Carbon sequestration by trees species and their contribution to air amelioration capability in Rome

In the last years, much attention has been focused on the atmospheric concentration of CO2. Human and automobile activity produce more than 80% input of CO2 into urban areas. Trees act as sink for CO2 by fixing carbon during photosynthesis and storing the excess as biomass. Increasing the number of trees in urban areas may potentially slow the accumulation of CO2 atmospheric concentration. The urbanization process in Rome has been increased during the last years and many new suburban areas has been built by scaling down free areas surrounding the city. Rome is characterised by the presence of a high volume of the green, representing an ideal system to study the possibility to improving air quality by the selection of species, according to their own amelioration capability. This research aims to analyse carbon sequestration capability by tree species widely distributed in Rome. The results on the whole suggest that the evergreen and deciduous trees play an important role in sequestring CO2; nevertheless, there is a trade-off between greater sequestration by Quercus ilex L. versus Quercus pubescens Willd. by the presence of leaves throughout the year, and also in winter when the traffic has the highest pick. Larger trees tend to extract on an average 72% more carbon dioxide than smaller trees. Understanding the relationship among urban trees, people, and the environment can facilitate future urban design that might enhance the environmental and social benefits from trees.