Agricultural Terraces As DNA Archives and Implications for Terrace Archaeology

Although agricultural terraces have a long history of use in the steepland areas of Europe very little is known about their use-history and its variability over space or time. This is partly because, being composed of generally inorganic well drained soil horizons, they often have poor preservation of pollen, spores and even phytoliths. The TerrACE project (ERC funded) set out to test the application of sedaDNA from terrace soils sampled from Greece to northern Norway using metabarcoding. The findings have been surprising - as the expectation was that only soils from the most northerly sites (Norway, UK) with mean annual temperatures below 10^oC would provide positive results. This has proven not to be the case, with most sites providing usable data except the very warmest and driest (Crete). This also relates to the timing of agriculture with usable data from the Bronze Age throughout all periods to Late Medieval times. This reveals soil DNA of both a variety of crops, including but not exclusively cereals, and domesticated stock. However, there are, as expected, indications of both leaching and bioturbation effecting these records. These taphonomic aspects will be discussed alongside the potential of sedaDNA for tracing agricultural histories from cumulative soils.