Ecological Succession

1
Ecological Succession

• Objectives
• Explain what succession is
• Explain the process of ecological succession
• Explain the role that plants play in maintaining
  biodiversity
• Explain how organisms survive after their
  ecosystem has been disturbed.

2
Definitions

• Succession The gradual change in the number and
  type of species, that make up a community, over
  time.
• Primary Succession Succession in an area that
  has no plants, animals, or soil.
• Pioneer Species The first species to colonize an
  area during succession.
• Secondary Succession Succession in an ecosystem
  that has been disturbed by a natural event or
  human activity.
• Ecosystem All living and non living components
  in an area.

3
Ecological Succession

• Succession is influenced by..
• Biotic (living) factors
• Abiotic (nonliving) factors
• Succession occurs in stages or steps. However,
  these steps are not always distinct and can often
  blend into each other..

4
Primary Succession

• Takes place on completely barren rock.
• No plants
• No animals
• No soil
• No shade
• No shelter
• Nothing!!!!

5
and then

• Pioneer organisms start to grow.
• Grasses, lichens start to grow on rocks.
• Forms soil and creates conditions that allow more
  vegetation to grow.

Still no shade or shelter.
6

• Mosses and other small plants start to colonize
  the area. They help keep water in soil and reduce
  erosion.
• Attract insects, birds and other small animals
  which feed on plants and eventually decompose to
  build more soil.

Soil becomes thicker and full of
nutrients. Plants provide some shelter to small
organisms.
7

• Small plants and soft wood trees (pine trees and
  larger shrubs) grow.
• These plants can survive in harsh conditions.
• Roots break up rock and help add more nutrients
  to soil when they decompose.
• Organisms slowly change the biotic and abiotic
  factors.

• Plants provide shelter for more species of
  insects, birds and small mammals.

8

• Bigger plants and hard wood trees grow.
• Provide more shelter and shade.
• Provide food and habitat for a wider range of
  mammals.
• Their droppings and remains enrich the soil.

• Soil continues to become deeper and richer.
  Plants moderate temperature, wind and moisture in
  area.

9
Climax Community

• A relatively stable population.
• All ages of plants and hard wood trees grow. Many
  shrubs, saplings and herbaceous plants grow.
• High biodiversity.
• Complex food webs.
• Diversity of plant life provides food and habitat
  for a wide range of other organisms.

10
Ecological Succession

• As succession proceeds the biodiversity of the
  community increases.

11
Secondary Succession
Happens more quickly. It usually happens after an
existing community has been disturbed by natural
events or human activity. Community grows from
pre-existing soil.
12
Competition and Forest Fires

• Succession is a long-term process driven by
  various types of competition.
• Read page hand out on Succession
• Using your resources answer the questions given.