Subfossil trees with their annual rings constitute the most accurate and precise archive to calibrate the radiocarbon (14C) method. The Holocene part of the IntCal curve is based on tree-ring chronologies, absolutely dated by dendrochronological matching. For the Northern Hemisphere, the absolute curve starts at 12,325 cal BP. For the early part of the Younger Dryas (YD) climatic event (≈ 12,850–11,650 cal BP), there are only a few floating dendrochronological sequences, mainly from Switzerland and France. We present new 14C results from subfossil trees (Pinus sylvestris L.) collected from the Barbiers site (southeast French Alps). The dendrochronological series covers 416 years, corresponding to the onset of the YD period. In order to date our sequence, we matched it with the 14C record based on kauri trees from New Zealand. The Barbiers data were first averaged at the same decadal resolution as the kauri record. Statistical comparison of the different averaging options and matching techniques enables dating the Barbiers sequence to 13,008–12,594 ±10 cal BP, which thus includes the boundary between the Allerød and YD events. The new Barbiers record allows to calculate the 14C inter-hemispheric gradient (14C-IHG) during the period overlapping the kauri sequence. For the optimal dating option, the mean 14C-IHG is 37 yr with a standard deviation (SD) of 21 yr based on 43 decadal estimations (−6‰ with SD of 2‰). The 14C-IHG record exhibits minimal values, down to zero, between 12,960–12,840 cal BP. Excluding these minima leads to an average 14C-IHG of 45 yr with a SD of 14 yr based on 33 decadal values, in agreement with observations for the last two millennia. The Barbiers record suggests a 14C-IHG increase between the end of the Allerød period (IHG of 37 yr with SD of 14 yr) and the early part of the YD (IHG of 48 yr with SD of 14 yr), which is compatible with previously reported drop of deep-water convection in the North-Atlantic and the associated increase in wind-driven upwelling in the Southern Ocean.

To cite this version:Lisa Shindo, Sandrine Claude. Buildings and wood trade in Aix-en-Provence (South of France) during modern period. Dendrochronologia, Elsevier, 2019, 54, pp. AbstractMany buildings are being restored in the city of Aix-en-Provence, southeastern France and allowed systematic dendrochronological analyses. 144 fir timbers (Abies alba Mill.) were examined and dated between 1303 and 1933. They highlight three felling phases (Medieval period, 17th-18th century, and 19th century). The best documented one corresponds to the 17th-18th centuries and coincides with significant building activity connected to the status of Aix, which is the parliamentary capital of Provence. Around Aix-en-Provence, it is difficult to find timbers with good dimensions. Our results show that timbers were transported from the Alps to Aix's buildings. Potential testimonies of this timber trade have been found, such as raft assemblage marks, and carved signs and letters. A dendroprovenancing case study shows that between 1810 and 1890, some of Aix's timbers could have come from the Northern French Alps or the Verdon-Durance region. Finally, the lack of timbers with good dimension and the difficulties of timber supply contributed to the development of reuse economy and technical innovation. These results are the foundation of a future well-established dendroprovenancing approach in the Southern Alps.

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In the Southern French Alps, the Cervières Valley (near Briançon city) has traditional houses in which wood plays an important role, both in the buildings' structures and in the activities of the humans who lived there. The six studied farms bear witness to an architecture perfectly adapted to the mountain environment and to the daily and seasonal activities of the inhabitants. Dendrochronology has revealed four major phases of logging from the 16th to the 19th century. The 90 sampled timbers are from larch and Scots pine type, and are of similar age and calibre. The choice of species for building was probably made on the basis of their proximity to the building site. However, until now we have not yet identified any Scots pine t. from before the 18th century in the buildings. Does this represent a sampling bias or forest reality? Future historical and pedo-anthracological studies should provide answers. Although archaeological Scots pine is a recalcitrant species in dendroarchaeology in the Southern Alps, probably due to the presence of many missing rings, in this study a Scots pine t. average data have been dated using a larch reference chronology for the first time. This dating is supported by archaeological observations.

Although variations in building activity are a useful indicator of societal well-being and demographic development, historical datasets for larger regions and longer periods are still rare. Here, we present 54,045 annually precise dendrochronological felling dates from historical construction timber from across most of Europe between 1250 and 1699 CE to infer variations in building activity. We use geostatistical techniques to compare spatiotemporal dynamics in past European building activity against independent demographic, economic, social and climatic data. We show that the felling dates capture major geographical patterns of demographic trends, especially in regions with dense data coverage. A particularly strong negative association is found between grain prices and the number of felling dates. In addition, a significant positive association is found between the number of felling dates and mining activity. These strong associations, with well-known macro-economic indicators from pre-industrial Europe, corroborate the use of felling dates as an independent source for exploring large-scale fluctuations of societal well-being and demographic development. Three prominent examples are the building boom in the Hanseatic League region of northeastern Germany during the 13th century, the onset of the Late Medieval Crisis in much of Europe c. 1300, and the cessation of building activity in large parts of central Europe during armed conflicts such as the Thirty Years’ War (1618–1648 CE). Despite new insights gained from our European-wide felling date inventory, further studies are needed to investigate changes in construction activity of high versus low status buildings, and of urban versus rural buildings, and to compare those results with a variety of historical documentary sources and natural proxy archives.