Dendroecology is the use of tree-ring dating and analyses to investigate events and processes involving the interactions of organisms with their environment. It provides a longer temporal perspective than other records through tree-ring evidence that has high precision. Chronological control allows comparison of multiple lines of evidence. However, tree-ring records can be irregular and some processes may be unknown. Past conditions may have no modern analog, complicating interpretation. Dendroecology is used to study forest demography, growth dynamics, and disturbance ecology like insect outbreaks and fire history.

1. DENDROECOLOGY

2. “ Many ecosystem processes, especially those affected
by climate changes, manifest themselves only over
longer time periods and broader spatial scales than
”
encompassed in typical ecological studies.
Swetnam and Brown, 2010

3. “ Understanding the dynamics of long-lived organisms
and ecosystems — and the role of climate in controlling
these dynamics — requires decadal to centennial and
”
landscape- to regional-scale perspectives.
Swetnam and Brown, 2010

4. Dendroecology is the use of tree-ring dating and analyses
to investigate events and processes involving
the interactions of organisms with their environment.

5. THE PRINCIPLE OF AGGREGATE TREE GROWTH
Rt = At + Ct + δD1t + δD2t + Et

6. THE PRINCIPLE OF AGGREGATE TREE GROWTH
Rt = At + Ct + δD1t + δD2t + Et

7. DENDROECOLOGY
A. Forest demography
B. Growth dynamics
C. Disturbance ecology

8. A. Forest demography

9. Photograph: Dawn Hopkins Photograph: Kurt Kipfmueller

10. “ Ecologists have long recognized that time series of
tree births and deaths are of fundamental value for
”
understanding forest and woodland dynamics.
Swetnam and Brown, 2010

11. Photograph: Kurt Kipfmueller

12. 1500 1600 1700 1800 1900 2000

13. 1500 1600 1700 1800 1900 2000

14. 1500 1600 1700 1800 1900 2000

15. Tree recruitment dates (by 50-year periods)
1500 1600 1700 1800 1900 2000

16. Tree mortality dates (by 50-year periods)
1500 1600 1700 1800 1900 2000

17. TREE
DOES
NOT DATE OF
EQUAL GERMINATION
RECRUITMENT

18. Pith
Hi ing the pith is easy when you collect an entire cross-section

19. It’s more difficult when coring, especially if growth is asymmetric.

20. Coring height
Root collar
How many years separate the root collar from the stem at coring height?

21. The germination date can be much earlier than tree age at coring height.
Source: Gutsell and Johnston (2002)

22. Photograph: Kurt Kipfmueller
Germination doesn’t happen immediately a er disturbance.

23. The ecesis interval is the amount of time between
an initial disturbance and the successful establishment
of the first trees.

25. The condition of dead trees affects the continuity of their record
Photograph: John Krumm

26. Snags may have lost an unknown number of outer rings.

27. How can we reduce the effects
of these different sources of uncertainty?

28. “ In old, uneven-aged forests, sometimes hundreds of trees
must be sampled to obtain adequate characterization
”
of age structure distributions.
Swetnam and Brown, 2010

29. 5-ha plots
Demographic surveys in the Mazama Mountains Tom Swetnam

30. Sampling dead trees in the pinon-juniper woodlands Tom Swetnam

31. Pinyon Demography at Sevilleta LTER, Central New Mexico
Source: Betancourt et al. (2004)

32. less than 85% of average precipitation
for 10 or more years
Source: Swetnam and Betancourt (1998)
Severe sustained drought in the Southwest during the 1950s

33. Source: Swetnam and Brown (2010)
Germination of ponderosa pine coincides with warm, wet summers

34. THE ‘FADING RECORD’ PROBLEM
The preservation of dead trees becomes less common
with time before present, and obtaining estimates of
past mortality events depends both on persistence of
woody material and the ability to adequately sample
the material to obtain death dates.

35. B. Growth dynamics
Photograph: Kyle Pierce

36. A growth suppression is a rapid reduction of growth
from one year to the next, usually lasting for several years.

37. Photograph: Eli Sagor
Growth suppressions are caused commonly by defoliating insects.

38. Source: Fri s and Swetnam, 1989
Suppression, possibly caused by 1064 eruption at Sunset Crater

39. A growth release is the opposite of a suppression,
with growth increasing rapidly for several years.

40. Growth releases may be caused by the death of ‘overstory’ trees.

41. Source: Fri s and Swetnam, 1989
Growth release caused by 1966 timber harvest.

42. Source: Berg et al. (2006)
Using release events to identify insect outbreaks

43. Source: Berg et al. (2006)
Studying the frequency of growth releases across many stands.

44. C. Disturbance ecology
Photograph: Miguel Vieira

45. THE PRINCIPLE OF AGGREGATE TREE GROWTH
Rt = At + Ct + δD1t + δD2t + Et

46. Photograph: William Ciesla

47. Western spruce budworm Choristoneura occidentalis Freeman

48. Photograph: brewbooks
White fir Abies concolor

49. Douglas-fir Pseudotsuga menziesii

50. Photograph: William Ciesla

51. “ No typical pa ern or trend in western spruce budworm epidemics
has been apparent; most of the early epidemics lasted for
a few years and then subsided naturally; others persisted longer,
”
at times without spreading over large areas.
Fellin and Dewey, 1982

52. Photograph: Dave Powell

53. “ The tree-ring basis for developing outbreak chronologies
is the observation of very sharply reduced ring growth
in the host species during the defoliation episode,
”
which typically lasts for a decade or longer.
Swetnam and Brown, 2010

54. Photograph: Tom Swetnam
Growth suppression in white fir defoliated by spruce budworm

56. THE PRINCIPLE OF AGGREGATE TREE GROWTH
Rt = At + Ct + δD1t + δD2t + Et
?

57. HOST NON-hOST

58. HOST NON-hOST
White fir
Ponderosa Pine
Douglas-fir

59. Photograph: Brewbooks

60. G(HOST) < G(NON-HOST)
=
potential outbreak

61. Source: Ryerson et al. (2003)

62. Using host/non-host comparisons to identify budworm outbreaks
BLACK = Host < Non-host GRAY = Host > Non-host
Source: Ryerson et al. (2003)

63. Percentage of trees recording an outbreak of western spruce budworm in the Rio Grande National Forest, Colorado
Source: Ryerson et al. (2003)

64. 397 trees

65. Do drought conditions inhibit spruce budworm outbreaks?
Source: Ryerson et al. (2003)

66. Dendroecology is the use of tree-ring dating and analyses
to investigate events and processes involving
the interactions of organisms with their environment.

67. Strengths of dendroecology

68. Strengths of dendroecology
1. Tree-ring records provide a much longer perspective
than documentary records or modern surveys.

69. Strengths of dendroecology
1. Tree-ring records provide a much longer perspective
than documentary records or modern surveys.
2. Tree-ring evidence has a high degree of temporal
precision compared to other paleoecological tools.

70. Strengths of dendroecology
1. Tree-ring records provide a much longer perspective
than documentary records or modern surveys.
2. Tree-ring evidence has a high degree of temporal
precision compared to other paleoecological tools.
3. Chronological control allows multiple lines of
evidence to be compared.

71. Limitations of dendroecology

72. Limitations of dendroecology
1. Tree-ring records are fragmentary and can be
distributed irregularly in time and space.

73. Limitations of dendroecology
1. Tree-ring records are fragmentary and can be
distributed irregularly in time and space.
2. Some species, events or processes cannot be
reconstructed and therefore remain unknown.

74. Limitations of dendroecology
1. Tree-ring records are fragmentary and can be
distributed irregularly in time and space.
2. Some species, events or processes cannot be
reconstructed and therefore remain unknown.
3. Past ecological conditions may have no analog in
the modern system, making their behavior difficult
to interpret.

75. ASSIGNED READING
Tom Swetnam and Peter Brown (2010), Climatic inferences
from dendroecological reconstructions. M.K. Hughes et al.
(eds.), Dendroclimatology, Developments in
Paleoenvironmental Research.

76. D. Fire history and fire climatology

77. Class visitor Dr. Kurt Kipfmueller

78. FOR NEXT CLASS
Read sections 9.2.1 (Fire History and Fire
Climatology) and 9.3 (The Late Eighteenth-
Century, Early Nineteenth-Century Fire Gap)