To collect samples for the European Isotope Network (ISONET)

To provide ring-width series

To provide dated and homogenized annual wood samples

To collect precipitation at sites without GNIP stations and provide the water samples

At each of the chosen sites chronologies will be developed from at least 12 trees from each of which four cores will be taken. The resulting site chronologies will be used to guarantee the absolute dating of the tree-ring sequences identified for isotopic analysis and to ensure that the various site chronologies and resulting climate reconstructions can be correctly and meaningfully compared with each other. From the 12 dated trees, four will be selected for isotope studies. This selection will be based upon physical similarities in ring-width characteristics, (sensitivity, complacency, etc.). From each selected tree two cores will be chosen for isotopic analysis. As it is possible that for particular questions with regard to modeling, individual tree-rings must be available, the two remaining cores from each of these selected trees will be archived for future analyses.

The eight sample cores will then be manually dissected by annual increment into thin slivers (≈40 μm thick) using a scalpel or razor blade. Since two cores from four trees will be analysed per annual increment, this requires physically combining the material from 8 rings to yield a representative sample for every year. In the event that individual tree ring chronologies must be combined in order to achieve 400 years coverage or to avoid juvenile effects, in additional to conventional dendrochronological cross-dating protocols to ensure correct dating, a minimum of 20 years isotopic overlap will be incorporated to ensure a representative signal. After the tree-rings have been separated they will be carefully combined prior to distibution to partner laboratories for the preparation of pure a-cellulose (nitrate) and subsequent stable isotope analyses. In preparing pure a-cellulose the wood is broken down such that the resulting material is completely homogenous.

In all, 24 site chronologies will be constructed (oak and pine). They will be independently verified against existing archived tree-ring chronologies and also examined for teleconnection across the ISONET network. Methodologies regarding preparation prior to measurement will also be standardised to prevent contamination and minimise sample loss. Regular sample exchange and interlaboratory comparison of individual and site chronologies will ensure the high level of quality assurance and task management required during preparation, measurement and distribution of this valuable dataset will be overseen by the Lead Participant who has considerable experience in dendrochronology and dendroecology. A total of more than 8000 samples will be provided for WP 2 (ISONET).