Human Ecology III - Ecosystem Organization-2.ppt

Human Ecology III - Ecosystem Organization-2.ppt -...

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ECOSYSTEM ORGANIZATION Energy and Energy Flow
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Energy is necessary for the physiological/biochemical processes used in the construction and maintenance of complex molecules, and the organization of complex molecules into recognizable life forms. Energy can be measured in terms of calories (the energy needed to raise 1 gram of water 1 o centigrade) – or, more commonly these days, using joules (the amount of energy necessary to produce 1 watt of energy for 1 second)
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Energy Flow Energy obeys the laws of thermodynamics . The first two laws are most applicable in understanding flow of energy through ecosystems Basically, the first law states that “energy can neither be created nor destroyed. It can only change forms”. Basically, the second law states "energy systems have a tendency to increase their entropy rather than decrease it."
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What happens to energy in ecosystems? (1) Energy is converted from one form to another (following the first law of thermodynamics) (2) Energy is used up in the conversion process; and this energy cannot be recaptured or recycled – it is lost (following the second law of thermodynamics)
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In ecosystem terms, plant or animal structure is called biomass
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Two Important Consequences of Thermodynamics for Ecosystems Most of the energy that enters an ecosystem (in the form of sunlight) is lost in energy conversion processes. The energy that is converted into plant and animal biomass remains substantially below the energy available to the ecosystem.
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Trophic Levels A way of thinking about the how thermodynamics organizes the living (energy- consuming) organisms in an ecosystem
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Why is the biomass of higher trophic levels smaller than the biomass of lower trophic levels? Only about 10% of the energy available in the biomass of one trophic
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