropical forest Rainfall (inches) 0-10 10-20 20-30+
  39. 39. 6/5/03 M-DCC / PCB 2340C 50 • Pioneer species colonize a bare or disturbed site. Soil building. • Changes in the physical environment occur (e.g., light, moisture). • New species of plants displace existing plants because their seedlings are better able to become established in the changed environment. • Newly arriving species alter the physical conditions, often in ways that enable other species to become established. • Animals come in with or after the plants they need to survive. • Eventually a climax community that is more or less stable will become established and have the ability to reproduce itself. • Disturbances will start the process of succession again. A summary of changes that occur during succession:
  40. 40. 6/5/03 M-DCC / PCB 2340C 51 Does Ecological Succession Ever Stop? • We must recognize that any ecosystem, no matter how inherently stable and persistent, could be subject to massive external disruptive forces (like fires and storms) that could re-set and re-trigger the success ional process. • As long as these random and potentially catastrophic events are possible, it is not absolutely accurate to say that succession has stopped.
  41. 41. 6/5/03 M-DCC / PCB 2340C 52 Does Ecological Succession Ever Stop? • Also, over long periods of time (“geological time”) the climate conditions and other fundamental aspects of an ecosystem change. • These geological time scale changes are not observable in our “ ecological” time, but their fundamental existence and historical reality cannot be disputed. • No ecosystem, then, has existed or will exist unchanged or unchanging over a geological time scale.
  42. 42. Climax Community • A stable group of plants and animals that is the end result of the succession process • Does not always mean big trees – Grasses in prairies – Cacti in deserts
  43. 43. Succession Summary Succession Creates new ecosystem Restores previous ecosystem Example: New land created by volcanic eruption Example: An area destroyed by fire Primary Secondary
  44. 44. Forest Ecosystem

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