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.

Plant colonization on archaeological structures is limited by the substrate conditions of stone surfaces. Despite its relevance for ecological studies and the management plans of archaeological sites, the knowledge on monuments substrate (e.g., stones, microhabitats, microsites), which could be suitable sites for plant establishment, is an underestimated topic. Here, we aim to identify the substrate preference of plants in colonizing stone surfaces as a first step in evaluating the biodeterioration risk. We selected the Pasargadae World Heritage Site (WHS) for its variety of different conditions, and we assessed the substrate preference of 142 ruderal plants occurring on nine monuments, two types of stones, and eight microsites. Our data indicated that stone typology and microsite conditions affected species composition, diversity, and richness. The porosity of the different limestone and the progressive weathering phenomena resulted as relevant factors in plant colonization. Significantly, microsites as a junction of two stone blocks (M1a) and big fractures covered by soil (M3) hosted the most favorable conditions, which needed periodic monitoring during the maintenance activities of the site. Evaluating the substrate preference of ruderal plants can contribute to the identification of the high-risk areas for plant colonization, which need to be considered in the management plans of archaeological sites.

Sorghum halepense is a synanthropic tall grass distributed worldwide from tropical to temperate zones, and it is often considered an invasive alien. It is a perennial, rhizomatous plant that tends to form dense stands derived from vegetative and sexual propagation. Despite roadside plant communities dominated by Sorghum halepense are very common in southern Europe, their phytosociological aspects are scarcely studied. In this work, we present the results of a vegetation survey in peninsular Italy, carried out by means of the phytosociological method. In total, we carried out 73 relevés in Liguria, Tuscany, Latium, Campania, Basilicata, and Apulia. We statistically compared our relevés to those from the Balkans classified in the Cynodonto-Sorghetum halepensis, an association of agricultural annual weed vegetation of the class Stellarietea mediae s.l. used in the past as a reference for Italian S. halepense-dominated communities. Our results show that the Italian communities are different from the Cynodonto–Sorghetum halepensis communities, since the latter are rich in annual species, while the former are rich in perennial species. From the syntaxonomic point of view, the Italian communities are better classified in the class Artemisietea vulgaris. We describe the new (sub-)ruderal association Potentillo reptantis–Sorghetum halepensis, including a meso-hygrophilous variant with Urtica dioica and an agricultural variant with Elymus repens. We have evidence that the Potentillo–Sorghetum occurs in Italy, Kosovo and Slovenia, but its distribution is possibly wider due to conspicuous presence of cosmopolitan species characterizing the association. Our work provides a baseline for the knowledge of an alien-dominated plant community that can invade habitats with high conservation value.

This study provides pioneering research on the vegetation of archaeological areas in Iran to enhance its naturalistic and bioindication values by selecting the Pasargadae World Heritage Site (WHS). Vegetation surveys were carried out in different homogeneous habitats, analyzing the plant communities through statistical elaboration, syntaxonomic role, mapping, and enhancement of plants with conservation interest. In an ecological approach, the study included an analysis of the recent climate changes and human interventions influencing the water resources. Results revealed seven main vegetation types reflecting ecological gradients shaped by environmental, edaphic, and anthropogenic factors. The syntaxonomic analysis showed a primary subdivision in semi-natural grasslands and synanthropic vegetation. Several key species were identified as bioindicators of multiple factors, such as: Launaea acanthodes, Stipa barbata, Alhagi maurorum, Bellevalia saviczii, Glycyrrhiza glabra, Convolvulus arvensis, and Hordeum murinum. The vegetation map showed how the hilly grassland communities hosted the highest number of species with conservation interest and their need to be better protected. Bio-climatic data, such as the construction of dams and the exploitation for irrigation purposes, pointed to the increasing xeric conditions, which make urging conservation efforts for the site’s historical and naturalistic values. The study underscores the importance of preserving places with high plant diversity for effective site management, and enhances the intricate relationship between vegetation and natural features in the occurring environmental changes.