Title: Principles of Dendrochronology
1Principles of Dendrochronology January 30
2- Uniformitarianism Principle
- James Hutton, British geologist (published
17851788) - The present is the key to the past.
- Corollary to this principle The past is the key
to the future. - Illustrates the trajectory of science, past,
present, and future
- Study processes as they occur at present
- Improved understanding comes from the past
- Extrapolate/predict the future applied!
3- Uniformitarianism Principle
Examples
A. Reconstructions of past climate
Dendroclimatology
Future?
Present
Assumes that climatic processes operating today
were operating similarly in the past.
4- Uniformitarianism Principle
Examples
B. Reconstructions of past fire
Dendropyrochronology
Assumes that wildfires operate today as an
ecosystem process just as they did in the
past.
Future?
Present
52. Principle of Limiting Factors
- Basic principle in biology
- Adaptation to dendrochronology
- Tree growth can proceed only as fast as allowed
by the primary environmental and physiological
mechanisms that restrict growth. - Sometimes, more than one mechanism operates to
restrict growth. - We MUST have variable tree growth!
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72. Principle of Limiting Factors
83. Ecological Amplitude
- A tree species will be more responsive and
sensitive to changes in environmental conditions
in the outer limits of its range.
- Latitudinally and longitudinally
93. Ecological Amplitude Range map of sugar maple.
103. Ecological Amplitude
- A tree species will be more responsive and
sensitive to changes in environmental conditions
in the outer limits of its range.
Not so good
11Red Spruce
124. Principle of Site Selection
- Within any given area chosen for study, specific
site characteristics should be sought that will
enhance a trees responsiveness to environmental
factors. - Notice how this is related to the principle of
limiting factors. We should select sites where
factors are more limiting. - Notice also that recognizing the growth forms of
trees will provide clues where such sensitive
sites exist.
134. Principle of Site Selection
Notice vastly different growth forms of these
trees
Notice vastly different ring patterns
145. Aggregate Tree Growth
- Tree growth can be decomposed into five basic
parts
- R ring width, t the current year, and delta
presence (1) or absence (0) indicator - A age-related trend
- C climate
- D1 exogenous (external) disturbance processes
(examples?) - D2 endogenous (internal) disturbance processes
(examples?) - E random error
155. Aggregate Tree Growth
- Tree growth can be decomposed into five basic
parts
Only ONE can be the desired signal. All OTHERS
constitute noise. We wish to maximize the signal
to noise (S/N) ratio (concept borrowed from
engineering). For example, if climate is our
desired signal, we must (1) mathematically remove
the effects of other parts, and (2) sample to
ensure no other noise affects tree growth in our
study area.
166. Principle of Replication
- The environmental signal being investigated can
be maximized (and the amount of noise minimized)
by sampling more than one stem radius per tree
and more than one tree per site. - Obtaining more than one increment core per tree
reduces the amount of "intra-tree variability"
the amount of undesirable environmental signal
peculiar to only that tree. - Obtaining numerous trees from one site (and
perhaps several sites in a region) ensures that
the amount of "noise" is minimized.
176. Principle of Replication
- Follows the basic statistical rule INCREASE YOUR
SAMPLE DEPTH !!! MORE IS BETTER !!!
187. Principle of Crossdating
- Matching patterns in ring widths or other ring
characteristics (such as ring density patterns)
among several tree-ring series allows the
identification of the exact year in which each
tree ring was formed. - Both a principle and a technique. Without either,
dendrochronology is unscientific ring-counting. - The Principle of Crossdating concerns why trees
have the same ring patterns. - The Technique of Crossdating concerns how we can
use this property to (1) ensure we have precisely
assigned the correct calendar year to each tree
ring, and (2) at the same time, account for those
problem rings, such as false or locally absent
rings.
19-
- Why does crossdating work?
- Because trees within a region will be responding
similarly to the overall climate regime in which
they grow. - Different rates of growth may occur due to local
micro-environmental effects, but this does not
matter!