UNIT 4: Sustainability of Ecosystems

Chapter 7: Factors that Affect Sustainability

Chapter 8: Shifting Perspectives on Ecosystems

What are some of the milestones that occurred during human history that would affect human population growth?

Chapter 7: Factors that Affect Sustainability

UNIT 4 Chapter 7: Factors that Affect Sustainability

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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.

7.1 Components of Sustainable Ecosystems

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.1

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• 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?

Sustainable EcosystemsUNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.1

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• 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.

Biotic and Abiotic Parts of EcosystemsUNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.1

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• 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?

Different Geographic Locations Can Sustain Similar Ecosystems

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.1

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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 anecosystem.

What are the features oftemperate deciduous forests?

Section 7.1 Review

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.1

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• 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.

7.2 Populations and SustainabilityUNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.2

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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.

What are some conditions in which a population grows exponentially?

Exponential GrowthUNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.2

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• 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.

Continued…

Exponential Growth

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.2

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• 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?

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

Carrying CapacityUNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.2

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• 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 fur seal population changed over time, as represented by the graph above.

Carrying Capacity

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.2

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Interactions Among Species

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.2

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• 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.

Human Niches and PopulationUNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.2

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• 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.

Ecological Footprints and Carrying CapacityUNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.2

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• 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 Earth’s resources, including land and water, at levels that can continue forever.

What data is used to measure an ecological footprint?

Section 7.2 Review

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.2

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• 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…

Section 7.2 Review

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.2

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• 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 person’s or population’s consumption habits have on the supporting ecosystems.

What could interrupt the natural cycling of matter?

7.3 How Human Activities Can Affect Sustainability

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.3

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• Matter and energy are recycled through all four of Earth’s systems—the 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.

• 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?

Nutrient Cycles and the Sustainability of Aquatic Ecosystems

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.3

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• Human activities, such as fertilizing crops, interrupt the nitrogen cycle and the phosphorus cycle.

• Excess nitrogen and phosphorus run off into aquatic ecosystems.

Carbon Dioxide and Other Greenhouse GasesUNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.3

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• 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.

Continued…

When did carbondioxide levelsstart to rise?

Carbon Dioxide and Other Greenhouse Gases

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.3

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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.

Trophic Levels

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.3

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• 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.

Trophic LevelsUNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.3

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• Bioaccumulation is a process in which materials, especially toxins, are ingested by an organism at a greater rate than they are eliminated from the organism’s 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…

Trophic LevelsUNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.3

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• 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?

Section 7.3 Review

UNIT 4 Chapter 7: Factors that Affect Sustainability Section 7.3

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• 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.