1. COMMUNITY CHANGE (SUCCESSION)
Krebs cpt. 21; pages ; 431
Biol 302 succession

2. SUCCESSION ….
Is the non-seasonal, directional and continuous pattern of colonization and extinction on a site by populations.
Is the replacement of one kind of community by another kind; the progressive changes in vegetation and animal life that may culminate in the climax community (Krebs 622)
Biol 302 succession

3. SECONDARY SUCCESSION …. … recovery of a disturbed site.
PRIMARY SUCCESSION ….
… recovery from a new sterile area that has been uncovered by a retreating glacier, or created by an erupting volcano.
SECONDARY SUCCESSION ….
… recovery of a disturbed site.
Biol 302 succession

4. PRIMARY SUCCESSION Mt. St. Helens pp403-405
Lake Michigan dunes pp
Biol 302 succession
Glacier Bay pp

5. Ice recession in Glacier Bay, Alaska, since 1760
1940
1860
Krebs Fig. 21.7; p414
1760
Biol 302 succession

6. SECONDARY SUCCESSION
Krebs pp
Biol 302 succession

7. From Drury and Nisbet 1973
“Succession can be considered as an expression of differences in colonizing ability, growth and survival of organisms adapted to a particular set of conditions on an environmental gradient.”
 “The replacement of one of several species or groups of species by others results from interspecific competition and the interactions of herbivores, predators, and disease which permit one group plants to suppress slower-growing or less tolerant ones.”
Biol 302 succession

8. A B C D SUCCESSION PATHWAYS (HENRY HORN) 1. OBLIGATORY SUCCESSION
Biol 302 succession

9. A B C D OBLIGATORY SUCCESSION CHRONIC, PATCHY DISTURBANCE
Biol 302 succession

10. A B C D OBLIGATORY SUCCESSION CHRONIC, PATCHY DISTURBANCE
COMPETITIVE HIERARCHY A B C D
Biol 302 succession

11. OBLIGATORY SUCCESSION CHRONIC, PATCHY DISTURBANCE
COMPETITIVE HIERARCHY
QUASI-REALITY
Biol 302 succession

12. Institute Woods, Princeton, N.J. (Henry Horn)
Eastern deciduous hardwood forests
Biol 302 succession

13. Grey Birch, Betula populifera
Black Gum, Nyssa sylvatica
Biol 302 succession

14. Beech, Fagus sylvatica
Red Maple, Acer rubrum
Biol 302 succession

15. 4. QUASI-REALITY GRAY BIRCH BLACK GUM RED MAPLE BEECH GRAY BIRCH
Biol 302 succession

16. Biol 302 succession

17. No. of individuals IN 50 YEARS GRAY BIRCH BLACK GUM RED MAPLE BEECH
Values in cells are percentages, and represent the probability (% probability) that any particular individual tree living now will be replaced by any other individual tree 50 years from now. e.g. out of every 100 individuals of grey birch now living, in 50 years, 36 of those grey birch will have died and will have been replaced by black gum.
No. of individuals IN 50 YEARS
GRAY BIRCH
BLACK GUM
RED MAPLE
BEECH
No. of individuals NOW 5 36 50 9 1 57 25 17 - 14 55 31 3 96
Biol 302 succession

18. The number of Red Maple in 50 years will be: 50% Gray Birch (now)
FOR EXAMPLE:
The number of Red Maple in 50 years will be:
50% Gray Birch (now)
25% Black Gum (now)
55% Red Maple (now)
3% Beech (now)
Biol 302 succession

19. The predicted percentage composition of a forest consisting initially of 100% Grey Birch.
Age of forest (yrs)
Now 50
100
150
200 
Data from old forest
GRAY BIRCH 5 1
BLACK GUM 36 29 23 18 3
RED MAPLE 39 30 24 9 4
BEECH 31 47 58 86 93
Biol 302 succession

20. Marine Ecologist, Joe Connell
From Connell and Slatyer 1977
FACILITATION
TOLERANCE (COMPETITION)
INHIBITION
Biol 302 succession
Marine Ecologist, Joe Connell

21.                                                                                                                                                                                                                                                                                                                                                                                                    
FACILITATION …later stages depend upon early-stage species to prepare a favorable environment for them
Biol 302 succession

22. TOLERANCE…later successional species tolerate lower resource levels [i
TOLERANCE…later successional species tolerate lower resource levels [i.e. have lower R*] than earlier occupants, and can invade and displace them by reducing resources to levels below those tolerated by earlier occupants i.e. the community is composed of those species most efficient at exploiting resources
Biol 302 succession

23. INHIBITION…all species resist the invasion of competitors and are displaced only by death, or damage by factors other than competition. i.e. colonizers will hold a site against all comers until death
Biol 302 succession

24. FACILITATION
TOLERANCE
INHIBITION
Biol 302 succession

25. FIELD ABANDONED IN FALL
A study from abandoned farmland illustrates some aspects of Facilitation, Tolerance and Inhibition (see Krebs pp )
FIELD ABANDONED IN FALL
1. INITIAL INVASION:
Horseweed
a winter annual
produces abundant seed
self-allelopathic
Conyza canadensis
Biol 302 succession

26. More susceptible to decaying roots of horseweed, than horseweed
2. NEXT SEASON:
Asters
More susceptible to decaying roots of horseweed, than horseweed
Tolerant of dry conditions
Biol 302 succession

27. 3. SECOND AND THIRD SEASONS: Bluestem
Seedlings invading since initial abandonment
Broomsedge
More tolerant of dry conditions than Asters
Decaying roots of Horseweed promote growth
Biol 302 succession

28. Bluestem
Broomsedge
Biol 302 succession

29. Broomsedge promoted by decaying root TOLERANCE:
SUMMARY
FACILITATION:
Broomsedge promoted by decaying root
TOLERANCE:
Broomsedge displaces Aster through competition for water
INHIBITION:
Horseweed seedlings more tolerant of horseweed decomposition than Asters
Biol 302 succession

30. THE RESOURCE RATIO HYPOTHESIS OF PLANT SUCCESSION
David TILMAN
Biol 302 succession

31. TILMAN, D. 1985. The resource-ratio hypothesis of plant succession
TILMAN, D The resource-ratio hypothesis of plant succession. American Naturalist 125:
READING FOR THESE LECTURES:
Krebs: selections from pp
Biol 302 succession

32. Resource Ratio Hypothesis
One species and one resource
One species and two resource
Two species and two resources
Multiple species and two resources
Biol 302 succession

33. R* Species A birth mortality Resource level [1]
Population growth [death] rate
mortality R*
Resource level [1]
Biol 302 succession

34. OPTIMAL FORAGING
Any (plant) species will absorb resources in the proportion by which it is equally limited by them.
This proportion is the ratio of the two values of R*
R* = the Requirement Value i.e. the level of resource required to hold a population (of a species) at equilibrium:
i.e. where birth rate = death rate
Biol 302 succession

35. 1 3 4 2 SPECIES A Population growth [death] rate SPECIES B Resource 1
SPECIES A 1 3
Population growth [death] rate
SPECIES B 4 2
Resource 1
Resource 2
Biol 302 succession

36. Resource Ratio Hypothesis
One species and one resource
One species and two resource
Two species and two resources
Multiple species and two resources
Biol 302 succession

37. Species A Resource [2] Resource [1] 8 7 6 54 3 2 1
Births [A] > Deaths [A] Population increases
Resource [2]
Zero Net Growth Isocline [ZNGI]: Births = Deaths
Births [A] < Deaths [A] Population declines
Resource [1]
Biol 302 succession

38. Species B Resource [2] Resource [1] 8 76 5 4 3 2 1
Births [B] > Deaths [B] Population increases
Resource [2]
Zero Net Growth Isocline [ZNGI]: Births = Deaths
Births [B] < Deaths [B] Population declines
Resource [1]
Biol 302 succession

39. Resource Ratio Hypothesis
One species and one resource
One species and two resource
Two species and two resources
Multiple species and two resources
Biol 302 succession

40. Species A and B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A]
ZNGI [B]
Resource [1]
Biol 302 succession

41. A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B]
Resource [1]
Biol 302 succession

42. Neither species can survive
A B 8 7 6 5 4 3 2 1
Both species can grow
A wins
Resource [2]
ZNGI [A]
ZNGI [B]
B wins
Neither species can survive
Resource [1]
Biol 302 succession

43. A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B]
Resource [1]
Biol 302 succession

44. Neither species can survive
A B 8 7 6 5 4 3 2 1
A & B coexist
A wins
Resource [2]
ZNGI [A]
ZNGI [B]
B wins
Neither species can survive
Resource [1]
Biol 302 succession

45. Plant Ecology Research Assistant for Garry Oak Ecosystem Study
Location: Greater Victoria area, Vancouver Island, BC Term: April/May – August 2006 (3 – 4 months) Salary: $1600 – 1800/month (depends on experience)
Duties: Vascular plant surveys, environmental data collection, data entry, etc.
Qualifications:
At least one year of study in Biology, Environmental Studies, Geography etc. - Interest in ecological research - Meticulous personality; highly-motivated, flexible, reliable and fun - Physically fit; valid Driver’s license - Previous field experience and experience identifying plants are assets - Based in Victoria or Vancouver area (Victoria preferred)
Apply via resume and brief covering to:
Patrick Lilley, M.Sc. Student, UBC Botany
Deadline: February 24, 2006
More details at
Biol 302 succession

46. Neither species can survive
A B 8 7 6 5 4 3 2 1
A & B coexist
A wins
WHY?
Resource [2]
ZNGI [A]
ZNGI [B]
B wins
Neither species can survive
Resource [1]
Biol 302 succession

47. A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B]
Resource [1]
Biol 302 succession

48. A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B]
Resource [1]
Biol 302 succession

49. Resource Ratio Hypothesis
One species and one resource
One species and two resource
Two species and two resources
Multiple species and two resources
Biol 302 succession

50. Resource [2] Resource [1] A B C D E 8 7 6 5 4 3 2 1 A B C D E
Resource [1]
Biol 302 succession

51. A AB B BC C CD Resource [2] D DE E Resource [1] A B C D E 8 7 6 5 4 3
None E D E
Resource [1]
Biol 302 succession

52. A AB B BC C CD Resource [2] D DE E Resource [1] Random Resource Supply
A B C D E 8 7 6 5 4 3 2 1 A AB B BC C CD
Resource [2] D A DE B C
None E D E
Resource [1]
Biol 302 succession

53. A AB B BC C CD Resource [2] D DE E Resource [1]
Positively Correlated Resources
A B C D E 8 7 6 5 4 3 2 1 A AB B BC C CD
Resource [2] D A DE B C
None E D E
Resource [1]
Biol 302 succession

54. A AB B BC C CD Resource [2] D DE E Resource [1]
Negatively Correlated Resources
A B C D E 8 7 6 5 4 3 2 1 A AB B BC C CD
Resource [2] D A DE B C
None E D E
Resource [1]
Biol 302 succession

55. A AB B BC C Resource [Light] CD D DE E Resource [Nitrogen]
PRIMARY SUCCESSION
A B C D E 8 7 6 5 4 3 2 1 A AB B BC C CD
Resource [Light] D A DE B C D E E
Resource [Nitrogen]
Biol 302 succession

56. A AB B BC C Resource [Light] CD D DE E Resource [Nitrogen]
SECONDARY SUCCESSION
A B C D E 8 7 6 5 4 3 2 1 A AB B BC
Poor soil
Rich soil C CD
Resource [Light] D A DE B C D E E
Resource [Nitrogen]
Biol 302 succession

57. Resource [Light] Resource [Nitrogen] Black Oak & Aspen 87 6 5 4 3 2 1
Aspen
Black Oak
Red Oak & Black Oak
Red Oak
White Oak & Red Oak
Resource [Light]
White Oak
Sugar Maple & White Oak
Sugar Maple
Resource [Nitrogen]
Biol 302 succession

58. 1 2 Resource [Light] 4 Resource [Nitrogen] DIVERSITY A B C D E 8 7 6 53 2 1 1 2
Resource [Light] A 4 B C D E
Resource [Nitrogen]
Biol 302 succession

59.                                    
                                   
                                   
                                   
TILMAN
THE END
Biol 302 succession

60. Studied trees in a New Hampshire forest
FORCIER, Keith
Studied trees in a New Hampshire forest
Trees with dbh <2 cm (400 plots)
90% of canopy:
Sugar maple
American beech
Yellow birch
Biol 302 succession

61. % plots with at least 1 seedling
SPECIES
Density
(#/m2)
(dmin/dmax )
x 100
% plots with at least 1 seedling
Mass/ind (mg)
Yellow birch
21.3 2 92 8
Sugar maple 10 57 73
268
Beech
3.9 66 55
569
Biol 302 succession

62. Number of cohort alive at beginning of interval
Age
interval
Yellow birch
Sugar maple
Beech
0-1
1-2
2-3
3-4
4-5
5-6
6-7
7-8
8-9
9-10
1000 70
<30
583
317
225
166
118 84 54 48 42
410
262
188
138
121
110 92 87 83
Biol 302 succession

63. CANOPY SEEDLINGS SAPLINGS < 0.5m tall 0.5 – 2 m tall Yellow birch
Sugar maple
Beech +
+ 0 - ++
Seed -
Sprouts +
Biol 302 succession

64. CLIMAX MICROSUCCESSION
Beech (sprouts)
Beech (seed)
MINOR DISTURBANCE
Sugar Maple
Yellow birch
CATASTROPHIC DISTURBANCE
Successional communities
Biol 302 succession