Natural Disturbances in the Ecosystems

How do disturbances create niches in an ecosystem?

• By eliminating all species

• By changing the environment and allowing new species to thrive

• By keeping the same species in place

• By preventing any changes in the community

Answer explanation

Disturbances change the environment, creating opportunities for new species to establish themselves. This process fosters biodiversity and allows ecosystems to adapt, making the correct choice 'By changing the environment and allowing new species to thrive'.

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What type of succession occurs in a lifeless area after a major disturbance, like an asteroid impact?

• Secondary succession

• Primary succession

• Tertiary succession

• Quaternary succession

Answer explanation

Primary succession occurs in lifeless areas, such as those created by an asteroid impact, where soil and organisms must develop from scratch. In contrast, secondary succession happens in areas where soil and some life already exist.

Why are disturbances important for ecosystems?

• They destroy habitats

• They create opportunities for new species to thrive

• They prevent any changes in the ecosystem

• They ensure that only one species can survive

Answer explanation

Disturbances are crucial for ecosystems as they create opportunities for new species to thrive. They promote biodiversity by allowing different species to establish themselves, rather than preventing changes or favoring a single species.

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What is secondary succession?

• The process of species returning after a major extinction

• The recovery of an ecosystem after a minor disturbance

• The establishment of a new ecosystem in a barren area

• The extinction of species in an ecosystem

Answer explanation

Secondary succession refers to the recovery of an ecosystem after a minor disturbance, such as a fire or flood, where soil and some organisms remain, allowing for quicker regrowth compared to primary succession.

Which of the following is an example of a small disturbance?

• A volcanic eruption

• A tree falling in the forest

• An asteroid impact

• A glacier melting

Answer explanation

A tree falling in the forest is a small disturbance compared to the other options, which involve large-scale events like volcanic eruptions, asteroid impacts, and glacier melting.

What does the Intermediate Disturbance Hypothesis suggest?

• More severe disturbances lead to more biodiversity

• No disturbances are best for ecosystems

• Moderate disturbances promote higher biodiversity

• Only primary succession leads to biodiversity

Answer explanation

The Intermediate Disturbance Hypothesis posits that moderate disturbances create opportunities for diverse species to thrive, thus promoting higher biodiversity compared to environments with no or severe disturbances.

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What happens to an ecosystem after a disturbance?

• It immediately returns to its original state

• It undergoes a series of predictable changes

• It remains unchanged indefinitely

• It is permanently destroyed

Answer explanation

After a disturbance, an ecosystem typically undergoes a series of predictable changes, known as ecological succession, as it gradually recovers and may eventually return to a stable state, but not immediately.

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Which of the following is a consequence of a lack of disturbances in an ecosystem?

• Increased biodiversity

• Catastrophic events when disturbances finally occur

• Stable ecosystems

• Immediate recovery of species

Answer explanation

A lack of disturbances can lead to ecosystems becoming overly stable, which may result in a lack of resilience. When disturbances do occur, they can cause catastrophic changes, as the ecosystem is unprepared to adapt.

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What might happen if a forest is not allowed to experience small, natural disturbances?

• The forest will thrive indefinitely

• The forest may face larger, more destructive disturbances

• There will be no changes in the forest

• The forest will become a desert

Answer explanation

If a forest is not allowed to experience small, natural disturbances, it can lead to an accumulation of dead material and increased competition among species, ultimately resulting in larger, more destructive disturbances like wildfires.

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How does the concept of a "mosaic of habitats" relate to ecological succession?

• It suggests that all habitats are identical

• It indicates that disturbances create diverse habitats within an ecosystem

• It means that habitats never change

• It shows that only one species can dominate an area

Answer explanation

The concept of a 'mosaic of habitats' highlights how disturbances, like fires or storms, create varied environments, promoting biodiversity and facilitating ecological succession, which leads to diverse habitats within an ecosystem.

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