How do ecosystems change?

A natural change to an ecosystem ocurrs when

• a severe drought causes plants to die

• trees are cut down to make paper

• roads are built through a forest

• a dam is constructed to hold back water

What kind of changes take place during succession?

• Animals move from one ecosystem to another.

• One or more species die out and no longer exist on Earth.

• Species slowly replace each other as the landscape changes.

• Plants stop growing and making food when days get colder and shorter.

After a forest fire, new plants and those that were not burned will _ because the fire released nutrients into the soil.

• slowly die

• grow faster

• stop growing

• become extinct

Some animals hibernate during the winter because they

• lay eggs that need to be kept warm

• need to avoid predators

• change from one form to another

• cannot find enough food

Climate change can cause changes to ecosystems. What can happen to organisms that do not change with their ecosystems?

• They can disappear from Earth.

• Theycan stop the ecosystem from changing.

• They can form new ecosystems.

• They can be unaffected by the change.

The volcano in Ecuador is erupting, shooting ash into the air. Burning hot gases and bits of rock flow down the side of the mountain. What is the most likely way the eruption will disturb the ecosystem around it?

• This is a slow change to the ecosystem, but the effects will last for a long time.

• This is a fast change to the ecosystem, and the effects will last for a long time.

• This is a slow change to the ecosystem, but the effects will last for a short time.

• This is a fast change to the ecosystem, and the effects will last for a long time.

This eastern gray squirrel lives in the temperate climate of the Midwest states such as Ohio. The squirrel collects nuts and buries them in preparation for the winter. How do seasonal changes explain the squirrel's behavior?

• There will be more plants to eat in the spring.

• There are more plants available to eat in the winter.

• There is less food available to eat in the winter.

• There is less food available to eat in the summer.

In 1988, one of the largest wildfires in Yellowstone National Park took place. The burned area of the park included a forest of tall pine trees. The photo shows how the forest looked in 1999, about 10 years after the fire. Using evidence from the photo, what claim can you make about the stage of succession in 1999?

• An ecosystem disturbance ocurred in 1999.

• It only took 10 years for pine trees to start to grow again.

• The 1988 fire destroyed or removed the soil needed for trees to survive.

• After 10 years, only wildflowers and grasses grew where the fire had burned.

Which of these is a natural cause?

• Cutting down trees

• Building dams across rivers

• Wildfire stared by lightning

• A wildfire started by a campfire

This tree is losing its leaves during the fall. After all its leaves fall to the ground, the tree branches will be bare for the winter. Then new leaves will grow in the spring. How can scientists predict these events will happen?

• The climate is changing quickly.

• The tree is going into hibernation.

• Seasonal changes occur in a cycle.

• An ecosystem disturbance has happened.