2.6.5

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2.6.5

  1. 1. 2.6.5-.7 Succession 5/11/2013 Author -Guru IB/ESS 1
  2. 2. • Succession is usually described as the orderly succession of communities to a climax community (biome) over time or as a sequence of communities (a sere) with each transitory community as a seral stage. 5/11/2013 Author -Guru IB/ESS 2
  3. 3. • There are two main types of succession: • 1. Primary succession which begins with bare rock exposed by geologic activity • eg. sere: rock -> lichen -> moss -> grass -> shrub -> trees -> maple-beech -hemlock forest • 2. Secondary succession which begins on soil from which a previous community has been removed (by fire, agriculture, etc.) 5/11/2013 Author -Guru IB/ESS 3
  4. 4. • Secondary succession can proceed much faster because the soil has already been prepared by the previous community 5/11/2013 Author -Guru IB/ESS 4
  5. 5. Differences between pioneer and climax communities Pioneer Community Climax Community Unfavorable environment favorable environment biomass increases quickly biomass is generally stable energy consumption inefficient energy consumption efficient some nutrient loss Nutrient cycling and recycling K - strategists r - strategists low species diversity, habitat high species diversity, diversity, genetic diversity -Guruhabitat diversity, genetic 5/11/2013 Author IB/ESS diversity 5
  6. 6. • One thing that limits the carrying capacity, during succession for many organisms, is that the presence of these organisms (themselves) essentially alters the environment (eg. shade, pH, moisture, temperature, chemical composition) sufficiently so that it is no longer suitable for their own offspring to continue. 5/11/2013 Author -Guru IB/ESS 6
  7. 7. • That is, the populations change the environment so drastically, both biotically and abiotically that it is now more suitable for other populations and less suitable for itself. • This leads to the succession of one sere after another until a climax is reached and the changes in the environment are now not so drastic as to produce any further major changes. 5/11/2013 Author -Guru IB/ESS 7
  8. 8. Primary Succession 5/11/2013 Author -Guru IB/ESS 8
  9. 9. Succession in South Florida 5/11/2013 Author -Guru IB/ESS 9
  10. 10. the succession of a pond ecosystem to a meadow over 250 years. 5/11/2013 Author -Guru IB/ESS 10
  11. 11. The following charts summarize the major trends as the ecosystem undergoes succession. Ecosystem characteristic Trends in ecological succession Food chains Simple food chains becoming more complex food webs Relative Species abundance Changes rapidly first, changes slower in the later stages. Total biomass Increasing Humus (non- Increasing living organic matter) Species diversity 5/11/2013 Low diversity in the early stages, then increasing in the intermediate stages and then stabilizing in the Author -Guru IB/ESS 11 final stages as an equilibrium is approached
  12. 12. Productivity Ecosystem characteristic Trends in succession Gross productivity (GP) Net productivity (NP) Increasing during early stages of primary succession then little or no increase during final stages of secondary succession Decreasing Respiration (R) Increasing 5/11/2013 Author -Guru IB/ESS ecological 12
  13. 13. Mineral and Nutrient cycles Ecosystem characteristic Trends in ecological succession Mineral cycles Becomes more self-contained in later stages Nutrient recycling Increases in later stages 5/11/2013 Author -Guru IB/ESS 13

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