BIOL332 Lecture Notes - Niche Differentiation, Trophic Cascade, Banff National Park
17 Dec 2013
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Document Summary
Human activity mediates trophic cascade caused by wolves. Human activity divided the community into high wolf areas and low wolf areas. Elk population density diverged over time in the two treatments. Female elk survived more often in low elk areas. Where there is more elk, there are fewer beavers. Recolonization of wolves had a substantial direct effect on elk demography. Predictions made by the trophic cascade hypothesis are supported. Believed that top down trophic impacts were more significant. Management based on trophic impact of large carnivores has support. Critical of current way of classifying interactions. Thinks a simple (+,-) style excludes many interactions and shapes ecologists world views. Believes we need to define indirect and direct effects. Ambiguity problem changing population density, growth rate, etc. can all change the interaction between species. The effects on individual fitness do not necessarily have the same effect on population growth or size.
