The Colosseum floras as bio-indicators of the climatic changes in Rome

Over the last four centuries several botanists have analysed the Colosseum flora, and by using modern ecological and biogeographical approaches to these same floras, we have observed similar trends with respect to the climatic phenomena as those of the historic Torre Calandrelli Observatory and by other older historical records. The elements of which can be summarised as follows: 1) a substantial reduction of all the biogeographical components taken as indicators of cooler and damper habitats, such as the Euro-Asiatic and Boreal areas starting from the 17th Century in particular; 2) a decrease in numbers of all the species more dependent on water (independent of their chorology); 3) similar clear-cut increases in the species belonging to phytosociological classes typical to Mediterranean climatic conditions, to the detriment of those typical to Middle-European temperate bioclimates. All of which can be interpreted as clear indicators of non-negligible climatic changes towards hotter and drier conditions independent of local variations due to urbanisation.