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Unformatted text preview: Energy Wednesday, January 14, 2009 11:17 AM Food Webs and Tropic Pyramids: 1. (both food webs and tropic pyramids have one) Fundamental purpose: tracing energy movement through ecosystems. 2. ecosystem concept (overview): a system is a bounded collection of interacting objects/factors Systems tend to nest (e.g.: a classroom is part of a school system, solar system is part of a galaxy) Ecosystems: a collection of interacting living and nonliving components within a boundary typically a soft or diffused boundary, but can be a hard boundary under certain circumstances (e.g.: a zoo, an aquarium, a cave, etc) 3. Food Webs: Description: an accounting system A method for tracing energy movement through the living components of an ecosystem Living components of an ecosystem A community Food webs track all cases of one organism eating another (nonlinear) Linear food web is a food chain (sub-part of a food web) Hypothetical example of a food web (simplified): TROUT BEAR DEER GRASSHOPPER MITES SCAVENGERS SUNLIGHT DRAGONFLY (saprophytes) OWL PLANTS BAT 4. Tropic pyramids: root- trophos (Greek reference to food) not to be confused with tropos Broad method (accounting) for tracing energy movement efficiency through a community Key component is efficiency : fraction of usable energy that is transferred during a consumption event Example of a tropic pyramid PANTHER (tertiary consumers) 0.08% of energy lost here SUNLIGHT (source of energy)...
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- Fall '08