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ZingPath: Population Dynamics

Ecological Succession

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Population Dynamics

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Lesson Focus

Ecological Succession

Life Science

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You get to discover how populations of organisms naturally change over time through the process of ecological succession. Then, view some adaptations that help different species to survive in their particular environments.

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Now You Know

After completing this tutorial, you will be able to complete the following:

  • Define primary succession.
  • Define secondary succession.
  • Describe how events that occur during ecological succession can change populations.
  • Describe how events that occur during ecological succession can change species diversity.
  • Describe how processes that occur during ecological succession can change populations.
  • Describe how processes that occur during ecological succession can change species diversity.

Everything You'll Have Covered

Describe the process of ecological succession.

~ First, lichens, which grow on rock, appear in a destroyed region. The lichens help break down the rock. Then, as lichens die and decompose, and weathering breaks apart rock, soil begins to form. As soil becomes richer, small plants like mosses and ferns appear, and the lichens start to disappear. The soil continues to become richer as plants continue to die and decompose, and flowering plants and grasses appear, bringing insects to the region. In time, shrubs and small trees cover the region, creating a suitable habitat for reptiles, birds, and mammals. As the shrubs and trees grow, smaller plants die from lack of sunlight and add more organic material to the soil. Eventually, the shrubs and trees die because taller trees cover the region. This all happens gradually over a long period of time.

What is the main difference between primary succession and secondary succession?

~ Primary succession is an ecological succession that takes place in a region that initially lacks soil, and secondary succession is the reestablishment of a damaged ecosystem due to natural disasters such as fires, droughts, or flooding.

What are some events and processes that determine the diversity of the organisms that will appear in either a primary or secondary successive environment?

~ A region's climate, its resources, and the relationships of the species in the community determine which organisms will appear in a successive ecosystem.

Describe how the events and processes that occur during ecological succession can change populations within an ecosystem.

~ Answers will vary. Example: First the populations of pioneer species such as mosses and ferns start to inhabit the ecosystem. Initially their populations are small, but later, increases in resources (water, food, nutrients, etc.) allow them to increase in size. At the same time, dying members of the populations increase the organic materials in the soil. This change prepares the soil for more complex plants such as flowering plants and trees. Growing populations of the complex plants prohibit sunlight from reaching moss and fern populations. Once the dominant species in the area, these mosses and ferns start to die due to this lack of sunlight. Due to a change in external factors, complex plants become the dominant populations in the ecosystem. As a result, the structure of the community in that ecosystem changes.

Describe how the events and processes that occur during ecological succession can change the species diversity within an ecosystem.

~ Answers will vary. Example: Initially, there is a very low number of species-just the pioneer species that are able to start inhabiting the area (like lichens and mosses). Thus, there is very little species diversity. As the soil becomes richer in nutrients, more plant life is able to inhabit the area. This obviously directly increases diversity, but also increases diversity further in that a higher number of plants in the area draws more animals. As new and larger species, like trees, inhabit the area, new ecological niches are created that further promote an increase in species diversity.

Tutorial Details

Approximate Time 3 Minutes
Pre-requisite Concepts Students should be able to define the following terms: ecological succession, primary succession, and secondary succession.
Course Life Science
Type of Tutorial Animation
Key Vocabulary ecological succession, primary succession, secondary succession