1. Ecological Succession
Ecology
Succession after the Yellowstone fires.
11/14/2018
Ecological Succession
Ecological succession is the set of changes in community composition that occur over time in a new or disturbed community.
Succession at Mt. St. Helens.
G. Podgorski, Biol. 1010

2. Terrestrial Primary Succession

3. Primary Succession
Primary succession involves the changes from pioneer species which colonize an environment through the seral stages to the climax community.
Changes in abiotic factors lead to more favourable conditions and increasing species diversity

4. Primary Succession Begins in a place without any soil
Sides of volcanoes
Creation of new land
Starts with the arrival of living things such as lichens that do not need soil to survive
Called PIONEER SPECIES

6. Primary Succession
Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces
When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil

8. Primary Succession
Simple plants like mosses and ferns can grow in the new soil

9. Primary Succession The simple plants die, adding more organic material
The soil layer thickens, and grasses, wildflowers, and other plants begin to take over

10. Primary Succession
These plants die, and they add more nutrients to the soil
Shrubs and tress can survive now

11. Primary Succession
Insects, small birds, and mammals have begun to move in
What was once bare rock now supports a variety of life

12. A Lithosere Primary Succession at Glacier Bay, Alaska Ecology
11/14/2018
Primary Succession at Glacier Bay, Alaska
A Lithosere
G. Podgorski, Biol. 1010

13. Secondary Succession
Begins in a place that already has soil and was once the home of living organisms
Occurs faster and has different pioneer species than primary succession
Example: After forest fires, human activity

17. Climax Community
A stable group of plants and animals that is the end result of the succession process
The climax community produced is controlled by the climate.
eg water present all year – generally woodland
distinct wet and dry seasons – grassland
wet and acidic – blanket bog
Does not always mean big trees
Grasses in prairies
Cacti in deserts
Reeds and grasses in saltmarshes

18. Speed of Succession
Changes are slower if the abiotic conditions are less suitable for life – too hot/cold, too dry or if the availability of plant nutrients is a limiting factor.
Changes are usually slower during the early stages of succession.
Secondary succession is usually a faster process than primary succession, in the same environment

19. General Trends in Succession
Biomass increase over time.
An increase in the
number and proportion
of longer-lived species.
Increased species
diversity over time.
Succession on Mt. St.Helens
– another site of intense study.