Absolutely dated tree rings

Absolutely dated tree rings with their age based on dendrochronology provide the best material for calibration purposes in the time period where they are available.

Convener

• Charlotte Pearson (c.pearson@ltrr.arizona.edu)

Submitting new tree ring data for inclusion in IntCal

In addition to the information covered in the main section on submitting data there are particular requirements relating to dendrochronological data.

The critical data required are the tree-ring measurement series on which the data is based and the master reference chronology against which the dating was confirmed. If your sample is part of an existing master chronology housed within the ITRDB, this process is greatly simplified using the IntChron tool. Alternatively measurements  can be uploaded using standard dendrochronological file types. If the sample used is not part of an existing master chronology then the sample measurement and master series can be uploaded separately and metadata added. If the sample used was calendar dated against a chronology which is not publicly available then special provision will have to made to make this available in the IntCal dataset. A link to a published SI should provide a ‘catch all’ to ensure maximum possible transparency and traceability for dendrodated 14C measurements.

Metadata required in the IntCal dataset

If using data submitted as per the ITRDB requirements, essential metadata (such as publication DOI, lat/lon, sample identifiers) will be automatically added to the data upload. In other cases it can be added manually working through the options in the IntChron tool interface.

Metadata / data to include in publications:

Data will not normally be included in IntCal before it has been published in a peer-reviewed journal. IntChron will  link through to the DOI for this publication. When publishing, please aim to include the following in your Supplementary Information:

Note: Categories here are broken down according to the internationally recognized Tree-Ring Data Standard (https://tridas.org/) and essential information marked with *

• *Object code (the unique identifier code for the site/structure the sample came from)
• *Element code (a unique identifier for the individual tree that the sample came from)
• *Sample code (if there are multiple samples from the same element, use 1,2 or A,B etc)
• *Object grid reference and other location details (full location name, lon/lat and elevation)
• Object type (forest, building, archaeological feature, artifact, paleoenvironmental context etc)
• Preservation state: (Wet, been wet-now dry, dry, carbonized, sub-fossil)
• *Dating: (specify BC/BCE (historic dates BC/BCE without the year zero), AD/CE dates (historic dates AD/CE) or astronomical “negative” year dates (AD/BC / CE/BCE with year zero), or ‘relative dating’ and provide details. Include details regarding the growth season represented by your sample.  If you are working with wood from the Southern Hemisphere note use (or not) of the ‘Schulman shift’) and how this relates to your packet annotation for each sample sent for radiocarbon analysis.
• *Cross-dating 1: Provide details describing the cross-dating methodologies and equipment used (e.g. measurement platform, software, isotope matching protocols, skeleton plotting etc - Baillie and Pilcher, 1973, Brewer 2016, 2014, Holmes, 1999, Larsson, 2014, Loader et al. 2019 Rinn, Munro, 1984, Rinn 1996, Stokes and Smiley 1968, Tyers 2004).
• *Cross-dating 2: Provide evidence of cross-dating credentials or references for any master reference chronology used  (reference published or publicly available master chronologies, or where not published, include a demonstration of these credentials within the document – ideally raw ring-widths should be published or deposited in a secure publicly-accessible archive).
• *Cross-dating 3: Provide evidence of cross-dating credentials of the element used for sample preparation. (Compelling visual matches with strong supporting statistics  e.g. t-scores (Loader et al. 2019, Fowler and Bridge 2017, Baillie and Pilcher 1973, Munro 1984), Gleichläufigkeit (Glk) indices (Buras and Wilmking 2015, Eckstein, D. and Bauch, 1969), GSL or sGLK significance tests (Schweingruber et al. 1990), and r-values (Holmes 1983).
• *Provide measurement series of the dissected tree-rings indicating the first and last year as dated
• Add any additional information that you think could be helpful, this could include an image of the dissected sample prior to dissection.
  

See Reimer et al. 2020 for further information.