Dendrochronology

1
Dendrochronology

• dendro refers to tree
• chronos refers to time
• ology the study of

2
Why does it work?

• Earlywood latewood cell boundaries

3
Woody plant growth

• Height growth
• Concentric secondary growth (tree rings)

4
Benefits

• Annual time scale (seasonal)
• compare with carbon dating, lake cores
• Repeatable
• Strong biological underpinning
• But
• Limited to Holocene, so far
• Analysis assumptions typically scrutinized

5
1. Uniformitarian Principle

• Present is the key to the past Hutton
• we assume biological and physical variables which
  limit tree ring increment that are operating now
  did so in the past

6
2. Limiting Factors Principle

• Growth processes are ultimately limited by some
  factor, environmental or biologic (precipitation,
  nutrients)
• Leaves gt roots gt defense gt increment

7
3. Aggregate tree growth principle

• Ring widths can be teased apart into factors that
  affected past growth
• i.e. competition, disturbance, environment,
  random error
• Maximize variation in tree ring signal by
  minimizing all other factors

8
4. Ecological amplitude principle

• Marginal trees are often most useful for
  dendrochronological investigation
• latitude
• longitude
• elevation

9
5. Site selection principle

• Select sites / trees on sites that will maximize
  variation of interest
• Climate high elevation
• Growth release forest grown
• Fire history fire-scarred

10
6. Crossdating principle

• Matching ring widths between tree ring series
  allows one to date past events, reconstruct past
  environmental data, or date the death of a tree

11
7. Replication principle

• Maximize variation of interest, signal, by
  sampling twice per tree, or multiple trees per
  site

12
Definitions

• Tree ring
• Increment borer / core
• Cookie or cross section

13
Definitions

• Tree ring series
• Tree ring chronology
• Standardization

14
Definitions

• Complacency versus sensitivity
• Species-specific
• Site-specific (slope)

15
(No Transcript)
16
(No Transcript)
17
Analysis

• Skeleton plotting
• Stage and microscope
• COFECHA (crossdate)

18
Standardization

• ARSTAN

Monserud. 1986. Forest Science
19
Douglas-fir chronology
20
Reconstructing drought
21
Reconstructing drought

• 286 grid points, 835 chronologies, 1,992 years

22
Reconstructing drought
23
Reconstructing precipitation
24
Reconstructing precipitation
25
Reconstructing fire
26
Reconstructing fire
27
Reconstructing fire
28
Reconstructing spruce beetle outbreaks

• Measure dead spruce trees
• Cross-date with chronology
• Reconstruct pattern of outbreak

29
Sclerochronology

• Geoduck clams, Pacific rockfish (otoliths),
  Arctic island clams
• Acetate peels from chondrophore (hinge)
• Closely tracked PDO
• Closely correlated with Jan-Mar SST
• Reconstruct SST