If you are going to start with dendrochronology dating you will be greatly helped if you find
already published tree ring data covering your area of interest and the time span you are interested in.
Lots of data is published in the International Tree Ring Data Bank
in Arizona. The ITRDB
works as an exchange center serving us all. If you develop a reference curve for your area
you should publish it at the ITRDB. Your data can be of great help to other people
interested in dendrochronology.
"The primary purpose for the ITRDB is to provide a permanent location for the storage of well-dated,
high-quality dendrochronological data from around the world. This central repository protects data
from loss due to: (1) mishandling of tree-ring data, (2) the relocation or termination of laboratories,
(3) scientists who move to other projects or retire, or (4) the death of scientists."
When I started with this in 1995, there was no data published from the area around Stockholm where I live.
So I got in contact with a university in Sweden and asked for help with reference data.
I was then told that I could indeed use data from them, but only if I signed an agreement saying that I
was never to publish any data originating in any way from their data or to use their data in any way
for commercial dating jobs. Because as they financed part
of their activities with commercial dating jobs, they did not want competing laboratories to learn about
their reference curves. As this had effectively prevented me from ever publishing and sharing dendro
data with others, I waived that agreement.
From the point of view of an outsider like me, I find such university laboratories to be like any
other commercial laboratory - keeping their secrets for the benefit of the company.
And - as I see this - by not publishing measurements they can be sure of not having their datings inspected and questioned by others.
In all a comfortable position, but not in accordance with my expectations on scientific research and on a university lab.
So from that university and from the ITRDB, where nothing of interest to me was published, I got no reference
curves at all. I had to start developing data from the very beginning.
I was lucky and found some very old trees which helped me develop my own reference curve from the island
of Nämdö east of Stockholm covering the years 1582 - 1995. This curve was published in the ITRDB in May 1997.
Though Swedish universities kept their secrets, we soon got help
from Swiss people. In August 2002 professor Fritz Schweingruber of the
Swiss Federal Institute for Forest, Snow and Landscape Research published their curve
from the island of Gotland in the middle of the Baltic sea. This curve covers the time 1127 - 1987.
It can be used along the Swedish coast adjacent to Gotland. This curve matches my curve from the island of
Out of co-operation between mainly four amateurs (Torbjörn Axelson, Arne Andersson, Bertil Israels and me) we
successively managed to develop or retrieve reference curves from several parts of Sweden and Norway.
Most data originates from our own measurements, but a lot also from Arne's work with digitizing unpublished or published data. Some data
has also been released by Swedish universities and by the National museum in Copenhagen, though the main bulk of university data is still unavailable to us.
Today, in 2013, you can find a lot of data related to southern and central Scandinavia
on our "Wiki" and also on the ITRDB.
My own contribution to all this dendro work has also been the development of the CDendro & CooRecorder software package, an inexpensive and very capable
piece of Windows based software, today sold to researchers all over the world.
Except for the Scandinavian data, a lot of European mean-value Middle Age and Roman time oak tree ring data has been made available on cybis.se as a result
of "the Hollstein project". This project is carried on by my wife, Petra, and me with the aim to try to properly crossdate
archaeological Roman time wood towards reference curves properly anchored in later times. A number of European dendrochronologists
have kindly made data available for this project.