Resumen
In archaeological sites, plants can be a risk for monument conservation. However, in these sites, a refugium for plant biodiversity is often detected, such as in the UNESCO site Etruscan necropolis of ?Monterozzi? in Tarquinia, which still holds a Special Protection Area for bats. In this site, we previously evaluated the positive and negative effects of vascular plants on the conservation of the hypogeal tombs. To contribute in assessing the role of archaeological sites in supporting plant diversity and interpreting its bioindication values for nature conservation, we analyse in this relevant place the floristic interest and richness and the plant communities growing on tumuli, trampled, and less disturbed areas. The results revealed the presence of several plants with high naturalistic interest, such as the community?s representative of synanthropic and natural Mediterranean grasslands, which arise both from the present and the past uses of the area. The high naturalistic values of the site are also assessed, considering its remarkable richness of species/area compared with the well-known archaeological sites of Rome. These findings further indicate that plant diversity needs to be considered in planning management activities in archaeological sites to also protect their natural values.