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Chapter 3


7 Pages

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Monika Kwiatkowski

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Chapter 3 Environmental Systems and Ecosystem Ecology Earths Environmental SystemsCycles Flows of elements compounds and energy from reservoir to reservoir through the Earth system Systems are Networks of RelationshipsSystem A network of relationships among a group of parts elements or components that interact with and influence one another through the exchange of energy matter andor informationReceive inputs of energy matter or information process these inputs and produce outputsTypes of systems o Open System A system that allow both energy and matter to cross its boundaries o Closed System A system that is self contained with regard to exchanges of matter but not energy with its surroundings no natural system is truly closed Feedbacks are Common to Environmental SystemsFeedback LoopCycle A circular process in which a systems output serves as input to that same system and it has two typesPositive Feedback LoopCycle A feedback loop in which output of one type acts as input that moves the system in the same direction the input and output drive the system further toward one extreme or another o Example Erosion Once vegetation has been cleared to expose soil erosion may become more severe if the forces of water or wind surpass the rate of vegetation regrowtho Example 2 Loss of arctic ice o Alter a system o Rare in nature but common in natural systems altered by human impact o Selfreinforcing selfperpetuating o Vicious cycleNegative Feedback LoopCycle A feedback loop in which output of one type acts as input that moves the system in the opposite direction the input and output essentially neutralize each others effects stabilizing the systemo Example Thermostat stabilizes rooms temperature by turning the furnace on when room gets cold and shutting it off when room gets hot o Example 2 Density dependent population regulation o Enhance stability and stable systems will persist in long run o Selfregulating homeostatic o Equilibrium cycleDynamic Equilibrium The state reached when processes within a system are moving in opposing directions at equivalent rates so that their effects balance out
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