The value of the archaeobotanical analysis of desiccated plant remains from old buildings : methodological aspects and interpretation of crop weed assemblages

For a long time plant material like threshing remains was used systematically as filling and isolation material in buildings. Such plant material can be found at several places, for example in blind floors[1] (Fehlböden) or in beamholes. For the first time in Switzerland desiccated plant material like this has been investigated. In this article the analysis of the material from three different sites, each dated to a different period, from the late medieval period to the time just before the industrial revolution, are presented. The samples consisted of chaff from Triticum spelta in bulk, and smaller amounts of other cereals like Triticum monococcum, Avena sativa, Panicum miliaceum and Secale cereale, plus various weeds. The assemblages in the late medieval samples show evidence of three-field rotation: the high percentage of grassland species is interpreted as an indicator for the fallow land phase within the three-field system. A higher ratio of annual to perennial plants in the more modern samples indicates the development of more intensive tillage and cultivation. Methodological questions regarding sampling strategies of the blind floor subsamples are investigated. The analyses suggest that the volume of these subsamples should be more than 2 litres.