1. ECOLOGICAL SUCCESSION

2. Ecological Succession
Change of environment involving a series of species replacements in a community.
Two types:
Primary
Secondary

3. Primary succession — occurs where there is no soil, e. g
Primary succession — occurs where there is no soil, e.g. after a volcanic eruption or a glacial retreat
“pioneer organisms”
Simple plants first – no or shallow roots.
Gradual influx of more complicated and larger plants as the habitat changes.
Ends with a “climax community” – ecosystem stays constant, provided there are no changes in abiotic influences.

4. Primary Succession: Sand Dune to Forest
Dune grassescottonwoods+shrubsevergreensoaksbeeches maples

5. Bare rock
bare rock→lichens→mosses→grasses→shrubs→trees

6. Glacial retreat

7. Man-made structures

8. Secondary succession — begins in an area where soil is already present, (e.g. a once cultivated field or after a forest fire.)
Old field succession:
grasses + weeds taller grasses + golden rod small trees (cherries, dogwood, sumac)  mature climax forest (oak, beech-maple, hickory)

9. Secondary Succession
Soil already present.

10. Pond Succession
Abandoned field succession

11. Pond→marsh→dry land/grasses →shrubs→forest

12. Pioneer species—first species to begin a succession.
Climax community—the final stage in a succession.

13. Primary vs. Secondary No soil Pioneer species
Weathering & decomposition
Humus and sand increase over time
End = climax community
Soil already exists
Seeds have suitable soil conditions.
Occurs much faster
Climax community.

14. Secondary Succession
After a forest fire

15. Hurricane

17. Table 53.2 The Pattern of Succession on Moraines in Glacier Bay

18. Figure 53.20 Alders and cottonwoods covering the hillsides

19. Figure 53.20 Spruce coming into the alder and cottonwood forest

20. Figure 53.20 Spruce and hemlock forest

21. Figure 53.18x1 Large-scale disturbance: Mount St. Helens

22. Figure 53.18x2 Forest fire

23. THE END