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The system is an assemblage of parts, working together, forming a functional whole. Many types of environmental systems exist. From cells to people, to cars, to economies to the whole planet. Systems occur on different scales.
The systems approach is central to the course and has been employed for a number of reasons. The very nature of environmental issues demands a holistic treatment. In reality, an environmental system functions as a whole, and the traditional reductionist approach of science inevitably tends to overlook or, at least, understate this important quality. Furthermore, the systems approach is common to many disciplines (for example, economics, geography, politics, ecology). It emphasizes the similarities between the ways in which matter, energy, and information flow (not only in biological systems but in, for example, transport and communication systems). This approach, therefore, integrates the perspectives of different disciplines.
In this unit, you will be introduced to the characteristics of environmental systems. Identifying some of the underlying principles that can be applied to living systems, from the level of the individual up to that of the whole biosphere.

Significant Ideas:

  • A systems approach can help in the study of complex environmental issues

  • The use of systems and models simplifies interactions but may provide a more holistic view without reducing issues to single processes.

Big questions:

  • What strengths and weaknesses of the systems approach and the use of models have been revealed through this topic?

  • How does a systems approach facilitate a holistic approach to understanding?

  • What are the strengths and weaknesses of the systems you have examined in this section?

  • What have you learned about models and how they can be used, for example, to predict climate change? Do their benefits outweigh their limitations?

Knowledge and Understanding

1 A systems approach is a way of visualizing a complex set of interactions that may be ecological or societal. (Guidance: A systems approach should be taken for all the topics covered in the ESS

  • Define systems

  • Explain the component parts and the emergent properties of a system. 

  • Outline the concept and characteristics of systems.​

  • Outline the Gaia Hypothesis

  • Using an example, describe the concept of systems diagrams. Include the descriptors of flows, storages, transfers, transformations, and feedback loops.

SYSTEM: An assemblage of parts and their relationship forming a functioning entirety or whole. There are two major components to a system:

  1. Elements - measurable things that can be linked together. For example, trees, shrubs, herbs, birds, and insects (items we can count, measure, or weight

  2. Processes - change elements from one form to another. These may also be called activities, relations, or functions. Example, growth, mortality, decomposition, and disturbances (what happens to the elements, or what the elements do)

A systems approach is a way of visualizing a complex set of interactions that may be ecological or societal. These interactions produce the emergent properties of the system.

  • ​Why the system as a whole is greater than the sum of its parts

  • The interactions of the parts create something they could not produce independently

  • ex: two forest stands may contain the same tree species, but the spatial arrangement and size structure of the individual trees will create different habitats for wildlife species. In this case, an emergent property of each stand is the wildlife habitat.

A system is comprised of storages and flows

  • Describe the structure of a system

  • Distinguish between flows (inputs and outputs) and storages (stock) in relation to systems

  • List two examples of storage

  • List two examples of flows

All living things use energy to do everything. Ecologists trace the flow of energy through ecosystems to identify nutritional relationships. The ultimate source of energy for nearly all living things is the sun.

Ecologists who trace energy and matter flow in ecosystems have identified a number of interesting things. Energy flows from one organism to another as each organism is eaten by the next. These relationships are called food chains. For example, a plant may capture the sun's energy then become food for a deer which may then be eaten by a bear. Each organism forms a link in the chain.

The flows provide inputs and outputs of energy and matter.

  • Describe the flow of energy and matter into and out of a system

  • Explain the differences between energy flows and matter cycles.

  • Define inputs, outputs, and stock

  • List two examples of inputs

  • List two examples of outputs

The flows are processes that may be either transfer (a change in location) or transformations (a change in the chemical nature, a change in state, or a change in energy

  • Explain with the use of examples the differences between transfers and transformations.


  • The movement of material through living organisms

  • Movement of material in the non-living process

  • The movement of energy


  • Matter to matter

  • Energy to energy

  • Matter to energy

  • Energy to matter

The flows are processes that may be either transfer (a change in location) or transformation (a change in the chemical nature, a change in state, or a change in energy) Transfers normally flow through a system and involve a change in location. Transformations lead to an interaction within a system in the formation of a new end product or involve a change of state. Using water as an example, run-off is a transfer process and evaporation is a transformation process. Dead organic matter entering a lake is an example of a transfer process; the decomposition of this material is a transformation process.

Transfers include

  • Harvesting of forest products

  • Fall of forest debris on the ground

Transformations include

  • Photosynthesis

  • Respiration

In system diagrams, storages are usually represented as rectangular boxes and flow as arrows, with the direction of each arrow indicating the direction of each flow. The size of the boxes and the arrows may be representative of the size/magnitude of the storage or flow. (Guidance Students should interpret given system diagrams and use data to produce their own for a variety of examples, such as carbon cycling, food production, and soil systems.)

  • Define storages

  • Define flows

  • Draw a systems diagram. Use examples of a real systems diagram

  • Interpret data from a stated systems diagram

System diagrams consist of: 

  • boxes show storages

  • arrows show flows (inputs/outputs)

Diagram can be labeled with the processes on each arrow:

  • Photosynthesis – the transformation of CO2, H2o, and light into biomass and oxygen O2

  • Respiration – the transformation of biomass into CO2 and water

  • Diffusion – The movement of nutrients and water

  • Consumption – tissue transfer from trophic level to another

The size of the boxes and arrows in the systems diagram a be drawn to represent the magnitude of the storage or flow.

 An open system exchanges both energy and matter across its boundary while a closed system exchanges only energy across its boundary.

  • Define and use the term open system.  Use examples of real systems to characterize an open system

  • Define and use the term closed system. Use examples of real systems to characterize a closed system.

  • Describe closed, open, and isolated systems in terms of matter and energy exchange

  • Draw systems diagrams of an open, closed, and isolated system

  • Using the terms open, closed, and/or isolated system describes a population of elephants living on an African grassland.

  • An open system is a system that regularly exchanges feedback with its external environment.

  • Open systems are systems, of course, so inputs, processes, outputs, goals, assessment and evaluation, and learning are all important.

  • Aspects that are critically important to open systems include the boundaries, external environment, and equifinality.

Healthy open systems continuously exchange feedback with their environments, analyze that feedback, adjust internal systems as needed to achieve the system’s goals, and then transmit necessary information back out to the environment. 

An isolated system is a hypothetical concept in which neither energy nor matter is exchanged across the boundary.

Define and use the term isolated system. Use examples of real systems to characterize an isolated system

A closed system in which there is no transfer of mass takes place across the boundaries of the system but energy transfer is possible. Other than the universe itself, an isolated system does not exist in practice.  However, a very well insulated and bounded system with negligible loss of heat is roughly an isolated system, especially when considered within a very short amount of time.

Ecosystems are open systems; closed systems only exist experimentally, although the global geochemical cycles approximate to closed systems.

Define open, closed, and isolated systems

Systems can be thought of as fitting into one of three types:

  • Open systems: exchanges matter and energy

  • Closed systems: exchanges only energy

  • Isolated systems: neither matter nor energy and is theoretical

A model is a simplified version of reality and can be used to understand how a system works and to predict how it will respond to change.

  • Explain, using examples, what models are.

  • Apply the systems concept on a range of scales.​

A model is a simplified description designed to show the structure or workings of an object, system or concept. In practice, some models require approximation techniques to be used. For example, predictive models of climate change may give very different results. In contrast, an aquarium may be a relatively simple ecosystem but demonstrates many ecological concepts.
Models summarize complex systems. Therefore they can lead to loss of information and oversimplification. A model involves some approximation and therefore losses accuracy.

A model inevitably involves some approximation and therefore loss of accuracy.

  • Evaluate the strengths and limitations of systems models.


  • allow scientist to predict/simplify complex systems

  • inputs can be changed and outcomes examined without having to wait for real events.

  • results can be shown to scientists and the public


  • might not be totally accurate

  • environmental factors are very complex

  • different models use slightly different data to calculate predictions

  • rely on the expertise of people making them

  • different people may interpret them in different ways

  • vested interests might hijack them politically

  • any model is only as good as the data goes in and these may be suspect

  • different models may show different effects using the same data

Application and Skills

Evaluate the use of models as a tool in a given situation, for example, climate change predictions. 

  • Define model

  • ​Evaluate the strengths and limitations of climate change models.

  • Using an example, evaluate the use of models as a tool.​

Below are 5 different climate model simulations. You should be able to discuss the strengths and weaknesses of each of these models. Which model do you believe is the best for understanding climate change? Justify your reasoning!

Construct a system diagram or a model from a given set of information. (Guidance: Students should interpret given system diagrams and use data to produce their own for a variety of examples, such as carbon cycling, food production, and soil systems.)

Construct and analyze quantitative models involving flows and storages in a system.

To make an ecosystem (diagram/ model) showing how an ecosystem works. It must contain at least three types of each of the following: abiotic elements, plants, herbivores, carnivores, and omnivores. Organism numbers must have the necessary resources in the ecosystem to maintain its carrying capacity. 

You are expected to be able to apply a systems approach to all of the topics in this course. You should be able to interpret system diagrams and use data to produce your own for a variety of examples.

Classroom Resources
Lake Lanier as a System activity
Inside Biosphere 2
Making Pancakes as a System activity
Candle as a System activity
Modeling Climate online activity

Case Studies
Be able to identify and describe inputs, outputs, processes, transfers, transformations, and  storages of both matter and\ energy for systems at different scales, including specific examples

  • Biosphere2

  • plant and animal cells

  • individual organism (one producer, one consumer)

  • farming systems

  • different ecosystems

Useful links

  1. Systems and Models Revision

  2.  - Pearson Education HotlinkSystems Thinking, Systems Tools and Chaos Theory

  3.  - Physical GeographyGaia Hypothesis

  4.  - Physical GeographyThe Layered AtmosphereThe Earths Atmosphere

  5.  - University of ArizonaBiosphere 2

  6.  - National Snow and Ice CenterNational Ice and Snow Databank

  7. - The Encyclopedia of EarthWhat is Albedo?

  8.  Concord ConsortiumClimate Interactive Models

  9. The Globe Progr

  10. Open, Closed & Isolated Systems

In The News
Hurricane Sandy: Global warming, pure and simple - SALON  31 Oct 2012
Energy Economics in Ecosystems - The Knowledge Project 



  • The use of models facilitates international collaboration in science by removing language barriers that may exist.




  • Models are simplified constructions of reality-in the construction of a model, how can we know which aspects of the world to include and which to ignore?  



Observe the events that show how Earth works as a set of interconnected systems.

























In this video Paul Andersen explains how matter and energy are conserved within the Earth's system. Matter is a closed system and Energy is open to the surroundings. In natural systems steady state is maintained through feedback loops but can be be affected by human society.


















David Suzuki talks with James Lovelock about the origins of his "Gaia" hypothesis, which suggests that the Earth is one organism.  From the documentary series "The Sacred Balance",
















This is the 2nd segment of a 12-minute overview of the shocking truth about global warming and climate change. This segment deals with the main positive feedback loops in action in Gaia's complex ecosystems: melting of the ice caps, deforestation, melting of permafrost regions of the planet, and the destruction of Ehux: vital marine algae that is a key component of the earth's climate regulation system.












Life is powerful, and in order to understand how living systems work, you first have to understand how they originated, developed and diversified over the past 4.5 billion years of Earth's history. Hang on to your hats as Hank tells us the epic drama that is the history of life on Earth












Jane Poynter tells her story of living two years and 20 minutes in Biosphere 2 -- an experience that provoked her to explore how we might sustain life in the harshest of environments.






























Systems and Models (1.2)


3 types of systems: 
Isolated, Open and Closed
Quick Summary


Modeling Ecosystems

Transformation and Transform

Energy Transformation

Transfers: energy moving from one place to another 

  • movement of material through living organisms 

  • movement of material in non-living processes 

  • movement of energy (conservation of energy)

Transformation: energy changing form (light to chemical, chemical to mechanical, etc)

  • matter to matter (glucose converted to starch)

  • energy to energy (light converted to heat)

  • matter to energy (burning fossil fuels)

  • energy to matter (photosynthesis)

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