FC19.txt

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Author:
hectev2000
ID:
122941
Filename:
FC19.txt
Updated:
2011-12-11 23:22:42
Tags:
community ecology
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Description:
BIOL 1215-19 Community Ecology
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  1. Community Structure:
    Species diversity and feeding relationships.
  2. Species Diversity:
    • Variety of organisms that make up the community.
    • Species richness and relative abundance.
    • Two communities can have same species richness but different relative abundance.
    • Compared using a diversity index.
  3. Species Richness:
    Total number of different species in community.
  4. Relative Abundance:
    Proportion each species represents of total individuals in community.
  5. Shannon Diversity Index (H):
    • H = -[(pA ln pA) + (pB ln pB) + (pC ln pC) + ...]
    • Determining number and abundance of species is difficult.
    • Molecular tools used to determine microbial diversity.
  6. Species with a Large Impact:
    Highly abundant or pivotal in community dynamics.
  7. Dominant Species:
    • Most abundant or have highest biomass.
    • Powerful control over occurence and distribution of others.
    • Most competitive for resources or fewest predators.
  8. Biomass:
    Total mass of individuals in population.
  9. Invasive Species:
    Introduced to new environment by humans, often lack predators or disease.
  10. Keystone Species:
    • Strong control on community by ecological roles, or niches.
    • Not necessarily abundant in a community.
  11. Foundation Species:
    • Ecosystem Engineers
    • Cause physical changes in environment affecting community structure.
    • Some facilitate +'ve effects on survival and reproduction of others.
  12. Bottom-Up and Top-Down Controls:
    • Bottom-up model is unidirectional influence from low to high trophic levels.
    • Presence or absence of mineral nutrients determines community structure.
    • Top-down model(trophic cascade model) is coming from above trophic level.
    • Predators control herbivores, which control primary producers.
  13. Disturbance:
    • Event changing community, removing organisms, altering resource supplies.
    • Climax community functioning as a superorganism debunked.
    • No longer believed to be in equilibirium.
    • Fire is significant disturbance in terrestrial ecosystems. (often necessary)
  14. Nonequilibrium model:
    Community is constantly changing after buffeted by disturbances.
  15. Intermediate Disturbance Hypothesis:
    • Moderate disturbance fosters greater diversity than high or low disturbance.
    • High disturbance exclude slow-growing species.
    • Low disturbance allow dominant species to exclude less competitive species.
  16. Ecological Succession:
    Sequence of community and ecosystem chang after a disturbance.
  17. Primary Succession:
    Occurs where no soil exists when succession begins.
  18. Secondary Succession:
    Area where soil remains after a disturbance.
  19. Human Disturbance:
    • Greatest impact on biological communities worldwide.
    • Usually reduces species diversity.
    • Prevent some important naturally occurring disturbances.

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