Testing flora as bioindicator of buried structures in the archaeological area of Maxentius's villa (Rome, Italy)

The flora of the archaeological area of Maxentius’s villa (Rome) was tested as bioindicator of buried remains of masonry and pavements. A total of 53 floristic surveys provided the occurrence of each species in sample units, as well as some their phenological features. The data were elaborated through multivariate statistical analysis in order to assess floristic affinities/differences among sample units, and define their ecological characteristics. The fuzzy set methodology was applied to evaluate relation between floristic richness, plant cover and soil depth. Results showed that the buried remains of stonework create a discontinuity in the ground, influencing the flora growing above it. This phenomenon may give rise to differential presence of some species (e.g., Cota tinctoria, Trifolium scabrum ssp. scabrum on thin soil; Ranunculus bulbosus, Trifolium pratense on deeper soil), but will not have such a great effect on floristic richness. The bioindication of this phenomenon also occurs through phenological irregularities in single specimens and changes in plant cover. Nevertheless other environmental factors (soil moisture/aridity, trampling, enrichment of nitrogen, cutting, ground depression) can interfere with the use of plants as bioindicators of buried structures. It is therefore necessary to consider other ecological factors influencing each site when you want to use plants as bioindicators in archaeological prospection