A long-term tree-ring chronology over 796 years for silver fir (Abies alba Mill.) in Southern France
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• Key message This paper presents ring width data of silver fir trees (Abies alba Mill.) from buildings and living trees from 1214 to 2009 in southeastern France. A 796-year chronology spanning the period 1214–2009 has been built. Data can be used for dating projects, paleoecology studies, and climate reconstructions. Dataset access is at https://hal.archives-ouvertes.fr/hal-01528324 . Associated metadata is available at https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/a74b4869-318c-458c-a5fe-f9ff44a5082c
KeywordsAbies alba Mill. Ring width Dating Ecology Climate Alps Chronology
Here is their acquisition context: Maurienne sites were studied as part of a research program on fluorinated pollution on trees radial growth (Tessier et al. 1990); F. Serre-Bachet studied Verdon Abies alba Mill. and created a long master chronology in order to work on climate reconstructions (Serre-Bachet 1986); Mercantour and Verdon Abies alba Mill. were part of a program on climate and tree-ring relations in IMEP/IMBE laboratory (European program FORMAT edited by L. Tessier and J.-L. Edouard, Belingard 1996, Saulnier 2012) and research on Aix-en-Provence and Riez ancient buildings (Edouard, unpublished reports, Shindo 2016).
Average growth chronology: “chronology averages from all the growth curves within a tree or a piece of timber.” (Kaennel and Schweingruber 1995, p.35). Here, we use this term to qualify archaeological site chronologies made with only one timber (three sites are concerned, see “Dataset content” section below). Several radii were measured and averaged on these timbers.
Site chronology: “Chronology averaged from raw tree-ring measurements or standardised indices for one to several cores per tree and for several trees growing on similar types of (ecological) sites.” (Kaennel and Schweingruber 1995, p.316). Here, there are 31 sites; therefore, there are 31 site chronologies. That means that the three “average growth chronologies” are “site chronologies” too because they are representative of these three sites.
Master chronology: “Chronology averaged from any tree-ring parameter, usually combining site or local chronologies from a given region, and used to date new tree-ring series.” (Kaennel and Schweingruber 1995, p.217). Here, the master chronology is the average of the 515 dated Abies alba Mill. trees and timbers and covers 796 years, from 1214 to 2009.
The methods used to obtain the samples are typical for dendrochronology. Different sampling techniques were required for the living trees and the timbers. Living trees were cored with Pressler increment borers at breast height (around 1.30 m above the ground). The timbers were sampled utilising one of the three different techniques with Pressler increment borers, with a borer on an electric drill and sometimes, when possible, the timbers were cut with a saw. In the case of the timbers, the sample area was strategically selected in order to obtain the largest amount of tree-rings as close as possible to the bark. Nevertheless, due to the building layout, it was not always possible to do this. Thus, the sampling was carried out on the only accessible location of the timber.
2.3 Measurement and cross-dating
In the lab, ring widths were measured using the incremental measuring table LINTAB with 0.01 mm accuracy and TSAP-Win software (Rinntech Company, Heidelberg, Deutschland). Then, the tree-ring series were cross-dated. Cross-dating is “the procedure of matching variations in ring width [...] among several tree-ring series” (Kaennel and Schweingruber 1995, p.81). Cross-dating was carried out by means of TSAP-Win software, COFECHA software (written in Fortran-77, Holmes 1983), or DENDRON IV software (developed with RunRev LiveCode, Edinburgh, Scotland, by G.-N. Lambert CNRS, University of Franche-Comté, Besançon, France and University of Liege, Belgium. Version: 20150221). For living trees, their various acquisition contexts caused a regrettable lack of uniformity into ecological condition information available (height of sampling, soil type, type of forest...).
2.4 Dataset content
The database is in a spreadsheet format with three sections (Shindo et al. 2017). The first spreadsheet in the database, labelled, “material description”, includes the following information: site dendrochronological code, the type of site (building or living trees), the geographic coordinates (longitude and latitude in WGS 84), the site altitude, the town and the geographical area, the author, the beginning, the end, the length, and the volume of the site chronologies.
The second spreadsheet, “sites_chronologies_data”, presents the dendrochronological raw data (1/100 mm) of the 31 sites without any standardisation. The first column in the spreadsheet is the site code, the second column is the time scale, the third column includes the ring width (1/100 mm), and the fourth column is the volume of the site chronology (number of tree-rings per year). Three of the sites (0411301, 0415506, 0511701) only have an average growth chronology because only one Abies alba Mill. timber has been dated for each of these sites. We chose to present them as they are representative of the site and are good dating tools. F. Serre-Bachet studied Ventoux living trees data (“FRAN7” in the International Tree-Rings Database, ITRDB, https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/tree-ring) that come from the same site than our “VTX” site chronology but are not included in our database yet.
The third and last spreadsheet, “master_chronology_data”, gives the ring width (1/100 mm) of this master chronology from 1214 to 2009 its volume and its standard deviation (1σ).
2.4.1 Access to data and metadata description
The URL to access the dataset is located in https://hal.archives-ouvertes.fr/hal-01528324. Associated metadata is available at https://metadata-afs.nancy.inra.fr/geonetwork/srv/fre/catalog.search#/metadata/a74b4869-318c-458c-a5fe-f9ff44a5082c. The data, which includes the calculations, can be used; however, you must attribute their origin (licence CC BY-NC 4.0).
The individual contact details of the six researchers are presented but three of the researchers are not in activity anymore. If complementary data is necessary, the corresponding author should be contacted.
2.4.2 Technical validation
The dataset has already been utilised for ecological studies and climate reconstructions. Published works utilising this data include research by Saulnier (2012), Serre-Bachet (1986), and Tessier et al. (1990). Furthermore, this master chronology is a very good tool for dating wood building structures as silver fir timber was commonly used in construction. Indeed, many constructions were built with silver fir timbers and the tree felling was precisely dated, in particular in Bouches-du-Rhône, Alpes-de-Haute-Provence, and Hautes-Alpes French departments (Shindo 2016).
2.4.3 Reuse potential and limits
Some years, the average standard deviation is particularly high (Fig. 3) even if the master chronology volume is important. For example, in 1430, there is a number of 80 tree-rings and the average standard deviation is 118. This could be due to the presence at the same year of wide and narrow tree-rings from young and old trees.
The potential use of this new database is numerous. It can serve to date Abies alba Mill. timbers from the Southeast France and, thanks to its good correlations, samples from other areas may be dated too.
It could act as an incentive to inter-species correlation studies, for example, on Abies alba Mill., Picea abies L., and Larix decidua Mill. in order to highlight a shared climatologic signal (we are developing a project on this subject).
This data paper is one of the only ways to ensure permanence of the dendrochronological data and metadata and to make them widely circulate. We hope that new research will be made on these data, for example, on Abies alba Mill. ecology and on climatology. In the end, this database may be improved and it is a stimulating tool for partnership.
The authors are grateful to Gina Watkinson of the Arizona State Museum (USA) for her help regarding the translation.
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- Shindo L, Belingard C, Edouard JL, Saulnier M (2017): A long-term tree-ring chronology over 796 years for silver fir (Abies alba Mill.) in southern France. On line only: https://hal.archives-ouvertes.fr/hal-01528324