Succession in Ecosystems

Succession in Ecosystems

by Joelle Lilavois

​Primary succession- stage one

​Primary succession begins when bare rock forms.

* Bare rock forms due to a volcano eruption or due to glacier retreat.

* These rocks do not have organic material from dead animals or plants.

There is no nutrient-rich soil for plant growth.

​Stage 2

​The first species that

settle and grow on new rock formations are called pioneer species.

Pioneers are often lichens.

* Lichens are composite organisms made of algae and fungi that grow together as one.

It obtains water and nutrients from the atmosphere and the algae produces carbohydrates through photosynthesis.

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​Soil forms as lichens break down rock into smaller particles.

Organic material from dead organisms

​increases in the soil.

​Early colonizing plants are often nitrogen-fixing species that increase the nitrogen content of the soil.

* With soil, grasses, ferns, and herbs can now grow, which provide a habitat for insects and small animals

​Stage 4

Once the soil has more organic material (that builds up with decomposing material from other dead organisms), larger plants like shrubs and trees can grow in the area.​

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More animals are attracted to the area. Once a steady state in the ecosystem is established, scientists say a climax community has been reached.

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Multiple Choice

Which of the following best describes primary succession?

• Volcano wipes out ecosystem that gradually grows back from ash covered soil

• Volcano creates a new island of rock that must break down to form an ecosystem

• Forest fire burns down forest that must bounce back over time

• Tornado destroys a crop that must slowly grow back over time.

Fill in the Blanks

the first organisms that appear in an ecological community

Multiple Choice

How do lichens contribute to primary succession?

• Lichens decompose organic matter from animals and plants

• Lichens begin to break down rock to form soil

• Lichens are nitrogen fixing bacteria

• I have no idea. I was not doing my job and listening

Multiple Choice

a stable ecological community that has reached equilibrium

• pioneer species

• lichens

• primary succession

• climax community 

​Secondary Succession

Secondary Succession begins after an event that reduces an established ecosystem to a smaller population, on an already established soil.

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* These events could be a hurricane, a forest fire, or

land that was farmed but then abandoned to grow wild again

* Larger trees begin to grow again and a climax community is reached.

The community remains relatively stable until another disturbance (disaster or fire) occurs.

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​Secondary succession can take up to 300 years for the ecosystem to recover back to a steady climax community state

Multiple Choice

Natural disasters such as flooding and tornadoes are linked to ________________.

• primary

• old field

• secondary

• ecosystem

Multiple Choice

What type of succession is shown going from figure A to figure B?

• primary

• secondary

Multiple Choice

Breaking News! A new island has formed off of Hawaii! What must occur for it to become an ecosystem?

• Primary 

• secondary 

• ferns must grow

• aquatic succession

​Human Impact