223_M4_EcologyofEcosystems.pptx

• Ecosystem Dynamics
• Food Chains and Food Webs
• Studying Ecosystem Dynamics
• Modeling Ecosystem Dynamics
Ecology of Ecosystems
Ecosystems > Ecology of Ecosystems
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• Biotic and abiotic factors interact through nutrient cycles and energy flows.
• External factors control resource inputs and are not influenced by the ecosystem
itself.
• Internal factors are processes that exist within the ecosystem, such as
decomposition, succession, and the types of species present.
• While in equilibrium, an ecosystem can recover from small changes through
negative feedback, returning to its original state.
• Resistance describes an ecosystem's ability to resist disturbances to the
ecosystems dynamics.
• Human disturbances to ecosystems can overwhelm the ecosystem's resilience,
crippling its ability to return to equilibrium.
Ecosystem Dynamics
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Human intervention in ecosystem equilibrium
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• Organisms can be organized into trophic levels: primary producer, primary
consumer, secondary consumer, and tertiary or higher-order consumer.
• Energy decreases in each successive trophic level, preventing more than four or
five levels in a food chain.
• An ecosystem usually has two different types of food webs: a grazing food web
based on photosynthetic plants or algae, along with a detrital food web based on
decomposers (such as fungi).
• There are different types of food webs including grazing food webs based on
photosynthetic plants (such as algae) or detrital food webs based on
decomposers (such as fungi).
Food Chains and Food Webs
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Food web

• A holistic ecosystem model quantifies the dynamics of an entire ecosystem.
• Scientists can use experimental systems, such as a microcosms or mesocosms,
to study ecosystems under controlled laboratory conditions.
• A conceptual model uses flow charts to show the interactions between living and
nonliving components of the ecosystem.
• An analytical model uses simple mathematical formulas to predict the effects of
environmental disturbances on an ecosystem's structure and dynamics.
• A simulation model predicts the effects of environmental disturbances using
complex computer algorithms; they are usually fairly-reliable predictors.
Studying Ecosystem Dynamics
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Mesocosm

• Conceptual models are often flow charts that demonstrate the relationships
between different organisms in a community and their environment, including the
transfer of energy and nutrients.
• Analytical models use mathematical equations to predict and describe simple,
linear components of ecosystems, such as food chains.
• Simulation models use computer algorithms to predict ecosystem dynamics; they
are considered the most ecologically-realistic and accurate.
Modeling Ecosystem Dynamics
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Conceptual model of energy

Appendix

Key terms
• analytical model a model that works best when dealing with relatively simple (often linear) systems, specifically those that can
be accurately described by a set of mathematical equations whose behavior is well known
• conceptual model a model that is represented by conceptual representations of the relationships between different organisms in
a community and their environment
• detritivore an organism that feeds on detritus; a decomposer
• equilibrium the condition of a system in which competing influences are balanced, resulting in no net change
• food chain the feeding relationships between species in a biotic community; a linear path through a food web
• mesocosm a small portion of the natural environment that is brought under controlled conditions for experimental purposes
• microcosm an artificial, simplified ecosystem that is used to simulate and predict the behaviour of natural ecosystems under
controlled conditions
• resilience the speed with which an ecosystem returns to its initial state after a disturbance
• resistance the tendency of a system to remain close to its equilibrium state, despite disturbances
• simulation model a model that utilizes mathematical algorithms to predict complex responses in ecosystem dynamics
• trophic level a particular position occupied by a group of organisms in a food chain (primary producer, primary consumer,
secondary consumer, or tertiary consumer)
Ecosystems

Conceptual model of energy
This conceptual model shows the flow of energy through a spring ecosystem in Silver Springs, Florida. Notice that the energy decreases with each
increase in trophic level. Conceptual models are useful for describing ecosystem structure, but are limited by their poor prediction of ecosystem changes.
Connexions. CC BY 3.0 http://cnx.org/content/m44885/latest/Figure_46_01_07.png View on Boundless.com
Ecosystems

Ecosystem dynamics can affect human populations
The Four Corners area had been in a drought for several years. In early 1993, the rainfall caused an increase in vegetation, which caused an increase
the local deer mice population. Hantavirus infected the high deer mouse population and was quickly transmitted to humans via aerosolized mouse
droppings.
Connexions. "Print." CC BY 3.0 http://cnx.org/content/m44883/latest/Figure_46_00_00.jpg View on Boundless.com
Ecosystems

Energy decreases per trophic level
The relative energy in trophic levels in a Silver Springs, Florida, ecosystem is shown. Each trophic level has less energy available and supports fewer
organisms at the next level.
Ecosystems

Human intervention in ecosystem equilibrium
The Australian Aboriginal practice of "Fire-stick farming" has fundamentally modified Australian ecosystems. The legacy of this practice over long
periods has resulted in forests being converted to grasslands. In this example, the forests became less and less resilient over time until the fundamental
system equilibrium had changed.
Wikipedia. "Australian savanna." CC BY-SA http://en.wikipedia.org/wiki/File:Australian_savanna.jpg View on Boundless.com
Ecosystems

Sin Nombre hantavirus
After a series of sudden deaths in 1993, scientists in the Four Corners area of the Southwestern United States rushed to determine the cause. They
isolated a previously unknown hantavirus that caused pulmonary failure or Hantavirus Pulmonary Syndrome (HPS). The new virus was named Sin
Nombre, or virus with "no name. "
Wikimedia. "Sin Nombre hanta virus TEM PHIL 1136 lores." Public domain
http://en.wikipedia.org/wiki/Hantavirus#mediaviewer/File:Sin_Nombre_hanta_virus_TEM_PHIL_1136_lores.jpg View on Boundless.com
Ecosystems

Mesocosm
Greenhouses contribute to mesocosm studies because they allow us to control the environment and, thus, the experiment. The mesocosms in this
example, tomato plants, have been placed in a greenhouse to control the air, temperature, water, and light distribution in order to observe the effects
when exposed to different amounts of each factor.
Wikipedia. "TomateJungpflanzenAnzuchtNiederlande." CC BY-SA http://en.wikipedia.org/wiki/File:TomateJungpflanzenAnzuchtNiederlande.jpg View on
Boundless.com
Ecosystems

Food web
This food web shows the interactions between organisms across trophic levels in the Lake Ontario ecosystem. Primary producers are outlined in green,
primary consumers in orange, secondary consumers in blue, and tertiary (apex) consumers in purple. The opossum shrimp eats both primary producers
and primary consumers; it is, therefore, both a primary consumer and a secondary consumer.
Connexions. CC BY 3.0 http://cnx.org/content/m44885/latest/Figure_46_01_05.jpg View on Boundless.com
Ecosystems

Food chain
These are the trophic levels of a food chain in Lake Ontario. Energy and nutrients flow from photosynthetic green algae at the bottom to the salmon at
the top of the food chain. There are only four links in this chain because significant energy is lost between each successive trophic level.
Ecosystems

Ecosystems
If an ecosystem is in equilibrium, which of the following is true?
A) the ecosystem is both resistant and resilient to disturbances
B) the ecosystem is consistent and contains very little variation
C) the ecosystem is equally affected by external and internal factors
D) energy flows through both abiotic and biotic factors within the
ecosystem

Boundless - LO. "Boundless." CC BY-SA 3.0 http://www.boundless.com/
Ecosystems
If an ecosystem is in equilibrium, which of the following is true?
A) the ecosystem is both resistant and resilient to disturbances
B) the ecosystem is consistent and contains very little variation
C) the ecosystem is equally affected by external and internal factors
D) energy flows through both abiotic and biotic factors within the
ecosystem

Ecosystems
A fire breaks out in a temperature grassland. Although it appears
at first that almost all life has been destroyed, the grassland
appears unchanged the following year. This is an example of:
A) ecosystem resilience
B) ecosystem equilibrium
C) ecosystem resistance
D) ecosystem decomposition

Ecosystems
A diagram shows grass at the bottom, then a rabbit, then a hawk,
in ascending order. There are arrows between them, pointing
upward. This diagram shows a:
A) food web
B) food chain
C) trophic pyramid
D) nutrient cycle

Ecosystems
Which of the following correctly describes the flow of energy
through a food web?
A) energy is recycled as it is transferred between trophic levels
B) energy is lost as it is transferred between trophic levels
C) there is unlimited number of trophic energy transfers
D) energy a maximum of three trophic levels

Ecosystems
Food webs are examples of _____, while flow charts are
examples of _____.
A) holistic ecosystem models; analytical models
B) simulation models; analytical models
C) holistic ecosystem models; conceptual models
D) simulation models; experimental models

Ecosystems
Which model best predicts the effects of environmental
disturbances?
A) simulation model
B) analytical model
C) conceptual model
D) holistic ecosystem model

Saylor OER. "BIO102: Introduction to Evolutionary Biology and Ecology « Saylor.org – Free Online Courses Built by Professors." CC BY
3.0 http://www.saylor.org/courses/bio102/
Ecosystems
Which model best predicts the effects of environmental
disturbances?
A) simulation model
B) analytical model
C) conceptual model
D) holistic ecosystem model

Ecosystems
Which of the following statements describes the difference
between microcosms and mesocosms?
A) mesocosms are partitions of ecosystems; microcosms are re-creations
of ecosystems
B) microcosms are partitions of ecosystems; mesocosms are re-creations
of ecosystems
C) microcosms are produced by complex algorithms; mesocosms are
produced by simple formulas
D) mesocosms are produced by complex algorithms; microcosms are

Ecosystems
Which of the following statements describes the difference
between microcosms and mesocosms?
A) mesocosms are partitions of ecosystems; microcosms are re-creations
of ecosystems
B) microcosms are partitions of ecosystems; mesocosms are re-creations
of ecosystems
C) microcosms are produced by complex algorithms; mesocosms are
D) mesocosms are produced by complex algorithms; microcosms are

Ecosystems
A scientist creates a conceptual model of the water cycle. Which
of the following most accurately describes how the scientist would
create the diagram?
A) arrows would illustrate the transfer of water between different
mathematical equations
B) organisms and resources are grouped into compartments, while
arrows show the transfer of water
C) organisms and resources are grouped into a linear chain of
compartments
D) all of the organisms and resources would be put into a table

Ecosystems
A scientist wants to predict the levels of the nutrient nitrogen (N)
as it moves up a food chain after an environmental disturbance.
Which model would be the best predictor of linear components of
ecosystems?
A) a simulation model
B) an analytical model
C) all of the above
D) a conceptual model

Attribution
• Wikipedia. "resistance." CC BY-SA 3.0 http://en.wikipedia.org/wiki/resistance
• Boundless Learning. "Boundless." CC BY-SA 3.0 http://www.boundless.com//biology/definition/resilience
• Wiktionary. "equilibrium." CC BY-SA 3.0 http://en.wiktionary.org/wiki/equilibrium
• Connexions. "Introduction." CC BY 3.0 http://cnx.org/content/m44883/latest/?collection=col11448/latest
• Connexions. "Ecology of Ecosystems." CC BY 3.0 http://cnx.org/content/m44885/latest/?collection=col11448/latest
• Wikipedia. "Ecosystem." CC BY-SA 3.0 http://en.wikipedia.org/wiki/Ecosystem
• Wikipedia. "1993 Four Corners Outbreak." CC BY-SA 3.0 http://en.wikipedia.org/wiki/1993_Four_Corners_hantavirus_outbreak
• Center for Disease Control and Prevention. "Tracking a Mystery Disease: The Detailed Story of Hantavirus Pulmonary
Syndrome (HPS)." Public domain http://www.cdc.gov/hantavirus/hps/history.html
• Wikipedia. "Ecosystem." CC BY-SA 3.0 http://en.wikipedia.org/wiki/Ecosystem
• Wiktionary. "detritivore." CC BY-SA 3.0 http://en.wiktionary.org/wiki/detritivore
• Wiktionary. "trophic level." CC BY-SA 3.0 http://en.wiktionary.org/wiki/trophic+level
• Wiktionary. "food chain." CC BY-SA 3.0 http://en.wiktionary.org/wiki/food+chain
• Wikipedia. "Mesocosm." CC BY-SA 3.0 http://en.wikipedia.org/wiki/Mesocosm
• Boundless Learning. "Boundless." CC BY-SA 3.0 http://www.boundless.com//biology/definition/microcosm
• Wiktionary. "mesocosm." CC BY-SA 3.0 http://en.wiktionary.org/wiki/mesocosm
Ecosystems

• Wikipedia. "Ecosystem model." CC BY-SA 3.0 http://en.wikipedia.org/wiki/Ecosystem_model
• Boundless Learning. "Boundless." CC BY-SA 3.0 http://www.boundless.com//biology/definition/conceptual-model
• Wikipedia. "analytical model." CC BY-SA 3.0 http://en.wikipedia.org/wiki/analytical%20model
• Boundless Learning. "Boundless." CC BY-SA 3.0 http://www.boundless.com//biology/definition/simulation-model
Ecosystems

223_M4_EcologyofEcosystems.pptx

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223_M4_EcologyofEcosystems.pptx