System - An assemblage of parts and their relationships forming a functioning                           entirety or whole.

• Closed system - A system in which there is no transfer of matter across its boundaries, only energy. Such systems are rare and never include natural ecosystems although some ecosystems (large ones, usually) may be more closed than others.

• Isolated Systems - A system in which there is no transfer of either matter or energy across its boundaries. Such systems do not occur naturally.
• Open System - A system in which both matter and energy are transferred across boundaries. All natural ecosystems fall into this category.

• Ecosystem - A community of organisms, interacting with one another and their inanimate environment to for a more or less balanced, self-sufficient unit with its own characteristic pattern of energy flow and nutrient cycling.

The nature of ecosystem

• Natural ecosystems attain equilibrium through feedback systems.
• Negative feedback is a process in which a change in a system results in the cause of the change to be counteracted. It maintains a pre-set state so it is stabilizing.
• Positive feedback is a process in which the system reacts to a change by increasing the change. Accelerates changes in the system so it is destabilizing.
• Transfers normally flow through a system and involve a change in location such as the movement of organic matter from producer to consumer.
• Transformations involve a change of state resulting from an interaction within the system such as energy changes of solar radiation to chemical energy.
• First law of thermodynamics (conservation of energy) states that within a system, energy is neither created nor destroyed but it can change in form or state.
• Flows refer to inputs and outputs of systems.
• Storages refer to stock located within a system.

[Welcome] [System] [Ecosystem] [Greenhouse] [Review] [Links]