Chapter 2
Section 2

 Imagine you have been hired to oversee the maintenance of a forest.
 How would you evaluate the health of the forest?
 What actions would you take to keep the forest healthy?
 What might be a threat to the health of the forest?

Ecological Succession
 In 1988 large areas of
Yellowstone
Park burned to the ground.
 How do you think the park looked the following spring?

Ecological Succession
 The “dead” forest began to change
 New plant growth began

Succession
 Succession
 1. Gradual development of a community of organisms over time
 Succession
 A. Takes place in all communities
 B. Takes place over time

Primary Succession
 Primary Succession
 A. Takes place after an ecosystem is completely destroyed, including its soil
 B. There is no soil in this area, usually just bare rock
 Example: volcanic eruption

Steps in Primary Succession
 1. After an volcanic eruption, lava covers the land and hardens into rock

Primary Succession
 2.Lichens begin to form on rocks
 A. Lichens-plant like organism that is a fungus and algae
 B. Acids from the lichens begin to break down the rock
 C. These pieces of broken rock and the remains of dead lichens start forming soil
Pioneer species- first organisms to grow in a succession example-lichens

Primary Succession
 3. After many years
 A. The soil is deep enough for mosses to grow
 B. Mosses replace lichens
 C. Tiny organisms like insects live the in the lichens and mosses
 Their remains add to the soil

Primary Succession
 4. Over time
 Soil layer thickens
 Moss is replaced by ferns
 Next
 Growth of grasses and wildflowers
 Once the soil is deep enough:
 Shrubs and small trees come into the area

Primary Succession
 5. After hundreds or even thousand of years
 The soil may be deep enough to support a forest
 The final stage of succession is the climax community

Primary Succession

Secondary Succession
 Secondary Succession
 Changes that takes place after an environment is disrupted in some way ( the soil must remain intact )
 Example-forest fire, hurricane, farm land left unused

Secondary Succession
 1. fast growing grasses and nonwoody plants appear

Secondary Succession
 2. Larger shrubs move in

Secondary Succession
 3. Fast growing trees
(such as pines) move in
 4. These are followed by slower-growing hardwood trees

Secondary Succession
 5. As new plants take root and grow, animals begin moving back in the ecosystem
 Succession ends with a climax community
(when species have adapted to the average conditions in that area)

Secondary Succession