What you’ll learn18 learning objectivesChoose one objective for a focused lesson, or study the complete topic.1.2.1Systems definition• Sets of interacting or interdependent components• Components organized to create functional wholeSyllabus objective1.2.2Systems approach• Holistic way of visualizing complex interactions• Applied to ecological or societal situations• Has storages and flows (inputs and outputs of energy and matter)Syllabus objective1.2.3System diagrams• Storages: rectangular boxes• Flows: arrows (direction indicates flow direction)Syllabus objective1.2.4Types of flows• Transfers: change in location of energy or matter• Transformations: change in chemical nature, state, or energySyllabus objective1.2.5Open vs. closed systems• Open: exchanges both energy and matter across boundary• Closed: exchanges only energy across boundary• Most systems are open (e.g., local ecosystem, Biosphere 2)• Global geochemical cycles approximate closed systemsSyllabus objective1.2.6Earth as integrated system• Encompasses biosphere, hydrosphere, cryosphere, geosphere, atmosphere, anthroposphere• Gaia hypothesis: Earth as single integrated systemSyllabus objective1.2.7System scales• Small-scale: bromeliad in rainforest• Large-scale: entire rainforest• Global: atmospheric circulation, Gaia hypothesisSyllabus objective1.2.8Negative feedback loops• Output inhibits/reverses same process to reduce change• Stabilizing, counteract deviation• Example: Daisyworld model (temperature regulation)Syllabus objective1.2.9Stable equilibrium in ecosystems• Maintained by stabilizing negative feedback loops• Steady-state equilibrium: inputs constantly balanced with outputs• Tendency to return to equilibrium following disturbanceSyllabus objective1.2.10Positive feedback loops• Disturbance leads to amplification of disturbance• Destabilizing, drives system away from equilibrium• Examples: population decline → reduced reproduction → further decline• Melting ice → reduced albedo → greater warmingSyllabus objective1.2.11Tipping points• Positive feedback drives system towards tipping point• Minimum change causing destabilization• System shifts to new equilibrium/stable stateSyllabus objective1.2.12Tipping point effects• Small alteration → large overall changes• Result in regime shifts between alternative stable states• Example: nutrient concentrations → eutrophicationSyllabus objective1.2.13Models• Simplified representation of reality• Used to understand system function and predict responses• Forms: graphs, diagrams, equations, simulations, wordsSyllabus objective1.2.14Model limitations• Simplification involves approximation• Results in loss of accuracy• Example: climate change predictions, population growth projectionsSyllabus objective1.2.15Emergent properties• Appear from component interactions• Components themselves don't have these properties• Examples: predator-prey oscillations, trophic cascadesSyllabus objective1.2.16System resilience• Tendency to avoid tipping points and maintain stability• Capacity to resist damage and recover from disturbanceSyllabus objective1.2.17Factors affecting resilience• Diversity within systems• Size of storages• Affect speed of response to change (time lags)• Example: prairie systems vs. monoculture cropsSyllabus objective1.2.18Human impacts on resilience• Reducing storages and diversity• Example: deforestation reduces storage size and diversitySyllabus objective
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