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
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
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
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.
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
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
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.
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.
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.