Dendrochronological evidence for long-distance timber trading in the Roman Empire.

Mauro Bernabei,Willy Tegel,Ulf Büntgen,Jarno Bontadi,Rossella Rea,Andrea Zerboni

doi:10.1371/journal.pone.0224077

Abstract

An important question for our understanding of Roman history is how the Empire's economy was structured, and how long-distance trading within and between its provinces was organised and achieved. Moreover, it is still unclear whether large construction timbers, for use in Italy, came from the widespread temperate forests north of the Alps and were then transported to the sparsely-wooded Mediterranean region in the south. Here, we present dendrochronological results from the archaeological excavation of an expensively decorated portico in the centre of Rome. The oak trees (Quercus sp.), providing twenty-four well-preserved planks in waterlogged ground, had been felled between 40 and 60 CE in the Jura Mountains of north-eastern France. It is most likely that the wood was transported to the Eternal City on the Saône and Rhône rivers and then across the Mediterranean Sea. This rare dendrochronological evidence from the capital of the Roman Empire gives fresh impetus to the ongoing debate on the likelihood of transporting timber over long distances within and between Roman provinces. This study reconstructs the administrative and logistic efforts required to transport high-quality construction timber from central Europe to Rome. It also highlights an advanced network of trade, and emphasises the enormous value of oak wood in Roman times.

Highlights

The Tree-ring widths (TRW) patterns of thirteen series were very similar, which is reflected in their significant, positive inter-series correlation (Rbar = 0.4, Table 2 and Fig 4)
Enormous quantities of wood were used in Roman times, south of the Alps dendrochronological analysis is difficult because few remains have survived intact [15]
The timber was rafted and floated down the principal waterways of the province of Gaul, the Saone and Rhone rivers, and crossed the Mediterranean Sea to be taken up the river Tiber to Rome

Summary

Introduction

“Mille praetera sunt usus earum, sine quis vita degi non possit”, (“Wood has thousands of uses, and without it, life would not be possible”, Pliny the Elder: Naturalis Historia XVI, 1–5). For the construction of buildings, silver fir (Abies alba) was the preferred tree species. Despite our understanding of the many uses of wood in Roman times, detailed insight into long-distance timber trading, the preferred tree species used and its sources of supply is still limited [1,9]. Due to the scarcity of datable wood, only a few and so far unpublished multi-millennial reference chronologies exist for Italy This circumstance effectively hampers the dendrochronological assessment of Roman timbers. Most studies on Roman timber constructions refer to archaeological sites outside of Italy concerning, for instance, the dating of ships [19,20,21,22], barrels [23] and the reconstruction of trade routes [24,25]. This study is, the rare exception of a successful dendrochronological investigation of archaeological timbers in the city of Rome, which has allowed us to: a) date these timbers by the method of dendrochronological cross-dating, b) determine the timbers’ geographical origin (provenance), and c) compare the dendrochronological results with those derived from historical and archaeological sources (multi-proxy comparison)

Material and methods

Results

Discussion

Conclusions