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. 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

5. 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

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

7. Other early species include mosses and ferns
Other early species include mosses and ferns. They begin the breakdown of rocks into soil
These rocks at Tyler State Park are slowly becoming the soil of Tyler State Park!

8. 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

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

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

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

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

14. Primary Succession:
Starts with bare rock

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

16. Secondary Succession:
Soil already in place

17. Climax Community
A stable group of plants and animals that is the end result of the succession process
Does not always mean large trees (although it does here in East Texas)
Grasses in prairies
Cacti in deserts
Nature is all about a balance (equilibrium).

18. Non-native Species
Sometimes non-native plants/animals get introduced into an ecosystem. This can upset the balance…
Without natural enemies the non-native species may take over! (invasive species)