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Community ecology

Community ecology. Outline: Community structure: attributes Factors influencing the structure of communities Community dynamics Chapter 16-18. Community attributes. # of species Relative abundance of species Nature of species interactions (food webs) Physical structure .

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Community ecology

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  1. Community ecology Outline: • Community structure: attributes • Factors influencing the structure of communities • Community dynamics Chapter 16-18

  2. Community attributes • # of species • Relative abundance of species • Nature of species interactions (food webs) • Physical structure

  3. Community structure • Species richness (# of species within community) 10

  4. Community structure • Relative abundance (% each species contributes to the total number of individuals)

  5. Stand one Stand two

  6. Simpson’s diversity index • D = 0 - 1 • 0: high diversity • 1: low diversity • Stand one (Table 16.1): D=0.13 • Stand two (Table 16.2): D=0.36

  7. Dominance Yellow-poplar

  8. Food webs

  9. Keystone species

  10. Functional groups • Feeding level • Exploitation of common resources (guilds) • Photosynthetic pathway • Shade tolerance • Life history

  11. Physical structure

  12. Zonation

  13. supratidal intertidal subtidal

  14. Association • Relatively consistent species composition • Uniform general appearance • Distribution that is characteristic of a particular habitat

  15. Organismic concept of communities

  16. Continuum concept of communities

  17. Factors controlling community structure

  18. Fundamental niche

  19. Species interactions

  20. Keystone predation

  21. Apparent competition

  22. Indirect commensalism

  23. Top-down vs. bottom-up control

  24. The number of trophic levels regulates plant, herbivore and carnivore numbers # trophic levels: B/comp: numbers limited by availability of resources (bottom-up regulation). Competition strong, predation weak. T/pred: numbers limited by predation (top-down regulation). Competition weak, predation strong.

  25. Stress tolerance and competition

  26. Black needle rush Salt meadow cordgrass Smooth cordgrass

  27. Environmental heterogeneity

  28. Relationship between the number of plants per 300m2 plot beside the hood river, NWT, and an index (ranging from 0 to 1) of spatial heterogeneity in abiotic factors associated with topography and soil. More spatially heterogeneous plots had higher species richness.

  29. Environmental quality

  30. Plant species diversity in a control plot and a fertilized plot in the Parkgrass experiment in Rothamstead, England. Fertilized plots have lower species diversity. The Parkgrass experiment, which began in 1856, is the longest running ecological experiment.

  31. Community stability Types of stability: • Resilient community: returns to former state after disturbance • Resistant community: changes little in response to disturbance

  32. Community dynamics: Succession

  33. Primary succession Pioneer species Late successional species

  34. Secondary succession

  35. beach grass shrubs pines oak

  36. Primary succession: newly exposed substrate

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