University at BuffaloEngineering for Ecosystem Restoration

Summer Workshop Series25 June 2010

David BlerschDept. of Civil, Structural and Environmental Engineering

University at Buffalo

Ecological Systems Modeling:Lecture 2: Systems and Ecosystems

Systems and EcosystemsWhat is a system?

A system is a group of parts which are connected and work together. Systems with living and nonliving parts are called ecosystems (short for ecological system) (Odum, Odum, and Brown, 1997)

What is an ecosystem?

Some definitions of “ecosystem”Classic: A dynamic set of living organisms (plants, animals and

microorganisms) all interacting among themselves and with the environment in which they live (soil, climate, water, and light).

A biotic and functional system or unit which is able to sustain life and includes all biological and non-biological variables in that unit (Jorgensen and Bendoriccio 2001).

A community of species interacting to process energy and nutrients through a complex of foodwebs (Adey and Loveland (2007)).

A network of biotic (species populations) and abiotic (nutrients, soil, water, etc.) components found at a particular location that function together as a whole through primary production, community respiration, and biogeochemical cycling (Kangas (2004)).

An organized system of land, water, mineral cycles, living organisms, and their programmatic behavioral control mechanisms. (Odum 1994).

Properties of EcosystemsAn ecosystem…Is the fundamental unit of ecology (?)…Is the “exquisite potential of the universe.” (Adey and Loveland

2007)Is conservative of matter and energyPerforms energy capture and transformationPerforms mineral retention and cyclingHas rate regulation and controlOrganizes towards production and respiration balance

Thermodynamic LawsFirst Law of Thermodynamics (Law of Conservation) The total energy of any system and its surroundings is

conserved (i.e., Energy is neither created nor destroyed, it changes from one form to another).

Second Law of Thermodynamics (Entropy Law)The entropy change of any system and its surroundings,

considered together, resulting from any real process, is positive and approaches a limiting value of zero for any process that approaches irreversibility (i.e., for any real process, some energy is lost as waste heat).

Energetic basis for ecosystems

Waste Heat

Less total energy at each level

Grazers

Plants

Sun

Carnivores

Hierarchy: Food Chains and Pyramid Charts

Embodied energy at each level

1000

100

10

1

Rudimentary Systems Diagrams

Odum 1956

“Electrical” Analog

“Pulmonary” analog

Using a Systems LanguageWhy a systems language?To convert non-quantitative verbal models to… more

quantitative, more accurate, more predictive, more consistent, and less confusing network diagrams.

Understanding systems…Understanding environment and society as a system means

thinking about parts, processes, and connections. To help understand systems, it is helpful to draw pictures of

networks that show components and relationships.

Energy Circuit Diagrams

From Odum (1994)

System Frame: A rectangular box drawn to represent the boundaries of the system selected.

ENERGY SYSTEMS SYMBOLS

Pathway Line: a flow of energy, often with a flow of materials.

SOURCE: outside source of energy; a forcing function..

STORAGE: a compartment of energy storage within the system storing quantity as the balance of inflows and outflows

Pathway Line: a flow of energy, often with a flow of materials.

SOURCE: outside source of energy; a forcing function..

STORAGE: a compartment of energy storage within the system storing quantity as the balance of inflows and outflows

Pathway Line: a flow of energy, often with a flow of materials.

SOURCE: outside source of energy; a forcing function..

STORAGE: a compartment of energy storage within the system storing quantity as the balance of inflows and outflows

INTERACTION: process which combines different types of energy flows or material flows to produce an outflow in proportion to a function of the inflows.

PRODUCER: unit that collects and trnasforms low-quality energy under control interactions of higher quality flows.

CONSUMER: unit that transforms energy quality, stores it, and feeds it back autocatalytically to improve inflow

.

Multiplier or Work Gate

A

B

AxB

HEAT SINK: A pathway for dissipated energy necessary forany real process.

Autocatalytic unit

A stored quantity is used in a feedbackloop to interact as a multiplier with theinput energy source of that quantity.

Maximum Power Principle: Systems prevail that develop designs that maximize the flow of useful energy (Lotka, 1922)

“Self-organization selects network connections that feed back transformed energy to increase inflow of resources or use them more efficiently.” (Odum and Odum 2001)

INTERACTION: process which combines different types of energy flows or material flows to produce an outflow in proportion to a function of the inflows.

PRODUCER: unit that collects and trnasforms low-quality energy under control interactions of higher quality flows.

CONSUMER: unit that transforms energy quality, stores it, and feeds it back autocatalytically to improve inflow

.

INTERACTION: process which combines different types of energy flows or material flows to produce an outflow in proportion to a function of the inflows.

PRODUCER: unit that collects and trnasforms low-quality energy under control interactions of higher quality flows.

CONSUMER: unit that transforms energy quality, stores it, and feeds it back autocatalytically to improve inflow

.

TRANSACTION: a unit that indicates the sale of goods or services (solid line) in exchange for payment of money (dashed line).

SWITCHING ACTION: symbol that indicates one or more switching functions where flows are interrupted or initiated.

BOX: miscellaneous symbol for whatever unit or function is labled.

Conventionssources arrangedaccording totheir quality

Components arranged withinboundary according to theirquality

Used Energy

Typical Energy Sources

Odum (1994)

Hierarchical arrangement of systemsI I I I I I I V

A

B

C

D

E

J

K

L

S

T

Z

Hierarchical Levels

Parallel Processes

EnergySource

Putting it together

Producer ConsumerEnergySource

Feedback

Simple Production-Consumption cycle

Systems Model: Aquatic system

Odum (1994)

A forest ecosystem….

Bio-mass

Plants

Bio-mass

Wildlife

Nutrients Nutrient Recycle

Used Energy

Forest Ecosystem

Sunlight

.

Bio-mass

Plants

Bio-mass

Wildlife

Nutrients Nutrient Recycle

Used Energy

Forest Ecosystem

Sunlight

More complexity. .

Bio-mass

Plants

Bio-mass

Wildlife

Nutrients

Positive Feedback

Nutrient Recycle

Used Energy

Forest Ecosystem

Sunlight

Goods &Services

Markets

Sales

Purchases

Cutting

X

Even more complexity…

Renewable Sources

NaturalEcosystems

AgricultureGreenSpace

Commerce& Industry

Infra-Structure

PeopleGov't

$

Waste

Fuel Goods Services

People

Support Region

City

.

Bio-mass

Plants

Bio-mass

Wildlife

Nutrients Nutrient Recycle

.

Bio-mass

Plants

Bio-mass

Wildlife

Nutrients Nutrient Recycle

Nested models…

Your turn…1st Annual Ecosystem Model Scavenger Hunt!

Procedures for Circuit Diagramming1. Draw the frame of attention that selects the boundary

2. Make a list of the important input pathways that cross the boundary

3. Make a list of the components believed to be important

4. Make a list of the processes believed to be important within the defined system.

5. Remember that matter is conserved.

6. Check to see that money flows form a closed loop within the frame and that money inflows across the boundary lead to money outflows.

7. Check all pathways to see that energy flows are appropriate.

8. If a complex diagram has resulted (> 25 symbols), redraw it to make it neat and save it as a useful inventory and summary of the input knowledge. Redraw the diagram with the same boundary definition, aggregating symbols and flows to obtain a model of the desired complexity (perhaps 3-10 symbols).

9. Conventions:

sources arrangedaccording totheir quality

Components arranged withinboundary according to theirquality

Used Energy

References

Abrams, P., B.A. Menge, G.G. Mittelbach, D. Spiller, and P. Yodzis. 1996. The role of indirect effects in food webs. Pp. 371-395. In: Food Webs: Integration of Patterns and Dynamics. G.A. Polis and K.O. Winemiller (eds.). Chapman & Hall, New York.

Adey, W.H., and K. Loveland. 2007. Dynamic Aquaria: Building and Restoring Living Ecosystems (3rd Edition). Academic Press, San Diego, California.

Gerardin, L. 1968. Bionics. McGraw-Hill, New York. Jorgensen, S.E., and G. Bendoricchio. 2001. Fundamentals of Ecological

Modelling (3rd Edition). Elsevier Science, New York.Kangas, P.C. 2004. Ecological Engineering: Principles and Practice. Lewis

Publishers, Boca Raton, Florida.Odum, H.T. 1994. Ecological and General Systems: An Introduction to Systems

Ecology. University Press of Colorado, Niwot, Colorado.Odum, H.T., and E.C. Odum. 2000. Modeling for All Scales: An Introduction to

System Simulation. Academic Press, San Diego, California.