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17 Cards in this Set
- Front
- Back
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system
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A set of components that are linked and interact to produce a whole. For example, the river as a system is composed of sediment, water, bank, vegetation, fish, and other living things that all together produce the river.
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open system
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A type of system in which exchanges of mass or energy occur with other systems.
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closed system
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A type of system in which there are definite boundaries to factors such as mass and energy such that exchange of these factors with other systems does not occur.
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feedback
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A kind of system response that occurs when output of the system also serves as input leading to changes in the system.
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negative feedback
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A type of feedback that occurs when the system's response is in the opposite direction of the output. Thus negative feedback is self-regulating
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positive feedback
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A type of feedback that occurs when an increase in output leads to a further increase in output. This is sometimes known as a vicious cycle, since the more you have the more you get
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exponential growth
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Growth in which the rate of increase is a constant percentage of the current size; that is, the growth occurs at a constant rate per time period.
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doubling time
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The time necessary for a quantity of whatever is being measured to double
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environmental unity
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A principle of environmental sciences that states that everything affects everything else, meaning that a particular course of action leads to an entire potential string of events. Another way of stating this idea is that you can't only do one thing.
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uniformitarianism
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The principle stating that processes that operate today operated in the past. Therefore, observations of processes today can explain events that occurred in the past and leave evidence, for example, in the fossil record or in geologic formations
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steady state
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When input equals output in a system, there is no net change and the system is said to be in a steady state. A bathtub with water flowing in and out at the same rate maintains the same water level and is in a steady state
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average residence time
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A measure of the time it takes for a given part of the total pool or reservoir of a particular material in a system to be cycled through the system. When the size of the pool and rate of throughput are constant, average residence time is the ratio of the total size of the pool or reservoir to the average rate of transfer through the pool
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biota
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All the organisms of all species living in an area or region up to and including the biosphere, as in “the biota of the Mojave Desert” or “the biota in that aquarium.”
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biosphere
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Has several meanings. One is that part of a planet where life exists. On Earth it extends from the depths of the oceans to the summit of mountains, but most life exists within a few meters of the surface. A second meaning is: the planetary system that includes and sustains life, and therefore is made up of the atmosphere, oceans, soils, upper bedrock, and all life
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ecosystem
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An ecological community and its local, nonbiological community. An ecosystem is the minimum system that includes and sustains life. It must include at least an autotroph, a decomposer, a liquid medium, a source and sink of energy, and all the chemical elements required by the autotroph and the decomposer
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lag time
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is the time between a stimulus and the response of a system
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overshoot and collapse
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Occurs when growth in one part of a system over time exceeds carrying capacity, resulting in sudden decline in one or both parts of the system
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