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PRINCIPLES OF DENDROCHRONOLOGY

PRINCIPLES OF DENDROCHRONOLOGY. Set of principles or “scientific rules” Some are specific to dendrochronology Tree selection Others are basic to many disciplines Replication. Crossdating. Matching of ring patterns across trees Widths, density, other features

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PRINCIPLES OF DENDROCHRONOLOGY

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  1. PRINCIPLES OF DENDROCHRONOLOGY • Set of principles or “scientific rules” • Some are specific to dendrochronology • Tree selection • Others are basic to many disciplines • Replication

  2. Crossdating • Matching of ring patterns across trees • Widths, density, other features • Allows year date of formation to be assigned to each ring • Critical to dendrochronology

  3. Limiting Factors • Liebig’s Law of the Minimum • Rate of a process is limited by most limiting factor • Interactions between nutrients • Other factors: water?

  4. Limiting Factors • Tree Growth • Cannot proceed faster than is allowed by most limiting factor • Degree and duration of a limiting factor change from year to year  ring variation • Could be different limiting factors relative to various frequencies of growth

  5. Limiting Factors • Sheep Mt bcp: moisture/temperature limited at high-frequency • Decadal ramp evidence of CO2 limitation?

  6. Aggregate Tree Growth • Ring variation is a function of • Age or size • Climate • Endogenous disturbances • Exogenous disturbances • Leftover

  7. Aggregate Tree Growth • To focus on one of these factors, others must be accounted for • To study past climate: • Sample trees without past disturbance • Remove age effect

  8. Aggregate Tree Growth • Age or size effects removed by detrending

  9. Site and Tree Selection • Select a site to maximize effect of an environmental factor on tree growth • Eliminate or equalize other factors • Isolate the single factor of interest • Edaphic variationcan be below surface

  10. Site and Tree Selection • Not random sampling in true ecological sense • Ramifications for inference • Instead of saying: Climate affects tree growth in such a way … • We might say: Past climate at this site has been such and such …

  11. Replication • Multiple radii to estimate tree growth • Multiple trees to crossdate, estimate site patterns • Multiple sites to estimate regional tendencies • Multiple samplesto establish building sequences

  12. Ecological Amplitude • Tree growth more sensitive to environmental factors at edge of species range • Altitudinal: • Pine sensitive tomoisture at lowerelevational limit

  13. Ecological Amplitude • Latitudinal: • Trees may occupy wide variety of microsites in center of range, not limited by single factor • Trees may occupy narrow variety of microsites along margins of range

  14. Ecological Amplitude • White oak is classic • Enormous range • Gentle topography • Itrdbfor: “In the East … tree sensitivity to climate increases from the range center out toward the range edge.”

  15. Ecological Amplitude • Might affect age of trees: • Schulman, Ferguson 1956 (Science 1954, v. 119, pg. 396, 883) • “Young” bcp ineast • Old bcp to west • Corresponds toaverage rainfalltotals

  16. Ecological Amplitude • Currey 1964: • Found oldest bcp on Wheeler Peak, NV • “The simple hypothesis of Schulman and Ferguson is … no longer tenable.”

  17. Uniformitarianism • Physical and biological processes that link current environmental processes with current patterns of tree growth operated similarly in the past • “Present is key to past” (Hutton 1785)

  18. Uniformitarianism • Tree rings from the 1900s calibrated with rainfall records from 1900s • Annual precipitation • Past rings indicate past precipitation

  19. Uniformitarianism • Have current environmental conditions existed in past? • Do past environmental conditions exist currently? • Young trees vs. old trees? • Szeicz and MacDonald 1994: Age-dependent tree-ring growth responses of subarctic white spruce to climate. CJFR 24:120-132.

  20. Uniformitarianism • Paleo twist: Past is key to future • This is why we do what why do

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