1.2: Systems Flashcards
What is a systems approach?
A term used to describe a method of simplifying and understanding a complicated set of interactions
How they combine and interact with one another
Systems and the interactions they contain can be environmental, ecological, social, economic, etc.
What are the two ways of studying systems?
Reductionist approach:
Breaking a system down to its parts and studying each individually
-> good for specific interactions in detail, but not at seeing the system as a whole
Holistic approach:
Looking at the systems process and interactions as a whole
What are the 2 components of systems?
Storage
flow
provides inputs and outputs of energy/matter
Processes that transfer or transform
Represented by arrows
What is a transfer?
The movement of matter/energy from one component of the system to another without any change in form or quality
What is a transformation?
Movement of matter/energy that does involve a change in form/quality
How are systems diagrams useful?
Help identify key transfers/transformations that occur in a system and how they are interconnected
Provides opportunity to improve efficiency or sustainability of a system
Transfer and transformations happen at many scales (molecular -> global)
What is a systems diagram?
A system represented as simplified diagrams made up of storages (shapes with defined boundaries) and flows (arrows)
What are emergent properties?
Properties of a system that appear as individual systems components interact
Components do not have these properties -> result of the interactions
What is an example of an unintended consequence of not understanding systems?
System not fully understood -> unpredictable outcome/potentially harmful
Ex:
Australia has pest problem
Cane frog -> but more food, good climate, no predators -> population boom
Toxin produced in skin kills native wildlife/domestic animals
What is an open system?
Both energy and matter are exchanged between the system and its surroundings
Usually organic (living) systems that interact with their surroundings
Ex: ecosystem, habitat, your body
What is a closed system?
Energy but not matter is exchanged between the system and its surroundings
Usually inorganic (non-living)
Ex: Earth, global geochemical cycles (continuous recycling and redistribution of elements and compounds within earths natural ‘reservoirs’ (atmosphere, hydrosphere, biosphere))
What is an example of an artificial closed system?
Biosphere 2-> attempt at a larger scale artificially closed system
Self-contained experimental research facility
Designed to stimulate earths ecosystems in a closed environment
Constructed 1980s
Several connected ecosystems (rainforest, ocean, desert,etc.)
To create closed -> sealed off, only sunlight/heat can get in
Air and water recycled and food grown
Goal:
Study the interactions between the different ecosystems and humans in a controlled environment
What is an isolated system?
Neither energy nor matter are exchanged between the systems and its surroundings
Do not exist naturally, more theoretical concept
(Maybe ex: the universe)
What is a system?
It is a structure made up of interconnected parts that work together towards a common goal or function
What is an environmental system?
Interconnected networks of components and processes within the environment, found at various scales (single organism -> ecosystems)
Includes interactions between living organisms, their habitats, physical elements (eg water) that shape earths environment and influence its dynamics
How can earth be seen as a single integrated system?
Not collection of parts -> interconnected
Earth is comprised of many interconnected components like:
Biosphere (all living organisms and interactions with environment)
Hydrosphere (bodies of water)
Cryosphere (forms of frozen water)
Geosphere (solid earth -> rocks, minerals, landforms)
Atmosphere (layers of gases surrounding earth)
Anthroposphere (human influence on environment)
What is the Gaia hypothesis?
James lovelock (1970s)
Holistic view off earth as a single, self-regulating system
Earths living organism and their environment are closely linked -> integrated system
Suggest that feedback mechanisms in earths systems help maintain stability and balance on global scale
(Think homeostasis but for earth)
What are some of the major variations and developments to the Gaia theory?
Initially used to explain how the composition of the earths atmosphere affects global temps
How these things are connected/controlled via feedback mechanisms
Over time:
Many interpretations and refinements (ex: Lynn Margulis)
Criticized for:
anthropomorphism -> compare earth to living organisms
Lack of testability
But many consider it useful for understanding Earths interconnected systems
What is a model?
A simplified version of reality
Often used to represent systems
Can be very simple or extremely complex
What are the strengths and limitations of models?
Strengths:
Simplify complex systems
Easier to understand
Allow to make predictions
Results can warn us about the future/plan ahead
Input can be changed to observe output
Results can be shared between individuals/groups
Weaknesses:
Can be oversimplified/inaccurate
Results could depend on quality of data
Results more unreliable the further into the future we predict
Different models can give different outputs with the same data
Results can be interpreted differently
Environmental systems are complex -> impossible to take all factors into account
What is equilibrium?
A state of balance occurring between the separate components of a system
Open systems -> usually stable equilibrium
-> allows it to return to original state after a disturbance
->stabilizing negative feedback loops
What is a steady-state equilibrium?
The main type of stable equilibrium
Most open systems in nature
Occurs when the system shows no major changes over a longer period of time
-> can have small/oscillating changes over shorter time period (within closely defined limits)
ALWAYS RETURN TO AVERAGE STATE
What is static equilibrium?
Type of stable equilibrium
No natural systems -> yes inanimate objects
No input or output to the system
-> the system shows no change over time
Stable v unstable equilibria
System can also have unstable equilibrium
Stable -> returns to same equilibrium after disturbance
Unstable -> even a small disturbance can cause the system to suddenly shift to a new equilibrium
What are feedback loops?
Feedback mechanisms that cause systems to react in response to disturbances
Allow for self-regulation
Two types:
Negative
Positive
What is negative feedback?
Any mechanism in a system that counteracts a change away from equilibrium
When output of a process in a system inhibits/reverses the same process in a way that brings the system back to its equilibrium
Stabilizing -> counteracts deviation from equilibrium
What is the daisyworld model?
James lovelock and Andrew Watson
Computer simulation (1980s)
Model based on theoretical planet with only 2 types of organisms: white and black daisies
Daisies interact with environment by affecting albedo (amount of solar radiation it can reflect away)
How does the daisyworld model demonstrate global temperature regulation?
Amount of sunlight increased:
black daisies thrive (ability to absorb more sunlight)
Albedo decreases -> more heat -> increase in temp
Increased temp:
White daises thrive
They cause albedo to increase -> decrease in temp
Decrease in temp:
Black daisies thrive…
As both compete they will eventually reach a stable equilibrium (steady-state)
Stabilize temp -> ensure both population survive long term
Cycle of temp regulation -> negative feedback loop
What would happen on the daisyworld model with a dead planet?
Dead planet (no daisies):
No negative feedback loop to regulate
No organisms to adjust albedo/trigger temp changes
-> climate becomes more extreme over time
-> cannot sustain life
What is positive feedback?
Any mechanism in a system that leads to additional and increased change away from equilibrium
Out of process in system feeds back into system in a way that moves the system increasing away from equilibrium
Destabilizing -> amplifies deviation and drives towards tipping point -> shift to new equilibrium
What are examples of positive feedback?
Population decline:
Less population -> less reproductive potential
Reduced reproductive potential -> decline in population
Population growth:
Population growth -> increases reproductive potential
Increased reproductive potential -> increase in population
What is a tipping point?
A critical threshold within a system
If it is reach, any small changes will have massive domino effects -> system moves away from equilibrium
Represent a point of irreversible damage ( or high cost required to return to stable state)
(Positive feedback can push ecological systems towards/past tipping point -> new equilibrium)
Why can tipping points be difficult to predict?
Often delays in feedback loops -> adds complexity
Not all components or processes in a system will change abruptly/at the same time
Can be impossible to identify until it has already been passed
Activities in one part of globe might cause tipping point in another part of the globe -> extensive research required to identify these links
Case study: melting of polar ice caps and glaciers
Consequences of tipping points -> severe, extend beyond immediate area
Rising sea levels:
polar ice cap/glaciers melt -> water adds to ocean -> rising sea levels -> flooding (esp. low lying places) -> erosion,damage to infrastructure
Changes in ocean currents:
Melting -> alter salinity+temp -> affect currents -> impact weather patterns, cascading effects on ecosystem
Loss of biodiversity:
Polar regions=home to many species who are adapted to the extreme conditions
melting -> loss of habitat, food source -> loss of biodiversity
Release of greenhouse gases:
Melting permafrost (soil that been frozen) -> release large amounts of methane and CO2 (greenhouse gases) -> contribute to climate change+more melting
Changes in global temp:
Melting -> change in reflective property of surface -> more sunlight absorbed -> increase in temp -> more melting
What does resilience mean (in the context of systems)?
Refers to the systems ability to maintain stability and avoid tipping points
What factors contribute to a systems resilience/speed of response?
Diversity and size of storage
Higher diversity and size of storage:
Less likely to reach tipping points
Ex:
rainforest
Disturbance ->
animals/plants have many ways to respond
Storage in the form of trees/dormant seeds
Agricultural crop systems
Disturbance ->
Only one species -> low resilience
What is an example of how size of storage aids stability?
Small pond v large lake
Large lake -> changes in input/output have less immediate impact on system
Ex: pollutant
Lake -> more dispersed -> reduced impact
Puddle -> pollutants quickly accumulate -> more immediate/concentrated pollution
How do humans affect the resilience of natural systems?
Humans:
reduce diversity and size of storage
Ex:
rainforest have very high biodiversity
Biodiversity reduced via hunting, deforestation/destruction of habitat
Resilience reduced -> more vulnerable
Grassland have high storage of seeds/nutrients/roots systems -> allow quick recovery after disturbance
Convert grasslands -> agricultural corps -> lack biodiversity+storage -> low resilience
Case study: coral reef- ecological system with low resistance
Multiple simultaneous stressors:
Coral reef under threat from many human activities:
Overfishing
Pollution
Coastal development
Etc.
Rising sea temps:
Coral reefs -> very vulnerable to climate change
Climate change -> increased temperatures and acidity
Leads to:
Coral bleaching
Mass coral mortality
Degradation of entire reef ecosystem
Slow recovery rate:
Once damaged -> recovery is slow and difficult
Vulnerable to further damage during recovery
Continual disturbance -> reef reach tipping point and cannot recover
Case study: mangrove forest- ecological system with high resistance
Costal ecosystems
Tropical and subtropical regions
Adaptability:
Evolved to survive harsh coastal conditions
- saltwater inundation (from tidal flooding)
- sea levels rise
- storm surges
- etc.
Self regeneration:
Production of propagules -> sprout new trees
Recover quickly from disturbances (storm, hurricane, etc)
Biodiversity:
High biodiversity -> all animals/plants adapted to unique ecosystem
Biodiversity -> buffer against disturbances -> maintenance of ecological processes
Nutrient cycling:
Mangroves -> efficient nutrient cycling (N, P)
Maintain soil fertility
Support growth of trees/vegetation
