1. Changes in Ecosystems: Ecological Succession

2. Definition:
Natural, gradual changes in types of species living in area; can be primary or secondary
Succession based on changes in plant communities over time.

3. Primary Succession Begins in place w/o soil
Sides of volcanoes where lava flow has occurred.
Landslides
Flooding
Step 1: Starts w/ arrival of living things (ex: lichens) - do not need soil to survive
Called PIONEER SPECIES

5. Primary Succession Step 2: Soil starts to form
Weathering & erosion break down rocks into smaller pieces
Lichens die & decompose - adding small amounts of organic matter (N,P,C) to the rock to make soil

7. Primary Succession
Step 3: Simple plants (mosses & ferns) grow in the new soil

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

9. Primary Succession
Step 4: Lower plants die, adding more nutrients to the soil
Step 5: Shrubs and tress can survive now

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

12. LAVA FLOWS & PRIMARY SUCCESSION

13. Secondary Succession
Begins in a place that already has soil and was once the home of living organisms
Occurs faster because the land doesn’t have to build up the soil.
has different pioneer species than primary succession
Very often occurs after natural disasters such as forest fires, volcanic eruptions involving the spewing of ash.

14. The Cedar Wildfire was the biggest wildfire in California
The Cedar Wildfire was the biggest wildfire in California. It was ignited was caused by a hunter when he lit a flammable shrub called chapparral. These fires burned down about 280,000 acres of land.
2 years after the fire…..

15. Mt. St. Helens
Washington
1980’s

18. Climax Community
A stable group of plants and animals that is the end result of the succession process
Climax Community!

19. Climax Communities are NOT always big hardwood trees such as oaks and maples!!!
Desert Climax Community
Beach Climax Community
Taiga Climax Community
Grasslands Climax Community