UNIT 4: Sustainability of Ecosystems

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UNIT 4 Sustainability of Ecosystems

• Chapter 7 Factors that Affect Sustainability
• Chapter 8 Shifting Perspectives on Ecosystems

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Chapter 7 Factors that Affect Sustainability
UNIT 4
Chapter 7 Factors that Affect Sustainability
Consider the small population of Homo sapiens
that grew to the population of about 7 000 000
000 today. Think about the milestones that
occurred in human history as that small
population grew.
What are some of the milestones that
occurred during human history that would affect
human population growth?
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7.1 Components of Sustainable Ecosystems
UNIT 4
Section 7.1
Chapter 7 Factors that Affect Sustainability

• An ecosystem includes all the interacting parts
  of a biological community.
• Examples of ecosystems include a pond, an urban
  park, a forest, a desert, an ocean, a spruce
  tree, a human body, and the entire Earth.

What are examples of ecosystems in your
community?
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Sustainable Ecosystems
UNIT 4
Section 7.1
Chapter 7 Factors that Affect Sustainability

• A sustainable ecosystem is an ecosystem that is
  capable of withstanding pressure and giving
  support to a variety of organisms.
• Ecosystems provide oxygen, water, food, and
  shelter for living things.
• Look at the photos below. What services do each
  ecosystem provide to living things?
• Identify a species that is dependent on more than
  one ecosystem.

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Biotic and Abiotic Parts of Ecosystems
UNIT 4
Section 7.1
Chapter 7 Factors that Affect Sustainability

• Biotic refers to the living parts of an ecosystem
  and the interactions among them.
• Abiotic refers to the non-living parts of an
  ecosystem.
• What are some biotic interactions that occur in
  ecosystems?
• What are six abiotic characteristics of an
  ecosystem?

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Different Geographic Locations Can Sustain
Similar Ecosystems
UNIT 4
Section 7.1
Chapter 7 Factors that Affect Sustainability
Temperate deciduous forests are defined by a
particular set of biotic and abiotic features.
They are found in Nova Scotia, the eastern United
States, western Europe, and eastern Asia, as
shown in green on the map. Threats to the
sustainability of temperate forests include acid
precipitation and clearcutting. These threats put
pressure on an ecosystem. What are the
features oftemperate deciduous forests?
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Section 7.1 Review
UNIT 4
Section 7.1
Chapter 7 Factors that Affect Sustainability

• Sustainable ecosystems endure, and they sustain
  the organisms within them.
• Every ecosystem has biotic and abiotic parts.
  Biotic parts include living things and the
  interactions among them. Abiotic parts are the
  non-living parts of an ecosystem, such as water,
  light, nutrients, oxygen, and soil.
• Different geographic locations can sustain
  similar ecosystems. For example, there are
  temperate deciduous forests in Nova Scotia,
  eastern United States, western Europe, and
  eastern Asia.

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7.2 Populations and Sustainability
UNIT 4
Section 7.2
Chapter 7 Factors that Affect Sustainability
A population is a group of organisms of one
species that lives in the same place, at the same
time, and can successfully reproduce.
Populations increase when individuals within the
population reproduce at rates that are greater
than what is needed to replace individuals that
have left the population or died.
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Exponential Growth
UNIT 4
Section 7.2
Chapter 7 Factors that Affect Sustainability

• Exponential growth is accelerating growth that
  produces a J-shaped curve when the population is
  graphed against time.
• Exponential growth only occurs under certain
  conditions for a short time.

What are some conditions in which a
population grows exponentially?
Continued
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Exponential Growth
UNIT 4
Section 7.2
Chapter 7 Factors that Affect Sustainability

• A limiting factor is a factor that limits the
  growth, distribution, or amount of a population
  in an ecosystem.
• A density-independent factor is a limiting factor
  in the environment that does not depend on the
  number of members in a population per unit area.
• A density-dependent factor is a limiting factor
  in the environment that depends on the number of
  members in a population per unit area.
• What are examples of density-independent factors
  and density-dependent factors?

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Carrying Capacity
UNIT 4
Section 7.2
Chapter 7 Factors that Affect Sustainability

• Carrying capacity is the size of a population
  that can be supported indefinitely by the
  resources of a given ecosystem.
• When a necessary resource is used at a rate that
  exceeds the carrying capacity, the population
  will be reduced until the population size is in
  balance with the available resources.

• Explain how the carrying capacity of white-tailed
  deer was estimated in Nova Scotia.

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Carrying Capacity
UNIT 4
Section 7.2
Chapter 7 Factors that Affect Sustainability
Explain how the fur seal population
changed over time, as represented by the graph
above.
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Interactions Among Species
UNIT 4
Section 7.2
Chapter 7 Factors that Affect Sustainability

• Ecological niche is the way an organism occupies
  a position in an ecosystem, including all the
  necessary biotic and abiotic factors.
• No two species can occupy the exact
  sameecological niche or provide the exactsame
  services to their ecosystem because no two
  species live in exactly the same way.

Describe the ecological niche of the
littlebrown bats shown.
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Human Niches and Population
UNIT 4
Section 7.2
Chapter 7 Factors that Affect Sustainability

• Sustainable use is use that does not lead to
  long-term depletion of a resource or affect the
  diversity of the ecosystem from which the
  resource is obtained.
• The exact carrying capacity of Earth for humans
  is unknown.

In your own words, explain these graphs
showing human population growth.
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Ecological Footprints and Carrying Capacity
UNIT 4
Section 7.2
Chapter 7 Factors that Affect Sustainability

• An ecological footprint is a measure of the
  impact of a human individual or population on the
  environment.
• The world has finite (limited) resources, and
  consuming large quantities of resources is
  unsustainable.
• Sustainability is the use of Earths resources,
  including land and water, at levels that can
  continue forever.

What data is used to measure an ecological
footprint?
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Section 7.2 Review
UNIT 4
Section 7.2
Chapter 7 Factors that Affect Sustainability

• Populations tend to increase exponentially when
  there are abundant available resources.
• When resources that are needed by populations
  become limited, the carrying capacity of an
  ecosystem has been reached.
• Each species occupies an ecological niche, which
  has biotic and abiotic components.

Continued
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Section 7.2 Review
UNIT 4
Section 7.2
Chapter 7 Factors that Affect Sustainability

• The ecological niche of humans has been broadened
  by our intellectual abilities and the development
  of technology.
• Humans have altered the ecosystems that support
  us, so our carrying capacity is high. However,
  modern human societies are still subject to the
  ecological principle of carrying capacity.
• An ecological footprint is used to describe the
  impact a persons or populations consumption
  habits have on the supporting ecosystems.

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7.3 How Human Activities Can Affect Sustainability
UNIT 4
Section 7.3
Chapter 7 Factors that Affect Sustainability

• Matter and energy are recycled through all four
  of Earths systemsthe lithosphere, the
  hydrosphere, the atmosphere, and the biosphere.
• Essential matter, such as carbon, nitrogen,
  phosphorus, sulfur, oxygen, water, and other
  nutrients, are used and reused in repeating
  cycles.

What could interrupt the natural cycling of
matter?
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Nutrient Cycles and the Sustainability of Aquatic
Ecosystems
UNIT 4
Section 7.3
Chapter 7 Factors that Affect Sustainability

• Human activities, such as fertilizing crops,
  interrupt the nitrogen cycle and the phosphorus
  cycle.
• Excess nitrogen and phosphorus run off into
  aquatic ecosystems.

• Eutrophication is a process in which nutrient
  levels in aquatic ecosystems increase, leading to
  an increase in the populations of primary
  producers such as algae.
• Why would fish die duringeutrophication?

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Carbon Dioxide and Other Greenhouse Gases
UNIT 4
Section 7.3
Chapter 7 Factors that Affect Sustainability

• Greenhouse gases are atmospheric gases that
  prevent heat from leaving the atmosphere, thus
  increasing the temperature of the atmosphere.
• Many scientists hypothesize that the increased
  concentration of carbon dioxide in the
  atmosphere, along with an increase in other
  greenhouse gases, such as methane, contributes to
  global climate change.

When did carbondioxide levelsstart to rise?
Continued
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Carbon Dioxide and Other Greenhouse Gases
UNIT 4
Section 7.3
Chapter 7 Factors that Affect Sustainability
There are many ways to reduce the amount of
carbon dioxide being released into the
atmosphere, including international initiatives
by governments from around the world, initiatives
by the federal, provincial, and local governments
of Canada, and efforts by individuals.
Name three examples of efforts to reduce
carbon dioxide emissions.
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Trophic Levels
UNIT 4
Section 7.3
Chapter 7 Factors that Affect Sustainability

• Matter and energy are transferred between trophic
  levels within the biosphere.
• Trophic efficiency is a measure of how much of
  the energy in organisms at one trophic level is
  transferred to the next higher trophic level.
• Describe in your ownwords how energymoves from
  onetrophic level to thenext trophic level.

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Trophic Levels
UNIT 4
Section 7.3
Chapter 7 Factors that Affect Sustainability

• Bioaccumulation is a process in which materials,
  especially toxins, are ingested by an organism at
  a greater rate than they are eliminated from the
  organisms body.
• Biomagnification is the increase in the
  concentration of a toxin as it moves from one
  trophic level to the next.
• DDT and PCBs are pollutants that have affected
  organisms.
• How might PCBsaffect herringgulls?

Continued
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Trophic Levels
UNIT 4
Section 7.3
Chapter 7 Factors that Affect Sustainability

• Terrestrial and aquatic ecosystems are connected.
• Beluga whales in the St. Lawrence River have a
  high rate of cancer, which scientists suspect is
  caused by exposure to pollutants from land and
  water.
• Why and how might beluga whales be exposed to
  toxic pollutants?

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Section 7.3 Review
UNIT 4
Section 7.3
Chapter 7 Factors that Affect Sustainability

• Human activities that increase the influx of
  nutrients into a terrestrial or aquatic ecosystem
  can upset the nutrient balance in the ecosystem.
• Burning fossil fuels has dramatically increased
  the concentration of carbon dioxide, a greenhouse
  gas, in the atmosphere.
• Most of the stored energy in one tropic level
  does not move to the next trophic level.
• Bioaccumulation and biomagnification can result
  in unhealthy levels of pollutants in organisms.