2. Community Ecology I. Introduction
II. Multispecies Interactions with a Trophic Level
III. Multispecies Interactions across Trophic Levels
IV. Succession
A. Definitions
- succession: a change in community composition through time

3. Community Ecology I. Introduction
II. Multispecies Interactions with a Trophic Level
III. Multispecies Interactions across Trophic Levels
IV. Succession
A. Definitions
- succession: a change in community composition through time
- sere: a particular stage or sequence

4. Community Ecology I. Introduction
II. Multispecies Interactions with a Trophic Level
III. Multispecies Interactions across Trophic Levels
IV. Succession
A. Definitions
- succession: a change in community composition through time
- sere: a particular stage or sequence
- pioneer: first community

5. Community Ecology I. Introduction
II. Multispecies Interactions with a Trophic Level
III. Multispecies Interactions across Trophic Levels
IV. Succession
A. Definitions
- succession: a change in community composition through time
- sere: a particular stage or sequence
- pioneer: first community
- climax: self-replacing community

6. B. Classifying Vegetative Communities
1. Focus on the Climax
Clements’ view of the climax as a ‘closed, mature, developmental state,’ dependent solely on climate.
In North America, he recognized only 9 climax community types:
2 grasslands (prairie, tundra)
3 scrub (sagebrush, desert, chaparral)
9 forests

7. B. Classifying Vegetative Communities
1. Focus on the Climax
Curtis and McIntosh:
‘Continuum’ index

8. B. Classifying Vegetative Communities 1. Focus on the Climax
Whittaker’s view:
‘Dominance’ classification
Red oak
Sugar maple

9. B. Classifying Vegetative Communities
1. Focus on the Climax
2. Classification by Indicator Species
Braun-Blanquet method of vegetative classification:
Based on whole floristic surveys and the identification of ‘indicator’ taxa – typically neither dominants nor extremely rare species.
440 vegetation types in South Africa.

10. B. Classifying Vegetative Communities 1. Focus on the Climax
2. Classification by Indicator Species
Vegetation Types of California
Jennings, et al Standards for associations and alliances of the U.S. National Vegetation Classification. Ecological Monographs 79:

11. Community Ecology I. Introduction
II. Multispecies Interactions with a Trophic Level
III. Multispecies Interactions across Trophic Levels
IV. Succession
A. Definitions
B. Classifying Vegetative Communities
C. Types of Succession

12. 1. Primary succession: on previously unvegetated substrate or ‘devoid of life’

13. 1. Primary succession: on previously unvegetated substrate or ‘devoid of life’

14. 1. Primary succession: on previously unvegetated substrate or ‘devoid of life’

15. 1. Primary succession: on previously unvegetated substrate or ‘devoid of life’

16. 1. Primary succession: on previously unvegetated substrate or ‘devoid of life’

17. 2. Secondary Succession: follows a disturbance (removes biomass)

18. 3. Disturbance-mediated Succession
Fire, grazers, predators, etc.

19. 3. Disturbance-mediated Succession
The effect of the disturbance depends on its intensity and size.
Small, low intensity disturbance:
One tree and a few plants underneath die.
Small canopy gap is quickly filled by neighboring trees in the understory; recovery by individual growth.

20. 3. Disturbance-mediated Succession
The effect of the disturbance depends on its intensity and size.
Large, high intensity disturbance:
Entire canopy gone; many species driven to local extinction.
Recovery by colonization.

21. These effects are really true of most successional seres, not just disturbance-mediated succession.

22. 4. Heterotrophic succession

23. 4. Heterotrophic succession
Eberhardt, TL and DA Elliot A preliminary investigation of insect colonisation and succession on remains in New Zealand. Forensic Science International 176:

24. 4. Heterotrophic successionno
yes

25. Community Ecology I. Introduction
II. Multispecies Interactions with a Trophic Level
III. Multispecies Interactions across Trophic Levels
IV. Succession
A. Definitions
B. Classifying Vegetative Communities
C. Types of Succession
D. Mechanisms
- facilitation, tolerance, and inhibition

26. examples: colonization of bare rock: lichens, moss, herbs;
Facilitated:
early species change environment and increase the probability of successful colonization by later species.
examples: colonization of bare rock: lichens, moss, herbs;
colonization of carcasses: beetles, flies, etc.
Effects of wildebeest
Aspen fix nitrogen that helps nitrogen-limited trees colonize

27. Tolerance:
Tolerance: early species have no effect on later species. This occurs if there is 'ecological equivalence' among the species. Many stages in later forest succession seem dominated by this mechanism.
Also, later species tolerate early species... so shade tolerant species come to dominate because they tolerate the shade of early species, but inhibit those early species with their own shade.

28. Inhibition:
Early species retard the colonization success of later species. If these effects vary among early species, there can be "priority effects". The species that gets there first has a differential and deterministic effect on the subsequent structure of the community. Important where allelopathic interactions occur. Bryozoans block colonization of tunicates and sponges.

29. Community Ecology I. Introduction
II. Multispecies Interactions with a Trophic Level
III. Multispecies Interactions across Trophic Levels
IV. Succession
A. Definitions
B. Classifying Vegetative Communities
C. Types of Succession
D. Mechanisms
- facilitation, tolerance, and inhibition
E. Invasive Species

30. “Invasive species” are facilitated or tolerated by natives, and subsequently inhibit them. Often they have escaped their predators or pathogens, and are ‘tolerated’ by native predators/pathogens…thus escaping limitation and increasing to densities where they compete with natives.
Here, field plants are affected by transplantation into a different mycorrhizal environment.

31. F. Modelling Succession: Tilman (1985)
A, B B
Our old 2-species model with stable coexistence possible.

32. F. Modelling Succession: Tilman (1985)
A, B B
If resource supply rates are negatively correlated, then the community may succeed from A to A-B coexistence to B as concentrations change

33. F. Modelling Succession: Tilman (1985)
A, B B
B, C C
...and then to B,C and C.... and etc....

34. F. Modelling Succession: Tilman (1985)
A, B B
B, C C
...and then to B,C and C.... and etc....
C, D D

35. Community Ecology I. Introduction
II. Multispecies Interactions with a Trophic Level
III. Multispecies Interactions across Trophic Levels
IV. Succession
A. Definitions
B. Classifying Vegetative Communities
C. Types of Succession
D. Mechanisms
- facilitation, tolerance, and inhibition
E. Invasive Species
F. Modelling Succession
G. Characteristics of Plants through Succession

36. Community Ecology I. Introduction
II. Multispecies Interactions with a Trophic Level
III. Multispecies Interactions across Trophic Levels
IV. Succession
A. Definitions
B. Types
C. Mechanisms
D. Model – Tilman 1985
E. Community Patterns

37. E. Community Patterns (From Morin, 1998)
Variable Early Late
Organism Size small large
life history r K
Biomass low high
Richness, Diversity low high
Structural complexity low high
Niches broad narrow
Nutrient cycles open closed
Stability low high
trophic relationships linear web-like
connectance low high