BILD 3 Chapter Notes - Chapter 42: Chemical Element, Primary Production, Eutrophication
30 May 2016
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Document Summary
An ecosystem is the sum of all the organisms living in a given area and the abiotic factors with which they interact. It can encompass a vast area, such as a lake or forest, or a microcosm, such as the place under a fallen log or a desert spring. Energy flows through ecosystems, whereas matter cycles within and through them. Ecosystem ecologists often measure transfers within and across ecosystems, in part to understand how many organisms a habitat can support and how much food humans can harvest from a site. Because of the second law of thermodynamics, energy conversions are inefficient because some energy is always lost as heat. Because mass is conserved, we can determine how much of a chemical element cycles within an ecosystem or is gained or lost by that ecosystem over time. The balance between inputs and outputs determines whether an ecosystem is a source or a sink for a given element.
