1. Community Ecology
Chapter 9

2. r vs. K strategists
Population density
Limiting factors
Range of tolerance

3. CLIMATE

4. What else influences climate?

5. Biomes

6. Zones of Tolerance

8. Create your own graph in order to interpret the data below.
The data shows the percentage of survivors in ponds with different densities of tadpoles.
Pool #
%Oxygen
% Survival 1 46 72 2 76 6 3 90 4 10 5 33 83 18 31

9. Succession Temporal patterns in communities
Replacement of species by others within particular habitat (colonization and extinction)
Non-seasonal, continuous, directional

10. Succession can occur under 2 different conditions
Primary succession
In an area that previously did not support any community
Example: terrestrial habitat devoid of soil
Secondary succession
In an area that previously supported a community, but now does not
Example: terrestrial habitat where vegetation was destroyed, but soil remained

11. Primary succession – bare rock
Volcanic eruptions, lava flow
Glaciers

12. Secondary Succession - soil
Floods
Fires
Mudslides

13. Rate of succession Primary - slow - may take 1000s of years
Secondary - faster - fraction of the time to reach same stage

14. Succession begins…
First community comprised of r-selected species - pioneer species

15. r-selected species Good colonizers Tolerant of harsh conditions
Reproduce quickly in unpredictable environs
Example: lichens

16. Pioneer species
Rapidly carry out life processes and begin to modify habitat
Extract resources from bare rock
Break up/fragment rock with roots
Collect wind-blown dust, particles
Waste products accumulate
Die and decompose
Soil development begins

17. Continuing change
Colonizers joined by other species suited for modified habitat
Eventually replace colonizers
Better competitors in modified habitat
Less r-selected, more K-selected

18. More change
Communities gradually become dominated by K-selected species
Good competitors, able to coexist with others for long periods of time

19. Stability Climax community Communities become stabilized
Reach equilibrium
Little or no change in species composition, abundance over long periods of time
End stage of succession

20. Will climax stage be reached?
Slow succession most common, climax stage almost never achieved
Community usually affected by some major disturbance (e.g., fire) before climax stage is reached
Resets succession, forces it to start again from some earlier stage

21. Terrestrial succession

23. According to the graph, what do alders do for the advancement of succession in this forest?

24. Lake or pond succession

25. Turn to page 63 in your textbook and answer the two Data Analysis lab questions.