Nitrophilous and ruderal species as indicators of climate change. Case study from the Italian Adriatic coast.

The aim of the present study is to demonstrate the value of some nitrophilous plants as bioindicators related to global warming. As a case study, the space–time dynamics of the populations of some nitrophilous and ruderal species have been investigated along the southern-central Adriatic side of the Italian Peninsula. These have been examined according to the range of their distribution areas, to their ecological needs, and to the availability of past data, which have then been related to the data on global warming across the same territories. The choice for this investigation was for nitrophilous species with a Mediterranean distribution – of the Stenomediterranean type – and for some recent entries into the local flora as alien species. The spread of these species occurs in areas with intense human activity, where they have exploited the conditions of the warmer niche, such that their presence and their spatial spread observed over time are clearly linked to global warming. For all of the species in question, rapid increases in the population numbers have been observed, along with a northward shift of their distribution areas. These changes correspond to the increase in average annual temperature as revealed by the thermometric measurements.