Figure 2. A tree fallen in a high-altitude lake. The roots are still attached to the stem
Figure 3. In the white circle, a trunk of Stone pine on rocky debris

Multimillenial dendrochronological series for the italian alpine conifers

I The trunks of trees that lived hundreds or thousands of years ago provide valuable information in various fields of research. They are the basic material for the construction of long reference chronologies, useful for archaeological dating and climatic reconstructions. They allow the radiocarbon dating calibration and the study of atmospheric isotopes concentration with year resolution.
Considering the environments in which subfossil woods are found, it is usually thought that such studies are feasible in cold climate areas such as North-Central Europe, Siberia and Sweden. In peninsular Italy environments suitable for trunks preservation are hard to find, but in the Alps researches in this field have been carried out successfully.
The samples come from various environments, mainly peat bogs, streams and lakes, all located in western Trentino, at altitude between 1600 and 2300 m a.s.l. Over 50% of the samples consists of Norway spruce (Picea abies Karst.), while the remaining part consists of European larch (Larix decidua Mill., 25%), stone pine (Pinus cembra L., 15%) and silver fir (Abies alba Mill.).
The mean series cover a time period from the end of the 20th century AD to around 9500 BC, for a total extent of about 11500 years (Figure 1). The series have been dated to the calendar year mainly by the comparison with the EACC (European Alpine Conifer Chronology, Nicolussi et al., 2009). Where the comparison with EACC has proved ineffective, the series have been dated through radiocarbon analysis.

Figura 1. Upper panel: the tree-rings mean series after detrending. Lower panel: the sample depth with the temporal distribution of samples.

 The distribution of samples demonstrates that environments as peat bogs, have gathered logs for very long times. Phases with high samples concentration are interspersed with periods of few or lack of trunks, probably in relation to the hydrological dynamics of high-altitude environments. The study of periods with different concentration of samples opens to important advances in the field of reconstruction of the hydrological dynamics of the past.From a dendro-archaeological point of view, the mean series proved to be a powerful tool for dating. The comparison with the tree ring series of archaeological woods has allowed the dating of many important artifacts and structures such as the roof of the Basilica of the Nativity in Bethlehem, the Baptistery of San Giovanni and the Campanile di Giotto in Florence and many others.

The research is carried out in collaboration with the Forestry and Fauna Service of the Autonomous Province of Trento.

Contact

Mauro Bernabei
Jarno Bontadi

[Last updated on: 02-11-2015]
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