BIOSC 0370 Lecture 20: Predation and Herbivory II
22 Dec 2015
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Document Summary
Work of hairston, smith and slobodkin (hss) top-down vs bottom-up view of the world: top-down: predators = herbivores = plants, bottom-up: poisonous nature of plants prevents herbivore pop from growing/ Higher insect number per plant in monocultures relative to polycultures. This is to say that predators and herbivores track prey density. most abundant plant in the northeast. Application of the resource concentration hypothesis to plant communities: goldenrods are dominant and the superior competitor in fields. Hypothesis: insect herbivores regulate goldenrod (solidago) dominated communities particularly in dense patches. Density = # of plants per area (e. g, # of stems per m2). spray plot. The negative impact of the insects on goldenrod plants did not occur until there was an outbreak of the beetle, microrhopala vittata. Beetle pop drastically increased in control plot, somewhat increased in. Insect herbivory decreased the abundance of the dominant goldenrod species, but only after the outbreak in 1987.
