1. SUCCESSION Natural Change Over Time

2. Organization in Ecology
Ecosystem
Community
Population
Organism

3. Ecology also studies how ecosystems change over time and how communities recover from a disturbance. This is called SUCCESSION.

4. What Is Succession?
The orderly, natural progression of stages that communities of an ecosystem go through

5. Two kinds of SUCCESSION.
There are two kinds of succession, depending on how the ecosystem starts out or how an ecosystem is disturbed

6. PRIMARY SUCCESSION
The colonization of barren land by communities of organisms
Primary Succession happens when a disturbance destroys the entire community so that there is not even any soil left behind
For example a glacier could melt away to expose bare rock.

7. PRIMARY SUCCESSION
Another way to think of primary succession is that it occurs when life enters an area for the first time.
In this case the land is completely devoid of soil and vegetation

8. SECONDARY SECESSION
Sequence of changes that takes place after an existing community is severely disrupted in some way
However, the disturbance was not big enough to remove the soil.
Secondary succession might occur after land is cleared for farming, or after a forest fire.

9. SECONDARY SECESSION
In secondary succession, the dominant plants in the community are removed, allowing new plants to colonize.

10. PIONEER SPECIES
The first species that move into a barren or disturbed area
Pioneer Species are tough and can live in conditions that other organisms cannot
Many PIONEER SPECIES create soil. For example, lichen attaches to rocks and breaks them down into soil. Mosses and grasses can also be pioneer species.
Pioneer Species often colonize a new area by seeds being blown by the wind.

11. PIONEER SPECIES Please answer the following questions on your own:
Why are mosses and lichens pioneer species, but pine trees and deer are not?

12. CLIMAX COMMUNITY
A stable, mature community that undergoes little or no change in species
A CLIMAX COMMUNITY is what the community would be like if no disturbances ever occurred.
Some ecosystems contain a climax community for hundreds or thousands of years. In other ecosystems, as soon as a climax community is reached a disturbance becomes much more likely.
For example, some climax communities use up the nutrients in the soil or increase the likelihood of a fire

13. CLIMAX COMMUNITY
Another way to think of a climax community is an ecosystem that has a steady amount of TOTAL BIOMASS.

14. Climax community – a mature, stable community - what the community would be like if no disturbances ever occurred.
Pioneer species – the first species to populate an area. These species start making the soil
 Lichens and mosses are an important pioneer species 
#1.6 Aim:
How do ecosystems change over time?
Agenda
QOD (10)
Lesson: succession (15)
Activity: courtyard scavenger hunt (15)
Summary
Share (5)
HW #5

15. Typical forest succession
Lichens and mosses
Flowers and weeds
Non-woody plants and grasses
Woody shrubs, grasses, tree saplings
Young forest
Mature trees
As the ecosystem changes, the animals change to accommodate the available food and shelter.

16. Forests
In the east, the climax community may be different than the northwest.

17. What does this graph tell us about succession?

18. Primary or Secondary? Volcanic Eruption Clear Cutting
Tornadoes, clear-cutting, and fires all cause secondary succession. Volcanic eruptions destroy the soil base, so succession is primary– first build soil.

19. Primary or Secondary?
Tornados
Mudslide

20. Exit Ticket
1) What is the difference between PRIMARY and SECONDARY succession?
2) How do PIONEER SPECIES help speed up the process of ecological succession?