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2013-04-23 08:13:06
community ecosystem ecology

biol 303
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  1. Describe the invasion process
    • transport and introduction
    • establishment in the recipient region
    • range expansion
  2. What are the characteristic of non-indigenous species?
    • widespread with high abundance
    • widespread with low abundance 
    • restricted range with high local abundance 
    • restricted range with low local abundance
  3. What kind of barriers do invasive species have to encounter?
    • geographical barriers
    • physiological barriers 
    • demographic barriers (early effects, biotic interactions)
  4. How are invasive species transported and introduced?
    • ballast water (unintentional transport)
    • food, recreation, etc (intentional transport)
  5. In an ecosystem, what is the relationship between native species richness and probability of establishment? Explain.
    • more diverse ecosystem, more resistance to invasion -> fewer niches and resources available 
    • more diverse ecosystem, less resistant to invasion -> what drives the increase in species richness in native species works the same way for invasive species
  6. Provide an example of how establishment may be naturally facilitated.
    • Zebra mussels ...
    • high filtering rate has large impact on native plankton communities 
    • --> increase water clearity, microphytes flourish
    • --> increase organic matter and provide substrate for benthic macroinvertebrates 
    • allows for both native and non native species to flourish
  7. What does geographic spread depend on?
    population growth and dispersal ability
  8. Describe the phosphorus cycle.
    • largest quantities of P occur in mineral deposits and marine sediments 
    • P is slowly released through the weathering of rock
    • P is absorbed by plants, moves through the food chain and decay eventually returns P to the environment 
    • Much P ends up dissolved in oceans 
    • P returns to terrestrial system through uplift of marine sedimentary rock
  9. Describe the nitrogen cycle.
    • atmospheric pool of N in the form of N2
    • N fixation- N2 is reduced into NHby N fixers, lightening, and burning of fossil fuels for human use 
    • ammonification after an organism dies 
    • nitrification by bacteria
  10. What can we say about the relationship between biodiversity and ecosystem functioning?
    • biodiversity loss reduced efficiency by which communities capture resources, produce biomass, decompose, and recycle nutrients 
    • biodiversity increases stability of ecosystem through time 
    • the impact of biodiversity is non-linear and saturating 
    • diverse communities are more productive because...
    • ...key species with large influence on productivity
    • ...differences in functional traits increase total resource capture 
    • loss of diversity across trophic levels may have stronger influence then within trophic levels 
    • function traits of organisms have large impact on magnitude of ecosystem function
  11. What are the factors that influence biodiversity?
    • abiotic environment 
    • species interactions 
    • spatial heterogeneity
    • disturbance 
    • migration of individuals
  12. Describe the carbon cycle.
    • plants absorb COfrom the atmosphere during photosynthesis 
    • release COduring respiration 
    • dissolved COin oceans used by marine 
    • fossil fuels and changing land use also contribute 
    • the ocean sink is growing, but the atmosphere sink is shrinking 
    • carbon in soils, peat, fossil fuels and carbonate  rock take a long time to return back to the atmosphere 
    • largest pool of carbon is contained in carbonate rocks
  13. What is the difference between a heterotroph and an autotroph?
    • heterotroph: consumes organic molecules from other organisms 
    • autotroph: assimilates inorganic resources and produces organic molecules  (use energy from sun or other chemical reactions), increases with increasing nutrient addition
  14. What evidence is there for hetertrophy in lakes?
    • many lakes are supersaturated with CO2
    • bacteria metabolize dissolved organic carbon
  15. What are the different kinds of competition?
    • intra-specific competition: among individuals within a species 
    • inter-specific competition: among individuals of different species 

    • direct competition: 
    • indirect ccompetition: Through a shared limiting resource 

    • interference (contest) competition: direct interaction among species 
    • exploitative (scramble) competition:
    • apparent competition: indirect competition through a shared predator
  16. What is the difference between fundamental niche and realized niche?
    • fundamental niche: range of biotic and abiotic conditions and resources that a species can persist in the absence of interactions with other species 
    • realized niche: range of biotic and abiotic conditions and resources that a species can persist in the presence of interactions with other species 
  17. What is environmental heterogeneity? How can it be classified?
    • the number of species in a given area can often be greater in heterogeneous environments.
    • extrinsic heterogeneity: heterogeneity is a feature of the environment 
    • intrinsic heterogeneity: heterogeneity is caused by the coupled action of environment and the community (eg nutrients)
  18. What is the intermediate disturbance hypothesis?
    • natural systems often experience disturbance 
    • low disturbance means high competition
    • high disturbance- few species with the appropriate fundamental niche 
    • intermediate disturbance has greater diversity
  19. Describe the equilibrium model of island biogeography.
    • on the x axis you have # of species present
    • on the y axis you have rate of immigration or extinction
    • the rate of immigration of new species decreases as the number of species on the island increases, the opposite is true for the rate of extinction 
    • higher rate of immigration for islands near a source of colonists 
    • higher rates of extinction on small islands
  20. How might biodiverisity influence ecosystem function?
    • complementarity
    • facilitation
    • redundancy
    • sampling effect
  21. How might nutrients change as a result of succession?
    • decrease in soil P: primary source of P is the weathered bedrock, over time it becomes less accessible and the demand for phosphorus increases so the concentration in the soil decreases
    • increase in soil N: more N fixers as succession progresses, and as the soil depth increases, increase in N retention b/c N binds well to soil particles and doesn't get washed away by water
  22. What kind of physiological and life history traits differ from early to late succession?
    • respiration rate- EARLY-high LATE-low
    • seeds 
    • seeds- EARLY- many, small,  LATE- few seeds, large 
    • transpiration rate- EARLY- high, LATE- low
    • growth rate- EARLY- rapid LATE- slow
    • mature size- EARLY- small LATE- large
  23. Why do species differ in their elemental ratios?
    • organic molecules that make them up differ in their elemental composition
    • species differ in their relative composition of the organic molecules
  24. How do nutrient ratios differ in terrestrial and aquatic organisms?
    terrestrial- more variation in C:N ratios
  25. What are the different metacommunity paradigms?
    • patch-dynamics: patches are identical, A is a better competitor, B is a better disperser, coexistence in region 
    • species sorting: A is a better competitor in one environment, B is a better disperser in another 
    • mass-effects: same as above, dispersal very high 
    • neutral: all species are similar, movement is random
  26. What are some important steps in the N cycle?
    • nitrification: the conversion of ammonia to nitrate, generally mediated by bacteria 
    • immobilization: the conversion of inorganic ions (eg nitrate) into organic compounds 
    • mineralization: the breakdown of organic matter from organic to inorganic for during decomposition
  27. How is the N cycle affected by temperature and moisture?
    • microbial activity increases with increasing temperature 
    • decomposition increases with increasing moisture 

    • N cycle also affected by...
    • substrate physical and chemical properties 
    • microbial biomass size 
    • shoot sink strength
  28. What are some effects the tar sands are having on water?
    • water becomes highly contaminated 
    • migratory waterfowl die by inadvertently landing in the ponds each year 
    • causes deformaties on fish and increases mortality