Ecological Succession

Objectives1. Explain what succession is

2. Explain the process of ecological succession3. Explain the role that plants play in maintaining biodiversity4. Explain how organisms survive after their ecosystem has

been disturbed.

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.

Ecological Succession…

• Succession is influenced by..

1) Biotic (living) factors

2) Abiotic (nonliving) factors

Succession occurs in stages or steps. However, these steps are not always distinct and can often blend into each other..

Primary Succession…

• Takes place on completely barren rock.

• No plants• No animals• No soil• No shade• No shelter• Nothing!!!!

…and thenPioneer 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 orshelter.

• 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.

• 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.

• 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.

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.

Ecological Succession• As succession proceeds the biodiversity of

the community increases.

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.

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.