The Laurisilva as a cultural heritage: proposal for the protection of the relict of laurel forest near Ponte Renaro

The name Laurisilva was introduced by Humboldt to indicate mixed broadleaved evergreen forests, with a consistent presence of Lauraceae, widespread in the subtropical-humid zone of South America; similar vegetation was successively described for SE-Asia, China, Japan, SW-Pacific Islands and S. Africa; besides, remnants of laurophyllous forests occur in the Canary Islands and Madeira. In the Mediterranean basin only one species of Lauraceae occurs: the endemic Laurus nobilis. The discontinuous distribution of L. nobilis can be interpreted as the relict of an ancient continuous presence from the Iberian Peninsula to Caucasus, fragmented during the salinity crisis of Messinian and the cold phases of Pleistocene. Very few occurrences of L. nobilis in the natural vegetation are recorded along the Tyrrhenian coast of Italy and in Sicily. In the Castelporziano area near Rome L. nobilis is relatively frequent in mixed (evergreen-deciduous) stands: the Lauro-Carpinetum betuli a plant community with peculiar ecological requirements, well distinct from the surrounding oak forests (Quercus cerris, Q. frainetto, Q. ilex). The area of Valle Renaro, where the laurel forest occupies large areas of natural appearance is proposed as a wildlife sanctuary, to preserve a valuable record of this rare relic vegetation. The structure of the forest and the particular microclimatic and edaphic conditions are discussed. The population of L. nobilis in Valle Renaro is witnessing the palaeogeographic vicissitudes of an area that along a millenary history became, as well, an important cultural heritage.