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19 Cards in this Set
- Front
- Back
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define biomass
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living plant matter that is consumed by herbivores
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define productivity
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amount of energy made available by plants (how much biomass exists in a community)
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define arrows and magnitude for energy flow and interaction chain for food chain length
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energy flow: arrows up, larger arrow means more biomass is flowing towards consumer
interaction chain: arrows down, larger arrows mean predator has stronger negative affect on prey |
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define biomagnification and how it relates to food chain length; give ex
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biomagnification occurs when toxins increase in concentration as you move up food chain.
-the longer the food chain the more the top predators will be affected -seen in DDT levels (pesticide) in falcons -seen in fish (mercury), which are digested by humans (sushi) |
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what three factors control Food Chain Length (FCL)
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-energy/productivity/biomass
-disturbances -ecosystem size |
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describe affect of energy/productivity/biomass on FCL
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-increase in productivity/biomass leads to an increase in FCL
-can support a longer food chain -biomass decreases as you move up the food chain (Elton's pyramid) |
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describe affect of disturbances on FCL
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more frequent disturbances lead to decreased FCL
-larger, top predators grow slowly and have slow reproduction, so they recover slower from disturbances |
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describe affect of ecosystem size on FCL
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increased ecosystem size increases FCL because the top, larger predators are able to exist in bigger areas
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what influences lake FCL
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-Ecosystem size ONLY
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what influences river FCL
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-ecosystem size
-disturbance frequency |
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what factor determines trophic structure
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regulated by predators (top-down regulation)
-energy/biomass does NOT determine tropic structure |
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define trophic cascade
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-top predator decreases biomass of next lowest trophic level, and this causes a cascade down effect
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what is the difference btwn Odd and Even trophic structures
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-Odd: larger plant biomass, green world
-Even: less plant biomass, barren world |
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main differences between food webs and food chains, and what does this measure
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horizontal structure
-diversity (S) -complexity (number of connections) |
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What is Elton's view on stability
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diversity should enhance stability
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what is May's view on stability
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trade-off between diversity (S) and connections (c)
-if community has high diversity, it is only stable if connectance is low or if strength of connections is low |
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what is Paine's critique of May w/ regards to stability
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is it too difficult to measure S and c due to research constraint
-that is why hyperbolic relationship is present |
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what is Polis view on food webs
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complicated food webs are able to persist
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what is the current view on stability
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weaker interactions within a community buffer that community from disturbances, allowing for higher stability
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