Simona Ceschin

Role of macrophyte communities as bioindicators of water quality: Application on the Tiber River basin (Italy)

Abstract The aquatic plant communities of the Tiber River basin have been examined to evaluate their role as bioindicators of the water quality of the Italian peninsular rivers. The compatibility curves of phytocoenoses to water chemico‐physical gradients show a correlation between the distribution pattern of the vegetation types and the water’s chemico‐physical features, such as different levels of water pollution. In particular, Fontinaletum antipyreticae, Ranunculo‐Sietum, Elodeo‐Potametum crispi and Nasturtietum officinalis develop in meso‐eutrophic and fairly clean water, Potamogeton nodosus community and Ceratophylletum demersi in eutrophic water of medium quality, while Myriophylletum spicati and especially Potametum pectinati and algal communities with Entheromorpha flexuosa are found in hypertrophic water of poor quality. These phytocoenoses can be utilised as valid bioindicators of water quality. On the contrary, Callitrichetum stagnalis, Myriophylletum verticillati, Najadetum marinae and algal communities with Cladophora glomerata are not effective bioindicators, showing a wide and sometimes unclear synecology.

Ecological analysis and biodeterioration processes over time at the Hieroglyphic Stairway in the Copàn (Honduras) archaeological site

Abstract The Copàn Hieroglyphic Stairway, one of the most important monuments of the Mayan culture, was excavated at the end of the 1800s. After a few decades it was extensively attacked by mosses and lichens. Different biocide treatments were applied in the late 1970s, and consolidation and stabilization works were carried out in the 1980s and 90s; a tarp was installed in 1985 over the Stairway for protection from rain. The present investigation shows an almost total death of lichens and a heavy reduction of the biodeterioration phenomena on the stone surfaces of this monument. The most frequent species presently growing are cyanobacteria and a few green algae. Notwithstanding this relatively low level of superficial colonization, cross-section staining and SEM analyses at times revealed a heavy biological growth just below the surface. The main structures found were exo-polymeric substances, fungal hyphae and moss protonema. Through a comparative analysis of the biodeteriorative phenomena of other monuments at the site, and with historical records, the relationships between the main ecological factors (water and light) and the biological colonization at the Copàn archaeological site are described. The ecological analysis and the changes that seem to have occurred in the biodeterioration of the Stairway provide useful information for planning future conservative interventions.

Natural habitats of typical plants growing on ruins of Roman archaeological sites (Rome, Italy)

In this study, we support the hypothesis that wall plant species come mainly from rocky habitats, taking into account that ancient walls show similar characteristics to rocks. The occurrence of wall species in natural habitats was investigated. The main literature concerning wall and natural vegetation of central-southern Italy was viewed. Vegetation synoptic tables were analysed through statistical procedures for comparing occurrence and behaviour of wall species in ruderal habitats as archaeological sites and natural ones.The study pointed out that wall species show similar ecological and coenological features in both habitats. This confirms that the main natural habitat from which wall species come from are rocks, but secondarily also ephemeral Mediterranean meadows and garrigues. Particularly, some wall species belonging to Parietarietea judaicae class are participating in the formation of natural rocky communities of Asplenietea trichomanis. Species occurring on emerging ruins form ephemeral meadows belonging to Helianthemetea guttati, also found in natural Mediterranean environment. On wide tops of ruins, where community dynamism is higher, some perennial herbaceous and shrubby species participate in the formation of impoverished communities matching to natural aspects of Mediterranean maquis. The knowledge of the natural habitat of wall species can be useful for a better management of archaeological sites.

Ecological comparison between duckweeds in central Italy: The invasive Lemna minuta vs the native L. minor

Abstract The American duckweed Lemna minuta shows an invasive behaviour in Europe, causing weed problems in aquatic habitats there. Few studies addressed this species’ ecological requirements for a suitable establishment in a site. In this paper, L. minuta populations were analysed through field surveys so as (1) to define the autoecology of this duckweed as regards the main environmental factors characterizing invaded habitats, and (2) to identify possible overlaps/differences in ecological requirements between the alien L. minuta and the common native L. minor, with which it is often associated and in direct competition. The occurrence/abundance of the two species and environmental data were collected from 41 wetlands in central Italy. Currently, L. minuta is more common and abundant than L. minor in the study-area, despite its recent arrival there (2007). The two species have a partially overlapped autoecology. However, L. minuta differs from L. minor since it occurs in waters which are less alkaline, slightly less warm, and richer in nitrates. It shows tolerance for environmental conditions which are limiting for most of macrophytes, including L. minor, such as high shading and low water oxygenation. This enables L. minuta to increase its invasion potentiality and thus to enlarge its distribution area.