es_100_Lecture_14

es_100_Lecture_14 - Terminology from last lecture: Prey...

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Unformatted text preview: Terminology from last lecture: Prey compensation Could you describe two examples? Metapopulation dynamics/structure Related terms: population linkage, source/sink dynamics Trophic level HSS hypothesis Eutrophication- stimulation of primary productivity by nutrient enrichment Top down versus bottom up control At population or ecosystem level Lecture 14 Top down versus bottom up Trophic cascades Disease ecology overview Last lecture main topic: Why dont predators control their prey? When is it more likely that predators control their prey? Top down control = when predators control their prey Bottom up control = when resources control the abundance of a species Top down or bottom up ? Mostly bottom uphare is controlled by availability of plants Mostly bottom uphare is controlled by availability of plants Lynx is also bottom up controlled. It has no predators. Nitrogen fixing shrub (gets N from atmosphere), --rarely resource limited Unlikely to be bottom up (resource) controlled. Controlled by insects that drive massive die offs every 4-6 yr Individual species are often controlled by a mix of bottom up and top down processes and the two can interact (e.g. starving hares, more susceptible to lynx predation) Different trophic levels maybe be controlled by opposite forces. Herbivores may be controlled by their predators (top down) BUT...
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This note was uploaded on 12/25/2009 for the course ENV S 100 taught by Professor Staff during the Fall '08 term at UCSB.

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es_100_Lecture_14 - Terminology from last lecture: Prey...

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