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Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
Succession(Bio1)
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Succession(Bio1)

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  • 1. Mount St. Helen’s
  • 2.  
  • 3.  
  • 4. 4.3 Succession
  • 5. Primary and Secondary Succession <ul><ul><li>Ecological succession </li></ul></ul><ul><ul><ul><li>series of more-or-less predictable changes that occur in a community over time. </li></ul></ul></ul>
  • 6. Primary and Secondary Succession <ul><ul><li>Ecological succession </li></ul></ul><ul><ul><ul><li>series of more-or-less predictable changes that occur in a community over time. </li></ul></ul></ul><ul><ul><ul><li>especially after disturbances, as some species die out and new species move in. </li></ul></ul></ul>
  • 7. Primary and Secondary Succession <ul><ul><li>Ecological succession </li></ul></ul><ul><ul><ul><li>series of more-or-less predictable changes that occur in a community over time. </li></ul></ul></ul><ul><ul><ul><li>especially after disturbances, as some species die out and new species move in. </li></ul></ul></ul><ul><ul><li>volcanic eruption </li></ul></ul><ul><ul><li>glaciers </li></ul></ul><ul><ul><li>storms </li></ul></ul><ul><ul><li>fire </li></ul></ul><ul><ul><li>logging </li></ul></ul><ul><ul><li>agricultural disturbance </li></ul></ul>
  • 8. Primary Succession <ul><ul><li>Succession that begins in an area with no remnants of an older community is called primary succession. </li></ul></ul>
  • 9. Primary Succession <ul><ul><li>Succession that begins in an area with no remnants of an older community is called primary succession. </li></ul></ul><ul><ul><ul><li>Volcanic explosions can create new land or sterilize existing areas. </li></ul></ul></ul>
  • 10. Primary Succession <ul><ul><li>Succession that begins in an area with no remnants of an older community is called primary succession. </li></ul></ul><ul><ul><ul><li>Volcanic explosions can create new land or sterilize existing areas. </li></ul></ul></ul><ul><ul><ul><li>Retreating glaciers can have the same effect, leaving only exposed bare rock behind them. </li></ul></ul></ul>
  • 11. Pioneer Species <ul><ul><li>The first species to colonize barren areas are called pioneer species. </li></ul></ul><ul><ul><li>One ecological pioneer that grows on bare rock is lichen—a mutualistic symbiosis between a fungus and an alga. </li></ul></ul>
  • 12. Lichen <ul><ul><li>Over time, lichens convert, or fix, atmospheric nitrogen into useful forms for other organisms, break down rock, and add organic material to form soil. </li></ul></ul>
  • 13. Secondary Succession <ul><ul><li>When existing communities are not completely destroyed by disturbances. </li></ul></ul>
  • 14. Secondary Succession <ul><ul><li>When existing communities are not completely destroyed by disturbances. </li></ul></ul><ul><ul><ul><li>proceeds faster than primary succession because soil survives the disturbance so new and surviving vegetation can regrow rapidly. </li></ul></ul></ul>
  • 15. Secondary Succession <ul><ul><li>When existing communities are not completely destroyed by disturbances. </li></ul></ul><ul><ul><ul><li>proceeds faster than primary succession because soil survives the disturbance so new and surviving vegetation can regrow rapidly. </li></ul></ul></ul><ul><ul><ul><li>often follows a wildfire, hurricane, or other natural disturbance </li></ul></ul></ul>
  • 16. Secondary Succession <ul><ul><li>When existing communities are not completely destroyed by disturbances. </li></ul></ul><ul><ul><ul><li>proceeds faster than primary succession because soil survives the disturbance so new and surviving vegetation can regrow rapidly. </li></ul></ul></ul><ul><ul><ul><li>often follows a wildfire, hurricane, or other natural disturbance </li></ul></ul></ul><ul><ul><ul><li>can also follow human activities like logging and farming </li></ul></ul></ul>
  • 17. Secondary Succession <ul><ul><li>We think of these events as disasters, but many species are adapted to them. </li></ul></ul><ul><ul><ul><li>some tree species’ seeds won’t germinate until heated by a fire </li></ul></ul></ul>
  • 18. Why Succession Occurs <ul><ul><li>Every organism changes the environment it lives in. </li></ul></ul>
  • 19. Why Succession Occurs <ul><ul><li>Every organism changes the environment it lives in. </li></ul></ul><ul><ul><li>For example, as lichens add organic matter and form soil, mosses and other plants can colonize and grow. </li></ul></ul>
  • 20. Why Succession Occurs <ul><ul><li>Every organism changes the environment it lives in. </li></ul></ul><ul><ul><li>For example, as lichens add organic matter and form soil, mosses and other plants can colonize and grow. </li></ul></ul><ul><ul><li>As organic matter continues to accumulate, other species move in and change the environment further. </li></ul></ul>
  • 21. Why Succession Occurs <ul><ul><li>Every organism changes the environment it lives in. </li></ul></ul><ul><ul><li>For example, as lichens add organic matter and form soil, mosses and other plants can colonize and grow. </li></ul></ul><ul><ul><li>As organic matter continues to accumulate, other species move in and change the environment further. </li></ul></ul><ul><ul><li>Over time, more and more species can find suitable niches and survive. </li></ul></ul>
  • 22. Climax Communities <ul><ul><li>Do ecosystems return to “normal” following a disturbance? </li></ul></ul><ul><ul><ul><li>Ecologists used to think that succession in a given area always proceeds through the same stages to produce a specific and stable climax community. </li></ul></ul></ul><ul><ul><ul><li>Recent studies, however, have shown that succession doesn’t always follow the same path, and that climax communities are not always uniform and stable. </li></ul></ul></ul><ul><ul><ul><li>Clearing and farming of tropical rain forests, for example, can change the microclimate and soil enough to prevent regrowth of the original community. </li></ul></ul></ul><ul><ul><ul><li>chance can play a large role in determining which species colonize at different times. </li></ul></ul></ul>
  • 23. Studying Patterns of Succession <ul><ul><li>On both Mount Saint Helens and Krakatau, primary succession proceeded through predictable stages. </li></ul></ul><ul><ul><li>The first plants and animals that arrived had seeds, spores, or adult stages that traveled over long distances. </li></ul></ul><ul><ul><li>Hardy pioneer species helped stabilize loose volcanic debris, enabling later species to take hold. </li></ul></ul><ul><ul><li>Historical studies in Krakatau and ongoing studies on Mount Saint Helens confirm that early stages of primary succession are slow, and that chance can play a large role in determining which species colonize at different times. </li></ul></ul>

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