Seeing the forest for the trees: New approaches and challenges for dendroarchaeology in the 21st century

The application of tree-ring research to the study of cultural heritage has seen important conceptual and methodological developments in the 21 st century. Following the breakthrough discovery in the 1980s of the importation of timber from the south-eastern Baltic to the Low Countries for panel paintings, the historical timber trade acquired paramount relevance in European dendrochronology. The improvement of methods and tools to locate the area of origin of the wood has since become a focal line of research. Reference chronologies of different variables (ring width, earlywood, latewood, earlywood vessel size in oak, latewood density in conifers, stable isotope chronologies of δ13C, δ18O) are now being developed in areas formerly (and currently) exploited for timber production, and isotopic signatures of 87Sr/86Sr are being mapped to provide a geochemical reference. In parallel, novel techniques to identify wood species (automated wood identification, chemical biomarkers, DNA barcoding) and their application on historical and ancient wood are being explored, given that this could sometimes help narrow down the timber source area. Modern technology is playing a key role in the study of wooden objects through non-invasive methods, and collaboration with (art) historians, mathematicians, engineers and conservators has proven essential in current achievements. Tree-ring series can now be retrieved from high resolution X-ray computed tomography images, allowing the research of otherwise inaccessible pieces. This paper reviews recent advances in those fields (tree-ring based dendroprovenancing, wood species identification, chemical fingerprinting, use of genetic markers, isotopic signatures, and non-invasive methods), and discusses their implementation and challenges in dendroarchaeological studies.