The Roman shipwrecks of Neapolis : timber-woodland relationship.

In 2004 three shipwrecks were found in the Roman harbour of Neapolis due to excavation for the Piazza Municipio station of the new subway line (Giampaola et al., 2005). A sediment succession of about six metres, representing the filling of the ancient harbour, was brought to light and sampled for sedimentological, paleontological and palynological studies. Sediment nature allowed preservation of organic content giving the opportunity to identify both the wood taxa used as timber and the ancient vegetation landscape through pollen analysis. The sedimentary succession is well constrained by archeological findings between the III century B.C. and VI century A.D.. The shipwrecks were dated at the boundary between I and II century A.D. (ships A and C) and at the end of the II century A.D. (ship B). Pollen analysis was realised on 22 samples covering the entire sedimentary succession. Almost all samples resulted rich and pollen grains in a good preservation state. A detailed pollen diagram was realised with the aim of showing the recognised taxa variation through time. A deciduous forest, dominated by Quercus, occupied the slopes surrounding Neapolis while a high altitude forest, with fir, was probably present on Mt Somma and/or Mt Faito. Pollen spectra are considerably influenced by human action especially concerning the use of certain herb taxa for food supply. In particular, it is interesting noting the abudance of Brassicaceae all along the diagram, probably representing the cabbage cultivation, well-known during the Roman age, especially in Campania, as stated by Columella and Plinio. A sharp decline in this cultivation is well evidenced during the III century A.D., corresponding to a general crisis of the Roman Empire. At the same time, the temporary field abandon was accompanied by a natural development of tree and shrub vegetation such as the mediterranean maquis. Other tree taxa seem to increase in the same time interval suggesting the decreasing human stress on vegetation. 500 wood samples were analysed from structural units of the ships. 20-25 μ thin sections were obtained with a frozen microtome and were identified to the genus or species level with the help of transmitted light microscope (magnification 40X-1000X) by using wood anatomy atlases and our reference collection. In this study a correlation is attempted between the availability of local wood resources, depicted through pollen analysis, and the timber used in the ship building. For this aim, only wood taxa were selected from the pollen diagram and their percentages recalculated to 100. Ships A and C were correlated with avaraged pollen percent values of I – beginning II cent. A.D., while ship B was correlated with avaraged pollen percent values of end II-III cent. A.D.. All timber used in the ship building were available in the landscape around Neapolis a part from Picea/Larix which was present only in ship A with 16%. The use of deciduous Quercus in all wrecks was widely expected being this taxon the most common feature of the surrounding landscape. On the contrary, the common use of Juglans as a timber, which reachs 56% in ship A, was not expected due to its main feeding usage. Pollen indicate its moderate presence thus, its use in ship building, as also reported in bibliography (i.e. Guibal and Pomey, 2003; Giachi, et al 2003), is probably linked to its excellent technological properties.Abies pollen are scarse in the sediments of Neapolis harbour but this could be the effect of the far distance from source areas. In fact, fir forests were probably located on Mt Somma and/or Mt Faito. Abies wood is elastic and easily carving even if rather perishable. Its common use in manufacturing during the Roman age testifies for its local availability and/or wide trading. The presence of fir forests in southern Apennines was well testified and their decline seems to date back to the end of Middle Ages (Russo Ermolli and Di Pasquale, 2002). Cupressaceae pollen (including Cupressus and Juniperus) are very scarse or absent in pollen spectra. On the contrary, Cupressus is present in all ships, reaching 16% in ship B. This discrepancy could be explained with an alloctonous origin of this timber. Anyway, Cupressus is commonly used in Roman ships from the Tyrrhenian Sea and the eastern Mediterranean (Boetto 2007, Giachi et al., 2003)