Ecology Chapter: Succession

Succession

• Succession is the gradual change in a community's species composition over time.
• It's a predictable process for a biome or micro-environment.
• Species fill roles and then disappear, starting with pioneer species and ending with a stable climax species.
• Communities are named by their climax species (e.g., aspen forest).

Types of Succession

• Primary succession: Begins on bare rock (e.g., after volcanic eruptions or landslides).

  • Pioneer species, like lichen and moss, break down rock into soil.
  • Small plants then colonize, followed by larger species.
  • Eventually, a stable community develops.

• Secondary succession: Begins on pre-existing soil.

  • Happens after a disturbance (e.g., fire, deforestation) removes some but not all organisms.
  • Soil remains, making the process faster than primary succession.
  • Pioneer species rapidly colonize.

Climax Species

• The final species in a community's succession.
• It's named after the climax species (e.g., aspen forest).

Why Succession Occurs

• Species change the habitat.
• Species change the available resources.
• Initially, only species tolerant of harsh conditions can survive.
• As the environment becomes more hospitable, other species can invade.

Biodiversity During Succession

• Biodiversity is higher at the climax of succession.
• A greater number of species can survive at later stages.

Forest Fires and Succession

• Forest fires can be positive and negative in nature.
• Positive effects include nutrient return to soil, seed germination.
• Negative effects include organism destruction, succession termination.
• Controlled burns mimic natural processes, often used in National Parks.

Traditional Uses of Fire

• First Nations people in Alberta historically used purposeful prairie fires in spring to begin secondary succession.
• Fireweed, a pioneer species, had traditional uses for food, medicine, etc.

Consumer Species Succession

• Producer species succession affects consumer species.
• Consumer species adapt to the changing food sources.

Factors Affecting Biodiversity in Succession

• Effect of time on biodiversity—increased biodiversity in later stages.
• Low biodiversity at the start of succession, due to harsh conditions.
• Gradually more species adapt to changing ecosystems.

Explore the concept of succession in ecological communities, including both primary and secondary succession. Understand the roles of pioneer and climax species as they contribute to the stability of biomes. This quiz will test your knowledge on these fundamental ecological processes.