Analysis of unusually well-preserved oak boards found in the centre of Rome has revealed they were sourced from as far as 1700 kilometres away.
The discovery, reported in the journal PLOS ONE, highlights the importance of a long-distance timber trade in building the Roman Empire, says a research team led by Mauro Bernabei, from Italy’s National Research Council.
Wood was highly valued, with different types used for construction, shipbuilding, metal working and firewood. In the words of Pliny the Elder, as quoted in the paper, “Mille praetera sunt usus earum, sine quis vita degi non possit” (“Wood has thousands of uses, and without it, life would not be possible.”)
This enormous demand rapidly depleted forests around the capital and in the Apennines, as well as the coveted sandarac trees (Tetraclinis articulate) from the forests of Algeria.
However, until now the full story of timber trading has been unclear because there has been insufficient wood preserved well enough for analysis.
Bernabei and colleagues used advances in dendrochronology – tree-ring dating – to analyse 24 oak planks (Quercus species) excavated during construction work on the Metro in Rome from 2014 to 2016.
The boards, which formed the foundations of a richly decorated Roman portico in the gardens of Via Sannio, were well preserved because they’d been saturated with water.
By measuring the tree-ring widths and running statistical tests to establish average chronology, the researchers successfully dated 13 planks and compared them to Mediterranean and central European oak reference chronologies.
They found the oak came from the Jura mountains in eastern France – all from the same area – and sapwood from eight of the samples helped them narrow the date the trees were felled to between 40 and 60 CE.
Drawing on converging historical evidence and existing waterways, the authors speculate that the ancient Romans, or their traders, likely floated the oak, pre-cut, on rafts down the Saône and Rhône rivers in what is now France then transported it over the Mediterranean Sea and up the Tiber river to Rome.
The discovery suggests their trade network and administration skills were highly advanced, according to the authors, building on evidence of extensive trade and transportation of other luxury resources such as metal, pottery and marble that helped create their dominant empire.
“Considering the distances, calculated to be over 1700 kilometres, the timber’s dimensions, road transport with all the possible obstacles along the way, floating the timber down rivers and finally shipping it across the sea, the logistical organisation of the Romans must have been formidable.”