1. Ecology – Part 5 - Succession
Ecology – Part 5 - Succession

2. Succession 1. What is Ecological Succession?
i. Natural, gradual changes in the types of species that live in an area. It is the gradual replacement of one plant community by another through natural processes over time.
ii. Succession is identified as primary or secondary succession

3. Succession 2. Succession types:
Succession
2. Succession types:
i. Primary succession: an area of newly exposed land that has NEVER been occupied by a living (biotic) community. Starts with barren rock.
ii. Secondary succession: takes place where a community has been removed (cut forest, forest fire).

4. Succession 3. Primary Succession:
i. Begins in a place without any soil (barren rock):
a. Sides of volcanoes
b. Landslides
c. FLASH Flooding (severe)
d. Receding glaciers
ii. First species: Lichens that do not need soil to survive grow on rocks
iii. Lichens are made up of a fungi and an algae (mutualistic relationships). The algae performs photosynthesis, providing food for both, while the fungi absorbs water and minerals and provides shelter for the algae.

5. Succession 3. Primary Succession:
iv. Next, mosses grow to hold newly made soil
v. First organisms to move into harsh growing conditions are known PIONEER SPECIES (i.e. lichen and mosses)
v. Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces
vii. When pioneer species die, they decompose, adding small amounts of organic matter to the rock to make soil
viii. The soil layer thickens, allowing other plants to begin to take over.

6. Succession 3. Primary Succession:
ix. Typically the order after soil development is:
a. Flowers/weeds (annual plants)
b. Ferns and grasses (perennial plants)
c. Shrubs and bushes (larger vascular plants)
d. Trees (largest vascular plants)
i. First softwoods, like pine and fir trees
ii. Second hardwoods, like oak and maple trees
x. As each new species decomposes, they enrich and thicken the soil.
xi. As the vegetation develops, insects, small birds, and mammals begin to move into the area.

8. Succession 4. Secondary Succession:
i. Begins in a place that already has soil and was once the home of living organisms
ii. Occurs faster and has different pioneer species than primary succession (i.e. grasses)
iii. Examples:
a. After forest fires
b. After creeping floods

9. Succession 5. Climax Community: a. Examples:
i. A stable group of plants and animals that is the end result of the succession process
ii. Does not always mean big trees
a. Examples:
i. Grasses in prairies
ii. Cacti in deserts
iii. Pond sedimentation growth

10. Succession 5. Climax Community:
iii. A mature climax community can exist until the environment changes, but forests are not immune to destruction. Fires, deforestation, and natural disasters can destroy a forest and force it to go back through the stages of ecological succession.