Ecology:  Theory & Practice Course Lecture Notes Site Map   Week 2: Biodiversity & Ecological Sustainability Characteristics of Open Systems How Do Systems Work? Structural Features Systems have structure and process energy Components include input, throughput and output Feedback loops exist which permit the system to make adjustments Open systems depend on an outside source of energy Open Systems  Entropy & Negative Entropy Energy transformations are not 100% efficient (Law of Entropy) As systems use energy, entropy increases Systems must gain negative entropy to compensate for entropy losses Entropy includes energy losses, system deterioration, disorder and waste Negative Entropy includes structure, order and energy availability An Open System needs an excess of negative entropy Net energy yield is the amount of energy remaining at end of process Stable systems have a high degree of homeostasis Energy Needs for a System Operational Energy (enough energy to maintain an ongoing system) Energy for Emergency Response to unexpected perturbances Energy for Growth and Elaboration of system Elaboration of Open Systems As systems expand and become more elaborate, their structures change Levels of organization increase and coordination becomes necessary Information processes must be well developed Usable information coding must be in place Integration of system parts is essential Cycles of Events Open Systems have repetitive cycles of events that help the system function Cycles in natural systems include daily and seasonal patterns Examples: trophic and reproductive patterns Organizational systems feature cycles related to the complexity and stage of development of the system Equifinality Equifinality suggests that different systems can reach the same endpoint by following different pathways Goal of an open system is to achieve optimal stability over time Greater homestasis and negative entropy More diverse systems tend to have greater chances for stability  
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copyright Gaytha A. Langlois, Ph.D., 1999 Bryant College, Smithfield, RI 02917 E-mail: langlois@bryant.edu Last Updated: August 2000