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Topic 1 Systems and models Topic 1 Systems and models Presentation Transcript

  • DP Environmental systems and societies Topic 1 Systems and models
  • What is a system?Is an organized collection of interdependent components that perform a function and which are connected through the transfer of energy and/or matterAll the parts are linked together and affect each other.Examples:• Ecosystems in which various elements such as air, water, movement, plants and animals work together to survive or perish.• Organizations in which people, structures, and processes work together to do business.
  • Local ecosystem
  • • What do the blue lines represent?
  • Figure 54.20 Review: Generalized scheme for biogeochemical cycles
  • Large ecosystem - biome• A biome (or ecosystem) is a climatically and geographically defined area often with similar communities of plants and animals.• Biome movie
  • Figure 50.24 The distribution of major terrestrial biomes
  • Figure 50.10 A climograph for some major kinds of ecosystems (biomes) in North America
  • Figure 50.25a Tropical forests
  • Figure 50.25b Savanna
  • Figure 50.25bx Savanna
  • Figure 50.25c Deserts
  • Figure 50.25d Chaparral
  • Figure 50.25dx Chaparral
  • Figure 50.25e Temperate grassland
  • Figure 20.25f Temperate deciduous forest
  • Figure 20.25g Coniferous forests
  • Figure 20.25h Tundra
  • Global ecosystem - GaiaThe Gaia hypothesis is an ecologicalhypothesis proposing that the biosphere andthe physical components of the Earth(atmosphere, hydrosphere and lithosphere)are closely integrated to form a complexinteracting system that maintains theclimatic and biogeochemical conditions onEarth in a preferred homeostasis.
  • Terminology• Open system - where matter and energy is exchange outside the system.eg. Local ecosystems (biomes)• Closed system – where only energy is exchanged outside the system.eg. Carbon, nitrogen, water, phosphate cycles• Isolated system – neither heat nor energy is exchanged.eg. The cosmos?
  • Open systems• Ecosystems animation
  • Closed systems• Water cycle• Carbon cycle• Nitrogen cycle• Phosphorus cycle
  • Closed systems - The water cycle
  • Closed systems - The carbon cycle
  • Closed systems - The nitrogen cycle
  • Closed systems - The phosphate cycle
  • TerminologyFirst law of thermodynamics – energy is neither created nor destroyedSecond law of thermodynamics – in any isolated system entropy tends to increase spontaneouslyEquilibrium – forward and reverse reactions are equal - balance
  • Transfer andtransformation
  • Figure 50.14 How mountains affect rainfall
  • Flows and storages Two basic processes must occur in an ecosystem: 1. A cycling of chemical elements. 2. Flow of energy.TRANSFERS: normally flow through a systemand involve a change in location.TRANSFORMATIONS: lead to an interactionwithin a system in the formation of a newend product, or involve a change of state.
  • Components of a system:1. Inputs such as energy or matter. Calories Protein
  • 2. Flows of matter or energy within the systems at Calori es certain rates. Protei n
  • 3.Outputs of certain forms of matter or energy that flow out of Waste the system into Calorie s Heat sinks in the environment. Waste Protei n Matte r
  • 4. Storage areas in which energy or matter can accumulate for Calorie various s lengths of time before being Protei released. n
  • Inputs and Outputs
  • Positive and Negative Feedback• Positive feedback includes a sequence of events that will cause a change in the same direction as the stimulus and thereby augments the change, moving the state of the system even further from the equilibrium point.• Negative feedback systems include a sequence of events that will cause an effect that is in the opposite direction to the original stimulus and thereby brings the system back to its equilibrium position.
  • Positive feedback
  • Positive feedback
  • Negative feedback = equilibrium
  • Negative feedback = equilibrium
  • • Predator/prey relationships are usually controlled by negative feedback where:• The increase in prey-increase in predator- decrease in prey decrease in predatorincrease in prey---and so on in a cyclical manner. The classic study in Northern Canada between the Lynx and the hare populations is famous for its regular 11 year cycle of rising and falling populations.
  • ModelsWhat is a model?• A representation or a simulation, could be conceptual, physical, mathematicalHow to evaluate a model?• Does it explain past observations• Does it agree with other models• Does it predict accurately
  • Models• What are the strengths and weakness of these models?• Determining if asteroids affected earth’s past but craters not formed due to ice - see impact crater Permafrost connecting ice layer Brittleness of crust vs sand• What problems might the aquarium model have? Biodiversity, storages…
  • SUSTAINABILITY is the extent to which a given interaction with the environment exploits and utilizes the natural incomewithout causing long-term deterioration to the natural capital.