1. Changes in Ecosystems: Ecological Succession
1.5

2. Changes by Fire
Naturally occurring catastrophic events can change the planet we live on. Earth is constantly changing.
Sometimes these changes take millions of years, but sometimes they happen in just minutes…

4. MOST DEADLY AND DESTRUCTIVE VOLCANO IN THE UNITED STATES:
MOUNT ST. HELENS

5. Definition of Succession
Natural, gradual changes in the types of species that live in an area
The gradual replacement of one plant/animal community by another through natural processes over time
Can be primary or secondary

6. Primary Succession Begins in a place without any soil
Sides of volcanoes
Land uncovered by retreating glacier
After flooding when soil was washed away
Starts with the arrival of living things such as lichens that do not need soil to survive
Called PIONEER SPECIES

7. Lichen: A combination of algae and fungus that can survive on bare rock, tree bark, and other surfaces.
Lichen is a “pioneer species”

8. Other early species include mosses and ferns
Other early species include mosses and ferns. They begin the breakdown of rocks into soil
These rocks are slowly becoming the soil!

9. 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 tiny amounts of soil

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

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

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

14. Primary Succession
Insects, small birds, and mammals have begun to move in
What was once bare rock now supports a variety of life
I’m cute!

15. Primary Succession: Starts on Bare Rock!
No SOIL yet.

16. Secondary Succession
Begins in a place that already has soil & was once the home of living organisms
Occurs faster than primary succession
Examples
after forest fires
after agriculture/cultivation

17. Secondary Succession:
Soil already in place

18. Climax Community
A stable group of plants and animals that is the end result of the succession process
AFTER SUCCESSION THE POPULATION AND NUMBER OF SPECIES INCREASES!!
Nature is all about a balance (equilibrium).

19. Today’s Reading/Questions
1. What is ecological succession?
A. The gradual change of an ecosystem over time; the gradual change of the types of species that live in an area

20. Today’s Reading/Questions
2. Explain the difference between primary and secondary succession.
A. Primary succession begins on bare rock/rocky surface with no existing soil, plants, etc. (“new” land) Secondary succession begins with soil already in place (nature takes over)

21. Ecological Succession
Create a Venn Diagram comparing primary and secondary succession and underneath write a Notes Summary!
Summary of the notes and information learned