Antonio Stradivari's violins are distinguished not only by the luthier's skill, but also by the carefully chosen wood: fir trees cultivated in high-altitude Alpine forests, particularly in the Fiemme Valley, during a period marked by low temperatures and a short growing season. An international study, coordinated by the National Research Council's Institute for Bioeconomy (CNR-IBE), shows how the Cremonese master carefully chose a particularly homogeneous sort of wood, excellent for soundboards. The study, published in the journal Dendrochronologia, is the most thorough investigation ever conducted on Stradivari's work and confirms that the luthier had a very precise understanding of wood properties, as well as the importance of Alpine forests in the Cremonese violin-making tradition. The evolution of Stradivari's manufacturing procedures matched the evolution of wood resources. "Many instruments have highly identical ring sequences, revealing how Stradivari frequently used boards cut from the same trunk to manufacture many violins, sometimes years apart. This pattern appears to reflect highly deliberate wood selection, with the goal of using resources that are regarded particularly suited", the researchers add. Indeed, tests demonstrate the distinct quality of Norway spruces (Picea abies) growing at high altitude, which are distinguished by thin, uniform rings. In essence, the wood characteristics of the oldest violins can be traced back to heterogeneous provenances that are not always precisely identifiable. However, a clear turning point can be observed at the beginning of the 18th century, coinciding with the 'golden age' (1645–1715), which specifically encompasses violins made using Norway spruce from the Val di Fiemme, in eastern Trentino.