Changing Ecosystems

Changing Ecosystems

How do ecosystems change over time?

Vocabulary

Dynamic system: any system that is characterized by constant change

Ecological succession: the predictable way that ecosystems change from one
type to another over time

Evidence: information obtained by observation or experimentation

1. Ecosystems Change Over Time

Dynamic system: any system that is characterized by constant change

-Small or large changes

-Gradual or sudden

Gradual change happens as resources fluctuate and populations rise and fall.

Ecological succession: the predictable way that ecosystems change from one
type to another over time

-Doesn’t happen overnight

1. Ecosystems Change Over Time

Sudden changes to ecosystems happen very quickly (ex.volcanic eruptions)

-Can be natural (hurricanes, fires, floods) or human-caused (pollution,
construction, farming)

-Can cause temporary or permanent changes

Multiple Choice

What is a dynamic system?

• A system that never changes

• A system that constantly changes

• A system that has changed before

• A system that will change eventually

2. Changes to Living Parts of Ecosystems

Prairie dogs

-Ground dwelling squirrels

-Dig elaborate tunnels that provide shelter for sleeping, hiding, and raising young

-Grassland environments

Prairie dog populations are harmed when their ecosystems are destroyed by humans, which effects
the population of other burrowing animals.

These changes in different populations are evidence that the living parts of ecosystems affect one
another.

-Populations of species that benefit from prairie dogs decrease; populations of species that don’t
benefit from prairie dogs increase

Evidence: information obtained by observation or experimentation

Open Ended

Name one species that benefits from prairie dogs and explain how:

3. Changes to Nonliving Parts of Ecosystems

Beavers chop down trees to build dams to create non-flowing water to live in

-Trees being cut down allows for more sunlight to reach the ground where
the trees used to be

-Dams being built creates ponds where rivers used to be and species that
live in still water can reside there

These changes to the nonliving parts of the ecosystem change populations of
organisms in the ecosystem, these changes then change the populations that
live in those ecosystems.

Open Ended

Summarize how beavers effect nonliving parts of their ecosystem:

4. Rebuilding Wetland Buffers

Storms in the Gulf of Mexico cause flooding that typically creates large coastal
wetlands with the sediment brought from the flood that protect areas from that
flooding. People have changed the path of the river and some places don’t get
those sediments anymore, or the protection.

1990s - engineers wanted to find a way to rebuild the wetlands to protect from
flooding and provide habitats for wildlife.

Criteria: restore wetlands

Constraints: expensive, could cause additional flooding

4. Rebuilding Wetland Buffers

Sediment Diversions Rebuild Wetlands

In the 1940s (Louisiana) workers dug a channel to divert water from a river into
the Gulf to divert that river away from communities and avoid flooding.

-Diverting the river caused the river to deposit sediment into the Gulf and
new wetlands were formed (at a rate of 2.8 sq. km. per year)

-The wetlands continue to expand create habitats and protecting
communities from flooding

4. Rebuilding Wetland Buffers

Protecting Local Communities from Flooding

The Wax Lake solution wouldn’t work well in New Orleans

-Permanent river diversion is difficult to construct in high populated areas

-Levees are used to prevent flooding but they don’t allow the flow of sediment or water

-Making a hole in a levee can be dangerous and cause more flooding

The Caernarvon Freshwater Diversion built into a levee is a door that opens and closes

-Allows for flow of water and sediment when there is no flooding and can be closed
when there is a risk of flooding

-Caused wetlands to start to grow again (so good solution! 🙂

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