Dynamic Nature of Ecosystems

Dynamic Nature of Ecosystems

Middle School

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Learning Objectives

• Define an ecosystem and differentiate between biotic and abiotic factors.

• Explain how energy flows through an ecosystem and how populations are interdependent.

• Describe the process of ecological succession, including primary and secondary succession.

• Analyze how disruptions affect an ecosystem’s balance and its ability to recover.

Key Vocabulary

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Ecosystem

All living and nonliving things that interact in a specific area, forming a complex, interconnected community.

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Biotic Factors

The living or once-living parts of an ecosystem, like plants, animals, fungi, and bacteria.

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Abiotic Factors

The nonliving physical and chemical parts of an ecosystem, such as soil, water, and sunlight.

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Ecological Succession

The gradual, predictable process of change in an ecological community's species structure over a period of time.

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Primary Succession

Ecological succession starting in a lifeless area where no soil or previous life existed before.

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Secondary Succession

A series of community changes that occur in a previously inhabited but disturbed or damaged habitat.

Key Vocabulary

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Pioneer Species

The first hardy species to colonize previously disrupted or damaged ecosystems, beginning a chain of ecological succession.

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Climax Community

A stable, mature ecological community with little change in the composition of species that develops from succession.

What is an Ecosystem?

• An ecosystem includes all living (biotic) and nonliving (abiotic) things in an area.

• Biotic factors are living parts of an ecosystem, like plants, animals, and fungi.

• Abiotic factors are nonliving parts, such as soil, water, and climate.

Multiple Choice

What is the definition of an ecosystem?

• All the living and nonliving things interacting in a specific area.

• Only the animals and plants that live in a specific area.

• The weather and climate patterns of a specific area.

• Only the nonliving components like rocks and soil in an area.

Multiple Choice

What is the primary difference between biotic and abiotic factors?

• Biotic factors are the living parts, while abiotic factors are the nonliving parts.

• Biotic factors include plants and soil, while abiotic factors include animals and water.

• Biotic factors are found in water, while abiotic factors are found on land.

• Biotic factors are large, while abiotic factors are small.

Multiple Choice

What would most likely happen to the plants and animals in an ecosystem if essential abiotic factors like water and soil were removed?

• The plants and animals would not be able to survive because they depend on the nonliving factors.

• The plants and animals would be unaffected by the change.

• The nonliving factors would be replaced by new living factors.

• The animals would learn to live without water and the plants would learn to live without soil.

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Energy Flow in Ecosystems

• Energy flows from one organism to another, shown by an energy pyramid.

• Producers, like plants, are at the bottom and have the most energy.

• Energy decreases at each level from primary to tertiary consumers.

• Removing one population, like foxes, affects the entire food web.

Multiple Choice

In an energy pyramid, which level contains the most energy?

• At the top, with the quaternary consumers

• In the middle, with the secondary consumers

• At the bottom, with the primary producers

• It is equal at all levels of the pyramid

Multiple Choice

What happens to the amount of available energy as it moves up from the bottom of the energy pyramid to the top?

• The amount of energy increases at each level.

• The amount of energy decreases at each level.

• The amount of energy stays the same at all levels.

• The amount of energy is unrelated to the level.

Multiple Choice

If a disease suddenly removed the fox population from the ecosystem, what would be the most likely immediate result?

• The mouse population would decrease, and the bear population would increase.

• The mouse population would increase, and the bear population would decrease.

• Both the mouse and rabbit populations would increase.

• Both the mouse and berry plants populations would decrease.

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What is Ecological Succession?

• Ecological succession is the process of change in an ecosystem over many years.

• Primary succession is slow as it begins in an area with no life or soil, like bare rock.

• Secondary succession occurs in an area where a disturbance left the soil intact.

• This can be caused by events like a forest fire, flood, or farming.

Multiple Choice

What is the main difference between primary and secondary succession?

• The presence or absence of soil at the start.

• The types of animals that first arrive.

• The speed at which the process occurs.

• The climate of the ecosystem.

Multiple Choice

Based on the information, why is primary succession described as a very slow process?

• Because it begins on bare rock without any soil.

• Because it is only caused by retreating glaciers.

• Because it happens in areas with very little sunlight.

• Because the initial plants grow very large.

Multiple Choice

A wildfire sweeps through a forest, clearing out most of the vegetation but leaving the soil intact. What process will most likely follow and why?

• Secondary succession, because the soil was not removed.

• Primary succession, because a major event occurred.

• Primary succession, because all the original plants are gone.

• Secondary succession, because forest fires are a human activity.

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From Pioneer to Climax Community

• Primary succession begins with bare rock exposed after a disturbance.

• Pioneer species, like lichens and mosses, are the first organisms to grow.

• Decaying pioneer species create soil, allowing shrubs and small trees to grow.

• Larger trees grow, leading to a stable and balanced climax community.

Multiple Choice

What are the first organisms, such as lichens and mosses, that grow on bare rock called?

• Pioneer species

• Climax communities

• Primary succession

• Natural disturbances

Multiple Choice

How do pioneer species help shrubs and trees to eventually grow in an area that was once bare rock?

• They provide shade that helps tree seeds sprout.

• They attract animals that bring in seeds from other areas.

• They die and decompose, creating the soil needed for larger plants.

• They break down rocks into sand with their roots.

Multiple Choice

After a volcano erupts and covers an island in a layer of bare rock, what must happen before a stable forest community can grow?

• The rock must be cleared of all ash and dust.

• Seeds from the original forest must land on the bare rock.

• Pioneer species must first colonize the rock and begin to form soil.

• Large animals must return to the area to fertilize the ground.

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Ecosystem Disruptions and Resilience

Disruptions

• Natural events like floods, droughts, forest fires, and hurricanes can disrupt ecosystems.

• Human-caused events, like the Deepwater Horizon oil spill, can also cause massive damage.

• The spill caused long-term harm to the Gulf Coast ecosystem for many years.

Resilience

• Despite major disturbances, ecosystems show resilience and can recover over a long time.

• This process of recovery and regrowth is known as secondary succession in an ecosystem.

• Over time, plants and animals will return, and the ecosystem can regain its balance.

Multiple Choice

What is ecosystem resilience?

• The ability of an ecosystem to recover after a disturbance.

• A type of natural event like a flood or hurricane.

• A process of regrowth caused only by human events.

• The immediate replacement of animals after a fire.

Multiple Choice

What is the relationship between an ecosystem disturbance and secondary succession?

• Secondary succession is the process of recovery that follows a disturbance.

• A disturbance is a type of secondary succession.

• Secondary succession only happens after human-caused disturbances.

• Only natural disturbances lead to secondary succession.

Multiple Choice

A forest fire, a type of natural disturbance, burns a large area of an ecosystem. What is the most likely long-term outcome for this area?

• The area will slowly recover as new plants grow and animals return.

• The ecosystem will be permanently destroyed and nothing will grow back.

• The exact same plants and animals will return immediately.

• Only human intervention, like the Deepwater Horizon cleanup, can restore the area.

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Common Misconceptions

Misconception	Correction
Ecosystems are static and do not change.	Ecosystems are dynamic and constantly change through ecological succession.
An ecosystem is just a collection of animals and plants.	Ecosystems also include nonliving (abiotic) factors like soil and water.
Once an ecosystem is destroyed, it is gone forever.	Ecosystems are resilient and can recover over time through secondary succession.

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Summary

• An ecosystem is the interaction between biotic (living) and abiotic (nonliving) components.

• Energy flows through a food web, and any change can impact the entire ecosystem.

• Ecological succession is the gradual change of an ecosystem over time.

• Succession demonstrates resilience by helping ecosystems recover from disturbances.

Poll

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