1. Competition (Ch. 10) Ken Jennings: my hero! 74 wins (2004)
$2.52 million

2. Target-neighborhood experiment
Remove around “target” shrub
Target monitored (water status)
Result:
little intraspecific comp. both sp.
great Larrea-Ambrosia comp.
Danger…

3. Danger for removal experiments: Apparent competition
Herbivore effects mimic competition
Ex: Herbivore eats A and B
Remove A, herbivore leaves,
Interaction b/w A & B

4. Other points 1) Herbivory influences competition
Ex, chalk grassland (England)
Lab studies: grass better competitor. How forbs persist?
Rabbits (“killer rabbits?”)
Plant Ecology Theatre!

5. Other points Rabbits prefer grass (help forbs)
Twist: Myxomatosis decimated rabbits 1950s—forbs declined
Rare butterflies (ex, marsh fritillary) declined
The marsh fritillary

6. Other points 2) Disturbance timing on competition species 1 numbers
No disturbance
time

7. Other points Can allow coexistence Frequent disturbances numbers
species 1
species 2
time

8. Other points 3) Phenology can affect competition Ex, lab study
Germinate same time: sp. 2
Sp. 2 germinate 2 wk earlier: sp. 1

9. Allelopathy Allelopathy: chemical May be
Allelopathy: chemicals added to env.

10. Plants “leaky”
Many ways
rainwater leaches
volatiles
Root
decay

11. Examples Ex, Salvia (sage): coastal sage scrub (CA)
Leaves release cineole & camphor
camphor

12. Examples Chemicals inhibit germination & growth annuals “Bare zones”
camphor

13. Examples
Ex, Juglans nigra (black walnut)
Roots: juglone

14. Examples
Ex, Ceratiola ericoides (beach rosemary)
Sandy soils

15. Examples
Ex, Ceratiola ericoides (beach rosemary)
Releases ceratiolin

16. Allelopathy: Problems with proof
Need to:
#3 hard! Allelopathy proof difficult

17. Allelopathy: Problems with proof
Other factors: herbivory
Cages:

18. Weeds and allelopathy Ex, Centaurea maculosa (spotted knapweed)
Invasive exotic

19. Weed example Ex, Centaurea maculosa (spotted knapweed)
Releases catechin
catechin

20. Ch. 10: Positive plant-plant interactions

21. Facilitation
Facilitation: + effect (
Commensalism:
Some epiphytes

22. Commensalism
Nurse plant effect (+,0)
Saguaro plant nurse……

23. Commensalism Nurse plant effect (+,0)
Ex, Saguaro cactus (Carnegiea gigantea)

24. Commensalism
Seedlings under Palo Verde trees
Provides:

25. Commensalism Ex, Marsh elder (Iva frutescens: salt marsh)
Juncus roemerianus shading decreases evaporation:

26. Commensalism
Can help exotics
Ex, chenopod shrubland

27. Mutualism
(+,+) interaction: pollination, seed dispersal, N-fixation….

28. Mutualism
Ex, root grafts connect

29. Mutualism
Radioactive tracers
Roots
Danger!

30. Mutualism
Danger: Disease

31. Lichens
Mutualism (+,+)
Lichen: fungus

32. Lichen
Together: