Grain on the ‘Island of Ringforts’: trends in cereal cultivation on Iron Age Öland, Sweden

Abstract Öland, a large island in the Baltic Sea, is well known for its rich archaeological records from the Migration Period and its well-preserved ringforts. Here, we investigate the agricultural economies at these ringforts and surrounding settlements through a compilation of macrofossil data from previous publications and unpublished material, supplemented by new analyses and radiocarbon dates. Plant distribution and diversity were analysed before and after the dust veil event of 536 ce and by geographical location (northern versus southern Öland) and settlement type (ringforts versus other settlements). Hordeum vulgare (hulled barley) was by far the most commonly found cereal grain on Öland from throughout the Iron Age in all settlement types. Around the Migration Period, the ringforts in southern Öland were associated with a greater diversity of cereal crops, including Avena (oat), Secale cereale (rye) and several Triticum (wheat) species. Following the dust veil event, cereal diversity declined sharply in southern Öland. In northern Öland, however, diversity gradually increased after it, with rye eventually becoming more common.