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Biodiversity and Ecosystem Health — Reading Comprehension

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MS-LS2-5

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This comprehensive middle school science passage explores the relationship between biodiversity and ecosystem health, aligned with NGSS standard MS-LS2-5. Students will discover how higher biodiversity increases ecosystem stability, productivity, and resilience. The passage examines the roles of keystone, foundation, and indicator species, providing real-world examples and discussing the results of ecosystem function experiments. Students are encouraged to understand systems thinking by tracing cause-and-effect chains and considering the broader implications for environmental policy and conservation. Multiple activities, including quizzes, writing prompts, and graphic organizers, deepen comprehension and analytical skills. This resource is ideal for grades 6-8 and is audio integrated, supporting all learners in building vocabulary and critical science literacy.

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ecosystem2 — Biodiversity and Ecosystem Health

Biodiversity refers to the variety of living organisms—plants, animals, fungi, and microbes—within a particular region or ecosystem. Scientists have observed that ecosystems with higher biodiversity are generally healthier, more stable, and better able to recover from disturbances like storms, fires, or disease outbreaks. When an ecosystem has many different species, each with unique roles, it often functions more efficiently and is less likely to collapse if one species is lost. This relationship between biodiversity and ecosystem health is a central topic in ecology and is studied through careful observation and experimentation.

How Biodiversity Supports Ecosystem Function

Ecosystems rely on different species to perform a wide range of functions, such as pollination, decomposition, and nutrient cycling. When there is high biodiversity, there is often redundancy—multiple species can perform similar roles. For example, in a grassland, several species of insects may pollinate plants. If one pollinator declines, others can fill its role, making the system more stable. Scientific experiments show that ecosystems with high biodiversity produce more biomass (total living matter) and are more resilient after disturbances. In a famous study, researchers found that grasslands with more plant species recovered faster after a drought compared to those with fewer species.

Special Roles: Keystone, Foundation, and Indicator Species

Some species have roles that are especially important for ecosystem health. Keystone species have a disproportionately large impact compared to their abundance. For example, sea otters are keystone species in kelp forests because they eat sea urchins, which would otherwise destroy kelp beds. When otters are removed, urchin populations explode, and kelp forests disappear. Foundation species, like coral and large trees, create habitats that support many other organisms. Indicator species are sensitive to environmental changes; scientists monitor them to assess ecosystem health. Amphibians and lichens often serve as indicator species because they respond quickly to pollution or climate change.

Biodiversity, Stability, and Human Impact

Research on biodiversity-ecosystem function helps scientists and policymakers understand how to protect natural environments. Ecosystems with high biodiversity are more productive and better able to provide ecosystem services, such as clean water, air, and food. Human activities like habitat destruction, pollution, and climate change can reduce biodiversity, weakening these natural systems. By protecting biodiversity, we help ensure that ecosystems remain healthy and capable of supporting both wildlife and human communities.

Maintaining biodiversity is not just about saving rare species—it is about preserving the complex web of relationships that keeps ecosystems functioning. Science continues to reveal more about these connections and their importance for our planet’s future.

Interesting Fact: The reintroduction of wolves to Yellowstone National Park in the 1990s reshaped the park’s rivers and forests, showing how one keystone species can transform an entire ecosystem.

What does biodiversity refer to?

The variety of living organisms in an ecosystemThe amount of sunlight an ecosystem receivesThe number of rivers in a forestThe speed at which plants grow

Which of the following is a function performed by species in an ecosystem?

PollinationBuilding citiesCreating plasticFlying airplanes

What is a keystone species?

A species with a big impact despite low numbersA species found only in the oceanA species that is always the most commonA species that is always a predator

What happens when there is redundancy in an ecosystem?

Multiple species can do the same job, making the system stableAll species become extinctOnly one species can perform each functionThe ecosystem collapses

Which is an example of an indicator species?

AmphibiansWolvesKelpOtters

What is the main benefit of high biodiversity after a disturbance?

Ecosystems recover fasterAll species disappearRivers dry upPlants stop growing

Why are foundation species important?

They create habitats for other organismsThey are always the rarest speciesThey cause pollutionThey are found only in deserts

True or False: Human activities like pollution can lower biodiversity.

TrueFalse

True or False: The reintroduction of wolves to Yellowstone had no effect on the ecosystem.

FalseTrue

What is one ecosystem service mentioned in the passage?

Clean waterBuilding roadsManufacturing carsInternet access